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The Crucible Titanium Gas Atomizer (TGA) uses a refractory-free melting and atomization process. Due to its highly reactive nature, titanium must be melted in a refractory-free crucible. Induction Skull Melting allows the molton alloy to be contained within a self-generating thin solid shell of the same composition. As shown in the accompanying TGA schematic, raw material is charged into a water cooled copper crucible in the vacuum induction furnace. The charge can be made up of virgin raw materials, or prealloyed melt stock. Once the charge is fully molten, the vigorous stirring action of the induction field ensures that the melt is homogenous.
To initiate atomization, power to a second induction coil causes localized melting at the center of the bottom of the skull. The liquid metal is bottom poured through a metal nozzle and free falls through the atomization die and high pressure gas jets. The force of the atomization gas breaks the molton stream into tiny droplets which rapidly solidify into powder particles as they fall through the tower. The resulting powder is spherical and virtually free of segregation.
The TGA is designed so that all of the powder particles are carried by the atomization gas down through the cooling tower, up into a cyclone separator, and are finally collected in a cooled canister.
All internal surfaces of the TGA are highly polished stainless steel. This facilitates thorough cleaning at every grade change to prevent cross contamination among the alloys. All portions of the TGA below the melt deck are contained in a positive pressure clean room equipped with high efficiency filters which prevent airborne contamination. Adjacent to this area are clean rooms containing screening and blending equipment for subsequent powder processing.
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