Meaning
Gas delivery hardware provides a pressurized stream of inert gas to disintegrate liquid metal into fine powders. The annular gas nozzle directs this flow through a circular orifice surrounding a central melt delivery tube. High velocity gas curtains contact the metal at a specific angle and pressure to ensure uniform droplet formation.
Operators adjust the gas flow rate to control the resulting particle size and cooling rate of the metal droplets.
Flow Pattern
Kinetic energy transfer from the gas to the liquid metal determines the efficiency of the powder production. The annular gas nozzle relies on the creation of a stagnation point where the gas streams converge below the melt tip. High pressure gas expands through the nozzle to reach sonic or supersonic speeds while maintaining a stable pressure field.
This rapid expansion creates a low pressure zone that assists in drawing the molten metal from the delivery tube through a vacuum effect. Constant monitoring of the gas to metal ratio ensures that the flow remains laminar and predictable. Stabilized flow is the result.
Nozzle Geometry
Design specifications for the exit gap and the angle of incidence govern the stability of the atomization zone. The annular gas nozzle requires precise machining to ensure uniform gas distribution around the entire circumference. Misalignment or uneven wear leads to an asymmetric gas flow that produces irregular particle shapes.
Regular inspection of the nozzle face prevents the buildup of solidified metal.
Operational Reliability
Maintaining a constant temperature at the tip of the melt tube prevents premature freezing. The annular gas nozzle must provide sufficient cooling for the gas while insulating the molten metal stream. Failure to maintain the nozzle integrity results in inconsistent powder quality.
