Basics of Ultrasonic Atomization
January 1, 2015
Foundational overview of how ultrasonic atomization works and its applications in thin-film coating.
Ultrasonic Atomization and Cavitation
Excessive energy will cause liquid emerging from the nozzle to prematurely aerosolize, which is not ultrasonic atomization. Cavitation occurs when the acoustic energy exceeds the threshold needed for controlled droplet formation, resulting in an uncontrolled spray rather than a fine, uniform mist.
What is the Difference Between an Ultrasonic Nebulizer and Ultrasonic Nozzle?
An ultrasonic nebulizer utilizes the surface of the piezoelectric disk as the surface for atomization, whereas an ultrasonic nozzle uses the piezos as a driver. The nozzle design allows for precise control of droplet size and flow rate, making it suitable for industrial coating applications.
Is Smaller Droplet Size Always Better?
Type of solvent, distance the nozzle is from the substrate, and flow rate all play a role in determining the final droplet size and thus quality of coating. Smaller droplets are not universally superior — the optimal size depends on the application, substrate, and desired coating characteristics.
How to Prevent Agglomeration of Spray Coatings
Ultrasonic nozzles can inhibit agglomeration ("clumping") of nanoparticles, nanowires, platinum carbon black inks used in hydrogen fuel cells, flux, and other nano-scale materials. The gentle, low-velocity spray produced by ultrasonic atomization keeps particles dispersed during deposition.
How Nozzle Design Impacts Flow Rate
Flow rate in an ultrasonic nozzle is not a function of air pressure as it is with conventional spray nozzles. What drives liquid velocity is the pumping mechanism and the orifice geometry. This decoupling of atomization energy from flow rate gives engineers precise, independent control over both parameters.