Carbon fiber used in a silencer baffle.

[Girf]

I am trying to produce a silencer baffle in carbon fiber. I have located a resin that will provide an operating range right at the expected envelope for typical useage.

http://news.cision.com/nexam-chemical/r/nexam-chemical-introduces-neximid--mht-r,c9669305

(420c) But this leaves no margin for those who might utilize the device in a more prolonged fashion. Ideally, I need to get closer to 550c. Is there a thermal barrier in a spray-on form that I could apply to the finished part that would allow me to approach those limits.

 

[RPstress]

Thin coatings are not very effective as thermal barriers. Even a material with a low thermal conductivity will let the substrate heat up after a few seconds of exposure. Thin coatings are sometimes used with actively cooled substrates, but the usual method is to put on a thermal blanket of material such as Min-K or Hi Temp's Micro-porous. This usually has to be a significant fraction of an inch thick, though (at least a tenth).

Hi Temp do have some layered material options but these usually need a certain volume of air in them.

A thinner layer of Min-K might help.

What are your constraints on thickness? What physical assaults might this have (air velocity, particulates)?

A PI or PETI (phenylethynyl-terminated imide) are the 'usual' high temperature resin options. 450°C is very high, though. I'm not at all sure that the Neximid MHT-R you link to is quite adequate. The only 'polymer' I've ever seen that might apply is a silicon-based material and I saw that in 2005. What little info I have is attached.

NB: if using a PI make sure it's not like PMR-15 with carcinogenic MDA (methylenedianiline) in it.

 

[RPstress]

D'oh! I put a non-standard character in the filename again. Here's another which should work.

 

[Compositepro]

And after you have considered all the issues you will likely conclude that a metal or ceramic baffle will be your optimal choice.

 

[RPstress]

High temp silicon-based 'polymers' may be geopolymers.

http://www.geopolymer.org/fichiers_pdf/TOOLING.pdf.