Argon Gas Supply Calibration in Metal Powder Atomization
Precision calibration of argon mass flow and trace purity controls particle size distribution and prevents interstitial oxide formation in atomized powders.
Subsonic Plume Expansion
Meaning
Fluid dynamic behavior measured against underexpanded supersonic flow describes gas stream spreading below local sonic velocity. Subsonic plume expansion occurs when gas exit velocity from an atomization nozzle remains below sound speed, resulting in gradual pressure equalizing across the jet boundary. This flow regime reduces shear stress at the gas-metal interface compared to supersonic breakup mechanisms, altering droplet detachment dynamics.
Velocity Profile
Gas velocity decays rapidly along the central axis of the jet plume due to turbulent viscous mixing with surrounding ambient gas. Entrainment of chamber gas widens the plume cross-section while reducing peak kinetic energy available for metal breakup.
Energy Transfer
Low gas kinetic energy results in coarse droplet formation during melt stream breakup. Subsonic velocity delivers insufficient shear stress to overcome liquid metal surface tension cleanly, leading to higher median particle diameters and broader size distributions. Processing high-viscosity alloys under subsonic flow increases liquid droplet coalescence risk.
Plume Divergence
Jet spreading angle determines the spatial boundary of gas-liquid contact. Wide divergence angles disperse energy over a broader area, lowering kinetic density at the central melt stream. Measuring divergence angle against gas supply pressure enables optimization of nozzle distance to prevent liquid splashing onto chamber walls.