From: Eugen Leitl (eugen@leitl.org)
Date: Sun Jan 12 2003 - 03:14:29 MST
On Thu, 9 Jan 2003, Michael M. Butler wrote:
> The best temp performance polymers I know of are high-temp liquid crystals
> used to mold, e.g., the connector housings for thermocouples. They spec out
> at something well under 500F.
Polymers are used in ablative heat shields in aerospace. I see no reason
why you can't have polymers performing adequately sustainably at 1000 K. I
would count any molecular crystal as polymer, so diamond and graphite are
polymers too.
> You're up against a pretty fundamental limit of materials, I suspect: any
> hydrocarbon polymer is going to poop out somewhere around the flash point of paper.
So don't use hydrocarbon polymers.
> Conceivable that, after forming, you could heat-drive the hydrogen off
> (as they do today with some Santa Claus casing forming tech) to get carbon
> matrix x y and z, but those are not very strong compared to bulk solid materials.
Do you remember that orthogonally aligned bucky reinforced polymer is on
par with metal carbides like TiC and WC, at orders of magnitude less
density? I don't know about thermal stability, but the matrix could be
essentially anything. I could see them surviving abovementioned 1 kK.
> Now, if you consider _diamond_ a polymer... :)
Of course diamond is a polymer. But we should be able to do better than
diamond, as far as thermal stability in oxidative environments is
concerned.
> Sintering metals or ceramics seems superficially plausible, but I'd guess
> it loses a lot in strength without very special manufacturing tech.
Next generation DVD lasers have 400 mW output. Plenty heat, if focused
down to um sized spots.
> For me, that leaves hypotech such as [s]elf-assembling ([Sic], given the monicker
> "Santa Claus Machine", plus the hypothetical nature) nano"crystals" in a slurry.
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