Low-temperature adaptive rare earth-ceramic composite titanium additive and application thereof in aluminum alloy

Abstract

The invention relates to the technical field of alloy additives, and discloses a low-temperature adaptive rare earth-ceramic composite titanium additive and application of the low-temperature adaptive rare earth-ceramic composite titanium additive in aluminum alloy. Comprising 45-55 parts of plasma activated titanium powder, 3-6 parts of yttrium oxide, 2-4 parts of boron nitride, 5-8 parts of a modified straw carbon dispersing agent, 25-35 parts of aluminum magnesium alloy powder and 1-2 parts of a low-fluorine refining agent. Plasma activated nano titanium powder is used as a core, rare earth (yttrium oxide) and a ceramic phase (boron nitride) are matched, and the high-temperature oxidation weight increment of the aluminum alloy is remarkably reduced through the formed BN isolation layer and yttrium oxide grain boundary strengthening, the BN layer hinders oxygen atom diffusion, yttrium oxide forms a compact Y-Al-O composite oxide film, oxidation is doubly blocked, and the aluminum alloy has the high-temperature oxidation resistance and the high-temperature oxidation resistance. The problem that a traditional additive is insufficient in high-temperature resistance is solved, and the additive has important significance in the industry.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloy additive, in particular to a low-temperature adaptive rare earth-ceramic composite titanium additive and its application in aluminum alloy. BACKGROUND

[0002] Aluminum alloy is widely used in industrial fields due to its light weight, high strength, easy processing and other advantages. Titanium additive, as a core auxiliary material for the preparation of high-end aluminum alloy, can significantly optimize the mechanical properties and high-temperature stability of aluminum alloy through grain refinement and interface bonding force strengthening, and widely supports the needs of key fields such as aerospace and high-end manufacturing. However, the current mainstream products have the following prominent shortcomings: the dispersion of traditional Al-Ti-B refiner is poor during low-temperature smelting, which easily leads to uneven grain refinement; high-titanium recovery rate titanium agent improves titanium utilization rate, but it is difficult to match the high-temperature service requirements (800℃ long-term service) in the aerospace field due to insufficient high-temperature oxidation resistance; TiC reinforced titanium additive is limited by complex preparation process and high cost, and the use of fluorine-containing refining agent causes environmental pollution problems.

[0003] Therefore, it is necessary to develop a green composite titanium additive that is suitable for low-temperature smelting conditions, has high titanium recovery rate and excellent high-temperature oxidation resistance, and accurately solves the three core pain points of high energy consumption, insufficient key performance and excessive pollution emission in existing technologies, to support the quality improvement and efficiency increase of high-end aluminum alloy materials and the upgrading of green manufacturing. SUMMARY

[0004] The present application aims to provide a low-temperature adaptive rare earth-ceramic composite titanium additive and its application in aluminum alloy, to solve the problems of high smelting temperature of the additive, unsatisfactory titanium recovery rate, and difficulty in meeting the aerospace service requirements of the high-temperature performance of the prepared aluminum alloy in the prior art.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a low-temperature adaptive rare earth-ceramic composite titanium additive, the raw materials are calculated by mass parts, including plasma activated titanium powder 45-55 parts, yttrium oxide 3-6 parts, boron nitride 2-4 parts, modified straw carbon dispersant 5-8 parts, aluminum-magnesium alloy powder 25-35 parts, and low-fluorine refining agent 1-2 parts. Preferably, as an improvement, the particle size of the plasma activated titanium powder is 20-80nm, and the purity is ≥99.8%.

[0006] Preferably, as an improvement, the particle size of the yttrium oxide is 50-100nm, and the purity is ≥99.5%.

[0007] Preferably, as an improvement, the boron nitride has a flaky structure with a particle size of 100-200nm.

[0008] Preferably, as an improvement, the modified straw charcoal dispersant is a straw charcoal fine silane coupling agent modification.

[0009] Preferably, as an improvement, the low-fluorine refining agent is a calcium fluoride and sodium carbonate compound system, and the mass ratio of calcium fluoride to sodium carbonate is 1:2.

[0010] Preferably, as an improvement, a preparation method of a low-temperature adaptive rare earth-ceramic composite titanium additive includes the following steps: Step one, titanium powder activation: plasma treatment of titanium powder to obtain activated titanium powder; Step two, composite modification: according to the proportion, take yttria, boron nitride, and modified straw charcoal dispersant, stir and mix to obtain a composite modifier; Step three, mixing and molding: add activated titanium powder, aluminum-magnesium alloy powder, and low-fluorine refining agent, continue to stir, and then dry and crush to obtain a rare earth-ceramic composite titanium additive.

[0011] Preferably, as an improvement, in step one, the power of plasma treatment is 600-800W, and the treatment time is 15-20min.

[0012] Preferably, as an improvement, in step two, the temperature of composite modification is 80-100℃, the treatment time is 30-40min, and the stirring speed of the modification process is 500-600r / min.

[0013] Preferably, as an improvement, a low-temperature adaptive rare earth-ceramic composite titanium additive is applied in aluminum alloy, and the addition amount of the rare earth-ceramic composite titanium additive is 2-3%, and the additive is added in batches.

[0014] The principle and advantages of the scheme are: in actual application, in view of the problems of high melting temperature of the additive, unsatisfactory titanium recovery rate, and difficult to meet the aerospace service requirements of the high-temperature performance of the prepared aluminum alloy in the prior art, the formula and preparation process of the titanium additive are comprehensively optimized and upgraded: taking plasma activated nano titanium powder as the core, matching rare earth (yttria) and ceramic phase (boron nitride), using rare earth segregation grain boundary to inhibit grain growth and ceramic phase to form isolation layer to reduce titanium burning loss, and synergistically improving the refinement effect and high temperature resistance.

[0015] Specifically, considering that the traditional micron-sized titanium powder has an oxide film on the surface, the interface bonding energy with the aluminum matrix is low, easy to agglomerate, and the reaction is incomplete. The present solution realizes two key changes through argon atmosphere plasma (600-800W, 15-20min) treatment: first, breaking the titanium powder surface oxide film, exposing high activity metal titanium atoms, significantly improving the interface bonding energy, and strengthening the metallurgical bonding with the aluminum matrix; second, the nano-sized particle size (20-80nm) increases the specific surface area, so that the titanium powder forms more nucleation cores in the aluminum liquid, laying the foundation for grain refinement. In addition, in terms of formula composition, the present technical solution complexly adds rare earth-ceramic phase, yttrium oxide as rare earth oxide, which has a significant difference in atomic radius (0.18nm) with aluminum atoms (0.143nm), preferentially segregates at the grain boundaries of aluminum at high temperature, forms a "pinning effect", hinders grain growth, and at the same time reduces the grain boundary mobility, solving the problem of uneven grain refinement of traditional additives. The flaky structure of boron carbide (particle size 100-200nm) forms a physical isolation layer in the aluminum liquid, which has low interlayer bonding energy and can wrap titanium powder particles, reducing the reaction loss of titanium and oxygen and nitrogen at high temperature, while the high thermal conductivity of BN can quickly conduct local heat to avoid titanium powder agglomeration. In the optimization of the refining agent, the present technical solution creatively replaces the traditional hexafluoroethane with a complex system of calcium fluoride and sodium carbonate, which decomposes the fluoride by the alkalinity of sodium carbonate, reduces the volatilization amount of fluoride, and the generated CaCO3 can be used as a nucleating agent to assist in grain refinement, realizing the dual functions of refining and refining.

[0016] In terms of the use process of the additive, the present technical solution adds the composite additive in batches, 60% of the first added additive forms initial nucleation sites in the aluminum liquid, and is uniformly distributed after stirring for 10-15min; the second addition of 40% of the additive fills the local nucleation vacancy, avoiding the problems of "local over-concentration agglomeration and local under-concentration without refinement", and finally realizing the titanium element recovery rate of 98.5-99%.

[0017] In summary, the beneficial effects of the present technical solution are: 1. Titanium utilization rate is extremely improved: through activation treatment and segmented addition, the titanium element recovery rate reaches 98.5-99%, which is 2.5-3.5 percentage points higher than the existing high recovery rate titanium agent, reducing the waste of titanium resources.

[0018] 2. Overall optimization of alloy performance: the tensile strength of aluminum alloy is improved by 25-30%, and the weight gain after 800℃ high temperature oxidation for 100h is only 0.3-0.35mg / cm 2 , which is much higher than the high temperature resistance of existing titanium additives.

[0019] 3. Energy consumption and pollution are reduced: it is suitable for low-temperature smelting at 680-720℃, which significantly reduces energy consumption compared to traditional processes; the dosage of low-fluorine refining agent is reduced by nearly 70%, and the amount of dross is reduced by nearly 40%, meeting the needs of green production.

[0020] 4. Wide applicability to various scenarios: It can be directly applied to the preparation of aluminum alloys for high-temperature service in aviation and aluminum alloy powders for 3D printing, solving the problem of poor application of existing additives. Detailed Implementation

[0021] The following detailed description provides further details on specific embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; and the materials and reagents used are all commercially available.

[0022] Overview of the plan: A low-temperature adaptable rare earth-ceramic composite titanium additive, by weight, comprises the following raw materials: 45-55 parts plasma-activated titanium powder, 3-6 parts yttrium oxide (Y2O3), 2-4 parts boron nitride (BN), 5-8 parts modified straw char dispersant, 25-35 parts aluminum-magnesium alloy powder, and 1-2 parts low-fluorine refining agent.

[0023] The plasma-activated titanium powder has a particle size of 20-80nm and a purity of ≥99.8%. It is activated by plasma treatment in an argon atmosphere for 15-20 minutes to activate its surface activity.

[0024] Yttrium oxide has a particle size of 50-100 nm and a purity of ≥99.5%. It can segregate at grain boundaries to inhibit grain growth.

[0025] Boron nitride has a plate-like structure with a particle size of 100-200 nm, forming an isolation layer to reduce the loss of titanium elements due to burning.

[0026] In the modified straw char dispersant, the straw char is calcined at 1000-1200℃ and then modified with a silane coupling agent to improve the dispersibility of titanium powder in molten aluminum.

[0027] The low-fluorine refining agent is a compound system of calcium fluoride and sodium carbonate, with a mass ratio of calcium fluoride to sodium carbonate of 1:2.

[0028] A method for preparing a low-temperature adaptable rare earth-ceramic composite titanium additive includes the following steps: Step 1: Titanium powder activation: Place the titanium powder in a plasma treatment device, under an argon atmosphere and a power of 600-800W, and treat for 15-20 minutes to obtain activated titanium powder. Step 2, Composite Modification: Weigh yttrium oxide, boron nitride, and modified straw char dispersant according to the formula, add them to a high-speed mixer, stir at 80-100℃ and 500-600 r / min for 30-40 min to obtain the composite modifier; Step 3, Mixing and Molding: Add activated titanium powder, aluminum-magnesium alloy powder, and low-fluorine refining agent, continue stirring for 20-30 minutes, then dry at 180-220℃ for 4-5 hours, and pulverize to 100-200 mesh to obtain rare earth-ceramic composite titanium additive.

[0029] A method for applying a low-temperature adaptable rare earth-ceramic composite titanium additive in aluminum alloys includes the following steps: S1. Low-temperature smelting: Place aluminum ingots into a graphite crucible, put it in a box-type resistance furnace, and heat it to 680-720℃ at 8-10℃ / min to melt it and obtain molten aluminum. Stir to remove impurities. S2. Segmented addition: Add titanium additive in two batches at a ratio of 2-3% of the aluminum liquid mass (add 60% for the first time, stir for 10-15 minutes; add the remaining 40% after a 5-minute interval, stir for 8-10 minutes at a speed of 120-150 r / min). S3. Refining and heat preservation: After adding additives, refine at 700-710℃ for 15-20 minutes, then heat preservation for 25-30 minutes, under nitrogen atmosphere protection, and then cast to obtain high-performance aluminum alloy.

[0030] Example 1 A low-temperature adaptable rare earth-ceramic composite titanium additive, by weight, comprises the following raw materials: 50 parts plasma-activated titanium powder, 5 parts yttrium oxide (Y2O3), 3 parts boron nitride (BN), 6 parts modified straw char dispersant, 30 parts aluminum-magnesium alloy powder, and 1.5 parts low-fluorine refining agent.

[0031] The plasma-activated titanium powder has a particle size of 60nm and a purity of ≥99.8%. It is treated with argon atmosphere plasma for 20min to activate its surface activity.

[0032] Yttrium oxide has a particle size of 80 nm and a purity of ≥99.5%, and can segregate at grain boundaries to inhibit grain growth.

[0033] Boron nitride has a plate-like structure with a particle size of 150 nm, forming an isolation layer to reduce the burning loss of titanium.

[0034] In the modified straw char dispersant, the straw char is calcined at 1200℃ and then modified with a silane coupling agent to improve the dispersibility of titanium powder in molten aluminum.

[0035] The low-fluorine refining agent is a compound system of calcium fluoride and sodium carbonate, with a mass ratio of calcium fluoride to sodium carbonate of 1:2.

[0036] A method for preparing a low-temperature adaptable rare earth-ceramic composite titanium additive includes the following steps: Step 1: Titanium powder activation: Place the titanium powder in a plasma treatment device, under an argon atmosphere and a power of 750W, and treat for 18 minutes to obtain activated titanium powder. Step 2, Composite Modification: Weigh yttrium oxide, boron nitride, and modified straw char dispersant according to the formula, add them to a high-speed mixer, stir at 90℃ and 550 r / min for 35 min to obtain the composite modifier; Step 3, Mixing and Molding: Add activated titanium powder, aluminum-magnesium alloy powder, and low-fluorine refining agent, continue stirring for 20-30 minutes, then dry at 200℃ for 4.5 hours, and pulverize to 150 mesh to obtain rare earth-ceramic composite titanium additive.

[0037] A method for applying a low-temperature adaptable rare earth-ceramic composite titanium additive in aluminum alloys includes the following steps: S1. Low-temperature smelting: Place aluminum ingots into a graphite crucible, put it into a box-type resistance furnace, and heat it to 700℃ at 8℃ / min to melt it and obtain molten aluminum. Stir to remove impurities. S2. Segmented addition: Add titanium additive in two batches at a ratio of 2.2% of the aluminum liquid mass (add 60% for the first time, stir for 10-15 minutes; add the remaining 40% after a 5-minute interval, stir for 8-10 minutes at a speed of 120-150 r / min). S3. Refining and heat preservation: After adding additives, refine at 705℃ for 18 minutes, then heat preservation for 26 minutes, under nitrogen atmosphere protection, and then cast to obtain high-performance aluminum alloy.

[0038] Example 2 A low-temperature adaptable rare earth-ceramic composite titanium additive, by weight, comprises the following raw materials: 45 parts plasma-activated titanium powder, 6 parts yttrium oxide (Y2O3), 2 parts boron nitride (BN), 8 parts modified straw char dispersant, 25 parts aluminum-magnesium alloy powder, and 2 parts low-fluorine refining agent.

[0039] A method for preparing a low-temperature adaptable rare earth-ceramic composite titanium additive includes the following steps: Step 1: Titanium powder activation: Place the titanium powder in a plasma treatment device, under an argon atmosphere and a power of 600W, and treat for 20 minutes to obtain activated titanium powder; Step 2, Composite Modification: Weigh yttrium oxide, boron nitride, and modified straw char dispersant according to the formula, add them to a high-speed mixer, stir at 100℃ and 500 r / min for 40 min to obtain the composite modifier; Step 3, Mixing and Molding: Add activated titanium powder, aluminum-magnesium alloy powder, and low-fluorine refining agent, continue stirring for 20-30 minutes, then dry at 180℃ for 5 hours, and pulverize to 200 mesh to obtain rare earth-ceramic composite titanium additive.

[0040] A method for applying a low-temperature adaptable rare earth-ceramic composite titanium additive in aluminum alloys includes the following steps: S1. Low-temperature smelting: Place aluminum ingots into a graphite crucible, put it in a box-type resistance furnace, and heat it to 680°C at 8°C / min to melt it and obtain molten aluminum. Stir to remove impurities. S2. Segmented addition: Add titanium additive in two batches at a ratio of 3% of the aluminum liquid mass (add 60% for the first time, stir for 10-15 minutes; add the remaining 40% after a 5-minute interval, stir for 8-10 minutes at a speed of 120-150 r / min). S3. Refining and heat preservation: After adding additives, refine at 700℃ for 20 minutes, then heat preservation for 30 minutes, under nitrogen atmosphere protection, and then cast to obtain high-performance aluminum alloy.

[0041] Example 3 A low-temperature adaptable rare earth-ceramic composite titanium additive, by weight, comprises the following raw materials: 55 parts plasma-activated titanium powder, 3 parts yttrium oxide (Y2O3), 2 parts boron nitride (BN), 8 parts modified straw char dispersant, 35 parts aluminum-magnesium alloy powder, and 1 part low-fluorine refining agent.

[0042] A method for preparing a low-temperature adaptable rare earth-ceramic composite titanium additive includes the following steps: Step 1: Titanium powder activation: Place the titanium powder in a plasma treatment device, under an argon atmosphere and a power of 800W, and treat for 15 minutes to obtain activated titanium powder. Step 2, Composite Modification: Weigh yttrium oxide, boron nitride, and modified straw char dispersant according to the formula, add them to a high-speed mixer, stir for 30 minutes at 80℃ and 600 r / min to obtain the composite modifier; Step 3, Mixing and Molding: Add activated titanium powder, aluminum-magnesium alloy powder, and low-fluorine refining agent, continue stirring for 20-30 minutes, then dry at 220℃ for 4 hours, and pulverize to 100 mesh to obtain rare earth-ceramic composite titanium additive.

[0043] A method for applying a low-temperature adaptable rare earth-ceramic composite titanium additive in aluminum alloys includes the following steps: S1. Low-temperature smelting: Place aluminum ingots into a graphite crucible, put it into a box-type resistance furnace, and heat it to 720°C at 10°C / min to melt it and obtain molten aluminum. Stir to remove impurities. S2. Segmented addition: Add titanium additive in two batches at a ratio of 2% of the aluminum liquid mass (add 60% for the first time, stir for 10-15 minutes; add the remaining 40% after a 5-minute interval, stir for 8-10 minutes at a speed of 120-150 r / min). S3. Refining and heat preservation: After adding additives, refine at 710℃ for 15-20 minutes, then heat preservation for 25-30 minutes, under nitrogen atmosphere protection, and then cast to obtain high-performance aluminum alloy.

[0044] Comparative Example 1 The difference between this comparative example and Example 1 is that the titanium powder in this comparative example was not subjected to plasma treatment.

[0045] Comparative Example 2 The difference between this comparative example and Example 1 is that yttrium oxide is replaced with an equal amount of lanthanum oxide in this comparative example.

[0046] Comparative Example 3 The difference between this comparative example and Example 1 is that in this comparative example, boron nitride is replaced with an equal amount of silicon nitride.

[0047] Comparative Example 4 The difference between this comparative example and Example 1 is that no modified straw char dispersant was added in this comparative example.

[0048] Comparative Example 5 The difference between this comparative example and Example 1 is that the refining agent in this comparative example is calcium fluoride.

[0049] Comparative Example 6 The difference between this comparative example and Example 1 is that the refining agent in this comparative example is hexafluoroethane.

[0050] Comparative Example 7 The difference between this comparative example and Example 1 is that in this comparative example, the mass ratio of calcium fluoride to sodium carbonate in the refining agent is 1:1.

[0051] Comparative Example 8 The difference between this comparative example and Example 1 is that in this comparative example, the composite additive was not added in batches, but all at once.

[0052] Experimental Performance Testing The aluminum alloys prepared in the above embodiments and comparative examples were subjected to performance tests. The test indicators and test methods are shown in Table 1. Table 1

[0053] Each group underwent three repeated tests. The test results are detailed in Table 2. Table 2

[0054] The titanium recovery rate (98.5%-99%), tensile strength (328-336 MPa), and high-temperature oxidation resistance (0.32-0.35 mg / cm³) of the various embodiments of the present invention are as follows: 2 Both are significantly better than the comparative example.

[0055] Comparative Example 1: Without plasma activation, the oxide film on the titanium powder surface was not removed, resulting in severe agglomeration. The titanium recovery rate was only 92.3%, and the weight gain from high-temperature oxidation reached 0.89 mg / cm³. 2 In Comparative Examples 2-3, replacing the rare earth / ceramic phase, lanthanum oxide instead of yttrium oxide, and silicon nitride instead of boron nitride weakened the grain boundary pinning effect and the protective effect of the isolation layer, resulting in a 15%-18% decrease in tensile strength and an increase in oxidation weight gain of over 70%. In Comparative Example 4, without modified straw charcoal dispersant, uneven titanium powder dispersion and localized agglomeration led to a decrease in recovery rate and strength, with "poor" dispersion uniformity. Data from Comparative Examples 5-7 indicate that single calcium fluoride, traditional hexafluoroethane, or inappropriate compounding ratios resulted in poor fluorine pollution control and weakened nucleation assistance, performing worse than the low-fluorine compounding system in the examples.

[0056] In Comparative Example 8, the composite additive was added all at once during use, resulting in uneven distribution of nucleation sites, a titanium recovery rate of only 91.7%, and a significant decrease in both strength and oxidation resistance.

[0057] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A low-temperature adaptable rare earth-ceramic composite titanium additive, characterized in that: The raw materials, by weight, include 45-55 parts plasma-activated titanium powder, 3-6 parts yttrium oxide, 2-4 parts boron nitride, 5-8 parts modified straw charcoal dispersant, 25-35 parts aluminum-magnesium alloy powder, and 1-2 parts low-fluorine refining agent.

2. The low-temperature adaptable rare earth-ceramic composite titanium additive according to claim 1, characterized in that: The plasma-activated titanium powder has a particle size of 20-80 nm and a purity of ≥99.8%.

3. The low-temperature adaptable rare earth-ceramic composite titanium additive according to claim 2, characterized in that: The yttrium oxide has a particle size of 50-100 nm and a purity of ≥99.5%.

4. The low-temperature adaptable rare earth-ceramic composite titanium additive according to claim 3, characterized in that: The boron nitride has a plate-like structure with a particle size of 100-200 nm.

5. The low-temperature adaptable rare earth-ceramic composite titanium additive according to claim 4, characterized in that: The modified straw char dispersant is obtained by modifying straw char concentrate silane coupling agent.

6. The low-temperature adaptable rare earth-ceramic composite titanium additive according to claim 5, characterized in that: The low-fluorine refining agent is a compound system of calcium fluoride and sodium carbonate, with a mass ratio of calcium fluoride to sodium carbonate of 1:

2.

7. A method for preparing a low-temperature adaptable rare earth-ceramic composite titanium additive according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: Titanium powder activation: Titanium powder is subjected to plasma treatment to obtain activated titanium powder; Step 2, Composite Modification: Weigh yttrium oxide, boron nitride, and modified straw char dispersant according to the formula, stir and mix to obtain the composite modifier; Step 3, Mixing and Molding: Add activated titanium powder, aluminum-magnesium alloy powder, and low-fluorine refining agent, continue stirring, then dry and pulverize to obtain rare earth-ceramic composite titanium additive.

8. The preparation method of a low-temperature adaptable rare earth-ceramic composite titanium additive according to claim 7, characterized in that: In step one, the plasma treatment power is 600-800W, and the treatment time is 15-20 minutes.

9. The preparation method of a low-temperature adaptable rare earth-ceramic composite titanium additive according to claim 8, characterized in that: In step two, the temperature for composite modification is 80-100℃, the treatment time is 30-40 min, and the stirring speed during the modification process is 500-600 r / min.

10. The application of a low-temperature adaptable rare earth-ceramic composite titanium additive according to any one of claims 1 to 6 in aluminum alloys, characterized in that: The addition amount of rare earth-ceramic composite titanium additive is 2-3%, and the additive is added in batches.

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