My experience is to us Alumina Oxide Beads of grit 120 or lower to obtain a
rough surface promoting good adhesion of the sputtered film.  If the adhesion of
the film is very good such as with Al the finish does not need to be as rough
and a higher grit could be used. 
 
We generally follow the cleaning by a hot DI rinse, blow dry, then bake in a hot
N2 purged oven or a vacuum oven.  It is generally best to go from the oven to
the system without cooling or prolonged time in air.


--- On Mon, 11/24/08, Mandar Sunthankar <mandar@...> wrote:

From: Mandar Sunthankar <mandar@...>
Subject: RE: [PVD_coatings Forum] Sand blasting problem
To: PVD_coatings@yahoogroups.com
Date: Monday, November 24, 2008, 1:39 PM






Dear Towheed,

Although it is difficult to answer your question without knowing the
purpose, what is it that you are trying to do and what your requirements are
for vacuum, you have received many answers to chose from. It is quite
likely that you have to do nothing more and use the parts as they are.
However, I will put my 2-cents anyway !

A general rules from my experience in sandblasting for vacuum coating:

1. the aerospace industry does not recommend using glass beads for
sandblasting steels because the glass chips get embedded in the steels
preventing uniform adhesion. They recommend using silica sand grit size 120
and higher, specifically 200. That worked very well for me.
2. This was followed by ultrasonic rinse and quick hot air dry. For
steels, I could use only acetone rinse. Alcohol caused severe corrosion
immediately.

Mandar Sunthankar

ionEdge Corp.

_____

From: PVD_coatings@ yahoogroups. com [mailto:PVD_coatings@ yahoogroups. com] On
Behalf Of towheedsul
Sent: Friday, November 21, 2008 1:57 PM
To: PVD_coatings@ yahoogroups. com
Subject: [PVD_coatings Forum] Sand blasting problem

Dear All
We had a problem in our factory there was some
misscommunication about sandblasting, instead of using special glass
beads they used ordinary building material sand.

The vacuum components were cleaned, after which they were washed in
water and then blow with air. There might be some microcracks on the
materials cleaned which may hold water other than that will there be
any other issues.

Thanks
Towheed

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