Method for preparing copper-manganese alloy by using copper-manganese intermediate alloy

Abstract

The invention relates to a method for preparing a copper-manganese alloy by using a copper-manganese intermediate alloy, which comprises the following steps: adding ultra-high-purity copper, carrying out primary smelting to a copper liquid state, adding an ultra-high-purity copper-manganese intermediate alloy into the copper liquid, and carrying out secondary smelting to obtain the copper-manganese alloy. The copper-manganese intermediate alloy is used for replacing pure manganese for feeding, the reaction activity of manganese is reduced by means of the dilution effect of copper on manganese, meanwhile, the density characteristic that the intermediate alloy is similar to the copper liquid is utilized, manganese is prevented from being enriched on the surface layer of the copper liquid, crucible corrosion is remarkably reduced, the service life of the crucible is prolonged, and volatilization loss of manganese can be reduced; and the process is adaptive to the existing graphite crucible smelting equipment, does not need to be greatly transformed, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal alloy technology, and in particular to a method for preparing copper-manganese alloys using a copper-manganese master alloy. Background Technology

[0002] Ultra-high purity 6N (99.9999%) copper-manganese (CuMn) alloy is a wiring material for integrated circuit chips. With the development of integrated circuit chips, the demand for copper-manganese alloy targets is increasing. In the large-scale production of copper-manganese alloy targets, due to the special requirements of the production process, high-purity graphite crucibles are generally used to manufacture copper-manganese alloy ingots. However, manganese is a metal whose chemical activity increases significantly at high temperatures. At high temperatures, it can react with carbon to form manganese carbide. Therefore, when using graphite crucibles to smelt copper-manganese alloys, manganese will react with the graphite crucible to produce manganese carbide, which corrodes the inner surface of the crucible, reducing its service life. Furthermore, manganese carbide also affects the quality of the ingot products.

[0003] Within the temperature range of 1200-1400℃, the Gibbs free energy of the compound Mn3C formed by the reaction of manganese and carbon at high temperatures is negative, indicating that the reaction can proceed spontaneously at high temperatures. Because the contact angle of liquid manganese is smaller than that of liquid copper, liquid manganese has better wettability and can more easily penetrate the surface pores of the graphite crucible. Furthermore, the melting point of Mn3C is 1520℃, which is higher than the temperature of this process node. Also, because Mn3C is hard and brittle, it easily peels off from the crucible surface, forming corrosion marks.

[0004] When using pure manganese as feedstock, the composition of the liquid alloy is uneven during the feeding process. Copper is known to have a higher density than manganese. After feeding, the manganese lumps float on the surface of the molten copper and melt into liquid manganese. The heating process in the induction furnace is accompanied by electromagnetic stirring, which diffuses the manganese from the surface liquid alloy to the entire surface. However, the manganese concentration at the surface is high, making it prone to reacting with the graphite crucible. This reaction generates Mn3C at the contact point between the liquid surface and the graphite crucible, corroding the inner wall of the crucible. The resulting corrosion pits are filled by the liquid alloy. After casting, these pits may solidify and become embedded, making them difficult to remove during furnace cleaning.

[0005] In summary, the existing method for producing copper-manganese alloy targets using direct feeding of pure manganese and melting in graphite crucibles suffers from two major drawbacks: severe crucible erosion, short service life, and high impurity content and poor compositional uniformity in the ingots. These drawbacks hinder the large-scale, high-quality production of ultra-high purity copper-manganese alloy targets. Therefore, how to suppress the reaction between manganese and the graphite crucible, reduce manganese carbide formation, and extend crucible lifespan while ensuring ultra-high alloy purity and compositional uniformity has become a pressing issue for the industry. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention employs a copper-manganese intermediate alloy instead of pure manganese blocks for feeding. By leveraging the dilution effect of copper on manganese, the reactivity of manganese is reduced, while simultaneously preventing manganese accumulation on the surface of the molten copper. This synergistic approach, considering thermodynamic conditions, reactivity, and concentration control, effectively inhibits the formation of manganese carbide (Mn3C). Ultimately, this achieves the technical effects of extending the service life of the graphite crucible, improving the uniformity and purity of the ingot composition, and reducing manganese volatilization loss, thus meeting the demand for large-scale, high-quality production of ultra-high purity copper-manganese alloy target ingots.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a copper-manganese alloy using a copper-manganese master alloy. The method involves adding ultra-high purity copper and melting it once to a molten copper state, then adding an ultra-high purity copper-manganese master alloy to the molten copper for a second melting process to obtain the copper-manganese alloy.

[0009] This invention uses a copper-manganese master alloy instead of pure manganese blocks in the prior art. The prior art directly adds pure manganese blocks, and according to Raoult's law, the activity α of manganese... Mn =γ Mn ×x Mn , where γ Mn x is the activity coefficient of manganese. Mn γ represents the mole fraction of manganese at 1200–1400 °C. Mn With x Mn The activity of manganese in the intermediate alloy is much lower than that of pure manganese, which fundamentally reduces the reactivity of manganese with carbon. At the same time, the density of the intermediate alloy is closer to that of molten copper, so it can sink into the center of the molten copper to melt after being added, avoiding enrichment on the surface. This specifically solves the technical problems of high manganese activity, high surface concentration, severe crucible erosion, and uneven ingot composition caused by the addition of pure manganese in the existing technology. It achieves the technical effects of inhibiting Mn3C formation, improving compositional uniformity, and reducing manganese volatilization.

[0010] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0011] As a preferred technical solution of the present invention, the manganese content in the ultra-high purity copper-manganese master alloy is 32wt%~35wt%, for example, it can be 32wt%, 33wt%, 33.7wt%, 34wt% or 35wt%, etc.

[0012] This invention limits the manganese content range of the ultra-high purity copper-manganese master alloy. On the one hand, it ensures that the master alloy has a suitable melting point and fluidity, enabling it to quickly fuse with molten copper and avoid the residue of unmelted particles. On the other hand, this content range forms a reasonable ratio with the manganese content requirements of the finished copper-manganese alloy. The composition of the finished product can be precisely controlled by precisely controlling the amount of master alloy added. This preferred solution solves the problems that excessive manganese content in the master alloy can easily lead to excessive local manganese concentration, while excessively low manganese content requires a large amount of addition, affecting production efficiency. It achieves the technical effect of precise control of the finished product composition and optimized production efficiency.

[0013] As a preferred technical solution of the present invention, the addition of the ultra-high purity copper-manganese master alloy is carried out in at least two stages, with the amount added each time being evenly distributed.

[0014] Preferably, the mass ratio of the single addition amount of the ultra-high purity copper-manganese master alloy to the addition amount of ultra-high purity copper is 0.001 to 0.04, for example, it can be 0.001, 0.003, 0.005, 0.007, 0.01, 0.02 or 0.04, etc.

[0015] This invention, through the design of multiple uniform additions of ultra-high purity copper-manganese master alloy, avoids the sudden increase in local manganese concentration caused by a single addition, allowing manganese to diffuse gradually and uniformly in the copper liquid, maintaining the manganese concentration in the system at a low and stable level. This reduces the probability of manganese reacting with the graphite crucible from the source. Furthermore, by limiting the mass ratio range of the single addition, it ensures that the amount of manganese added each time is compatible with the copper liquid system. This prevents both low smelting efficiency due to insufficient addition and excessive local concentration due to excessive addition. This preferred solution solves the problems of uneven composition and increased crucible erosion risk that may be caused by a single addition of master alloy, achieving the technical effects of further improving alloy composition uniformity and further suppressing crucible erosion.

[0016] As a preferred technical solution of the present invention, after each addition of the ultra-high purity copper-manganese master alloy, the smelting system is shaken and then allowed to stand still.

[0017] Preferably, the shaking is performed three times with slight shaking to promote uniform mixing of the liquid metal in the smelting system.

[0018] Preferably, the melting is carried out in a graphite crucible.

[0019] As a preferred technical solution of the present invention, the settling time is 30s to 60s, for example, it can be 30s, 35s, 45s, 55s or 60s.

[0020] As a preferred technical solution of the present invention, the ultra-high purity copper-manganese alloy is kept warm after it is fully added.

[0021] Preferably, the heat preservation time is 30 min to 120 min, for example, it can be 30 min, 45 min, 60 min, 90 min or 120 min.

[0022] As a preferred technical solution of the present invention, the temperature of the first melting is 1050℃~1300℃, for example, it can be 1050℃, 1100℃, 1150℃, 1200℃ or 1300℃.

[0023] As a preferred technical solution of the present invention, the temperature of the secondary melting is 1200℃~1450℃, for example, it can be 1200℃, 1250℃, 1300℃, 1400℃ or 1450℃.

[0024] As a preferred technical solution of the present invention, the purity of the ultra-high purity copper is ≥99.9999wt%.

[0025] As a preferred technical solution of the present invention, the purity of the ultra-high purity copper-manganese master alloy is ≥99.9999wt%.

[0026] As a preferred embodiment of the present invention, the manganese content in the copper-manganese alloy is 0.1wt% to 10wt%, for example, it can be 0.1wt%, 0.3wt%, 1.5wt%, 5wt%, 7wt% or 10wt%, etc.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] (1) The present invention replaces pure manganese with copper-manganese intermediate alloy, which reduces the activity of manganese and melts into the center to avoid manganese enrichment on the surface, significantly prolongs the service life of graphite crucible, inhibits the generation of Mn3C from the source, avoids manganese from penetrating into the crucible pores and causing corrosion, and reduces the crucible replacement frequency and furnace cleaning difficulty.

[0029] (2) The intermediate alloy melts in the center of the molten copper, avoiding the problem of pure manganese blocks floating on the surface and volatilizing at high temperatures, thus reducing raw material waste; it improves the uniformity and purity of the alloy composition, ensuring product quality. The low activity and uniform diffusion of manganese in the intermediate alloy reduce manganese volatilization loss and improve raw material utilization.

[0030] (3) The process is highly controllable and adaptable to large-scale production. It does not require major modifications to existing graphite crucible melting equipment and can be directly connected to industrial production lines. The production efficiency is comparable to existing processes. The products are widely adaptable and can meet the performance requirements of semiconductor, electronic components, special electronic devices and other scenarios, significantly improving overall production efficiency. Detailed Implementation

[0031] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0032] Example 1

[0033] This embodiment provides a method for preparing copper-manganese alloys using a copper-manganese master alloy. The specific steps are as follows:

[0034] (1) Add 99.9999wt% ultra-high purity copper to a graphite crucible and perform a first melting at a temperature of 1050℃ for 30 minutes to obtain a uniform copper liquid.

[0035] (2) Prepare an ultra-high purity copper-manganese master alloy with a purity of 99.9999 wt% and a manganese content of 33.7 wt%. Add it evenly to the copper liquid in 9 portions. The mass ratio of the amount added in each portion to the ultra-high purity copper is 0.005. The manganese content added is 1.45 wt%. Maintain the secondary melting temperature at 1350 ℃. After each addition of the high purity copper-manganese master alloy, gently shake the melting system 3 times and then let it stand for 30 seconds. After all the master alloys have been added, keep it at the temperature for 90 minutes. After casting, a copper-manganese alloy ingot is obtained. There are no obvious corrosion pits on the inner wall of the graphite crucible.

[0036] Example 2

[0037] This embodiment provides a method for preparing copper-manganese alloys using a copper-manganese master alloy. The specific steps are as follows:

[0038] (1) Add 99.9999wt% ultra-high purity copper to a graphite crucible and perform a first melting at a temperature of 1200℃ for 30 minutes to obtain a uniform copper liquid.

[0039] (2) Prepare an ultra-high purity copper-manganese master alloy with a purity of 99.9999 wt% and a manganese content of 32 wt%. Add it evenly to the copper liquid in three batches. The mass ratio of the amount added at one time to the ultra-high purity copper is 0.001. The manganese content added is 0.1 wt%. Maintain the secondary melting temperature at 1450 ℃. After each addition of the high purity copper-manganese master alloy, gently shake the melting system three times and then let it stand for 30 s. After all the master alloys have been added, keep it at the temperature for 30 min. After casting, a copper-manganese alloy ingot is obtained. There are no obvious corrosion pits on the inner wall of the graphite crucible.

[0040] Example 3

[0041] This embodiment provides a method for preparing copper-manganese alloys using a copper-manganese master alloy. The specific steps are as follows:

[0042] (1) Add 99.9999wt% ultra-high purity copper to a graphite crucible and perform a single melting process at a melting temperature of 1300℃ for 30 minutes to obtain a uniform copper liquid.

[0043] (2) Prepare an ultra-high purity copper-manganese master alloy with a purity of 99.9999 wt% and a manganese content of 35 wt%. Add it evenly to the copper liquid in 10 portions. The mass ratio of the amount added at one time to the ultra-high purity copper is 0.04. The manganese content added is 10 wt%. Maintain the secondary melting temperature at 1300℃. After each addition of the high purity copper-manganese master alloy, gently shake the melting system 3 times and then let it stand for 60 seconds. After all the master alloys have been added, keep it at the temperature for 120 minutes. After casting, a copper-manganese alloy ingot is obtained. There are no obvious corrosion pits on the inner wall of the graphite crucible.

[0044] Example 4

[0045] This embodiment provides a method for preparing copper-manganese alloy using a copper-manganese master alloy. The method is the same as in Example 1 except that the manganese content of the ultra-high purity copper-manganese master alloy is 50 wt%, and it is added to the copper liquid in 9 equal portions. The mass ratio of the single addition amount to the ultra-high purity copper is adaptively adjusted to 0.0033 to maintain the same manganese content as in Example 1. Slight crucible erosion is present.

[0046] Example 5

[0047] This embodiment provides a method for preparing copper-manganese alloy using a copper-manganese master alloy. The method is the same as in Example 1, except that the manganese content of the ultra-high purity copper-manganese master alloy is 20 wt%, and it is added to the copper liquid in 9 equal portions. The mass ratio of the single addition amount to the ultra-high purity copper is adaptively adjusted to 0.0085 to maintain the same manganese content as in Example 1.

[0048] Comparative Example 1

[0049] This comparative example provides a method for preparing a copper-manganese alloy. The method uses pure manganese as feed material, which is added uniformly in 9 portions. The manganese content and other preparation conditions are the same as in Example 1. Obvious erosion pits are present on the inner wall of the graphite crucible.

[0050] Test methods

[0051] The manganese content was determined by glow discharge mass spectrometry, and the manganese recovery rate was calculated as: (total manganese mass in the finished alloy / total manganese mass in the feed) × 100%. The Mn3C impurity content was determined by X-ray diffraction combined with energy dispersive spectroscopy. The test results are shown in Table 1.

[0052] Test Results

[0053] Table 1

[0054] Examples and Comparative Examples Manganese content (wt%) Manganese recovery rate (%) <![CDATA[Mn3C impurity content (ppm)]]> Example 1 1.43 98.6 0.3 Example 2 0.098 97.4 0.4 Example 3 9.82 98.2 0.3 Example 4 1.33 91.7 12 Example 5 1.41 97.2 3 Comparative Example 1 1.27 87.6 28

[0055] (1) As can be seen from Examples 1 to 3, the present invention uses a copper-manganese intermediate alloy feeding method and a step-by-step uniform feeding method. The finished product has a manganese content in the low, medium and high ranges of 0.1wt% to 15wt%, and can achieve the technical effect of uniform composition, no obvious crucible erosion and Mn3C impurity content ≤1ppm.

[0056] (2) As can be seen from Examples 1, 4 and 5, by further limiting the manganese content of the ultra-high purity copper-manganese master alloy to 32wt%~35wt%, the present invention can achieve better composition uniformity and higher manganese recovery rate. When the manganese content of the master alloy exceeds this range, although an alloy with the target manganese content can be prepared, the composition uniformity becomes worse, the manganese recovery rate decreases, the impurity content increases, and even slight crucible erosion occurs, highlighting the technical advantages of this preferred range.

[0057] (3) As can be seen from Example 1 and Comparative Example 1, by using copper-manganese intermediate alloy instead of pure manganese as feed, the present invention can achieve the technical effects of high manganese recovery rate, excellent composition uniformity, no crucible erosion and extremely low Mn3C impurity content; while when copper-manganese intermediate alloy is not used and pure manganese is used instead, manganese volatilization loss is serious, composition segregation is obvious, and the graphite crucible is severely eroded, and the core invention objective of the present invention cannot be achieved.

[0058] In summary, this invention achieves the technical effects of suppressing Mn3C formation, extending crucible lifespan, improving alloy composition uniformity, and increasing manganese recovery rate through a combination of copper-manganese master alloy replacing pure manganese feed and optimizing the manganese content of the master alloy and adding it in stages and uniformly. Moreover, the solution has strong universality and can cover the preparation of ultra-high purity copper-manganese alloys with different manganese content requirements.

[0059] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing copper-manganese alloys using a copper-manganese master alloy, characterized in that, The method involves adding ultra-high purity copper and smelting it into a molten copper state in one step, then adding an ultra-high purity copper-manganese master alloy to the molten copper for a second smelting to obtain the copper-manganese alloy.

2. The method according to claim 1, characterized in that, The manganese content in the ultra-high purity copper-manganese master alloy is 32wt%~35wt%.

3. The method according to claim 1 or 2, characterized in that, The ultra-high purity copper-manganese master alloy is added in at least two separate processes, with the amount added each time being evenly distributed. Preferably, the mass ratio of the single addition amount of the ultra-high purity copper-manganese master alloy to the mass of ultra-high purity copper is 0.001 to 0.

04.

4. The method according to claim 3, characterized in that, After each addition of the ultra-high purity copper-manganese master alloy, the smelting system is shaken and then allowed to stand. Preferably, the settling time is 30s to 60s.

5. The method according to claim 4, characterized in that, After all the ultra-high purity copper-manganese alloy has been added, it is kept at a constant temperature. Preferably, the heat preservation time is 30 min to 120 min.

6. The method according to any one of claims 1 to 5, characterized in that, The temperature of the first melting is 1050℃~1300℃.

7. The method according to any one of claims 1 to 6, characterized in that, The temperature for the secondary melting is 1200℃~1450℃.

8. The method according to any one of claims 1 to 7, characterized in that, The purity of the ultra-high purity copper is ≥99.9999 wt%.

9. The method according to any one of claims 1 to 8, characterized in that, The purity of the ultra-high purity copper-manganese master alloy is ≥99.9999wt%.

10. The method according to any one of claims 1 to 9, characterized in that, The manganese content in the copper-manganese alloy is 0.1wt% to 10wt%.