ADVANCED MATERIALS & PROCESSES | APRIL 2024 1 1 PROCESS TECHNOLOGY WELDING METAL FOAM WITHOUT BUBBLES Using an induction welding technique, researchers at North Carolina State University (NCSU), Raleigh, successfully joined composite metal foam (CMF) components together without impairing the properties that make CMF desirable. CMFs hold promise for a wide array of applications because the pockets of air they contain make them light, strong, and effective at insulating against high temperatures. CMFs are foams that consist of hollow, metallic spheres—made of materials such as stainless steel or titanium—embedded in a metallic matrix made of steel, titanium, aluminum, or other metallic separation, the MSX process is more efficient and uses much less energy, labor, and chemical solvents, and can be applied to a variety of critical material recovery efforts. The MSX system contains porous hollow fibers with a neutral extractant that creates a selective barrier, letting only REEs pass through. The REE-rich solution collected can then be further processed to yield rare earth oxides with purities exceeding 99.5%. “The Pea Ridge iron ore mine is the only fully permitted domestic source for heavy REEs critical for high operating temperature, high value neodymium magnets,” says Jim Kennedy, president of Caldera. “The Caldera mine has three distinct rare earth deposits, open at depth, containing 700,000 tons of REEs and significant levels of praseodymium, neodymium, terbium, dysprosium, holmium, and other heavy REEs. Caldera seeks to integrate ORNL’s technology into a domestic, vertically integrated value chain to produce neodymium magnets,” comments Kennedy. For ORNL researchers working on the MSX technique for the past decade, the license to Caldera provides a longsought opportunity to test their method on a mining source. The team is planning for a continued research relationship, which includes a demonstration of the technology. ornl.gov. alloys. The resulting material is both lightweight and remarkably strong, with potential applications ranging from aircraft wings to vehicle armor and body armor. In addition, CMF is better at insulating against high heat than conventional metals and alloys, such as steel. The combination of weight, strength, and thermal insulation means that CMF also holds promise for use in storing and transporting nuclear material, hazardous materials, explosives, and other heat- sensitive materials. However, in order to realize many of these applications, manufacturers would need to weld multiple CMF components together— which, until now, has been a challenge. “Because CMF is only 30-35% metal, the electromagnetic field is able to penetrate deeply into the material—allowing for a good weld,” explains researcher Afsaneh Rabiei. “The air pockets that make up the remaining 65-70% of the CMF serve to insulate the material against the heat. It’s essential to have a means of welding the CMF components without impairing the properties that make it attractive in the first place.” ncsu.edu. RARE EARTH ELEMENT SEPARATION TECHNOLOGY Oak Ridge National Laboratory (ORNL), Tenn., and Caldera Holding, St. Louis, the owner and developer of Missouri’s Pea Ridge iron mine, entered a nonexclusive research and development licensing agreement to apply a membrane solvent extraction technique, or MSX, developed by ORNL researchers to mined ores. MSX provides a scalable, efficient way to separate rare earth elements (REEs) from mixed mineral ores. Compared with other traditional separation methods such as hydrometallurgy and chemical On January 19, Bodycote acquired Lake City Heat Treating, Warsaw, Ind., a provider of hot isostatic pressing and vacuum heat treatment services for the aerospace and medical industries. bodycote.com. BRIEF Researchers use an induction coil to create an electromagnetic field that heats a metal for welding without compromising important CMF properties. Courtesy of NCSU. Syed Islam co-invented a process to recover rare earth elements from scrap magnets. Courtesy of Carlos Jones/ ORNL, U.S. Dept. of Energy.
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