Meaning
Mechanical wear and thermal degradation enlarge the flow orifice of a gas or melt nozzle during high temperature atomization processes. Continuous nozzle erosion alters the flow rate and shape of the metal stream, which causes drift in the final powder size distribution. This wear results from the corrosive action of the molten alloy and high velocity gas currents.
Powder producers use wear resistant ceramics to minimize this degradation and extend production run times.
Wear Mechanism
Hot liquid metal dissolves the nozzle material, while abrasive particles in the gas stream erode the exit geometry. This action increases the diameter of the orifice.
Flow Disturbance
Enlarger nozzle dimensions decrease the velocity of the atomizing gas, which lowers the energy transferred to the melt. This change increases the median particle size.
Maintenance Frequency
Regular inspection and replacement of the nozzles prevents drift in the quality of the powder. Suppliers must document wear rates to guarantee consistent batch properties.