Do you have any experience about coating a teflon layer on 8um glass spheres

Now I meet some problems when I am preparing to make a high contact angle
hydrophobic particles in powder. I have some borosilicate glass spheres
(diameter is about 8um) and teflon solution. I make the hydrophilic particles
into the teflon solution and mix them a long time. But when I spray the solutin
on a surface, the particles come together and hardly removal from the surface.
What I want is to get the powdery teflon coating glass spheres, but I think the
method I used could not work.

Do you have some suggestions to me? Which method should I take? Thanks in
advance.

Zhao Yuejun