Gary,

Interesting application of hard coatings!  Not knowing what material
you are putting down makes it hard to figure out why some areas are
blue.  If you are there are areas that get varying thicknesses of
material, it may simply be destructive interference with the light at
a film thickness that corresponds to blue.  If you have rotation of
your part during deposition, this may improve the coating uniformity,
which may eliminate those film thicknesses that are responsible for
the blue color.  Or just simply deposit a thicker film to ensure the
interference is out of the visible spectrum.

With respect to the shadowing of areas on your part, you're a little
stuck as long as you use evaporation.  You'll need to use a higher
pressure technique such as sputtering to eliminate some of the
shadowing you're seeing.  By increasing the chamber pressure during
deposition, you'll decrease the sputtered material's mean free path
and produce a coating that will coat areas hidden from the arc
evaporation source.

Good luck,

Paul


At 07:56 PM 7/10/2006, you wrote:
>Hello all,
>
>We work in decorative hard coatings on 3D objects. I
>am having two problems:
>
>1. I am seeing some blue color on some portions of the
>parts whereas rest of the parts on the turntable look
>fine. Any suggestions???
>
>2. Also, some of the parts even do not get any PVD
>coating whereas other parts on the same turntable get
>PVD coating fine. Any suggestions to solve these two
>problems in my Arc Evaporation PVD system. Thanks in
>advance.


==================================
Paul Sunal, PhD
MEMS Engineer

MEMS and Nanotechnology Exchange / CNRI
1895 Preston White Drive
Suite #100
Reston, VA  20191

Tel: 703.262.5323
Fax: 703.262.5367
==================================