A gas under pressure p1 flows from around a melt nozzle into
a Laval nozzle, which is the classical case of a converging - diverging
flow duct. The pressure behind the Laval nozzle is p2.
In the narrowst cross section of the Laval nozzle sonic speed (Mach number Ma = 1) is reached, after it transsonic speed (Ma>1) can be reached depending on the pressure ratio p1/p2. The gas flow is strictly laminar due to the extremely high acceleration and the short entry lengths. The melt monofilment is being attenuated thinner and thinner until it bursts open spontaneously as a result of the Nanoval effect.
This non-turbulent mechanism of disintegration gives fine and ultra fine powder of spherical shape in narrow particle size distribution. Less satellites are observed compared with common turbulent processes.
The process is patented.