A low-cost flame-retardant magnesium alloy and its preparation method

Abstract

This invention belongs to the field of magnesium alloys and discloses a low-cost flame-retardant magnesium alloy and its preparation method. Based on the total weight of the low-cost flame-retardant magnesium alloy, it comprises: Al 4.0-6.0 wt%, Ca 1.0-3.0 wt%, Mn 0.4-0.7 wt%, Gd 0-0.6 wt%, Ce 0-0.6 wt%, Y 0-0.3 wt%, with the remainder being Mg. This invention solves the problems of high cost and insufficient ignition point of existing flame-retardant magnesium alloys.

Description

Technical Field

[0001] This invention belongs to the field of magnesium alloys, and more specifically, relates to a low-cost flame-retardant magnesium alloy and its preparation method. Background Technology

[0002] Magnesium alloys, as the lightest metallic structural materials currently used, have broad application prospects in aerospace and rail transportation. Magnesium alloys have many advantages, such as low density and high specific strength, but they also have several disadvantages, including poor corrosion resistance and flammability, with flammability being a major concern. Therefore, developing magnesium alloys with high ignition points is of great significance for their future applications.

[0003] Currently, the ignition point of magnesium alloys can be increased by adding certain elements. Existing flame-retardant magnesium alloys all involve the addition of large amounts of rare earth elements, which increases costs. For example, CN103469040 discloses a flame-retardant magnesium alloy that increases the ignition point of AZ31 magnesium alloy from 571℃ to 598℃ by adding Nd and Y; CN111254334 discloses a flame-resistant magnesium alloy that increases the ignition point of AM60 to 720℃ by adding a small amount of Ca and a large amount of Y. These alloys all contain a significant amount of RE-type rare earth elements, increasing production costs, and the improvement in ignition point is not particularly significant, which is detrimental to subsequent applications. Therefore, developing alloys with lower costs and higher ignition points is of great importance.

[0004] Mg-Al-Ca alloys have advantages such as high strength and high ignition point, but excessive Ca content is very detrimental to plasticity.

[0005] Therefore, there is an urgent need to develop a low-cost flame-retardant magnesium alloy. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a low-cost flame-retardant magnesium alloy and its preparation method. This invention solves the problems of high cost and insufficient ignition point of existing flame-retardant magnesium alloys.

[0007] To achieve the above objectives, the present invention provides a low-cost flame-retardant magnesium alloy, wherein, based on the total weight of the low-cost flame-retardant magnesium alloy, the low-cost flame-retardant magnesium alloy comprises: Al 4.0-6.0 wt%, Ca 1.0-3.0 wt%, Mn 0.4-0.7 wt%, Gd 0-0.6 wt%, Ce 0-0.6 wt%, Y 0-0.3 wt%, with the remainder being Mg.

[0008] According to the present invention, preferably, the low-cost flame-retardant magnesium alloy comprises, by weight: Al 4.0-6.0 wt%, Ca 1.0-3.0 wt%, Mn 0.4-0.7 wt%, Gd 0.3-0.6 wt%, Ce 0.3-0.6 wt%, Y 0.2-0.3 wt%, with the remainder being Mg.

[0009] According to the present invention, preferably, the ignition point of the low-cost flame-retardant magnesium alloy reaches 824°C or higher, and more preferably 900°C or higher.

[0010] Another aspect of the present invention provides a method for preparing the aforementioned low-cost flame-retardant magnesium alloy, comprising the following steps:

[0011] S1: Preheat pure Mg, pure Al, Mg-25wt%Ca master alloy, Mg-10wt%Mn master alloy, optional Mg-20wt%Gd master alloy, optional Mg-25wt%Ce master alloy and optional Mg-30wt%Y master alloy.

[0012] S2: The pure Mg, pure Al, Mg-25wt%Ca master alloy, Mg-10wt%Mn master alloy, optional Mg-20wt%Gd master alloy, optional Mg-25wt%Ce master alloy and optional Mg-30wt%Y master alloy treated in step S1 are mixed and smelted to obtain an alloy melt.

[0013] S3: The alloy melt is stirred, degassed, slag removed, allowed to stand, and then poured in sequence to obtain the low-cost flame-retardant magnesium alloy.

[0014] In this invention, as a preferred embodiment, in step S2, the pure Mg is placed in an iron crucible, and after the pure Mg is completely melted in the resistance furnace, pure Al, Mg-25wt%Ca master alloy, Mg-10wt%Mn master alloy, optional Mg-20wt%Gd master alloy, optional Mg-25wt%Ce master alloy, and optional Mg-30wt%Y master alloy are sequentially placed into the iron crucible for mixing and smelting to obtain an alloy melt.

[0015] According to the present invention, preferably, the temperature of the preheating treatment is 180-220°C.

[0016] According to the present invention, preferably, the melting temperature of the mixed melting is 740-760°C.

[0017] According to the present invention, preferably, the protective gas for the mixed smelting is a mixture of CO2 and SF6.

[0018] According to the present invention, preferably, the melting time of the mixed melting is 10-20 minutes.

[0019] According to the present invention, preferably, the settling time is 15-20 minutes.

[0020] The beneficial effects of the technical solution of the present invention are as follows:

[0021] This invention uses Mg-Al-Ca alloy as the base alloy, appropriately reduces the Ca content in the alloy, and adds a small amount of rare earth elements to ensure low cost while achieving an ignition point of over 824℃, and even not burning at 900℃, thus improving the flame retardant properties of magnesium alloy and further expanding the application range of magnesium alloy.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0023] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0024] Example 1

[0025] This embodiment provides a low-cost flame-retardant magnesium alloy, which, based on the total weight of the low-cost flame-retardant magnesium alloy, comprises: Al 5.0wt%, Ca 2.0wt%, Mn 0.5wt%, Gd 0wt%, Ce 0wt%, Y 0wt%, with the remainder being Mg.

[0026] The above-mentioned method for preparing low-cost flame-retardant magnesium alloy includes the following steps:

[0027] S1: Preheat pure Mg, pure Al, Mg-25wt%Ca master alloy, and Mg-10wt%Mn master alloy at 200℃.

[0028] S2: Place the pure Mg treated in step S1 into an iron crucible and melt it completely in a resistance furnace. Then, place the pure Al, Mg-25wt%Ca master alloy, and Mg-10wt%Mn master alloy treated in step S1 into the iron crucible in sequence for mixing and smelting. The smelting temperature is 750℃, the protective gas is a mixture of CO2 and SF6, and the smelting time is 20 minutes to obtain the alloy melt.

[0029] S3: The alloy melt is stirred, degassed, slag removed, allowed to stand for 20 minutes, and then rapidly and steadily poured to obtain the ingot of the low-cost flame-retardant magnesium alloy.

[0030] Examples 2-6

[0031] Examples 2-6 provide a low-cost flame-retardant magnesium alloy. The only difference between Examples 2-6 and Example 1 is the amount of each element used, as detailed in Table 1.

[0032] Table 1

[0033] Example Al Ca Mn Gd Ce Y Mg Example 1 5.0 2.0 0.5 0 0 0 92.5 Example 2 5.0 2.0 0.5 0.3 0 0 92.2 Example 3 5.0 2.0 0.5 0.6 0 0 91.9 Example 4 5.0 2.0 0.5 0 0.3 0 92.2 Example 5 5.0 2.0 0.5 0 0.6 0 91.9 Example 6 5.0 2.0 0.5 0 0 0.3 92.2

[0034] Test Case

[0035] In this test example, the ingots of the low-cost flame-retardant magnesium alloys obtained in Examples 1-6 were wire-cut into small cylindrical samples with a diameter of φ10mm*10mm, polished, and used for ignition point testing. The results are shown in Table 2. As can be seen from Table 2, the ignition points of the magnesium alloys described in this invention are all 824℃ and above. Furthermore, with the addition of a small amount of Y (Example 6) on the basis of a certain amount of Ca, the alloy did not burn at 900℃, demonstrating good flame-retardant properties.

[0036] Table 2

[0037] Example Ignition point Example 1 824 Example 2 832 Example 3 860 Example 4 827 Example 5 830 Example 6 No combustion occurred at 900℃

[0038] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A low-cost flame-retardant magnesium alloy, characterized in that, Based on the total weight of the low-cost flame-retardant magnesium alloy, the low-cost flame-retardant magnesium alloy comprises: Al 5.0wt%, Ca 2.0wt%, Mn 0.5wt%, Y 0.3wt%, with the remainder being Mg; The low-cost flame-retardant magnesium alloy did not burn at 900°C; The preparation method of the low-cost flame-retardant magnesium alloy includes the following steps: S1: Preheating treatment is performed on pure Mg, pure Al, Mg-25wt%Ca master alloy, Mg-10wt%Mn master alloy and Mg-30wt%Y master alloy. S2: The pure Mg, pure Al, Mg-25wt%Ca master alloy, Mg-10wt%Mn master alloy and Mg-30wt%Y master alloy treated in step S1 are mixed and melted to obtain an alloy melt. S3: The alloy melt is stirred, degassed, slag removed, allowed to stand, and then poured in sequence to obtain the low-cost flame-retardant magnesium alloy.

2. The low-cost flame-retardant magnesium alloy according to claim 1, wherein, The preheating temperature is 180-220℃.

3. The low-cost flame-retardant magnesium alloy according to claim 1, wherein, The melting temperature for the mixed smelting is 740-760℃.

4. The low-cost flame-retardant magnesium alloy according to claim 1, wherein, The protective gas used in the mixed smelting is a mixture of CO2 and SF6.

5. The low-cost flame-retardant magnesium alloy according to claim 1, wherein, The melting time for the mixed smelting is 10-20 minutes.

6. The low-cost flame-retardant magnesium alloy according to claim 1, wherein, The settling time is 15-20 minutes.

7. The method for preparing the low-cost flame-retardant magnesium alloy according to any one of claims 1-6, characterized in that, The preparation method includes the following steps: S1: Preheating treatment is performed on pure Mg, pure Al, Mg-25wt%Ca master alloy, Mg-10wt%Mn master alloy and Mg-30wt%Y master alloy. S2: The pure Mg, pure Al, Mg-25wt%Ca master alloy, Mg-10wt%Mn master alloy and Mg-30wt%Y master alloy treated in step S1 are mixed and melted to obtain an alloy melt. S3: The alloy melt is stirred, degassed, slag removed, allowed to stand, and then poured in sequence to obtain the low-cost flame-retardant magnesium alloy.