Powder charging tribocharging

In this entry, we review basic charging concepts, corona charging, internal charging, tribocharging, and electrostatic fluidized beds. Along with these methods, some of the properties of powders needed for their application are also discussed. 

Bipolar charge and particle count with aerodynamic particle diameter using E-SPART system of paint powder after tribocharging (Mazumder 1993)... 

Discs use large conical-type deflectors usually mounted in the vertical downward position so that powder is deflected in a horizontal position in a 360°radius. An omega (Q) loop conveyor system normally surrounds the powder disc that is usually mounted on an oscillator or reciprocator for vertical up-and-down motion. The powder can be charged by a corona edge or by tribocharging guns. Typical applications for the powder disc are vertical extrusions or wire goods. 

The powder is transported through the supply tubing to the spray gun. If the powder is passed through the gun without further interaction, it would just be sprayed into the air as a cloud. There would be no physical reason for the powder to deposit on the substrate to be coated. To make this attraction happen, a charge must be applied to the powder. This is done by two methods called corona charging and tribocharging. 

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