Doug, it's been a long time since I worked on corona or partial discharge phenomena, but here are some bits of information.

If you are concerned about altitude in Earth's atmosphere, my estimate is that the minimum voltage for partial discharge in air is 320-450 volts when the product of pressure in Torr and the dimension of a cavity (or electrode spacing) in cm  is approximately 500 Tor-cm.  
At other pressure-dimension products, the partial discharge voltage is higher.  Other simple gases like argon, nitrogen, hydrogen exhibit similar behavior.

Resistance to partial discharge degradation is, crudely, best in inorganics, natural organics (paper), synthetic organics (thermoplastics, theromosets).

The dielectric breakdown strength would relate to pure material property, with no cavities.  I wager coating manufacturers specify dielectric breakdown strength.

My old book on 'Corona Measurement and Interpretation' from ASTM still is current: http://www.astm.org/DIGITAL_LIBRARY/STP/SOURCE_PAGES/STP669.htm  

Maybe the above is some help.

 Louis Hart

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
Sent: Tuesday, December 09, 2014 3:35 PM
To: [log in to unmask]
Subject: [TN] Coating vs. Altitude

Good afternoon all,

I am wondering if anyone in the Net knows of any studies on dielectric strength of conformal coating type and/or thickness, vs. altitude?  Along the lines of protection against arcing and corona (effect, not the beer).

I figured if anyone knows, this group would.

Doug Pauls
Principal Materials and Process Engineer Rockwell Collins


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________