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High temp coating for carbon steel that is an electrical insulator

It there a coating that is commercially available for hot (~650 deg F)heavy hydrocarbon service (initial boiling point above 650 deg F)? I have an application where two carbon steel parts that are in physical contact must be electrically isolated from each other so as to have different voltage potentials.

Dennis Salbilla
Design Engineer - Houston, Texas
July 20, 2009

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First of three simultaneous responses --

Other than attaching ceramic insulators, not much will work. That is at the absolute max for most Teflon type materials and because they are thin, the dielectric is not wonderful at higher voltages.
You might look into high energy thermal spray ceramic type material to see if it might be ok. I would look at something higher energy than normal plasma spray, such as HVOF or d-gun or diamond jet and etc.

James Watts
- Navarre, Florida
August 6, 2009

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Second of three simultaneous responses --

Sounds like a job for ceramic spacers.

Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.
August 7, 2009

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Third of three simultaneous responses --

They plasma/thermal spray or e-beam deposit zirconium oxide on turbine blades as a thermal barrier coating. The coating is both thermally and electrically insulating, and can withstand much higher temperatures than your parts will ever see.

Jim Treglio - scwineryreview.com
PVD Consultant & Wine Lover - San Diego,
California
August 7, 2009

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You may consider aluminum nitride or oxide coatings by PVD techniques. Thickness could be in the range of few microns. What is the level of insulation required?
Plasma spray of alumina may also work if the adhesion is good.

H.R. Prabhakara - Consultant
Bangalore Plasmatek - Bangalore Karnataka India
August 7, 2009

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You might want to look into the family of PEEK (polyaryletherketones) plastics. Victrex PLC has a liquid dispersion spray-on product and also a powder coat version as well as solid products. My company has experimented with the powder and liquid forms with good results. Very tough, very high temperature resistant. Cure temperature is 800 F

Tim Hamlett, CEF
- West Palm Beach, Florida, USA
August 18, 2009