A chromium additive for aluminum alloys and a method for preparing the same

Abstract

The application relates to the technical field of additive technology for aluminum alloy, and discloses a chromium additive for aluminum alloy and a preparation method thereof. The chromium additive for aluminum alloy comprises the following components in parts by weight: 85-95 parts of chromium powder, 5-10 parts of aluminum powder, 1-5 parts of manganese powder, 0.1-0.3 parts of silicon powder, 2-4 parts of potassium fluoroaluminate and 1-2 parts of chloride. The technical scheme solves the problem of insufficient chromium element yield when the chromium catalyst in the prior art is applied to aluminum alloy production.

Description

Technical Field

[0001] This invention relates to the field of additives for aluminum alloys, and more specifically, to a chromium additive for aluminum alloys and its preparation method. Background Technology

[0002] Chromium is an important alloying element in aluminum alloys, which can improve the alloy's strength, corrosion resistance, and high-temperature stability. Existing chromium additives for aluminum alloys mainly include metallic chromium powder, chromium-aluminum alloy blocks, and chromium salt additives. The preparation methods are mostly mechanical mixing, melt casting, or powder metallurgy. By combining the chromium source with an aluminum-based carrier, the addition and diffusion of chromium in aluminum alloys can be achieved.

[0003] However, chromium and aluminum have large differences in melting point and small diffusion coefficient. Additives are prone to agglomeration and incomplete dissolution in aluminum alloy melt. Some chromium elements form refractory compounds or are lost with slag. This makes it difficult to control the yield stably, affects the consistency of alloy performance, and increases production costs. Summary of the Invention

[0004] This invention proposes a chromium additive for aluminum alloys and its preparation method, which solves the problem of insufficient chromium recovery rate when chromium additives are applied to aluminum alloy production in related technologies.

[0005] The technical solution of the present invention is as follows:

[0006] This invention proposes a chromium additive for aluminum alloys, comprising the following components in parts by weight: 85-95 parts chromium powder, 5-10 parts aluminum powder, 1-5 parts manganese powder, 0.1-0.3 parts silicon powder, 2-4 parts potassium fluoroaluminate, and 1-2 parts chloride.

[0007] As a further technical solution, the mass ratio of the chromium powder, aluminum powder, manganese powder and silicon powder is 90:7:1.5~2.5:0.15~0.2.

[0008] In this invention, the mass ratio of chromium powder, aluminum powder, manganese powder, and silicon powder is limited to 90:7:1.5~2.5:0.15~0.25, which further improves the actual recovery rate of chromium. An appropriate amount of manganese powder can fully promote the diffusion of chromium powder without affecting the synergistic effect of other elements. A suitable proportion of silicon powder can better control the interfacial tension, ensuring good wettability of aluminum liquid to chromium powder, and preventing the melting of chromium powder and the actual recovery rate of chromium from being affected by excessively low interfacial tension.

[0009] As a further technical solution, the chromium additive for aluminum alloys also includes the following components in parts by weight: 0.3~0.7 parts of grain refiner, 0.5~1.2 parts of dispersant, and 0.5~0.8 parts of binder.

[0010] As a further technical solution, the chloride includes one of potassium chloride and magnesium chloride.

[0011] In this invention, the addition of chloride can remove hydrogen from aluminum alloys and reduce the formation of defects such as porosity; the chloride can be one or more of the conventional chlorides in the art, such as magnesium chloride, sodium chloride, potassium chloride, etc., preferably, the chloride is one of potassium chloride and magnesium chloride.

[0012] As a further technical solution, the grain refiner includes one or two of aluminum-titanium-boron alloy and aluminum-titanium-carbon alloy.

[0013] As a further technical solution, the dispersant includes one of stearic acid and zinc stearate.

[0014] In this invention, the addition of a dispersant can reduce the surface tension between the particles of each component and prevent particle agglomeration. The dispersant can be one or more of the conventional dispersants in the art, such as stearic acid, zinc stearate, calcium stearate, polyethylene wax, etc. Preferably, the dispersant is one of stearic acid and zinc stearate.

[0015] As a further technical solution, the adhesive includes polyanionic cellulose.

[0016] As a further technical solution, when the grain refiner is an aluminum-titanium-boron alloy and an aluminum-titanium-carbon alloy, the mass ratio of the aluminum-titanium-boron alloy to the aluminum-titanium-carbon alloy is 1~2:1.

[0017] In this invention, when aluminum-titanium-boron alloy and aluminum-titanium-carbon alloy are used together, they exhibit a synergistic effect, further shortening the melting time. During the aluminum alloy melting process, the aluminum-titanium-boron alloy and aluminum-titanium-carbon alloy generate TiAl3, TiB2, and TiC phases. Compared to a single alloy, the multiple heterogeneous nucleation sites generated by the combined action of the two alloys complement each other, resulting in more grains and refining the grain structure of the aluminum alloy. Furthermore, these fine particles help prevent the formation of pores, ensuring the density of the melt and thus improving heat transfer efficiency, further shortening the melting time. The mass ratio of aluminum-titanium-boron alloy to aluminum-titanium-carbon alloy is limited to 1~2:1. Exceeding this range, excessive amounts of one alloy may cause compositional segregation, reducing the uniformity of the melt and hindering the prevention of pore formation and improvement of heat transfer efficiency.

[0018] This invention also proposes a method for preparing a chromium additive for aluminum alloys, comprising the following steps:

[0019] S1. Chromium powder, aluminum powder, manganese powder and silicon powder are pulverized in an inert atmosphere to obtain a mixed powder;

[0020] S2. Polyanionic cellulose is dissolved in water to obtain a polyanionic cellulose solution;

[0021] S3. The mixed powder, polyanionic cellulose solution and other remaining components are mixed in an inert atmosphere, pressed and dried to obtain a chromium additive for aluminum alloys.

[0022] As a further technical solution, the particle size of the mixed powder is 150~300 mesh.

[0023] As a further technical solution, in the mixed powder, by mass fraction, 35% are 200 mesh < particle size ≤ 150 mesh, 55% are 250 mesh ≤ particle size ≤ 200 mesh, and 10% are 300 mesh ≤ particle size < 250 mesh.

[0024] In the preparation process of the chromium additive for aluminum alloys of the present invention, a suitable particle size distribution is beneficial to the melting, diffusion and reaction of chromium powder, aluminum powder, manganese powder and silicon powder in the aluminum alloy melt, so that they can better play their role in improving the performance of aluminum alloys.

[0025] The working principle and beneficial effects of this invention are as follows:

[0026] In this invention, chromium powder, aluminum powder, manganese powder, and silicon powder work together to significantly improve the actual yield of chromium when chromium additives are used in aluminum alloy production. Chromium powder is the core component. Manganese powder has a lower melting point than chromium and melts first to form a manganese-rich aluminum liquid, allowing the chromium powder to melt and diffuse more quickly and fully, thereby improving the actual yield of chromium. Silicon powder forms a low-melting-point eutectic with aluminum powder. When it exists on the surface of chromium powder, it can reduce the interfacial tension, making it easier for the aluminum liquid to diffuse into the interior of the chromium powder particles, further improving the actual yield of chromium in the aluminum alloy. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] In the following examples and comparative examples, the polyanionic cellulose has a moisture content of <8% and a viscosity of 50~200 mPa·s; the aluminum-titanium-boron alloy is AlTi5B1; and the aluminum-titanium-carbon alloy is AlTi5C. 0.2 .

[0029] Example 1

[0030] A chromium additive for aluminum alloys comprises the following components in parts by weight: 85 parts chromium powder, 5 parts aluminum powder, 1 part manganese powder, 0.1 parts silicon powder, 2 parts potassium fluoroaluminate, 1 part potassium chloride, 0.3 parts aluminum-titanium-boron alloy, 0.5 parts zinc stearate, and 0.5 parts polyanionic cellulose.

[0031] A method for preparing a chromium additive for aluminum alloys includes the following steps:

[0032] Chromium powder, aluminum powder, manganese powder and silicon powder are pulverized in a nitrogen atmosphere to obtain a mixed powder (by mass fraction, 35% for particles with a particle size of 200 mesh < 150 mesh, 55% for particles with a particle size of 250 mesh ≤ 200 mesh, and 10% for particles with a particle size of 300 mesh ≤ 250 mesh).

[0033] Polyanionic cellulose is dissolved in deionized water (deionized water accounts for 4% of the total mass of all components of the chromium additive for aluminum alloys) to obtain a polyanionic cellulose solution.

[0034] The mixed powder, polyanionic cellulose solution, and other remaining components were mixed in a nitrogen atmosphere, pressed at 10 MPa, and dried to obtain a chromium additive for aluminum alloys.

[0035] Example 2

[0036] A chromium additive for aluminum alloys comprises the following components in parts by weight: 95 parts chromium powder, 10 parts aluminum powder, 5 parts manganese powder, 0.3 parts silicon powder, 4 parts potassium fluoroaluminate, 2 parts magnesium chloride, 0.7 parts aluminum-titanium-boron alloy, 1.2 parts zinc stearate, and 0.8 parts polyanionic cellulose.

[0037] A method for preparing a chromium additive for aluminum alloys includes the following steps:

[0038] Chromium powder, aluminum powder, manganese powder and silicon powder are pulverized in a nitrogen atmosphere to obtain a mixed powder (by mass fraction, 35% for particles with a particle size of 200 mesh < 150 mesh, 55% for particles with a particle size of 250 mesh ≤ 200 mesh, and 10% for particles with a particle size of 300 mesh ≤ 250 mesh).

[0039] Polyanionic cellulose is dissolved in deionized water (deionized water accounts for 4% of the total mass of all components of the chromium additive for aluminum alloys) to obtain a polyanionic cellulose solution.

[0040] The mixed powder, polyanionic cellulose solution, and other remaining components were mixed in a nitrogen atmosphere, pressed at 10 MPa, and dried to obtain a chromium additive for aluminum alloys.

[0041] Example 3

[0042] A chromium additive for aluminum alloys comprises the following components in parts by weight: 90 parts chromium powder, 7 parts aluminum powder, 2.5 parts manganese powder, 0.25 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-boron alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0043] A method for preparing a chromium additive for aluminum alloys includes the following steps:

[0044] Chromium powder, aluminum powder, manganese powder and silicon powder are pulverized in a nitrogen atmosphere to obtain a mixed powder (by mass fraction, 35% for particles with a particle size of 200 mesh < 150 mesh, 55% for particles with a particle size of 250 mesh ≤ 200 mesh, and 10% for particles with a particle size of 300 mesh ≤ 250 mesh).

[0045] Polyanionic cellulose is dissolved in deionized water (deionized water accounts for 4% of the total mass of all components of the chromium additive for aluminum alloys) to obtain a polyanionic cellulose solution.

[0046] The mixed powder, polyanionic cellulose solution, and other remaining components were mixed in a nitrogen atmosphere, pressed at 10 MPa, and dried to obtain a chromium additive for aluminum alloys.

[0047] Example 4

[0048] The difference between this embodiment and Embodiment 3 lies only in the presence of a chromium additive for aluminum alloys, comprising the following components by weight: 90 parts chromium powder, 7 parts aluminum powder, 2.5 parts manganese powder, 0.2 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-boron alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0049] Example 5

[0050] The difference between this embodiment and Embodiment 3 lies only in the presence of a chromium additive for aluminum alloys, comprising the following components by weight: 90 parts chromium powder, 7 parts aluminum powder, 2.5 parts manganese powder, 0.15 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-boron alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0051] Example 6

[0052] The difference between this embodiment and Embodiment 3 lies only in the presence of a chromium additive for aluminum alloys, comprising the following components by weight: 90 parts chromium powder, 7 parts aluminum powder, 2.5 parts manganese powder, 0.1 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-boron alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0053] Example 7

[0054] The difference between this embodiment and Embodiment 5 lies only in the presence of a chromium additive for aluminum alloys, comprising the following components in parts by weight: 90 parts chromium powder, 7 parts aluminum powder, 2 parts manganese powder, 0.15 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-boron alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0055] Example 8

[0056] The difference between this embodiment and Embodiment 5 lies only in the presence of a chromium additive for aluminum alloys, comprising the following components by weight: 90 parts chromium powder, 7 parts aluminum powder, 1.5 parts manganese powder, 0.15 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-boron alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0057] Example 9

[0058] The difference between this embodiment and Embodiment 7 lies only in the presence of a chromium additive for aluminum alloys, comprising the following components in parts by weight: 90 parts chromium powder, 7 parts aluminum powder, 2 parts manganese powder, 0.15 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-carbon alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0059] Example 10

[0060] The difference between this embodiment and Embodiment 7 lies only in the presence of a chromium additive for aluminum alloys, comprising the following components in parts by weight: 90 parts chromium powder, 7 parts aluminum powder, 2 parts manganese powder, 0.15 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.5 parts aluminum-titanium-boron alloy, 0.1 parts aluminum-titanium-carbon alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0061] Example 11

[0062] The difference between this embodiment and Embodiment 7 lies only in the presence of a chromium additive for aluminum alloys, comprising the following components by weight: 90 parts chromium powder, 7 parts aluminum powder, 2 parts manganese powder, 0.15 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.4 parts aluminum-titanium-boron alloy, 0.2 parts aluminum-titanium-carbon alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0063] Example 12

[0064] The difference between this embodiment and Embodiment 7 lies only in the presence of a chromium additive for aluminum alloys, comprising the following components in parts by weight: 90 parts chromium powder, 7 parts aluminum powder, 2 parts manganese powder, 0.15 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.3 parts aluminum-titanium-boron alloy, 0.3 parts aluminum-titanium-carbon alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0065] Example 13

[0066] The difference between this embodiment and Embodiment 7 lies only in the presence of a chromium additive for aluminum alloys, comprising the following components by weight: 90 parts chromium powder, 7 parts aluminum powder, 2 parts manganese powder, 0.15 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.2 parts aluminum-titanium-boron alloy, 0.4 parts aluminum-titanium-carbon alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0067] Comparative Example 1

[0068] The only difference between this comparative example and Example 3 is that it uses a chromium additive for aluminum alloys, comprising the following components in parts by weight: 90 parts chromium powder, 7 parts aluminum powder, 2.5 parts manganese powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-boron alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0069] Comparative Example 2

[0070] The only difference between this comparative example and Example 3 is that it uses a chromium additive for aluminum alloys, comprising the following components in parts by weight: 90 parts chromium powder, 7 parts aluminum powder, 0.25 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-boron alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0071] Comparative Example 3

[0072] The only difference between this comparative example and Example 3 is that it uses a chromium additive for aluminum alloys, comprising the following components in parts by weight: 90 parts chromium powder, 2.5 parts manganese powder, 0.25 parts silicon powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-boron alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0073] Comparative Example 4

[0074] The only difference between this comparative example and Example 3 is that it is a chromium additive for aluminum alloys, comprising the following components in parts by weight: 90 parts chromium powder, 7 parts aluminum powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-boron alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0075] Comparative Example 5

[0076] The only difference between this comparative example and Example 3 is that it uses a chromium additive for aluminum alloys, comprising the following components in parts by weight: 90 parts chromium powder, 3 parts potassium fluoroaluminate, 1.5 parts potassium chloride, 0.6 parts aluminum-titanium-boron alloy, 0.8 parts stearic acid, and 0.6 parts polyanionic cellulose.

[0077] Experimental Example 1

[0078] Aluminum ingots were melted to obtain molten aluminum, and the mixture was stirred thoroughly. Chromium additives prepared in Examples 1-8 and Comparative Examples 1-5 were added to the molten aluminum. Samples were taken after melting at 680°C for 5 minutes, and the actual yield of chromium in the samples was determined. The test results are shown in Table 1.

[0079] Chromium recovery rate = (mass of chromium powder dissolved in molten aluminum / total mass of chromium powder in chromium additive) × 100%;

[0080] Table 1. Test results of the chromium additives prepared in Examples 1-8 and Comparative Examples 1-5 in the preparation of aluminum alloys.

[0081]

[0082] 1. Compared with Comparative Examples 1-5, the chromium additives prepared in Examples 1-8 showed a chromium yield of more than 90% after 5 minutes at 680°C when preparing aluminum alloys, which was higher than that in Comparative Examples 1-5. This indicates that the synergistic effect of chromium powder, aluminum powder, manganese powder and silicon powder can significantly improve the chromium yield.

[0083] 2. Compared with Examples 3-8, the chromium additives prepared in Examples 7-8 achieved a chromium recovery rate of over 99.4% after 5 minutes at 680°C when preparing aluminum alloys, which is higher than that in Examples 3-6. This indicates that adjusting the mass ratio of chromium powder, aluminum powder, manganese powder and silicon powder to 90:7:1.5~2:0.15~0.2 can further improve the chromium recovery rate.

[0084] Experiment Example 2

[0085] Aluminum ingots were melted to obtain molten aluminum, and the mixture was stirred thoroughly. Chromium additives prepared in Examples 7 and 9-13 were added to the molten aluminum. The time for different samples to completely melt was recorded at 680°C. The test results are shown in Table 2.

[0086] Table 2. Test results of the chromium additives prepared in Examples 7 and 9-13 in the preparation of aluminum alloys.

[0087]

[0088] Compared with Examples 7 and 9-13, the chromium additive for aluminum alloys prepared in Examples 11-12 can achieve complete melting at 680°C in only 4 minutes. The melting time is shorter than that of Examples 7, 9-10 and 13. This shows that using aluminum-titanium-boron alloy and aluminum-titanium-carbon alloy together, and limiting the mass ratio of aluminum-titanium-boron alloy to aluminum-titanium-carbon alloy to 1-2:1, can shorten the melting time.

[0089] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A chromium additive for aluminum alloys, characterized in that, It is composed of the following components in parts by weight: 85-95 parts chromium powder, 5-10 parts aluminum powder, 1-5 parts manganese powder, 0.1-0.3 parts silicon powder, 2-4 parts potassium fluoroaluminate, 1-2 parts chloride, 0.3-0.7 parts grain refiner, 0.5-1.2 parts dispersant, and 0.5-0.8 parts binder; The binder includes polyanionic cellulose.

2. The chromium additive for aluminum alloys according to claim 1, characterized in that, The mass ratio of chromium powder, aluminum powder, manganese powder and silicon powder is 90:7:1.5~2.5:0.15~0.

2.

3. The chromium additive for aluminum alloys according to claim 1, characterized in that, The chloride includes one of potassium chloride and magnesium chloride.

4. The chromium additive for aluminum alloys according to claim 1, characterized in that, The grain refiner includes one or two of aluminum-titanium-boron alloy and aluminum-titanium-carbon alloy.

5. A chromium additive for aluminum alloys according to claim 1, characterized in that, The dispersant includes one of stearic acid and zinc stearate.

6. A chromium additive for aluminum alloys according to claim 4, characterized in that, When the grain refiner is an aluminum-titanium-boron alloy and an aluminum-titanium-carbon alloy, the mass ratio of the aluminum-titanium-boron alloy to the aluminum-titanium-carbon alloy is 1~2:

1.

7. A method for preparing a chromium additive for aluminum alloys, used to prepare the chromium additive for aluminum alloys according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Chromium powder, aluminum powder, manganese powder and silicon powder are pulverized in an inert atmosphere to obtain a mixed powder; S2. Polyanionic cellulose is dissolved in water to obtain a polyanionic cellulose solution; S3. The mixed powder, polyanionic cellulose solution and other remaining components are mixed in an inert atmosphere, pressed and dried to obtain a chromium additive for aluminum alloys.

8. The method for preparing a chromium additive for aluminum alloys according to claim 7, characterized in that, The particle size of the mixed powder is 150~300 mesh; In the mixed powder, by mass fraction, 35% are 200 mesh < particle size ≤ 150 mesh, 55% are 250 mesh ≤ particle size ≤ 200 mesh, and 10% are 300 mesh ≤ particle size < 250 mesh.

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