Preparation method of rare earth modified Al-Ti-C-B refiner based on loose graphite rotor

Abstract

This invention discloses a method for preparing a rare-earth modified Al-Ti-C-B grain refiner based on a porous graphite rotor, belonging to the field of aluminum alloy grain refinement technology; it solves at least one technical problem in traditional processes, namely poor carbon wettability, high preparation cost, TiB2 agglomeration, and refiner poisoning. The method for preparing the rare-earth modified Al-Ti-C-B grain refiner of this invention includes: Step 1, preparing a precursor; Step 2, preparing a porous graphite rotor; using porous graphite to prepare a porous graphite rotor; Step 3, preparing an Al-Ti-C-B alloy solution; heating an aluminum ingot to form an aluminum melt, adding potassium fluorotitanate and potassium fluoroborate to the aluminum melt and stirring with a porous graphite rotor, then adding the precursor prepared in Step 1, continuing stirring until the reaction is complete, removing the salt solvent melt to obtain an Al-Ti-C-B alloy solution; Step 4, preparing a rare-earth modified Al-Ti-C-B grain refiner using the Al-Ti-C-B alloy solution. The refining agent provided by this invention has a good refining effect, and its preparation process is simple and the preparation cost is low.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy grain refinement technology, and in particular to a method for preparing a rare earth modified Al-Ti-CB grain refiner based on a porous graphite rotor. Background Technology

[0002] Currently, commonly used aluminum-titanium-boron (ATiB) aluminum alloy grain refiners suffer from reduced refining effect and duration due to the tendency of the refining phase TiB2 to agglomerate. They also easily induce defects such as pinholes in aluminum foil and cracks in the sheet. In high-strength aluminum alloys containing Zr and / or Cr and / or Mn, TiB2 reacts with solute elements to form high-melting-point compounds, resulting in the loss of refining effect. Its refining effect is significantly reduced when refining high-silicon aluminum alloys, a phenomenon known as "Si poisoning." ATiB carbon (TiC) grain refiners, on the other hand, have attracted widespread attention because the TiC refining phase is fine, uniformly distributed, and does not easily agglomerate, exhibiting good coherence with Al, thus providing superior refining effects compared to ATiB refiners. However, C has poor wettability in Al, resulting in low conversion rates when directly adding carbon powder and insufficient TiC formation. Preparation through vigorous stirring or high-temperature reactions is costly and prone to generating harmful phases, limiting their application.

[0003] In recent years, researchers have developed new refining agents to solve these problems. For example, some use graphite powder or carbon powder as carbon sources, but carbon is difficult to penetrate, harmful phases are easily generated at high temperatures, and the cost is high. Some use aluminum-carbon and aluminum-titanium alloys as raw materials, which are simple to process but costly and have large sizes. Some use nano-sized TiC as carbon sources, but it is costly and has poor wettability with Al, making it difficult to distribute evenly. Some use Al-Al3BC master alloys as carbon sources, but the process is long, and byproducts such as AlB2 are easily generated, affecting the refining effect and costing high. Others use graphite powder and aluminum-boron master alloys at the same time, but carbon is difficult to penetrate, the preparation temperature is high, and the cost is high. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a method for preparing rare earth modified Al-Ti-CB refining agent based on loose graphite rotor, so as to solve at least one of the technical problems of poor carbon wettability, high preparation cost, TiB2 agglomeration and refining agent poisoning in existing refining agents.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] This invention provides a method for preparing a rare earth modified Al-Ti-CB refining agent based on a porous graphite rotor, comprising the following steps: Step 1: Add rare earth oxides to salt solvent melt, stir to form a liquid-solid mixture, cool to obtain a precursor; wherein, the weight ratio of the rare earth oxides to the salt solvent melt is (10-60):(30-80). Step 2: Prepare a porous graphite rotor; Prepare porous graphite rotors using porous graphite; Step 3: Prepare Al-Ti-CB alloy solution; The aluminum ingot is heated to form an aluminum melt. Potassium fluorotitanate and potassium fluoroborate are added to the aluminum melt and stirred with a loose graphite rotor. Then the precursor prepared in step 1 is added and the stirring is continued until the reaction is complete. The salt solvent melt is removed to obtain an Al-Ti-CB alloy solution. Step 4: Prepare rare earth modified Al-Ti-CB refining agent using Al-Ti-CB alloy solution.

[0007] Furthermore, in step 1 above, the salt solvent melt is prepared by heating cryolite, sodium chloride, and potassium chloride.

[0008] Furthermore, in step 1 above, the total weight of the salt solvent melt contains 65-85 wt% cryolite, 8-15 wt% sodium chloride, and 10-15 wt% potassium chloride.

[0009] Furthermore, in step 1 above, the rare earth element in the rare earth oxide is lanthanum and / or cerium.

[0010] Furthermore, in step 1 above, the weight ratio of rare earth oxides to salt solvent melt is (15-50):(30-80).

[0011] Furthermore, in step 2 above, the process of preparing a loose graphite rotor using loose graphite is as follows: the loose graphite is processed into an impeller-shaped rotor, then the impeller-shaped rotor is immersed in CeCl3 solution and stirred, then taken out and dried, and the loose graphite rotor is obtained after drying.

[0012] Furthermore, in step 2 above, the stirring time is 0.5-1.5 hours and the drying temperature is 100-150°C.

[0013] Furthermore, in step 2 above, the porosity of the loose graphite is 50-80%.

[0014] On the other hand, the present invention also provides a rare earth modified Al-Ti-CB refining agent based on a porous graphite rotor, the components of which, by mass percentage, include: Ti: 3.0-6.0 wt%, C: 0.01-0.5 wt%, B: 0.2-1.2 wt%, Ce and / or La: 0.05-1.5 wt%, with the balance being Al.

[0015] An application of a rare earth modified Al-Ti-CB refining agent based on a porous graphite rotor, which is suitable for high-Si cast aluminum alloys, high-strength aluminum alloys containing Zr / Cr, and recycled aluminum alloys.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: (1) This invention achieves in-situ synthesis and nanoscale dispersion of TiC / TiB2 dual-phase particles by modifying a porous graphite rotor with rare earth elements and synergizing the multiple effects of rare earth elements in aluminum melt, and endows the finer agent with excellent anti-poisoning properties.

[0017] (2) In this invention, loose graphite with a porosity of 60-70% is processed into a loose graphite rotor, which is then immersed in a CeCl3 solution to form a rare earth catalytic layer on the surface of the loose graphite rotor. When the loose graphite rotor rotates at high speed in the aluminum melt, the aluminum solution continuously washes over the loose graphite rotor, and the microbubble flow generated by the porous structure of the loose graphite rotor uniformly carries the carbon powder into the aluminum melt. The rare earth catalytic layer reduces the surface energy of carbon, and combined with the mechanism by which rare earth atoms in the aluminum melt reduce surface tension, purify impurities, and promote interfacial reactions, it significantly improves the wettability of carbon powder and aluminum melt, thereby greatly improving the carbon conversion rate and effectively solving the problems of poor carbon wettability and insufficient TiC generation in traditional processes.

[0018] (3) Based on improving carbon wettability, potassium fluorotitanate and potassium fluoroborate are added to the aluminum melt, and a loose graphite rotor is used for stirring, so that Ti, C, and B elements react in situ in the aluminum melt to generate fine and dispersed TiC and TiB2 biphase particles. The synergistic effect of rare earth elements ensures that TiC and TiB2 biphase particles can exist in a nanoscale dispersed state, avoiding the agglomeration problem of traditional TiB2, thereby greatly increasing the number of heterogeneous nucleation particles and significantly improving the grain refinement efficiency.

[0019] (4) On the surface of the TiB2 phase, free Ti atoms react with rare earth elements (RE) to form Ti2Al. 20 RE phase, Ti2Al 20 The RE phase not only effectively inhibits the growth and aggregation of the TiB2 phase, extending the shelf life of the refining agent, but more importantly, it prevents the adsorption of Si or Zr poisoning elements on the TiB2 phase surface, thus avoiding TiB2 from becoming ineffective due to poisoning. Simultaneously, the TiC phase itself has excellent resistance to Si or Zr poisoning. The combined effect of these two mechanisms allows the refining agent of this invention to maintain excellent refining effects in high-Si aluminum alloys and Zr / Cr-containing high-strength aluminum alloys, solving the problems of "Si poisoning" and refining effect failure in high-strength aluminum alloys associated with traditional refining agents.

[0020] (5) The grain refiner of the present invention refines the phase with small size, diffuse distribution, and uniform composition. The grain refiner of the present invention has a good refining effect (the grain size of aluminum after refining by the grain refiner is 68.29-77.44 μm), the preparation process is simple, and the preparation cost is lower.

[0021] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained through the embodiments described and the accompanying drawings, which are particularly pointed out. Attached Figure Description

[0022] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0023] Figure 1 The image shows the microstructure of the rare earth modified Al-Ti-CB refining agent prepared in Example 1. Figure 2 The image shows the TiB2 phase morphology in Example 1. Figure 3 The image shows the TiC phase morphology in Example 1. Figure 4a This is a metallographic structure diagram of aluminum raw materials; Figure 4b The image shows the metallographic structure of the refined aluminum obtained in Experiment Example 1. Figure 4c The image shows the metallographic structure of the refined aluminum obtained in Experiment Example 2. Figure 4d The image shows the metallographic structure of the refined aluminum obtained in Experiment Example 3. Figure 4e The image shows the metallographic structure of the refined aluminum obtained in Experiment Example 4. Figure 4f The metallographic structure of the refined aluminum obtained in Comparative Example 1 is shown in the diagram. Figure 5a Metallographic diagram of recycled A356 aluminum alloy (raw material); Figure 5b The image shows the metallographic structure of the refined recycled A356 aluminum alloy obtained in Example 5. Figure 5c The image shows the metallographic structure of the refined recycled A356 aluminum alloy obtained in Comparative Example 2. Detailed Implementation

[0024] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0025] This invention provides a method for preparing a rare earth modified Al-Ti-CB refining agent based on a porous graphite rotor, comprising the following steps: Step 1: Add rare earth oxides to salt solvent melt, stir to form a liquid-solid mixture, cool to obtain a precursor; wherein, the weight ratio of the rare earth oxides to the salt solvent melt is (10-60):(30-80). In step 1 above, the salt solvent melt is made by heating cryolite, sodium chloride and potassium chloride; the weight ratio of cryolite, sodium chloride and potassium chloride in the total weight of the salt solvent melt is 65-85 wt%: 8-15 wt%: 10-15 wt%.

[0026] In step 1 above, a medium-frequency induction furnace is used to heat the salt solvent melt at a temperature of 750℃-850℃, and the mixture is kept at this temperature and stirred for 0.5-1h to ensure that the molten salt has no solid phase and a uniform composition.

[0027] For example, the rare earth element in the rare earth oxide is lanthanum and / or cerium. As rare earth elements, lanthanum and cerium both have good chemical activity. In aluminum alloys, they can not only effectively improve the wettability of carbon and increase the activity of carbon, promoting the formation of TiC phase, but also combine with impurity elements (such as oxygen and sulfur) in the aluminum melt to form high-melting-point compounds, thus purifying the melt.

[0028] In step 1 above, the weight ratio of rare earth oxides to salt solvent melt is (15-50):(30-80).

[0029] In step 1 above, the content of rare earth oxides is 15 to 50 parts by weight (e.g., 15 parts by weight, 20 parts by weight, 30 parts by weight, 35 parts by weight, 45 parts by weight, 50 parts by weight).

[0030] In one embodiment, the rare earth element in the rare earth oxide is a mixture of lanthanum and cerium; wherein the content of lanthanum oxide is 5 to 20 (e.g., 5 parts by weight, 8 parts by weight, 10 parts by weight, 15 parts by weight, 18 parts by weight, 20 parts by weight) parts by weight, and the content of cerium oxide is 5 to 40 (e.g., 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight) parts by weight.

[0031] For example, the content of the salt solvent melt is 40 to 70 (e.g., 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 70 parts by weight) parts by weight.

[0032] For example, in the total weight of the salt solvent melt, the weight percentage of cryolite is 70-80 wt% (70 wt%, 72 wt%, 75 wt%, 77 wt%, 79 wt%, 80 wt%), the weight percentage of sodium chloride is 10-15 wt% (10 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%), and the weight percentage of potassium chloride is 11-14 wt% (11 wt%, 12 wt%, 14 wt%).

[0033] Compared with existing technologies, this invention utilizes a salt solvent melt composed of cryolite, sodium chloride, and potassium chloride as a solvent, which lowers the melting temperature of rare earth oxides and makes rare earth elements easier to disperse. Adding rare earth oxides to the salt solvent melt and stirring to form a liquid-solid mixture, followed by cooling of the mixture to form a precursor, facilitates more uniform dispersion of rare earth elements when subsequently added to the aluminum melt, avoiding excessively high local concentrations or agglomeration. Furthermore, the reduction of rare earth elements from their oxides during the fluoride salt reaction maximizes the effect of rare earths and improves the wettability of carbon and Al, increasing the activity of carbon and thus improving the overall reaction efficiency of the refining agent. Moreover, the improved dispersibility of rare earth elements helps prevent premature precipitation of the refining phase during preparation, ensuring the uniformity of the refining agent.

[0034] Step 2: Prepare a porous graphite rotor; Loose graphite is processed into an impeller-shaped rotor; then, the impeller-shaped rotor is immersed in a CeCl3 solution with a mass concentration of 3-6wt% and stirred for 0.5-1.5h. After being taken out, it is dried at 100-150℃ to obtain a loose graphite rotor.

[0035] It should be noted that the present invention processes the graphite rotor into an impeller-shaped rotor, which not only enhances its stirring effect, but also increases the contact area between the loose graphite rotor and the aluminum liquid, making it easier and more uniform for carbon to enter the aluminum liquid.

[0036] Preferably, in step 2 above, the mass concentration of the CeCl3 solution is 3.5-5.5 wt% (e.g., 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, 5.5 wt%), the impregnation and stirring time is 0.75-1.25 h (e.g., 0.75 h, 0.90 h, 1.0 h, 1.2 h, 1.25 h), and the drying temperature is 110-140 °C (110 °C, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C).

[0037] In step 2 above, the porosity of the loose graphite is 50-80% (e.g., 50%, 55%, 60%, 65%, 70%, 75%, 80%).

[0038] It is important to emphasize that this invention utilizes rare earth element modification, specifically in the following aspects: First, the formation of a rare earth catalytic layer: After impregnating the surface of the porous graphite rotor with CeCl3 solution, a rare earth catalytic layer can be formed on the surface of the porous graphite rotor. This rare earth catalytic layer can reduce the surface energy of carbon, improve the wettability of carbon and Al, and enhance the activity of carbon. Second, the multiple mechanisms of rare earth atoms: Rare earth atoms in the aluminum melt synergistically improve the wettability of carbon powder and aluminum melt through multiple mechanisms, including reducing the surface tension and interfacial energy of the melt, purifying impurities in the aluminum melt, promoting interfacial reactions to form a transition layer, and optimizing the fluidity of the aluminum melt. Furthermore, in-situ generation of Ti2Al... 20 RE phase: Free Ti atoms can form Ti2Al on the TiB2 surface. 20 RE phase, Ti2Al 20 The RE phase can inhibit the growth and aggregation of the TiB2 phase, while increasing its refinement and long-lasting effect. Furthermore, it has anti-poisoning effects: Ti2Al 20 The RE phase can prevent Si or Zr atoms from adsorbing on the TiB2 phase surface, and the TiC phase itself has a good anti-Si or Zr poisoning effect, thus giving the refining agent a good anti-refining agent poisoning effect.

[0039] Compared with the prior art, the present invention uses a loose graphite rotor as a carbon source. The rotation of the loose graphite rotor causes the aluminum solution to continuously wash it, incorporating the carbon powder on it into the aluminum solution, thereby significantly increasing the carbon-aluminum melt contact area, improving the carbon powder addition efficiency and carbon conversion rate (up to 80% or more), and reducing costs.

[0040] Step 3: Preparation of Al-Ti-CB alloy solution; The preparation process of the Al-Ti-CB alloy solution is as follows: An aluminum ingot is heated to form an aluminum melt; the temperature of the aluminum melt is controlled at 900-910℃ (e.g., 900℃, 902℃, 906℃, 910℃); potassium fluorotitanate and potassium fluoroborate are added to the aluminum melt and stirred using a loose graphite rotor; then the precursor prepared in step 1 is added, and stirring continues until the reaction is complete; the salt solvent melt is removed to obtain the Al-Ti-CB alloy solution; the chemical reaction formulas involved in this step are shown below: 3K2TiF6+6KBF4+10Al→3TiB2+9KAlF4+K3AlF6 (1) 3K2TiF6+13Al→3TiAl3+3KAlF4+K3AlF6 (2) RE2O3+2Al→2RE+Al2O3(3) Ti + C → TiC (4) RE + 2TiAl³ + 14Al → Ti₂Al 20 RE(5) It needs to be explained that reaction (1) is the reaction of potassium fluorotitanate (K2TiF6) and potassium fluoroborate (KBF4) in aluminum melt, which generates nano-sized TiB2 particles, KAlF4, and K3AlF6. This reaction is a key step in the in-situ generation of the TiB2 refining phase. The generated TiB2 has a small initial size, which lays the foundation for obtaining a dispersed TiB2 phase in the future. The byproducts KAlF4 and K3AlF6 form a low-melting-point salt melt (covering a protective layer) to prevent TiB2 oxidation. Reaction (2) indicates that potassium fluorotitanate decomposes in aluminum melt and reacts with aluminum to generate TiAl3 intermetallic compounds and fluoride salts. The generation of TiAl3 provides a titanium source for the subsequent reaction with carbon to generate TiC. On the other hand, TiAl3 can also serve as a nucleation core for Al grains, which plays a certain auxiliary role in refining. Reaction (3) is the process of rare earth oxides (RE2O3) being reduced by aluminum, generating free active rare earth atoms (RE) and Al2O3. The generated Al2O3 enters the slag or is adsorbed by TiB2 / TiC. The free active rare earth elements play a role in improving carbon wettability, purifying the melt, promoting TiC formation, and subsequently forming Ti2Al on the TiB2 surface. 20 The important role of the RE phase. Reaction (4) is the process by which titanium (mainly derived from the active Ti released by the decomposition of TiAl3 or unreacted free Ti atoms) and carbon (derived from the porous graphite rotor) directly combine under high temperature to form the TiC phase. The TiC phase has excellent refining properties. TiC and TiB2 form a composite nucleation core, which synergistically enhances the heterogeneous nucleation effect and improves the anti-fading ability of the refining agent. Reaction (5) is the reaction of rare earth elements (RE), TiAl3 and aluminum to form Ti2Al 20 The RE phase process. Ti2Al 20 RE preferentially precipitates in the melt, becoming a "parasitic nucleation substrate" for TiB2 / TiC, significantly increasing the nucleation rate; in addition, this Ti2Al 20 The RE phase can adsorb onto the surface of the TiB2 phase, effectively hindering the growth and aggregation of the TiB2 phase, thereby improving the dispersibility and long-lasting refinement of the TiB2 phase, while also endowing the refiner with good anti-poisoning ability. These synergistic chemical reactions ensure the fine and dispersed distribution of the TiB2 and TiC phases in the rare earth-modified Al-Ti-CB refiner prepared in this invention, as well as the beneficial effects of rare earth elements, ultimately achieving excellent refinement effect and anti-poisoning performance.

[0041] This invention adds potassium fluorotitanate and potassium fluoroborate to aluminum melt, and Ti and B atoms are replaced by fluoride salt reaction. The Ti and B atoms directly react with C atoms in situ to generate TiB2 and TiC, thereby realizing the in-situ synthesis and nanoscale dispersion of TiC / TiB2 two-phase particles.

[0042] In step 3 above, the weight ratio of aluminum ingot: potassium fluorotitanate: potassium fluoroborate: precursor: loose graphite rotor is 900-1000: 150-250: 40-70: 20-50: 0.2-10.

[0043] It needs to be explained that the weight ratio of aluminum ingot: potassium fluorotitanate: potassium fluoroborate: precursor: loose graphite rotor is controlled within the above range in this invention because: aluminum ingot, as the matrix material, accounts for 900-1000 parts by weight, providing a sufficient aluminum melt environment for the entire reaction system, ensuring that subsequent reactions can proceed fully, and serving as the main component of the final Al-Ti-CB alloy solution. Potassium fluorotitanate, as the titanium and fluorine source, is set at 150-250 parts by weight. This ratio can provide enough Ti atoms to ensure the formation of the TiB2 phase in reaction (1) and the formation of TiAl3 in reaction (2), thereby providing the necessary titanium source for the formation of the TiC phase in reaction (4). At the same time, the fluoride salts (such as KAlF4, K3AlF6) formed by fluoride ions and potassium ions can also play the role of covering and protecting the TiB2 phase, preventing the oxidation of the refined phase. Potassium fluoroborate, as a boron source, is present in a weight ratio of 40-70 parts. It works synergistically with potassium fluorotitanate to generate the TiB2 phase through reaction (1). This ratio ensures the effective precipitation and dispersion of the TiB2 phase by forming a suitable proportion of TiB2 with the Ti atoms in potassium fluorotitanate. The precursor, in a weight ratio of 20-50 parts, contains rare earth oxides that, after reduction by reaction (3), generate active rare earth atoms that can effectively improve the wettability of carbon, purify the melt, and participate in reaction (5) to generate Ti2Al. 20 RE phase, this dosage range can give full play to the above-mentioned beneficial effects of rare earth elements, while avoiding the excessive rare earth phase caused by excessive rare earth content, which would affect the alloy performance. Loose graphite rotor weight parts 0.2~10 parts, as carbon source, its dosage needs to be precisely controlled. Too little will not provide enough C atoms for reaction formula (4) to generate TiC phase, too much may lead to the residue of unreacted carbon, affecting the purity and performance of the refiner. This ratio range can ensure effective carbon supply and high carbon conversion rate, thereby generating an appropriate amount of dispersed TiC phase, which works synergistically with TiB2 phase to achieve good refinement effect. The components cooperate with each other within this weight ratio range, jointly promoting TiB2, TiC and Ti2Al 20 The generation, dispersion, and stabilization of key refining phases such as the RE phase ensure the excellent performance of the final refining agent.

[0044] Step 3 above includes: heating 900-1000 parts by weight of aluminum ingot to form aluminum melt; adding 150-250 parts by weight of potassium fluorotitanate and 40-70 parts by weight of potassium fluoroborate to the aluminum melt and stirring with a loose graphite rotor; then adding 20-50 parts by weight of the precursor prepared in step 1; continuing to stir until the reaction is complete; removing the salt solvent melt to obtain an Al-Ti-CB alloy solution.

[0045] For example, the content of aluminum melt is 920 to 980 parts by weight (e.g., 920 parts by weight, 940 parts by weight, 960 parts by weight, 960 parts by weight, 980 parts by weight), the content of potassium fluorotitanate is 160 to 230 parts by weight (e.g., 160 parts by weight, 170 parts by weight, 190 parts by weight, 200 parts by weight, 220 parts by weight, 230 parts by weight), and the content of potassium fluoroborate is 45 to 68 parts by weight (e.g., 45 parts by weight, 48 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 68 parts by weight).

[0046] Compared with the prior art, the present invention strictly controls the amount of potassium fluorotitanate and potassium fluoroborate added (150~250 parts by weight and 40~70 parts by weight respectively) and the amount of precursor added (20~50 parts by weight), which can ensure that the proportion of Ti, B, C and rare earth elements is appropriate, which is conducive to the formation of a large number of small and uniformly distributed TiC / TiB2 dual-phase particles.

[0047] In step 3 above, the amount of precursor added is 20 to 50 parts by weight (e.g., 20 parts by weight, 25 parts by weight, 27 parts by weight, 32 parts by weight, 35 parts by weight, 40 parts by weight, 46 parts by weight, 48 parts by weight, 50 parts by weight).

[0048] In step 3 above, the temperature of the aluminum melt is 800-950℃ (e.g., 800℃, 830℃, 850℃, 870℃, 880℃, 890℃, 950℃), and the rotation speed of the loose graphite rotor is 400-600 rpm (e.g., 400 rpm, 430 rpm, 450 rpm, 480 rpm, 550 rpm, 600 rpm).

[0049] It should be emphasized that this invention provides optimal kinetic and thermodynamic conditions for the in-situ reaction of Ti, C, and B elements in the aluminum melt by precisely controlling the temperature of the aluminum melt (800-950℃) and the rotor speed (400-600rpm), thereby promoting the formation of TiC and TiB2 two-phase particles.

[0050] It should be noted that if the rotation speed of the loose graphite rotor is too slow, the scouring effect of the aluminum solution on the graphite will be weak, resulting in less carbon powder entering the aluminum solution and thus extending the production cycle. If the rotation speed of the loose graphite rotor is too fast, the aluminum solution will splash out during stirring, posing a safety hazard. Simultaneously, this operation will increase the motor load, increase energy consumption, and shorten the motor's lifespan.

[0051] This invention improves grain refinement efficiency by strictly controlling the temperature of the aluminum melt (800-950℃), the rotation speed of the loose graphite rotor (400-600 rpm), the amount of potassium fluorotitanate and potassium fluoroborate added (150-250 parts by weight and 40-70 parts by weight, respectively), and the amount of precursor added. By optimizing these parameters, the catalytic and dispersing effects of rare earth elements are synergistically enhanced, thereby increasing the number of heterogeneous nucleation particles.

[0052] Step 4: Prepare rare earth modified Al-Ti-CB refining agent.

[0053] The Al-Ti-CB alloy solution prepared in step 3 is subjected to refining, degassing, and slag removal to obtain a slag-removed Al-Ti-CB alloy solution; the slag-removed alloy solution is then shaped to obtain an Al-Ti-CB refining agent.

[0054] This invention can effectively remove impurities and gases from Al-Ti-CB alloy solutions through refining, degassing, and slag removal operations, thereby improving the purity of the refining agent and avoiding defects in subsequent processing.

[0055] For example, the Al-Ti-CB alloy solution after slag removal is cast into shape.

[0056] For example, the Al-Ti-CB alloy solution after slag removal is cast into a rod, and then the rod is extruded. During extrusion, the extrusion temperature is 300-500°C and the extrusion speed is 15-30 mm / min.

[0057] For example, the extrusion molding temperature is 300°C, 365°C, 380°C, 400°C, 420°C, 500°C; the extrusion speed is 15 mm / min, 20 mm / min, 21 mm / min, 23 mm / min, 25 mm / min, 27 mm / min, 30 mm / min.

[0058] For example, the Al-Ti-CB alloy solution after slag removal is poured into trapezoidal ingots, rolled into thin rods, and then coiled. During rolling, the rolling temperature is 400–600°C (e.g., 400°C, 450°C, 500°C, 550°C, 600°C), and the continuous casting and rolling speed is 1–3 m / s (e.g., 1 m / s, 1.5 m / s, 2.0 m / s, 2.5 m / s, 3 m / s).

[0059] In step 4 above, the alloy solution is cast into trapezoidal ingots and rolled into thin rods with a diameter of 9-13 mm, such as 9.0 mm, 9.5 mm, 11 mm, and 12.5 mm, and then coiled. This form facilitates storage, transportation, and subsequent addition and dissolution in the aluminum alloy melt, improving the ease of use of the refining agent.

[0060] For example, during rolling, the rolling temperature is 450–550°C (e.g., 450°C, 480°C, 500°C, 520°C, 540°C, 550°C), and the rolling speed is 1.2–2.5 m / s (e.g., 1.2 m / s, 1.5 m / s, 1.8 m / s, 2.0 m / s, 2.3 m / s, 2.5 m / s).

[0061] This invention, through precise control of rolling temperature (400~600℃) and continuous casting and rolling speed (1~3m / s), helps to further optimize the distribution of the refining phase (TiC / TiB2 dual-phase particles) during the forming process, making it more uniformly dispersed, thereby ensuring the performance of the final refining agent.

[0062] In step 4 above, the alloy nucleation phases of the rare earth modified Al-Ti-CB refiner include TiAl3 phase, TiB2 phase, TiC phase, and Ti2Al phase. 20 One or more of the RE phases, with the matrix phase being the α-Al phase.

[0063] For example, the alloy nucleation phase of the rare earth modified Al-Ti-CB refiner is the TiAl3 phase, and the matrix phase is the α-Al phase; or, the alloy nucleation phase of the rare earth modified Al-Ti-CB refiner is the TiAl3 and TiB2 phases, and the matrix phase is the α-Al phase; or, the alloy nucleation phase of the rare earth modified Al-Ti-CB refiner is the TiAl3, TiB2, and TiC phases, and the matrix phase is the α-Al phase; or, the alloy nucleation phase of the rare earth modified Al-Ti-CB refiner is the TiAl3 and TiC phases, and the matrix phase is the α-Al phase; or, the alloy nucleation phase of the rare earth modified Al-Ti-CB refiner is the TiAl3 and Ti2Al phases. 20The RE phase is the matrix phase, which is the α-Al phase; or, the alloy nucleation phases of the rare earth modified Al-Ti-CB refiner are TiAl3 phase, TiB2 phase, TiC phase, and Ti2Al phase. 20 RE phase, with α-Al phase as the matrix phase.

[0064] For example, in step 4 above, the alloy nucleation phase of the rare earth modified Al-Ti-CB refiner is the TiB2 phase, and the matrix phase is the α-Al phase; or, the alloy nucleation phase of the rare earth modified Al-Ti-CB refiner is the TiB2 and TiC phases, and the matrix phase is the α-Al phase; or, the alloy nucleation phase of the rare earth modified Al-Ti-CB refiner is the TiB2 and Ti2Al phases. 20 RE phase, with α-Al phase as the matrix phase; or, the alloy nucleation phases of the rare earth modified Al-Ti-CB refiner are TiB2 phase, TiC phase, and Ti2Al phase. 20 RE phase, with α-Al phase as the matrix phase.

[0065] For example, in step 4 above, the alloy nucleation phase of the rare earth modified Al-Ti-CB refiner is the TiC phase, and the matrix phase is the α-Al phase; or, the alloy nucleation phase of the rare earth modified Al-Ti-CB refiner is a combination of the TiC phase and Ti2Al. 20 RE phase, with α-Al phase as the matrix phase.

[0066] For example, in step 4 above, the alloy nucleation phase of the rare earth modified Al-Ti-CB refining agent is Ti2Al. 20 RE phase, with α-Al phase as the matrix phase.

[0067] In step 4 above, the size of the TiAl3 phase is less than or equal to 20 μm; the size of the TiB2 phase is less than or equal to 1.5 μm; the size of the TiC phase is less than or equal to 1 μm; and the size of the Ti2Al phase is less than or equal to 1 μm. 20 The size of the RE phase is less than or equal to 10 μm.

[0068] This invention utilizes rare earth-modified porous graphite rotors and the synergistic effects of rare earth elements in aluminum melts to achieve in-situ synthesis and nanoscale dispersion of TiC / TiB2 two-phase particles. It also endows the refining agent with excellent anti-poisoning properties, successfully solving the technical problems of poor carbon wettability, high preparation cost, TiB2 agglomeration, and refining agent poisoning in traditional refining agents. It achieves small-sized, diffusely distributed, and uniformly composed refined phases with good anti-poisoning effects.

[0069] Compared with traditional preparation processes involving strong stirring or high-temperature reaction, the preparation method of this invention has a simpler process, lower energy consumption, avoids the generation of harmful Al4C3 phase, and significantly reduces preparation costs, providing a new path for the industrial application of aluminum alloy grain refinement technology.

[0070] On the other hand, the present invention also provides a rare earth modified Al-Ti-CB grain refiner, which is prepared by the above-mentioned preparation method of rare earth modified Al-Ti-CB grain refiner based on porous graphite rotor; the components of the rare earth modified Al-Ti-CB grain refiner (grain refiner) include, by mass percentage: Ti: 3.0-6.0 wt%, C: 0.01-0.5 wt%, B: 0.2-1.2 wt%, Ce and / or La: 0.05-1.5 wt%, with the balance being Al.

[0071] In the above rare earth modified Al-Ti-CB refining agent, the roles of each component are as follows: Ti, as a key alloying element in refining agents, mainly reacts with Al to form the TiAl3 phase. The TiAl3 phase can serve as a heterogeneous nucleation core for α-Al during the solidification of aluminum alloy melt. At the same time, Ti also participates in the formation of the TiB2 and TiC phases, which are important nucleation sites that directly affect the refining effect of the refining agent.

[0072] C is mainly used to form the TiC phase, which has a lattice constant close to that of α-Al. It is a very effective nucleation core and has good resistance to poisoning by elements such as Si, Zr, and Cr. It can maintain a stable nucleation effect in aluminum alloys with complex compositions.

[0073] B element mainly combines with Ti to form TiB2 phase. TiB2 phase is also one of the main nucleation phases in traditional Al-Ti-B refining agents and has excellent nucleation potential.

[0074] Rare earth elements Ce and / or La can promote the nucleation and refinement of the TiC phase, resulting in smaller and more uniform TiC phase size and enhanced nucleation efficiency. Furthermore, rare earth elements can react with Al and Ti to form Ti₂Al. 20 RE phase, Ti2Al 20 RE phase can preferentially adsorb on the surface of TiB2 phase, forming a physical barrier that effectively prevents the adsorption and poisoning reaction of harmful atoms such as Si, Zr, and Cr on the surface of TiB2 phase, thereby protecting the nucleation activity of TiB2 phase and improving the anti-poisoning performance of the refining agent.

[0075] Al is the matrix phase, and various nucleation particles are uniformly dispersed within it to form an integral refining agent alloy.

[0076] In one specific embodiment, the components of the above-mentioned rare earth modified Al-Ti-CB refining agent, by mass percentage, include: Ti: 3.2-5.5 wt%, C: 0.05-0.3 wt%, B: 0.5-1.1 wt%, Ce and / or La: 0.05-1.5 wt%, with the balance being Al.

[0077] In one specific embodiment, the components of the above-mentioned rare earth modified Al-Ti-CB refining agent, by mass percentage, include: Ti: 3.2-5.5 wt%, C: 0.05-0.3 wt%, B: 0.5-1.1 wt%, Ce and / or L: 0.1-1.2 wt%, with the balance being Al.

[0078] In one specific embodiment, the components of the above rare earth modified Al-Ti-CB refining agent include, by mass percentage: Ti: 3.5-5.0 wt%, C: 0.1-0.15 wt%, B: 0.8-1.0 wt%, Ce and / or La: 0.5-1.0 wt%.

[0079] The alloy nucleation phases of the grain refiner of the present invention include TiAl3 phase, TiB2 phase, TiC phase, and Ti2Al phase. 20 One or more of the RE phases, with the matrix phase being the α-Al phase.

[0080] For example, the size of the TiAl3 phase is less than or equal to 20 μm.

[0081] Preferably, the size of the TiAl3 phase is less than or equal to 10 μm.

[0082] For example, the size of the TiB2 phase is less than or equal to 1.5 μm.

[0083] Preferably, the size of the TiB2 phase is less than or equal to 0.5 μm.

[0084] For example, the size of the TiC phase is less than or equal to 1 μm, preferably less than or equal to 0.5 μm; Ti2Al 20 The size of the RE phase is less than or equal to 10 μm, preferably less than or equal to 5 μm.

[0085] According to the standard for average grain size of metals (GB / T6394-2017) - intercept method, the grain size was measured using the metallographic image analysis software AON-STUDIO. The grain size of aluminum refined by the grain refiner of this invention was found to be 68.29-77.44 μm.

[0086] The rare earth modified Al-Ti-CB grain refiner prepared by this invention has a small grain size, a diffuse distribution, and a uniform composition, and can refine the grain size of pure aluminum to ≤80μm.

[0087] The rare earth modified Al-Ti-CB refining agent of the present invention is suitable for high-Si cast aluminum alloys, high-strength aluminum alloys containing Zr and / or Cr and / or Mn, and recycled aluminum alloys.

[0088] For high-Si cast aluminum alloys: traditional aluminum-titanium-boron refining agents show a significant decrease in refining effect when refining high-silicon aluminum alloys (Si≥3.0wt.%), a phenomenon known as "Si poisoning" of the refining agent. The Ti2Al of this invention... 20 The RE phase can prevent Si atoms from adsorbing on the TiB2 phase surface, and the TiC phase itself has a good anti-Si poisoning effect. Therefore, the rare earth modified Al-Ti-CB refiner of the present invention can maintain excellent refining effect in high-Si aluminum alloys.

[0089] For high-strength aluminum alloys containing Zr and / or Cr and / or Mn: In high-strength aluminum alloys containing Zr and / or Cr and / or Mn, TiB2 readily reacts with solute elements to form high-melting-point compounds, resulting in complete failure of the refining effect. The Ti2Al of this invention... 20 The RE phase can prevent Zr / Cr atoms from adsorbing on the TiB2 phase surface, and the TiC phase itself also has a good anti-Zr and Cr poisoning effect, thus solving the problem of refinement effect failure in high-strength aluminum alloys containing Zr and / or Cr and / or Mn.

[0090] For recycled aluminum alloys: The complex composition of recycled aluminum alloys results in limited refining effects from traditional refining agents. The refining agent of this invention, due to its superior refining and anti-poisoning effects, can improve the refining effect of recycled aluminum while reducing the amount of refining agent required, thereby achieving cost reduction.

[0091] Example 1 The preparation process of the rare earth modified Al-Ti-CB refining agent based on the porous graphite rotor in this embodiment includes the following steps: Step 1: Place 200g cryolite, 35g sodium chloride, and 37g potassium chloride in a graphite crucible and heat to prepare a salt solvent melt. Add 30g cerium oxide to 70g of the salt solvent melt and stir to form a liquid-solid mixture. Cool the liquid-solid mixture to obtain the precursor.

[0092] Step 2: Using graphite with a porosity of 65%, process it into an impeller-shaped rotor; immerse the rotor in CeCl3 solution (mass concentration 5wt%) for 0.9h, remove it and dry it at 140℃ to obtain a loose graphite rotor.

[0093] By impregnating the porous graphite rotor with CeCl3 solution, a rare earth catalytic layer is formed on the surface, reducing the surface energy of carbon. This, in turn, works with rare earth atoms to reduce the surface tension and interfacial energy of the melt, thereby improving the wettability of the carbon powder and the molten aluminum. The porous structure of the porous graphite rotor and the microbubble flow generated by its rotation can uniformly carry the carbon powder into the molten aluminum, improving the utilization rate of the carbon powder.

[0094] Step 3: Form 944g of aluminum ingot into an aluminum melt, and control the temperature of the aluminum melt at 900℃. Add 200g of potassium fluorotitanate and 64g of potassium fluoroborate to the aluminum melt in batches and stir with a loose graphite rotor (450rpm, 880℃). After the potassium fluorotitanate and potassium fluoroborate have completely melted, add 27g of precursor. After the precursor has completely melted, continue stirring to remove the salt solvent from the melt, and obtain an alloy solution.

[0095] This step introduces Ti and B elements by adding potassium fluorotitanate and potassium fluoroborate, which react in situ with C elements introduced by the loose graphite rotor and rare earth elements introduced by the precursor in the aluminum melt to form TiC / TiB2 biphase particles, and utilize the synergistic effect of rare earth elements to achieve nanoscale dispersion.

[0096] Step 4: The alloy solution is refined, degassed, and slag removed sequentially, then cooled to 710℃ and cast into a trapezoidal ingot. The trapezoidal ingot is rolled into a thin rod with a diameter of 9.5mm, and then coiled. The rolling temperature is 500℃ and the speed is 2.0m / s to obtain a grain refiner.

[0097] Example 2 The preparation process of the rare earth modified Al-Ti-CB refining agent based on the porous graphite rotor in this embodiment includes the following steps: Step 1: Place 200g cryolite, 35g sodium chloride, and 37g potassium chloride in a graphite crucible and heat to prepare a salt solvent melt. Add 10g lanthanum oxide and 20g cerium oxide to 70g of salt solvent melt and stir to form a liquid-solid mixture. Cool the liquid-solid mixture to obtain the precursor.

[0098] Step 2: Using graphite with a porosity of 67%, process it into an impeller-shaped rotor; immerse the rotor in CeCl3 solution (mass concentration 6wt%) for 1.0 h, remove it and dry it at 120℃ to obtain a loose graphite rotor.

[0099] Step 3: Form 950g of aluminum ingot into an aluminum melt, and control the temperature of the aluminum melt at 900℃. Add 170g of potassium fluorotitanate and 49g of potassium fluoroborate to the aluminum melt in batches and stir with a loose graphite rotor (temperature 800℃, speed 400rpm). After the potassium fluorotitanate and potassium fluoroborate have completely melted, add 46g of precursor. After the precursor has completely melted, continue stirring to remove the salt solvent from the melt, and obtain an alloy solution.

[0100] Step 4: The alloy solution is refined, degassed, and slag removed sequentially, and then cooled to 730℃ and cast into ingots to obtain a product grain refiner.

[0101] Example 3 The preparation process of the rare earth modified Al-Ti-CB refining agent based on the porous graphite rotor in this embodiment includes the following steps: Step 1: Place 200g cryolite, 35g sodium chloride, and 37g potassium chloride in a graphite crucible and heat to prepare a salt solvent melt. Add 10g lanthanum oxide and 20g cerium oxide to 70g of salt solvent melt and stir to form a liquid-solid mixture. Cool the liquid-solid mixture to obtain the precursor.

[0102] Step 2: Using graphite with a porosity of 65%, process it into an impeller-shaped rotor; immerse the rotor in CeCl3 solution (mass concentration of 4wt%) for 1.1h, remove it and dry it at 140℃ to obtain a loose graphite rotor.

[0103] Step 3: Form 954g of aluminum ingot into an aluminum melt, and control the temperature of the aluminum melt at 900℃. Add 178g of potassium fluorotitanate and 51g of potassium fluoroborate to the aluminum melt in batches and stir using a loose graphite rotor (temperature 900℃, speed 500rpm). After the potassium fluorotitanate and potassium fluoroborate have completely melted, add 20g of precursor. After the precursor has completely melted, continue stirring to remove the salt solvent from the melt, and obtain an alloy solution.

[0104] Step 4: The alloy solution is refined, degassed, and slag removed sequentially, then cooled to 730℃ and cast into a rod. The rod is then hot-extruded into a thin rod with a diameter of 9.5mm; the extrusion temperature is 400℃ and the extrusion speed is 20mm / min, yielding a grain refiner.

[0105] Example 4 The preparation process of the rare earth modified Al-Ti-CB refining agent based on the porous graphite rotor in this embodiment includes the following steps: Step 1: Place 200g cryolite, 35g sodium chloride, and 37g potassium chloride in a graphite crucible and heat to prepare a salt solvent melt. Add 25g cerium oxide to 75g of salt solvent melt and stir to form a liquid-solid mixture. Cool the liquid-solid mixture to obtain the precursor.

[0106] Step 2: Using graphite with a porosity of 70%, process it into an impeller-shaped rotor; immerse the rotor in CeCl3 solution (mass concentration of 5wt%) for 1.2h, remove it and dry it at 130℃ to obtain a loose graphite rotor.

[0107] Step 3: Form 945g of aluminum ingot into an aluminum melt, and control the temperature of the aluminum melt at 900℃. Add 213g of potassium fluorotitanate and 63g of potassium fluoroborate to the aluminum melt in batches and stir using a loose graphite rotor (temperature 880℃, speed 600rpm). After the potassium fluorotitanate and potassium fluoroborate have completely melted, add 45g of precursor. After the precursor has completely melted, continue stirring to remove the salt solvent from the melt, and obtain an alloy solution.

[0108] Step 4: The alloy solution is refined, degassed, and slag removed sequentially, and then cooled to 730℃ and cast into ingots to obtain a product grain refiner.

[0109] The chemical composition of the grain refiners obtained in Examples 1-4 was analyzed using inductively coupled plasma atomic emission spectrometry (ICP). The results are shown in Table 1.

[0110] The grain refiners obtained in Examples 1 to 4 were analyzed using a Shimadzu ICPS-8100 inductively coupled plasma optical generator. The results are shown in Table 1 below.

[0111] Table 1. Chemical composition analysis of the grain refiners obtained in Examples 1-4

[0112] As shown in Table 1, the contents of the main elements Ti, B, C and rare earth elements Ce and / or La in the rare earth modified Al-Ti-CB refining agents prepared in Examples 1 to 4 are all within the range defined by this invention (the components of the rare earth modified Al-Ti-CB refining agent include, by mass percentage: Ti: 3.0-6.0 wt%, C: 0.01-0.5 wt%, B: 0.2-1.2 wt%, rare earth elements Ce and / or La: 0.05-1.5 wt%, with the balance being Al). The Ti content is between 3.52 wt% and 4.31 wt%, falling within the preferred range of 3.2 to 5.5 wt% (3.0-6.0 wt%), with some embodiments, such as Examples 1 and 4, being closer to the further preferred range of 3.5 to 5.0 wt%. The B content is between 0.41 wt% and 0.52 wt%, meeting the basic requirement of 0.2-1.2 wt%, and falling within the preferred range of 0.5 to 1.1 wt%, with some embodiments, such as Examples 1 and 4, also approaching the more preferred range of 0.8 to 1.0 wt%. The C content is between 0.10 wt% and 0.13 wt%, meeting the requirement of 0.01-0.5 wt%, falling within the preferred range of 0.05 to 0.3 wt%, and all falling within the more preferred range of 0.1 to 0.15 wt%. Regarding rare earth elements, Example 1 contains only Ce with a content of 0.60 wt%, Example 4 contains only Ce with a content of 0.55 wt%, and Example 2 contains La. Example 1 contains 0.35wt% La and 0.63wt% Ce, while Example 2 contains 0.19wt% La and 0.35wt% Ce. The total content of each rare earth element is in the range of 0.05-1.5wt%. The total rare earth content of Examples 1, 2, and 4 (Example 1: 0.60wt%, Example 2: 0.35+0.63=0.98wt%, Example 4: 0.55wt%) is in the preferred range of 0.5-1.0wt%, with the balance being Al. This indicates that the composition design of each example is reasonable and conforms to the setting of the rare earth modified Al-Ti-CB refining agent components in this invention, laying a solid compositional foundation for its subsequent excellent refining performance and anti-poisoning effect.

[0113] Comparative Example 1 945g of aluminum ingot was formed into an aluminum melt, and the temperature of the aluminum melt was controlled at 900℃. 213g of potassium fluorotitanate and 63g of potassium fluoroborate were added to the aluminum melt in batches and stirred using a common graphite rotor (porosity 30%, not impregnated with CeCl3 solution). After the potassium fluorotitanate and potassium fluoroborate were completely melted, the stirring reaction was continued to remove the salt solvent melt, and an alloy solution was obtained.

[0114] The alloy solution was successively refined, degassed, and slag removed, and then cooled to 730°C and cast into ingots to obtain a product grain refiner.

[0115] Experimental Example 1 Aluminum raw materials are melted to obtain aluminum melt; the grain refiner prepared in Example 1 is added to the aluminum melt and mixed evenly to obtain molten metal; a refining agent is added to the molten metal, and argon gas is simultaneously introduced into the molten metal for degassing using a degasser for 5 minutes, slag is removed, and then the temperature is lowered to 720°C for solidification and shaping to obtain refined aluminum (also known as aluminum material). The mass of the grain refiner added is 0.1% of the mass of the aluminum melt.

[0116] It should be noted that the aluminum raw material used in this embodiment is a high-strength aluminum alloy containing Cr, Zr and Mn, with an aluminum content of more than 99.7%, a Cr and Mn content of 0.05%, and a Zr content of 0.01%.

[0117] Experiment Example 2 The difference from Experimental Example 1 is that the grain refiner prepared in Example 2 was used.

[0118] Experimental Example 3 The difference from Experimental Example 1 is that the grain refiner prepared in Example 3 was used.

[0119] Experiment Example 4 The difference from Experimental Example 1 is that the grain refiner prepared in Example 4 was used.

[0120] Experimental Example 5 The difference from Experimental Example 1 is that the aluminum raw material in Experimental Example 1 was replaced with recycled aluminum alloy (A356 aluminum alloy, with a silicon content of 7-8%), and the grain refiner added was 0.5% of the mass of the recycled A356 aluminum alloy.

[0121] Comparative Experiment Example 1 The difference from Experimental Example 1 is that the grain refiner prepared in Comparative Example 1 was used.

[0122] Comparative Experiment Example 2 The difference from Comparative Experiment 1 is that the aluminum raw material was replaced with recycled A356 aluminum alloy, and the grain refiner added was 0.5% of the mass of the recycled A356 aluminum alloy.

[0123] The rare earth modified Al-Ti-CB grain refiners prepared in the above examples were subjected to elemental analysis, SEM analysis, metallographic analysis, and grain size measurement. Elemental analysis was performed using a Shimadzu ICPS-8100 inductively coupled plasma optical transilluminator (as shown in Table 1). SEM microstructure analysis was performed using a Zeiss SIGMA500 microscope (as shown in Table 1). Figures 1 to 3 (As shown); metallographic observation was performed using a Zeiss AxioImager2 metallographic microscope (as shown). Figures 4a to 4f(As shown in Table 3) According to the standard for average grain size of metals (GB / T6394-2017) - intercept method, the grain size was measured using the metallographic image analysis software AON-STUDIO.

[0124] Metallographic structure diagram of aluminum raw material as shown below Figure 4a As shown; the metallographic structure of the refined aluminum obtained in Experiment Example 1 is shown in the figure. Figure 4b As shown; the metallographic structure of the refined aluminum obtained in Experiment Example 2 is shown in the figure. Figure 4c As shown; the metallographic structure of the refined aluminum obtained in Experiment Example 3 is shown in the figure. Figure 4d As shown; the metallographic structure of the refined aluminum obtained in Experiment Example 4 is shown in the figure. Figure 4e As shown; the metallographic structure of the refined aluminum obtained in Comparative Example 1 is shown in the figure below. Figure 4f As shown in the figure; by comparison, it can be seen that the grain size of aluminum refined by the grain refiner obtained in Experimental Examples 1-4 of this invention is significantly smaller. The grain size measurement results of aluminum raw materials, experimental examples 1-4 and comparative experimental example 1 are shown in Table 2.

[0125] Table 2. Grain size measurement results of aluminum raw materials, experimental examples 1-4, and the refined aluminum of comparative experimental example 1.

[0126] As shown in Table 2, the grain size of blank aluminum (i.e., unrefined aluminum raw material) reached 423.2 μm. In contrast, the grain size of aluminum refined using the grain refiner of this invention was 68.29-77.44 μm, lower than 80 μm. While the grain size of aluminum refined with the grain refiner in Comparative Experiment 1 showed some refining effect, the effect was not as good as that of the grain refiner of this invention.

[0127] Recycled A356 aluminum alloy raw materials, such as Figure 5a As shown, the refined metallographic structure of the regenerated A356 aluminum alloy obtained in Experimental Example 5 is shown in the figure. Figure 5b The metallographic structure of the refined regenerated A356 aluminum alloy obtained in Comparative Experiment Example 2 is shown below. Figure 5c As can be seen from the comparison, the grain size of the recycled aluminum refined by the grain refiner obtained in the embodiments of the present invention is significantly smaller.

[0128] The grain size measurement results of the refined recycled A356 aluminum alloy raw material, Experimental Example 5, and Comparative Experimental Example 2 are shown in Table 3.

[0129] Table 3. Grain measurement results of refined recycled A356 aluminum alloy

[0130] The grain size of the unrefined recycled A356 aluminum alloy was 186.42 μm, while the grain size of the refined recycled A356 aluminum alloy obtained in Experimental Example 5 was 57.38 μm. The metallographic structure of the refined recycled A356 aluminum alloy obtained in Experimental Example 5 is shown below. Figure 5b .from Figure 5a and Figure 5c It can be seen that the traditional Al-Ti-B grain refiner has a weak grain refining effect on recycled A356 aluminum alloy. However, the rare earth modified Al-Ti-BC grain refiner prepared in this invention has a strong grain refining effect on recycled A356 aluminum alloy, solving the problem of insufficient grain refinement by the traditional Al-Ti-B grain refiner in recycled aluminum alloy.

[0131] In summary, the preparation method of this invention involves the in-situ generation of a finely dispersed TiB2 phase, and the formation of Ti2Al on the TiB2 surface using RE and free Ti atoms. 20 The RE phase hinders the growth and aggregation of the TiB2 phase, while simultaneously enhancing the long-term refining effect. Utilizing the natural dissolution of loose graphite at high temperatures, a carbon source is introduced at low cost. Simultaneously, rare earth elements are introduced to increase the wettability of C and Al, promoting the formation of the TiC phase with highly efficient refining effect. By fully utilizing the in-situ generation of fine and dispersed TiB2 and TiC phases, the number of heterogeneous nucleation particles in the refining agent is significantly increased, resulting in a substantial improvement in refining efficiency. Ti2Al is formed on the TiB2 surface. 20 The RE phase can prevent the poisoning of the refining agent caused by the adsorption of Si or Zr atoms on the TiB2 phase surface. The TiC phase itself has a good anti-Si or Zr poisoning effect. Therefore, the refining agent prepared by this invention has a good anti-refining agent poisoning effect, thereby expanding the application of the refining agent in the fields of high-Si aluminum alloys and Zr-containing aluminum alloys.

[0132] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing a rare earth modified Al-Ti-C-B refiner based on a loose graphite rotor, characterized by, Includes the following steps: Step 1: Add rare earth oxides to salt solvent melt, stir to form a liquid-solid mixture, cool to obtain a precursor; wherein, the weight ratio of the rare earth oxides to the salt solvent melt is (10-60):(30-80). Step 2: Prepare a loose graphite rotor using loose graphite; Step 3: Heat the aluminum ingot to form an aluminum melt, add potassium fluorotitanate and potassium fluoroborate to the aluminum melt and stir with the loose graphite rotor, then add the precursor prepared in step 1, continue stirring until the reaction is complete, remove the salt solvent melt, and obtain the Al-Ti-CB alloy solution. Step 4: Prepare rare earth modified Al-Ti-CB refining agent using the Al-Ti-CB alloy solution.

2. The method for producing a rare earth modified Al-Ti-C-B refiner based on a loose graphite rotor according to claim 1, characterized by, In step 1, the salt solvent melt is prepared by heating cryolite, sodium chloride, and potassium chloride.

3. The method for producing a rare earth modified Al-Ti-C-B refiner based on a loose graphite rotor according to claim 2, characterized by, In step 1, the total weight of the salt solvent melt contains 65-85 wt% cryolite, 8-15 wt% sodium chloride, and 10-15 wt% potassium chloride.

4. The preparation method of rare earth modified Al-Ti-CB refining agent based on porous graphite rotor according to claim 1, characterized in that, In step 1, the rare earth element in the rare earth oxide is lanthanum and / or cerium.

5. The preparation method of rare earth modified Al-Ti-CB refining agent based on porous graphite rotor according to claim 4, characterized in that, In step 1, the weight ratio of the rare earth oxide to the salt solvent melt is (15-50):(30-80).

6. The preparation method of rare earth modified Al-Ti-CB refining agent based on porous graphite rotor according to claim 4, characterized in that, In step 2, the process of preparing a loose graphite rotor using loose graphite is as follows: the loose graphite is processed into an impeller-shaped rotor, then the impeller-shaped rotor is immersed in CeCl3 solution and stirred, then taken out and dried, and the loose graphite rotor is obtained after drying.

7. The preparation method of rare earth modified Al-Ti-CB refining agent based on porous graphite rotor according to claim 6, characterized in that, In step 2, the stirring time is 0.5-1.5 hours and the drying temperature is 100-150°C.

8. The preparation method of rare earth modified Al-Ti-CB refining agent based on porous graphite rotor according to claim 6, characterized in that, In step 2, the porosity of the loose graphite is 50-80%.

9. A rare earth modified Al-Ti-CB refining agent based on a porous graphite rotor, characterized in that, It was prepared by the method for preparing rare earth modified Al-Ti-CB refining agent based on porous graphite rotor as described in any one of claims 1 to 8; The rare earth modified Al-Ti-CB refining agent comprises, by mass percentage: Ti: 3.0-6.0 wt%, C: 0.01-0.5 wt%, B: 0.2-1.2 wt%, Ce and / or La: 0.05-1.5 wt%, with the balance being Al.

10. An application of a rare earth modified Al-Ti-CB refining agent based on a porous graphite rotor, characterized in that, The rare earth modified Al-Ti-CB refining agent is prepared by the method for preparing rare earth modified Al-Ti-CB refining agent based on porous graphite rotor as described in any one of claims 1 to 8. Alternatively, the rare earth modified Al-Ti-CB refining agent based on a porous graphite rotor as described in claim 9 may be used; The rare earth modified Al-Ti-CB refining agent based on porous graphite rotor is suitable for high-Si cast aluminum alloys, high-strength aluminum alloys containing Zr / Cr, and recycled aluminum alloys.

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