An electrostatic fluidized bed is essentially a fluidized
bed with a high voltage dc grid installed above the porous plate to charge
the finely divided particles. Once charged, the particles are repelled
by the grid, and they repel each other, forming a cloud of powder above
the grid. These electrostatically charged particles are attracted to and
coat products that are at ground potential. Film thicknesses are similar
to what can be achieved in the electrostatic spray process.
The advantages of electrostatic fluidized bed coating
is that preheating of parts is generally not necessary and small products,
such as electrical components, can be coated uniformly and quickly. The
disadvantages are that the product size is limited and inside corners
have low film thickness owing to the well known Faraday cage effect.
