Composite flame-retardant magnesium alloy added with Al, Ca and rare earth and combustion test method thereof

Abstract

The invention discloses a composite flame-retardant magnesium alloy added with Al, Ca and rare earth elements and a combustion test method of the composite flame-retardant magnesium alloy. The magnesium alloy comprises the following components in percentage by weight: 0-2% of Ca, 0-4% of Al, 0.1-2% of Zn, 0.1-1% of Mn, 0.1-5% of La + Ce, 0.01-0.5% of Zr and the balance of Mg and other inevitable impurities. The rare earth elements La and Ce, the alkaline earth element Ca and other elements Al are comprehensively utilized for multi-component alloying, the structure is improved, the performance is improved, and the mechanical property and the flame retardant property of the magnesium alloy are remarkably improved. The strength of the alloy is further improved through a subsequent extrusion process, and the high-strength flame-retardant wrought magnesium alloy is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of flame-retardant magnesium alloys, in particular to a flame-retardant magnesium alloy with composite additions of Al, Ca and rare earth and a combustion test method thereof. Background Art

[0002] Magnesium alloy is the lightest metal structural material known so far. It has many advantages: high specific strength and specific stiffness, good thermal conductivity, low density, etc. It has very broad development prospects.

[0003] The ignition point of magnesium alloy is generally 650℃, which can easily cause violent combustion in the event of a fire, greatly limiting the application of magnesium alloy.

[0004] Currently, many scholars have conducted research on flame-retardant magnesium alloys. For example, CN117403116A discloses a high-strength flame-retardant deformable magnesium alloy and its preparation method; CN114934218B discloses a microalloyed high-strength and plastic flame-retardant magnesium alloy and its preparation method; CN108385006A discloses a high-strength flame-retardant die-cast magnesium alloy and its preparation method; CN103469040A discloses a flame-retardant magnesium alloy with composite rare earth elements Nd and Y and its ignition point test method. All of the above magnesium alloys increase their ignition point by adding more rare earth elements, which is not conducive to reducing costs. However, the element Ca can significantly increase the ignition point of magnesium alloys while reducing their cost. Among Ca-containing magnesium alloys, Mg-Al-Ca magnesium alloys have a high ignition point while ensuring certain mechanical properties. However, excessive Ca content can significantly reduce their plasticity.

[0005] Therefore, the present invention develops a low-cost, high-ignition-point flame-retardant magnesium alloy based on Mg-Al-RE alloy by adding a small amount of Ca element. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a flame-retardant magnesium alloy with composite additions of Al, Ca and rare earth elements and a combustion test method thereof. The flame-retardant magnesium alloy with composite additions of Al, Ca and rare earth elements has a high ignition point, and the combustion test method is simple and effective, thereby solving the shortcomings of the prior art.

[0007] In order to achieve the above-mentioned object, the present invention provides a flame-retardant magnesium alloy with composite additions of Al, Ca and rare earth, comprising the following components and mass contents: Ca 0-2%, Al 0-4%, Zn 0.1-2%, Mn 0.1-1%, La+Ce 0.1-5%, Zr 0.01-0.5% and the remaining content of Mg and impurities.

[0008] In order to achieve the above object, the present invention also provides a combustion test method for testing the flame retardant magnesium alloy with composite additions of Al, Ca and rare earth, comprising the following steps:

[0009] S1. Melting and Casting:

[0010] 1.1 Weigh the raw materials, wherein Mg and Al are added using industrial pure magnesium ingots and industrial pure aluminum ingots, and Ca, Mn, La, Ce, and Zr are added using Mg-Ca master alloy, anhydrous manganese chloride, La-Ce mixed rare earth, and Mg-Zr master alloy;

[0011] 1.2 Heat the magnesium ingot and aluminum ingot to 700-740℃ and melt them into liquid metal;

[0012] 1.3 Gradually add La-Ce mixed rare earth and master alloy to the molten metal, stir until melted and then let it stand for 10-20 minutes;

[0013] 1.4 Add anhydrous manganese chloride and refining agent for refining, stir for 10-20 minutes and then let it stand for 20-30 minutes;

[0014] 1.5 Cool down to 700℃ and let it stand for 20-30 minutes. Take samples for analysis and then cast into shape.

[0015] S2. Combustion test:

[0016] 2.1 Cut a 80×20×2mm test piece from the ingot;

[0017] 2.2 Clamp one end of the test piece vertically and apply 900℃ and 1300℃ flames to the other end;

[0018] 2.3 Record the ignition time and self-extinguishing time of the test piece when white smoke appears.

[0019] Preferably, in any of the above schemes, the refining agent in step 1.4 is a mixture of KCl, MgCl2, NaCl, CaF2 and BaCl2.

[0020] Preferably, in any of the above schemes, the heating process in step 1.2 is protected by argon and sulfur hexafluoride.

[0021] Preferably, in any of the above solutions, the flame in step 2.2 is generated by an acetylene-oxygen spray gun, and the flame temperature varies according to the distance between the gun muzzle and the sample.

[0022] Preferably, in any of the above schemes, the mass ratio of La:Ce in the La-Ce mixed rare earth in step 1.3 is 1:3.

[0023] Preferably, in any of the above schemes, the casting temperature in step 1.5 is 680-720°C, and the mold preheating temperature is 200-300°C.

[0024] Preferably, in any of the above solutions, the self-extinguishing time determination criterion in step 2.3 is that the flame is completely extinguished and no continuous white smoke is generated from the test piece.

[0025] The present invention has the following advantages:

[0026] 1. The flame-retardant magnesium alloy with composite additions of Al, Ca and rare earth elements has low production cost. Through the reasonable combination of Al, Ca and rare earth elements, the magnesium alloy can quickly self-extinguish after ignition at a flame temperature of 900°C while ensuring certain mechanical properties, thereby improving the flame retardancy of the magnesium alloy and expanding its application range.

[0027] 2. This combustion test method for flame-retardant magnesium alloys with composite additions of Al, Ca and rare earth elements clearly distinguishes the flame retardancy levels of different formulations by recording the ignition time and self-extinguishing time, intuitively reflecting the improvement in the flame retardant performance of the alloy. It adopts dual tests at 900°C, which is higher than the ignition point of magnesium alloy, and 1300°C, an extreme high temperature, to cover different thermal conditions in actual fires, verifying the stability of the material in mild and harsh environments. It unifies the specimen specifications and vertical flame loading method, reduces experimental variables, and ensures the repeatability and horizontal comparability of test results of different batches or alloy formulations. Post-combustion metallographic analysis can detect the density of the oxide layer, correlate the self-extinguishing ability with the microstructure, ensure that the material maintains structural integrity in a fire, and avoid the risk of secondary collapse. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the magnesium alloy combustion device of the present invention;

[0029] Figure 2 This is a metallographic diagram of the magnesium alloy after combustion according to Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

[0031] A flame retardant magnesium alloy with composite additions of Al, Ca and rare earth, comprising the following components and mass contents: Ca 0-2%, Al 0-4%, Zn 0.1-2%, Mn 0.1-1%, La+Ce 0.1-5%, Zr 0.01-0.5%, and the balance comprising Mg and other inevitable impurities.

[0032] A combustion test method for testing the flame-retardant magnesium alloy with composite additions of Al, Ca and rare earth, comprising the following steps:

[0033] Step 1: Weigh raw materials based on the components and mass percentages of the magnesium alloy. Mg and Al are added in the form of industrially pure magnesium ingots or industrially pure aluminum ingots, and Ca, Mn, La, Ce, and Zr are added in the form of Mg-Ca master alloys, Mg-Mn master alloys, La-Ce mixed rare earths, or Mg-Zr master alloys. Raw materials are prepared according to the compositional ratios of the flame-retardant magnesium alloy containing the composite additions of Al, Ca, and rare earth elements described in the present invention.

[0034] Step 2: First, industrial pure magnesium ingots and industrial pure aluminum ingots are placed in a crucible of a resistance furnace and heated to 700-740°C to obtain molten metal. Then, lanthanum, cerium and master alloy are gradually placed in the crucible and kept warm until melted. After continuous stirring, anhydrous manganese chloride and a refining agent are added and mixed for refining after standing for 10-20 minutes. The stirring and refining time is 10-20 minutes, and then the mixture is allowed to stand for 20-30 minutes. After completion, the slag is skimmed.

[0035] Step 3: Lower the temperature of the molten metal to 700°C, let it stand for 20-30 minutes, take samples for analysis, and cast the finished product if the composition is qualified;

[0036] Step 4: Cut a test piece with a size of 80x20x2mm from the ingot, clamp one end of the test piece against the other end, and perform a flame combustion test at 900℃ and 1300℃, with the flame perpendicular to the test piece;

[0037] Step 5: When combustion occurs on the surface of the sample accompanied by white smoke, this is the ignition time point of the flame-retardant magnesium alloy with composite additions of Al, Ca and rare earth elements. Then observe whether the test piece extinguishes itself and record the self-extinguishing time.

[0038] Example 1:

[0039] A flame-retardant magnesium alloy with composite additions of Al, Ca, and rare earth elements and a combustion test method thereof, comprising the following components by weight: 3.5 wt.% Al, 0.21 wt.% Mn, 0.21 wt.% Ca, 0.52 wt.% La / Ce, 0.22 wt.% Zn, 0.05 wt.% Zr, with the remainder being magnesium (Mg) and unavoidable impurities.

[0040] Example 2:

[0041] A flame-retardant magnesium alloy containing composite additions of Al, Ca, and rare earth elements, and a combustion test method thereof, comprises the following components, by weight: 3.6 wt.% Al, 0.19 wt.% Mn, 0.53 wt.% Ca, 0.55 wt.% La / Ce, 0.22 wt.% Zn, 0.03 wt.% Zr, with the remainder being magnesium (Mg) and unavoidable impurities. The preparation and combustion test methods of this embodiment are the same as those of Example 1.

[0042] Example 3:

[0043] A flame-retardant magnesium alloy containing composite additions of Al, Ca, and rare earth elements, and a combustion test method thereof, comprising the following components, by weight: 3.7 wt.% Al, 0.22 wt.% Mn, 0.23 wt.% Ca, 4.1 wt.% La / Ce, 0.21 wt.% Zn, 0.07 wt.% Zr, with the remainder being magnesium (Mg) and unavoidable impurities. The preparation and combustion test methods of this embodiment are the same as those of Example 1.

[0044] Example 4:

[0045] A flame-retardant magnesium alloy containing composite additions of Al, Ca, and rare earth elements, and a combustion test method thereof, comprises the following components, by weight: 3.4 wt.% Al, 0.23 wt.% Mn, 0.55 wt.% Ca, 3.8 wt.% La / Ce, 0.25 wt.% Zn, 0.02 wt.% Zr, with the remainder being magnesium (Mg) and unavoidable impurities. The preparation and combustion test methods of this embodiment are the same as those of Example 1.

[0046] Embodiment 5:

[0047] A flame-retardant magnesium alloy containing composite additions of Al, Ca, and rare earth elements, and a combustion test method thereof, comprises the following components, by weight: 3.9 wt.% Al, 0.18 wt.% Mn, 0.85 wt.% Ca, 4.1 wt.% La / Ce, 0.18 wt.% Zn, 0.03 wt.% Zr, with the remainder being magnesium (Mg) and unavoidable impurities. The preparation and combustion test methods of this embodiment are the same as those of Example 1.

[0048] Example 6:

[0049] A flame-retardant magnesium alloy containing composite additions of Al, Ca, and rare earth elements, and a combustion test method thereof, comprising the following components, by weight: 3.7 wt.% Al, 0.21 wt.% Mn, 1.22 wt.% Ca, 4.1 wt.% La / Ce, 0.22 wt.% Zn, 0.03 wt.% Zr, with the remainder being magnesium (Mg) and unavoidable impurities. The preparation and combustion test methods of this embodiment are the same as those of Example 1.

[0050] Embodiment seven:

[0051] A flame-retardant magnesium alloy containing composite additions of Al, Ca, and rare earth elements, and a combustion test method thereof, comprises the following components, by weight: 3.5 wt.% Al, 0.23 wt.% Mn, 1.44 wt.% Ca, 3.9 wt.% La / Ce, 0.21 wt.% Zn, 0.05 wt.% Zr, with the remainder being magnesium (Mg) and unavoidable impurities. The preparation and combustion test methods of this embodiment are the same as those of Example 1.

[0052] Embodiment 8:

[0053] A flame-retardant magnesium alloy containing composite additions of Al, Ca, and rare earth elements, and a combustion test method thereof, comprises the following components, by weight: 3.9 wt.% Al, 0.21 wt.% Mn, 0.53 wt.% Ca, 2.9 wt.% La / Ce, 0.22 wt.% Zn, 0.08 wt.% Zr, with the remainder being magnesium (Mg) and unavoidable impurities. The preparation and combustion test methods of this embodiment are the same as those of Example 1.

[0054] Comparative Example 1:

[0055] The AZ91D magnesium alloy ingot without Ca and rare earth elements was obtained by smelting according to the method steps of Example 1 for comparison with the flame-retardant magnesium alloy of the present invention, and was tested according to the combustion test method of Example 1.

[0056] Comparative Example 2:

[0057] An AE44 magnesium alloy ingot without Ca and rare earth elements was obtained by smelting according to the method steps of Example 1 for comparison with the flame-retardant magnesium alloy of the present invention, and was tested according to the combustion test method used in Example 1.

[0058] Comparative Example 3:

[0059] An AE42 magnesium alloy ingot without Ca and rare earth elements was obtained by smelting according to the method steps of Example 1 for comparison with the flame-retardant magnesium alloy of the present invention, and was tested according to the combustion test method used in Example 1.

[0060] The mechanical properties test data results of each embodiment are shown in Table 1, and the combustion test data results of each embodiment are shown in Table 2.

[0061] Table 1 Mechanical properties of each embodiment

[0062] Tensile strength / MPa Yield strength / MPa Elongation / % Example 1 170 70 4 Example 2 178 77 6 Example 3 185 82 10 Example 4 188 85 12 Example 5 192 90 10 Example 6 195 92 9 Example 7 201 90 6 Example 8 177 78 8 Comparative Example 1 182 111 3 Comparative Example 2 180 80 8 Comparative Example 3 178 77 6

[0063] Table 2 Combustion test data of each embodiment

[0064]

[0065] In summary, the present invention has low production cost. Through the reasonable combination of Al, Ca elements and rare earth elements, the magnesium alloy can ensure certain mechanical properties while quickly self-extinguishing after ignition at a flame temperature of 900°C, thereby improving the flame retardant properties of the magnesium alloy and expanding the scope of application. By recording the ignition time and self-extinguishing time, the flame retardant grades of different formulations are clearly distinguished, and the improvement of the flame retardant properties of the alloy is intuitively reflected. Dual tests at 900°C close to the ignition point of the magnesium alloy and 1300°C extreme high temperature are used to cover different thermal conditions in actual fires, verifying the stability of the material in mild and harsh environments, unifying the test piece specifications and the flame vertical loading method, reducing experimental variables, and ensuring that the test results of different batches or alloy formulations are repeatable and horizontally comparable. Metallographic analysis after combustion can detect the density of the oxide layer, correlate the self-extinguishing ability with the microstructure, ensure that the material maintains structural integrity in a fire, and avoid the risk of secondary collapse.

[0066] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A flame-retardant magnesium alloy with composite additions of Al, Ca and rare earth, characterized by: It includes the following components and mass contents: Ca 0-2%, Al 0-4%, Zn 0.1-2%, Mn 0.1-1%, La+Ce 0.1-5%, Zr 0.01-0.5% and the remaining content of Mg and impurities.

2. A combustion test method for testing the flame-retardant magnesium alloy with composite additions of Al, Ca and rare earth as claimed in claim 1, characterized in that it comprises the following steps: S1. Melting and Casting: 1.1 Weigh the raw materials, wherein Mg and Al are added using industrial pure magnesium ingots and industrial pure aluminum ingots, and Ca, Mn, La, Ce, and Zr are added using Mg-Ca master alloy, anhydrous manganese chloride, La-Ce mixed rare earth, and Mg-Zr master alloy; 1.2 Heat the magnesium ingot and aluminum ingot to 700-740℃ and melt them into liquid metal; 1.3 Gradually add La-Ce mixed rare earth and master alloy to the molten metal, stir until melted and then let it stand for 10-20 minutes; 1.4 Add anhydrous manganese chloride and refining agent for refining, stir for 10-20 minutes and then let it stand for 20-30 minutes; 1.5 Cool down to 700℃ and let it stand for 20-30 minutes. Take samples for analysis and then cast into shape. S2. Combustion test: 2.1 Cut a 80×20×2mm test piece from the ingot; 2.2 Clamp one end of the test piece vertically and apply 900℃ and 1300℃ flames to the other end; 2.3 Record the ignition time and self-extinguishing time of the test piece when white smoke appears.

3. The combustion test method according to claim 2, characterized in that: The refining agent in step 1.4 is a mixture of KCl, MgCl2, NaCl, CaF2 and BaCl2.

4. The combustion test method according to claim 2, characterized in that: The heating process in step 1.2 is protected by argon and sulfur hexafluoride.

5. The combustion test method according to claim 2, characterized in that: In step 2.2, the flame is generated by an acetylene-oxygen spray gun, and the flame temperature varies according to the distance between the gun muzzle and the sample.

6. The combustion test method according to claim 2, characterized in that: The mass ratio of La:Ce in the La-Ce mixed rare earth in step 1.3 is 1:

3.

7. The combustion test method according to claim 2, characterized in that: In step 1.5, the casting temperature is 680-720°C, and the mold preheating temperature is 200-300°C.

8. The combustion test method according to claim 2, wherein: The self-extinguishing time determination standard in step 2.3 is that the flame is completely extinguished and no continuous white smoke is generated by the test piece.

9. The combustion test method according to claim 2, characterized in that: The refining process in step 1.4 is carried out in two steps, with each step lasting 5-10 minutes and an interval of 5 minutes.

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