Alloy Stoichiometry and Gas Entrapment Control in Atomized Powders
Controlling melt superheat and nozzle pressure limits vapor pressure elemental loss while helium purge or vacuum degassing eliminates micro-cavity gas voids.
Closed Coupled Nozzle
Meaning
Gas atomization components direct a high velocity stream of inert gas at the exit of a liquid metal delivery tube to break the melt into fine droplets. Utilizing a closed coupled nozzle minimizes the distance between the gas exit and the molten metal stream to optimize kinetic energy transfer. The design yields spherical metal powders with narrow size distributions suitable for battery powder metallurgy.
This nozzle configuration is selected to prevent molten metal from pooling or forming irregular shapes during the process.
Gas Dynamics
High pressure gas emerges from a ring of small apertures or a continuous annular slot directly surrounding the melt tip. This arrangement prevents the molten metal from freezing prematurely in the delivery tube. Controlled gas flow rates are maintained to prevent aspiration of molten metal back into the atomization chamber.
Powder Distribution
Powder particle size is determined by the gas to melt ratio and the nozzle geometry. Finer powders are preferred for electrode coatings, but they increase the risk of dust explosions during processing. Sourcing engineers select specific nozzle configurations to match the desired particle size distribution.
Thermal Management
Cool gas streams solidify the droplets rapidly as they fall through the atomizing tower. This rapid cooling prevents phase separation and ensures a homogeneous microstructure in the powder. Consistent thermal control is required to prevent agglomeration of the metal particles.