A foamed alloy, method of manufacture and use

Abstract

The application belongs to the technical field of foam alloy preparation, and particularly relates to a foam alloy, a preparation method and application, and comprises the following steps: uniformly mixing copper, copper-manganese alloy and a pore-forming agent to obtain mixed dry powder, wherein the pore-forming agent is a mixture of polymethyl methacrylate and ammonium bicarbonate; under stirring, spraying a binder solution into the mixed dry powder to obtain a mixture, wherein the binder is a mixture of paraffin and polyethylene glycol, and the solvent in the binder solution is a mixed solution of limonene and ethanol; granulating and compression molding; then, pore-forming; finally, sintering to obtain the foam alloy; the application has low production cost, low manganese segregation degree, and effectively improves the uniformity of the electric conductivity and mechanical properties of the foam alloy.

Description

Technical Field

[0001] This invention belongs to the field of foam alloy preparation technology, specifically relating to a foam alloy, its preparation method, and its application. Background Technology

[0002] Solid oxide fuel cells (SOFCs) are all-solid-state power generation devices that directly convert chemical energy into electrical energy. They have advantages such as high energy conversion efficiency (>60%), strong fuel adaptability (can use H2, CO, CH4 and hydrocarbon fuels), and low emissions.

[0003] SOFC cathode current collectors often use ceramic materials such as perovskite compounds. While these traditional materials possess some conductivity, they exhibit the following key shortcomings in practical applications: 1. The coefficient of thermal expansion of ceramic materials differs significantly from that of other components in a battery. During the repeated start-stop thermal cycling of a SOFC, this difference generates enormous thermal stress, which can easily lead to component cracking or delamination, affecting the structural integrity and lifespan of the stack.

[0004] 2. Traditional split-type anodes and current collectors have a mechanical contact interface, which increases ohmic losses and assembly difficulty. During long-term high-temperature operation, the conductivity of traditional ceramic materials will significantly decrease, leading to increased internal resistance and a decline in power generation efficiency.

[0005] 3. When using hydrocarbon fuels as the gas source, Ni-based anodes are prone to catalytic carbon deposition, leading to electrode blockage, stratification, and performance degradation; and are extremely sensitive to sulfur impurities in the fuel.

[0006] 4. Although Cu metal has better resistance to carbon deposition than Ni, its catalytic reforming and oxidation activity for hydrocarbon fuels is relatively low. It usually requires the introduction of additional catalytic phases such as CeO2 and ZrO2, which increases the complexity of preparation.

[0007] Foamed alloys can be used as novel materials for cathode current collectors. Patent application publication number CN 121629210 A discloses a continuous strip-shaped foamed copper-manganese alloy and its preparation method. In this method, a manganese-containing slurry is coated onto the surface of an activated copper foam substrate under a protective atmosphere; the coated substrate is then dried and shaped under a protective atmosphere; finally, the dried substrate undergoes multi-stage heat treatment under a hydrogen atmosphere, allowing manganese and copper to form an alloy through solid-state diffusion, thus obtaining a continuous strip-shaped foamed copper-manganese alloy. However, its manufacturing efficiency is low, its cost is high, making industrial application difficult, and batch consistency is generally poor. Therefore, traditional powder metallurgy remains an important production method. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a foam alloy, a preparation method and an application that has low production cost, low manganese segregation degree and effectively improves the uniformity of electrical conductivity and mechanical properties of the foam alloy.

[0009] This invention provides a method for preparing a foamed alloy, comprising the following steps: Copper, copper-manganese alloy and pore-forming agent are mixed evenly to obtain a mixed dry powder. The pore-forming agent is a mixture of polymethyl methacrylate and ammonium bicarbonate. Under stirring, the binder solution is sprayed into the mixed dry powder to obtain a mixture. The binder is a mixture of paraffin and polyethylene glycol, and the solvent in the binder solution is a mixture of limonene and ethanol. Granulation and pressing are then performed; pores are then created, and finally sintering is carried out to obtain a foam alloy.

[0010] Preferably, the weight ratio of copper, copper-manganese alloy and pore-forming agent is 40-60:30-40:10-20.

[0011] Preferably, the weight ratio of polymethyl methacrylate to ammonium bicarbonate is 0.5-2:1.

[0012] Preferably, the weight ratio of paraffin wax to polyethylene glycol is 0.5-2:1.

[0013] Preferably, the weight ratio of limonene to ethanol is 3-5:1.

[0014] Preferably, the adhesive solution contains 15-25% by mass of adhesive.

[0015] Preferably, the pore-forming process is achieved by drying at 60-70°C.

[0016] Preferably, the sintering step involves heating to 400-500°C at a heating rate of 0.1-1°C / min, then heating to 500-600°C at a heating rate of 1-2°C / min and holding at that temperature; then heating to 800-1000°C at a heating rate of 4-10°C / min and holding at that temperature.

[0017] This invention provides a foam alloy prepared using the aforementioned preparation method.

[0018] This invention provides an application of the foam alloy described above, which is used to prepare cathode current collectors, anode materials, or electrode supports for fuel cells.

[0019] The beneficial effects of this invention are as follows: Firstly, pure manganese exhibits delayed dissolution during copper alloy smelting due to its high melting point (up to 1246℃), making it difficult to rapidly melt and diffuse at conventional copper melt temperatures. Secondly, it suffers from poor high-temperature chemical stability; manganese readily undergoes oxidation reactions in high-temperature melts, generating slag, or its high volatility leads to the emission of dust, resulting in severe element loss and reduced yield. Finally, kinetic lag and component segregation occur; its slow dissolution rate easily leads to excessively high local concentrations in the melt, resulting in uneven overall alloy composition distribution and macroscopic or microscopic segregation defects. Inconsistent particle size and weight between metal powder and pore-forming agents make it difficult to achieve uniform mixing. Furthermore, manganese is chemically highly reactive; during high-temperature sintering or smelting, it readily oxidizes to form oxide inclusions, or volatilizes significantly due to high temperatures. This not only causes the actual composition of the final product to deviate from the designed ratio but also results in significant instability in material properties.

[0020] This invention utilizes polymethyl methacrylate (PMMA) and ammonium bicarbonate as pore-forming agents, paraffin wax and polyethylene glycol as binders, and limonene and ethanol as solvents for the binders. This process effectively reduces manganese segregation while simultaneously creating pores. By stirring the copper-manganese alloy powder, copper powder, and PMMA in a protective atmosphere, manganese is uniformly distributed within the powder, mitigating the risk of oxidation. Furthermore, gradient temperature settings during sintering further prevent manganese segregation from the structural and heat treatment perspectives. Through the synergistic effect of these three processes, an unexpected alloying effect is achieved. Detailed Implementation

[0021] Example 1 A method for preparing a foamed alloy includes the following steps: 1) Raw material preparation Copper powder: Irregularly shaped electrolytic copper powder with an average particle size of 300 mesh and a purity of ≥99.5% is selected. Copper-manganese alloy powder: Selected copper-manganese alloy powder with an average particle size of 50μm, wherein the manganese content is 40wt%. Pore-forming agent: A mixture of polymethyl methacrylate (PMMA) and ammonium bicarbonate (mass ratio 1:1) is selected. Adhesive: A mixture of paraffin wax and polyethylene glycol (mass ratio 1:1) is selected.

[0022] 2) Pretreatment Preparation of adhesive solution: Dissolve 0.5g paraffin and 0.5g polyethylene glycol in a mixed solution consisting of 3g D-limonene and 1g ethanol to prepare an adhesive solution with a mass fraction of 20%.

[0023] Dry powder mixing: Place 100g of copper powder, 70g of copper-manganese alloy powder and 29g of pore-forming agent into a closed magnetic stirrer and stir magnetically at a frequency of 2000 RPM to ensure thorough dry mixing. During mixing, argon gas is introduced for protection to prevent manganese from being oxidized at high temperatures and to ensure that the pore-forming agent is evenly distributed in the metal powder to obtain mixed dry powder.

[0024] 3) Wet mixing and granulation Spraying adhesive: While continuously stirring, the prepared adhesive solution is evenly sprayed onto the mixed dry powder to obtain a mixture.

[0025] Kneading and drying: After kneading the mixture evenly, spread it evenly on a tray and place it in an oven to dry at 65℃ for 2 hours.

[0026] Sieving: The dried granules are sieved to remove clumps. The sieve mesh size is 60 mesh.

[0027] 4) Press molding The dried mixed powder is loaded into a mold and cold-pressed using a tablet press. The pressure is 100 MPa, resulting in a green compact with a certain strength.

[0028] 5) Low temperature hole making The green blanks are placed in a drying device for low-temperature pore formation. The drying temperature is 70℃ and the drying time is 2 hours. Ammonium bicarbonate decomposes to form preliminary pores.

[0029] 6) High-temperature sintering Low-temperature debinding stage: The temperature is increased to 450℃ in an argon atmosphere at a heating rate of 0.2℃ / min.

[0030] High-temperature debinding stage: In an argon atmosphere, the temperature is increased to 550℃ at a heating rate of 1℃ / min and held for 2 hours.

[0031] High-temperature sintering stage: The temperature is increased to 900℃ in an argon atmosphere at a heating rate of 5℃ / min.

[0032] High-temperature insulation stage: Insulate at 900℃ for 2 hours.

[0033] 7) Cooling and unloading from the furnace The porous foamed copper-manganese alloy was obtained by cooling to room temperature.

[0034] Product porosity ≥70%.

[0035] Comparative Example 1 The difference from Example 1 is that the pore-forming agent is polymethyl methacrylate (PMMA). Everything else is the same as in Example 1.

[0036] Comparative Example 2 Compared to Example 1, the difference is that the pore-forming agent is ammonium bicarbonate. Everything else is the same as in Example 1.

[0037] Comparative Example 3 Compared to Example 1, the difference is that the adhesive solution is 5g of ethanol. Everything else is the same as in Example 1.

[0038] Comparative Example 4 Compared with Example 1, the difference is that the adhesive solution is prepared by dissolving 0.5g of solid paraffin and 0.5g of polyethylene glycol in a mixed solution composed of 4g of ethanol to prepare an adhesive solution with a mass fraction of 20%.

[0039] Example 2: Manganese segregation quantification based on micro-area four-probe method 1. Sample preparation and pretreatment Representative pore wall (metal skeleton) areas were selected from the sintered copper-manganese foam alloy and cut into 10mm × 10mm pieces. The test surfaces were progressively ground and polished (until mirror finish) to eliminate the influence of surface roughness and oxide layer on contact resistance. The surfaces were then ultrasonically cleaned with anhydrous ethanol for 5 minutes, dried, and set aside for later use.

[0040] 2. Test equipment and parameter settings Equipment: A micro-area four-probe resistivity meter equipped with an automatic two-dimensional scanning platform (Mapping function) was used. Equally spaced linear four-probe arrays were selected. The testing environment was room temperature, and the testing mode was a DC constant current source.

[0041] 3. Test path and data collection Data collection strategy: A 5 mm × 5 mm test area was defined on the polished sample surface. An automatic scanning grid was set, and a data point was collected every 0.5 mm, for a total of 11 × 11 = 121 data points. The device automatically recorded the voltage drop and the set current at each coordinate point (x, y).

[0042] 4. Data processing and analysis of quantitative indicators Resistivity calculation: According to the formula r = C (V / I) t Calculate the resistivity at each point (where t The average thickness of the hole wall. C (This is a correction factor related to sample size and probe spacing).

[0043] Segregation quantification values: Overall average ( ): Reflects the overall electrical conductivity level of the material. Relative Standard Deviation (RSD): RSD = (σ / )×100%. RSD is the core indicator for quantifying the degree of segregation. The larger the RSD, the more uneven the distribution of manganese.

[0044] Range r max r min This reflects the situation of local extreme segregation.

[0045] The experimental results are shown in the table below.

[0046]

[0047] Results Analysis: The data shows that the RSD of Example 1 is only 3.6%, far lower than all comparative examples. This indicates that the combination of composite binder and composite pore-forming agent can most effectively suppress manganese segregation and ensure highly uniform electrical and mechanical properties of the foam alloy.

[0048] The RSD values ​​of all comparative examples were significantly higher than those of Example 1, with Comparative Example 3 (using ethanol only) showing the most severe segregation (RSD of 17.0%), indicating that the binder plays an important role in preventing segregation.

[0049] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0050] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A method for preparing a foamed alloy, characterized in that, Includes the following steps: Copper, copper-manganese alloy and pore-forming agent are mixed evenly to obtain a mixed dry powder. The pore-forming agent is a mixture of polymethyl methacrylate and ammonium bicarbonate. Under stirring, the binder solution is sprayed into the mixed dry powder to obtain a mixture. The binder is a mixture of paraffin and polyethylene glycol, and the solvent in the binder solution is a mixture of limonene and ethanol. Granulation and pressing are then performed; pores are then created, and finally sintering is carried out to obtain a foam alloy.

2. The preparation method according to claim 1, characterized in that, The weight ratio of copper, copper-manganese alloy and pore-forming agent is 40-60:30-40:10-20.

3. The preparation method according to claim 1, characterized in that, The weight ratio of polymethyl methacrylate to ammonium bicarbonate is 0.5-2:

1.

4. The preparation method according to claim 1, characterized in that, The weight ratio of paraffin wax to polyethylene glycol is 0.5-2:

1.

5. The preparation method according to claim 1, characterized in that, The weight ratio of limonene to ethanol is 3-5:

1.

6. The preparation method according to claim 1, characterized in that, The adhesive solution contains 15-25% adhesive by mass.

7. The preparation method according to claim 1, characterized in that, The pore-forming process involves drying at 60-70℃.

8. The preparation method according to claim 1, characterized in that, The sintering steps are as follows: heating to 400-500℃ at a heating rate of 0.1-1℃ / min, then heating to 500-600℃ at a heating rate of 1-2℃ / min and holding at that temperature; then heating to 800-1000℃ at a heating rate of 4-10℃ / min and holding at that temperature.

9. A foam alloy, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

10. An application of the foam alloy as described in claim 9, characterized in that, The foam alloy is used to prepare cathode current collectors, anode materials, or electrode supports for fuel cells.

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