Professor French and his students wanted to develop a demonstration of how a de Laval nozzle (also called a convergent-divergent nozzle) converts subsonic gas flow into supersonic flow.
When the pressure exceeds about 620kPA, the tape bursts, allowing a pressure wave into a special nozzle - called a de Laval nozzle.
The deposition rate with De Laval nozzle is more finely controlled to be able to produce coatings in addition to near net-shape solids, and keeps over-spray losses to a minimum.
Researchers at the Idaho National Engineering Laboratory (INEL) are developing spray-forming technology for producing near net-shape solids and coatings of a variety of metals, polymers, and composite materials using De Laval nozzles. INEL researchers have produced low-carbon steel strip and polymer membranes as thin as 5 microns.