Novel high-magnesium zinc-aluminum-magnesium alloy for ultrahigh corrosion-resistant coating and production method of novel high-magnesium zinc-aluminum-magnesium alloy

Abstract

The invention discloses a novel high-magnesium zinc aluminum magnesium alloy for an ultrahigh corrosion-resistant coating and a production method of the novel high-magnesium zinc aluminum magnesium alloy, and relates to the technical field of metal alloys. The novel high-magnesium zinc-aluminum-magnesium alloy comprises the following chemical components in percentage by weight: 15 to 30 percent of Al, 5 to 8 percent of Mg, 0.15 to 0.4 percent of Si, 0.01 to 0.05 percent of La, 0.05 to 0.2 percent of Ce and the like, and the balance of zinc and inevitable impurities. The Ce contained in the alloy comprises Ce and CeO2. The preparation method comprises the following steps: heating a zinc ingot to 550-650 DEG C in an induction furnace, raising the temperature of a melt to 750-780 DEG C after the zinc ingot is completely molten, adding an aluminum ingot, a magnesium ingot, an aluminum-lanthanum intermediate alloy, an aluminum-cerium intermediate alloy and CeO2, uniformly stirring the melt by adopting a magnetic stirring device until the added alloys are completely dissolved, then cooling the melt to 600-630 DEG C, refining, removing slag, and cooling to room temperature to obtain a finished product. And finally, the temperature of the molten liquid is reduced to 530-560 DEG C, slag fishing and casting are conducted, alloy ingots are formed, and the cooling speed of the cast alloy ingots is smaller than 10 DEG C / s. The obtained zinc-aluminum-magnesium alloy is uniform in component, and the problems of segregation and alloy ingot brittle fracture easily generated during casting of the high-magnesium zinc-aluminum-magnesium alloy are solved.

Description

Technical Field

[0001] The invention relates to the technical field of metal alloys, in particular to a novel high-magnesium zinc-aluminum-magnesium alloy for ultra-high corrosion-resistant coatings and a production method thereof. Background Art

[0002] Zinc-aluminum-magnesium coating is a newly developed alloy coating in recent years. Due to its excellent surface corrosion resistance and cut corrosion resistance, it has become an important development direction of alloy coating and has been widely used. Since 2020, with the increase in corrosion demand in some special fields, the development of zinc-aluminum-magnesium coating with higher corrosion resistance has become a trend.

[0003] When producing zinc-aluminum-magnesium alloys with a magnesium content greater than 3%, surface oxidation occurs during casting.

[0004] Patent No. 201811157769.9, "A hot-dip galvanized aluminum-magnesium alloy containing titanium and antimony and its preparation method", contains 2.5-3.5% magnesium, 10-12% aluminum, 0.1-0.2% titanium, 0.1-0.1% antimony, and the balance is zinc. This process adds pure zinc, pure aluminum, Al-50% Mg master alloy, Al-5% Ti master alloy, and Al-5% Sb master alloy into a crucible, heats it to 700-720°C, adds a covering agent (NaCl+KCl) to melt, uses ZnCl2 for refining and slag removal, and cools down to 550°C for casting. This process technology uses a covering agent (NaCl+KCl) to melt and cast directly. It cannot be directly used for the smelting of zinc-aluminum-magnesium alloys containing more than 3.5% magnesium. Oxidation will occur during casting, the surface will turn black, and qualified products cannot be produced.

[0005] Patent No. 202211010328.2, "A method for producing high-magnesium zinc-aluminum-magnesium alloy", uses a refining agent for refining, which can further enhance the diffusion performance, surface tension and chemical stability of the flux. Its melting point and specific gravity are lower than those of zinc-aluminum-magnesium alloy. Sprinkling it on the surface can isolate the melt from the air, reduce the oxidation and combustion of magnesium metal, increase the direct recovery rate of magnesium, and reduce burning loss.

[0006] When high-Mg-Zn-Al-Mg alloy is produced, in addition to surface oxidation, a large amount of Mg is formed due to the high magnesium content. x Zn y The alloy increases its brittleness and the alloy ingot is easy to break. At the same time, due to uneven cooling, the segregation of alloy elements is serious, which seriously affects the quality and yield of the product. Summary of the invention

[0007] The present invention creatively adds La and Ce elements in the production of high-magnesium zinc-aluminum-magnesium alloy. The chemical composition of the novel zinc-aluminum-magnesium alloy is that the alloy ingot includes Zn, Al, Mg, Si, La, Ce and other elements, calculated by weight percentage: Al 15-30%, Mg 5-8%, Si 0.15-0.4%, the balance is zinc and inevitable impurities; La: 0.01-0.05%, Ce: 0.05-0.2%; Ce contained in the alloy includes Ce and CeO2. The preparation method is as follows: the zinc ingot is heated to 550-650°C in an induction furnace, and the temperature of the melt is increased to 750-780°C after it is completely melted, and aluminum ingots, magnesium ingots, aluminum-lanthanum intermediate alloys, aluminum-cerium intermediate alloys, and CeO2 are added, and the melt is stirred evenly by a magnetic stirring device until the added alloy is completely dissolved, and then the melt is cooled to 600-630°C for refining and slag removal, and finally the melt temperature is reduced to 530-560°C for slag removal and casting into alloy ingots, and the cooling rate of the alloy ingot after casting is less than 10°C / s.

[0008] The beneficial technical effects of the present invention are as follows:

[0009] The purification effect of La and Ce is mainly manifested in significantly reducing inclusions and harmful elements in the alloy aluminum liquid, reducing the pinhole rate and porosity; at the same time, La and Ce can also refine grains and dendrites, inhibit the appearance of coarse phases, enhance the toughness of the alloy, and reduce the fracture phenomenon of the alloy ingot after casting; adding a certain amount of La and Ce to the aluminum alloy can effectively improve the high-temperature oxidation resistance of the alloy and reduce surface oxidation during the alloy casting process. In particular, the Ce element is added in the form of Ce and CeO2. CeO2 can reduce the surface tension and critical nucleation resistance of the liquid metal, promote nucleation, and hinder grain growth. At the same time, CeO2 makes the flow of the molten pool more sufficient, so the organization is more dense and uniform.

[0010] The addition of La and Ce adopts the method of aluminum-lanthanum master alloy, aluminum-cerium master alloy and CeO2, without significantly increasing the heating temperature of the melt; the casting temperature is controlled at 530-560°C, and the cooling rate is less than 10°C / s, so that the obtained alloy solidifies evenly, reduces the brittleness and internal shrinkage cavities of the alloy, and reduces the segregation problem of alloy elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a qualified high-magnesium zinc-aluminum-magnesium alloy ingot produced in Example 3 of the present invention.

[0012] Figure 2 It is a brittle fracture high-magnesium zinc-aluminum-magnesium alloy ingot produced in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0013] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0014] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0015] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0016] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0017] The novel high-magnesium zinc-aluminum-magnesium alloy with ultra-high corrosion-resistant coating according to the present invention and its production method will be described in more detail below in conjunction with specific embodiments.

[0018] In an embodiment according to the present invention, a novel high-magnesium zinc-aluminum-magnesium alloy for ultra-high corrosion-resistant coating is manufactured by the following method.

[0019] The chemical composition of the new high-magnesium zinc aluminum-magnesium alloy used for ultra-high corrosion-resistant coating is calculated by weight percentage: Al 15-30%, Mg 5-8%, Si 0.15-0.4%, and the balance is zinc and unavoidable impurities.

[0020] Calculated by weight percentage, the new high-magnesium zinc aluminum-magnesium alloy also contains La: 0.01-0.05%, Ce: 0.05-0.2%.

[0021] The Ce contained in the alloy includes Ce and CeO2.

[0022] The preparation method of high-magnesium zinc-aluminum-magnesium is as follows: heat the zinc ingot to 550-650°C in an induction furnace, increase the temperature of the melt to 750-780°C after it is completely melted, add aluminum ingots, magnesium ingots, aluminum-lanthanum master alloys, aluminum-cerium master alloys, and CeO2, and use a magnetic stirring device to stir the melt evenly until the added alloy is completely dissolved, then cool the melt to 600-630°C for refining and slag removal, and finally reduce the temperature of the melt to 530-560°C for slag removal and casting into alloy ingots.

[0023] The cooling rate of the alloy ingot after casting is less than 10° C. / s. The novel high-magnesium zinc-aluminum-magnesium alloy for ultra-high corrosion-resistant coating of the present invention will be described below in conjunction with specific embodiments.

[0024] Example 1

[0025] 1. The chemical composition of the new high-magnesium zinc aluminum-magnesium alloy used for ultra-high corrosion-resistant coating is calculated by weight percentage: Al 15%, Mg 5%, Si 0.15%, and the balance is zinc and unavoidable impurities.

[0026] 2. Calculated by weight percentage, the new high-magnesium zinc aluminum-magnesium alloy also contains La: 0.01%, Ce: 0.05%.

[0027] 3. The Ce contained in the alloy includes Ce and CeO2.

[0028] 4. The preparation method of high-magnesium zinc-aluminum-magnesium is as follows: heat the zinc ingot to 550°C in an induction furnace, increase the temperature of the melt to 750°C after it is completely melted, add aluminum ingots, magnesium ingots, aluminum-lanthanum intermediate alloys, aluminum-cerium intermediate alloys, and CeO2, and use a magnetic stirring device to stir the melt evenly until the added alloy is completely dissolved, then cool the melt to 600°C for refining and slag removal, and finally cool the melt temperature to 530°C for slag removal and casting into alloy ingots.

[0029] 5. The cooling rate of the alloy ingot after casting is 5℃ / s.

[0030] Example 2

[0031] 1. The chemical composition of the new high-magnesium zinc aluminum-magnesium alloy used for ultra-high corrosion-resistant coating is calculated by weight percentage: Al30%, Mg8%, Si0.4%, and the balance is zinc and unavoidable impurities.

[0032] 2. Calculated by weight percentage, the new high magnesium zinc aluminum magnesium alloy also contains La 0.05% and Ce 0.2%.

[0033] 3. The Ce contained in the alloy includes Ce and CeO2.

[0034] 4. The preparation method of high-magnesium zinc-aluminum-magnesium is as follows: heat the zinc ingot to 650°C in an induction furnace, increase the temperature of the melt to 780°C after it is completely melted, add aluminum ingots, magnesium ingots, aluminum-lanthanum intermediate alloys, aluminum-cerium intermediate alloys, and CeO2, and use a magnetic stirring device to stir the melt evenly until the added alloy is completely dissolved, then cool the melt to 630°C for refining and slag removal, and finally reduce the temperature of the melt to 560°C for slag removal and casting into alloy ingots.

[0035] 5. The cooling rate of the alloy ingot after casting is 10℃ / s.

[0036] Example 3

[0037] 1. The chemical composition of the new high-magnesium zinc aluminum-magnesium alloy used for ultra-high corrosion-resistant coating is calculated by weight percentage: Al 19%, Mg 6%, Si 0.25%, and the balance is zinc and unavoidable impurities.

[0038] 2. Calculated by weight percentage, the new high-magnesium zinc aluminum-magnesium alloy also contains La: 0.03%, Ce: 0.1%.

[0039] 3. The Ce contained in the alloy includes Ce and CeO2.

[0040] 4. The preparation method of high-magnesium zinc-aluminum-magnesium is as follows: heat the zinc ingot to 600°C in an induction furnace, increase the temperature of the melt to 760°C after it is completely melted, add aluminum ingots, magnesium ingots, aluminum-lanthanum intermediate alloys, aluminum-cerium intermediate alloys, and CeO2, and use a magnetic stirring device to stir the melt evenly until the added alloy is completely dissolved, then cool the melt to 620°C for refining and slag removal, and finally reduce the temperature of the melt to 550°C for slag removal and casting into alloy ingots.

[0041] 5. The cooling rate of the alloy ingot after casting is 8℃ / s.

[0042] Comparative Example 1

[0043] 1. Chemical composition of high magnesium zinc aluminum magnesium alloy, by weight percentage: Al 15-30%, Mg 5-8%, Si 0.15-0.4, the balance is zinc and unavoidable impurities.

[0044] 2. The preparation method of high magnesium zinc aluminum magnesium is as follows: heat the zinc ingot to 600°C in an induction furnace, raise the temperature of the melt to 760°C after it is completely melted, add aluminum ingots and magnesium ingots, and use a magnetic stirring device to stir the melt evenly until the added alloy is completely dissolved, then cool the melt to 620°C for refining and slag removal, and finally reduce the temperature of the melt to 550°C for slag removal and casting into alloy ingots.

[0045] 3. The cooling rate of the alloy ingot after casting is 8℃ / s.

[0046] Comparative Example 2

[0047] 1. Chemical composition of high magnesium zinc aluminum magnesium alloy, by weight percentage: Al 19%, Mg 6%, Si 0.25%, the balance is zinc and unavoidable impurities.

[0048] 2. In terms of weight percentage, the alloy further comprises La: 0.03%.

[0049] 3. The preparation method of high-magnesium zinc-aluminum-magnesium is as follows: heat the zinc ingot to 600°C in an induction furnace, increase the temperature of the melt to 760°C after it is completely melted, add aluminum ingots, magnesium ingots and aluminum-lanthanum intermediate alloys, and use a magnetic stirring device to stir the melt evenly until the added alloy is completely dissolved, then cool the melt to 620°C for refining and slag removal, and finally reduce the temperature of the melt to 550°C for slag removal and casting into alloy ingots.

[0050] 4. The cooling rate of the alloy ingot after casting is 15℃ / s.

[0051] Evaluation example

[0052] The high-Mg-Zn-Al-Mg alloys obtained by Examples 1-3 and Comparative Examples 1-2 were analyzed respectively, and 20 pieces of alloys with a size of 2 mm×2 mm×2 mm were taken from 20 different positions on the alloy ingot to analyze their chemical composition, and the probability of segregation in the alloy was statistically analyzed. The effect of the present invention in solving the problem of alloy component segregation was evaluated, and the results are shown in Table 1 below.

[0053] Table 1

[0054] Serial number The number of composition segregation points in the alloy ingot (20 areas analyzed) Example 1 1 Example 2 2 Example 3 1 Comparative Example 1 11 Comparative Example 2 9

[0055] It can be seen from Table 1 that the proportions of component segregation points in the alloys of Examples 1-3 are much smaller than those of Comparative Examples 1 and 2, indicating that the addition of La, Ce, especially CeO2, and the method of reducing the cooling rate after casting in the present invention can greatly reduce the occurrence of segregation.

[0056] The brittleness of the high-magnesium-zinc-aluminum-magnesium alloy ingots obtained by Examples 1-3 and Comparative Examples 1-2 was analyzed respectively, and the large ingots (weight 800Kg / ingot) after casting were impact tested, and the proportion of 20 large ingots that broke was counted. The effect of the present invention on solving the problem of brittle fracture of high-magnesium-zinc-aluminum-magnesium alloys was evaluated, and the results are shown in Table 2 below.

[0057] Table 2

[0058] Serial number Number of brittle fractures of alloy ingots (impacting 20 ingots) Example 1 0 Example 2 1 Example 3 0 Comparative Example 1 15 Comparative Example 2 10

[0059] As shown in Table 2, the proportion of brittle fractures after impact in the alloy ingots of Examples 1-3 is much smaller than that of Comparative Examples 1 and 2, indicating that the addition of La, Ce, especially CeO2, and the method of reducing the cooling rate after casting in the present invention can increase the plasticity of the alloy and reduce the occurrence of brittle fracture problems in the alloy ingots.

[0060] Although the present invention has been specifically shown and described with reference to exemplary embodiments of the present invention, it will be understood by those skilled in the art that various changes in form and detail may be made herein without departing from the spirit and scope of the present invention as defined by the claims and their equivalents. The embodiments should be considered in a descriptive sense only and not for the purpose of limitation. Therefore, the scope of the present invention is not limited by the specific embodiments of the present invention, but by the claims, and all differences within the scope will be interpreted as included in the present invention.

Claims

1. A new high-magnesium zinc-aluminum-magnesium alloy for ultra-high corrosion-resistant coating, characterized by: The chemical composition of the novel high-magnesium-zinc aluminum-magnesium alloy is, by weight percentage, 15-30% Al, 5-8% Mg, 0.15-0.4% Si, and the balance is zinc and unavoidable impurities.

2. The novel high-magnesium zinc-aluminum-magnesium alloy with ultra-high corrosion-resistant coating according to claim 1 is characterized in that: Calculated by weight percentage, the novel high-magnesium zinc aluminum-magnesium alloy further contains La: 0.01-0.05%, Ce: 0.05-0.2%.

3. The novel high-magnesium zinc-aluminum-magnesium alloy with ultra-high corrosion-resistant coating according to claim 2 is characterized in that: The Ce contained in the alloy includes Ce and CeO2.

4. The preparation method of the new high-magnesium zinc aluminum-magnesium alloy described in claim 1 is: heating the zinc ingot to 550-650°C in an induction furnace, raising the temperature of the melt to 750-780°C after it is completely melted, adding aluminum ingots, magnesium ingots, aluminum-lanthanum master alloys, aluminum-cerium master alloys, and CeO2, and using a magnetic stirring device to stir the melt evenly until the added alloy is completely dissolved, then cooling the melt to 600-630°C for refining and slag removal, and finally reducing the temperature of the melt to 530-560°C for slag removal and casting into alloy ingots.

5. The preparation method according to claim 4, characterized in that: The cooling rate of the alloy ingot after casting is less than 10°C / s.

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