Optimizing ultrasonic atomization of pure Copper and it's Alloys for Additive Manufacturing applications

Copper is known for its exceptional physical and chemical properties. Its high thermal conductivity (400 W/(m·K)) and electrical conductivity (58 × 10⁶ S/m) make it an ideal choice for a wide range of applications. The corrosion resistance of copper allows it to maintain its integrity in various environments, making it suitable for use in challenging conditions. Additionally, copper exhibits excellent machinability, facilitating its use in manufacturing processes. 

These properties have led to the widespread use of copper in industries such as aerospace, automotive, electronics, and construction. In the aerospace sector, copper components are crucial for applications requiring thermal and electrical management, such as heat exchangers and wiring systems. In automotive manufacturing, copper is commonly found in electrical systems and connectors. The electronics industry relies heavily on copper for circuit boards, connectors, and various components due to its superior electrical conductivity. 

Overall, the unique combination of properties in copper and its alloys makes them indispensable in modern industrial applications, driving the need for high-quality copper powders in additive manufacturing. 

One of the greatest challenges in utilizing copper in additive manufacturing, particularly in processes such as selective laser melting (SLM) and laser powder bed fusion (LPBF), is its high reflectivity to laser beams. Copper is the second most reflective material after gold, reflecting a significant portion of the laser energy, which often leads to incomplete melting of powder particles. This challenge necessitates careful selection of laser type, wavelength, and power. For example, recent studies have shown that blue lasers, with shorter wavelengths (450–500 nm) and higher photon energy, improve energy absorption and enhance the density of fabricated parts. Achieving high-quality 3D-printed copper components depends on precise energy input, efficient layer-by-layer re-melting, and mitigation of defects such as porosity and cracks. 

In this context, having pure and perfectly spherical copper powders is crucial. Such powders enhance flowability, packing density, and uniform laser interaction, ensuring the success of additive manufacturing processes. This study demonstrates how our advancements in ultrasonic atomization contribute to the production of high-quality copper powders, paving the way for more effective and reliable 3D printing applications. 

At the beginning of our research, we received pure copper in various forms from different production processes, including sheets, chips, and cylinders. The primary objective of this benchmark was to identify the optimal form of the material that would provide the most effective and rapid atomization, considering factors such as speed, quality, and cost. Additionally, we aimed to achieve the highest possible sphericity of the produced powder. 

For the tests, we utilized a standard ultrasonic atomization system. This system is designed to facilitate the efficient transformation of molten copper into fine powders, leveraging ultrasonic energy to achieve optimal atomization characteristics. To increase the efficiency and effectiveness of the process, we have introduced several refinements to our system that allowed for better control and repeatability of the atomization process. 

Throughout the research, we addressed various challenges such as oxide formation, crucible limitations, and process repeatability. By continuously refining our processes, we improved the overall quality and consistency of the atomized copper powder. 

After implementing the improvements, the atomization process became efficient and problem-free. The following parameters highlight the effectiveness of our advancements:   

• We achieved a high yield of fine copper powder with excellent sphericity and uniform particle size distribution.
• Scrap generation was minimized, ensuring optimal material usage and sustainability.
• The process was stabilized, allowing for consistent and repeatable powder production within a short cycle time.

Furthermore, utilizing raw material in the form of cylinders or plates enabled us to maximize the amount of material processed in each cycle. The standard ultrasonic system, once stabilized, delivered exceptional results, particularly in achieving a high fraction of fine powder suitable for additive manufacturing. 

Another advantage of our process is that any scrap generated during atomization can be re-melted and reintroduced into the system for further atomization. This capability highlights the potential of recycling copper feedstock for producing high-performance powders and sets a new benchmark for sustainability and efficiency in additive manufacturing technologies. 

In addition to pure copper, we also explored the atomization of copper alloys, specifically bronze and Incusil - ABA. The results of these atomization processes are summarized in the table below, which presents the particle size distribution and circularity for each material. 

The data shows that each atomization process produced nearly perfectly spherical powders, with high average circularity values for all materials. The average particle sizes were consistently around 50 µm, demonstrating excellent control over the particle size distribution. Moreover, the standard deviations were relatively low for each alloy, indicating a very narrow particle size distribution. This uniformity is critical for ensuring consistent flowability and optimal performance in additive manufacturing applications. 

The efficiency and reliability of the atomization processes for these alloys were noteworthy, yielding high-quality powders without significant issues. These results further validate our advancements in ultrasonic atomization technology and its applicability to a range of copper-based materials. 

This case study outlines the research and development efforts undertaken to enhance the ultrasonic atomization process of pure copper and its alloys for additive manufacturing applications. By leveraging advanced induction melting and ultrasonic atomization techniques, we successfully produced high-quality, spherical copper powders with excellent flowability and consistency. 

The study explored the influence of different feedstock forms, refining the atomization process to achieve optimal material characteristics. Throughout the research, challenges such as oxide formation, material dosing, and process repeatability were systematically addressed, leading to stable and efficient powder production. 

In addition to pure copper, the atomization of copper alloys, including bronze and Incusil - ABA, was also analyzed. The results demonstrated that all materials achieved high circularity and a narrow particle size distribution, ensuring their suitability for demanding additive manufacturing applications. 

The findings underscore the importance of high-quality powders in additive manufacturing, paving the way for future innovations in this field. For those interested in a deeper dive, detailed reports on the atomization processes of copper, bronze, and Incusil - ABA can be accessed via the provided links, offering comprehensive data and insights into the research.