Full and Hollow Metal–Ceramic Beads Based on Tantalum and Alumina Produced by Alginate Gelation

Metal–ceramic composite beads containing different amounts of tantalum and alumina, particularly 100 vol% 60–40 tantalum/alumina, are produced by the alginate gelation process. Sodium is used as gelling agent in metal–ceramic suspension, while a calcium chloride solution prepared to trigger consolidation As previous study, nozzles order obtain three sizes. The largest result be hollow, hence require freeze-drying step prevent their collapse. After debinding air, sintered at 1600 °C under inert atmosphere. Samples green state analyzed digital light microscopy scanning electron microscopy. Investigations mercury intrusion porosimetry reveal that feature smaller pores compared pure beads, well lower open porosity. fracture strength evaluated on single beads. Despite high metallic content, both show brittle behavior. X-ray powder diffraction (XRD) analyses presence NaTaO 3 , Ta 2 C 0.95 AlTaO 4 alongside samples from tantalum. impurities due reactions with Na, C, Ca additives.