China Nonferrous Metallurgy

Superalloys have been widely used in aerospace, aviation, energy and other high-end manufacturing industries. A large amount of waste superalloys are produced every year. The purification and regeneration technology of waste superalloys is of great significance to promote the healthy development of Chinas high-tech industry. Research indicates that inclusions insuperalloys alloys primarily originate from chemical reactions during the melting process, elemental contamination from service environments, and foreign impurities introduced during processing and storage. These inclusions can be categorized into various types such as oxides, sulfides, and nitrides based on their composition and morphology. The presence of these inclusions significantly degrades the mechanical performance, corrosion resistance, and fatigue life of materials, potentially leading to failure in critical components.In response to this issue, this paper focuses on a comparative analysis of the advantages and disadvantages of six mainstream purification processes, including mechanical grinding, electroslag remelting, vacuum induction melting, foam ceramic filtration, electron beam melting, and bottom-blown bubble flotation technology. Among these methods, mechanical grinding is suitable for the removal of surface inclusions; it is cost-effective but has limited processing depth. Electroslag remelting can effectively eliminate large-sized inclusions; however, it poses challenges due to high energy consumption. Vacuum induction melting significantly reduces oxygen and nitrogen content but generally shows moderate effectiveness in removing already formed inclusions. Foam ceramic filtration demonstrates excellent interception capabilities for micron-sized inclusions but is classified as a consumable process. Electron beam melting offers outstanding purification results yet involves complex equipment and substantial energy requirements. Lastly, bottom-blown bubble flotation exhibits high efficiency in removing small-sized inclusions; nevertheless, its process stability requires further improvement. In the future, the research on the recovery of waste superalloys should focus on the development of new composite purification processes with high efficiency and low consumption, improve the continuity and automation level of the process, and suggest the establishment of a sound waste recovery system.