Supergravity metallurgy: principles, experimental methods, techniques, and applications

Supergravity significantly increases the gravity difference between two phases and thus can accelerate phase separation in solid–liquid mixtures, liquid–liquid mixtures, and liquid–bubble mixtures that have high temperatures and viscosities. Due to its directionality, supergravity avoids turbulent backmixing in melts, typically seen in agitation and other separation techniques, and is applicable toward the deep removal of fine inclusions in liquid metals. Under supergravity, solid–liquid interfacial tension is negligible and microporous seepage is straightforwardly achievable. Particle–liquid separation during crystallization can be performed under supergravity to prepare gradient materials. Supergravity accelerates particle–liquid separation, which refines solidified grains, but can also produce macroscopic segregation in noneutectic melts. Supergravity is widely applicable and beneficial to many fields. In metallurgy and materials production, supergravity can be used to improve the separation and extraction of valuable components from metallurgical slags of complex ores, separation and recovery of molten metal in smelting slags, melt crystallization separation of polymetals, and slag–metal separation of reduced iron from complex ores. In addition, supergravity can also be applied to high-end metal materials to improve the refinement and removal of impurities in metal materials toward near zero inclusion. Furthermore, supergravity can improve the manufacturing of functional gradient materials, metal–ceramic composites, porous metal materials, and device materials via electrodeposition modification. Finally, supergravity solidification can be used as a high-throughput method for the preparation of material genomes.