Cyrus
Hazard to Others
Posts: 397
Registered: 24-4-2004
Location: Ancient Persia
Member Is Offline
Mood: No Mood
|
|
Phenolic Resins
I've been doing some research on SiC crucibles, namely glassy carbon bonded SiC. The "glassy" carbon is supposed to come from a
phenolic resin.
All I know about these is that they may be made from phenol and formaldehyde,
or as some kind of "furfuryl" resin, and that they may come under the names of novolac or resol. Google is also showing some results with
bakelite, but I didn't think bakelite was exactly a high temperature refractory material.
My goal is to synthesise some SiC, and some phenolic resin, and use them to make some crucibles.
Any help would be appreciated.
Cyrus
[Edited on 17-12-2004 by Cyrus]
|
|
|
Ollie Snowie
Harmless
Posts: 4
Registered: 9-9-2003
Member Is Offline
Mood: No Mood
|
|
I've got an ebook with information about this - try searching eMule for "Handbook of Carbon, Graphite, Diamond and Fullerenes".
It's got a chapter on vitreous carbon, and mentions other polymers which can be used to make it, like cellulose, as well as what you've
mentioned. It doesn't explain the method in much detail though.
If all you want is a SiC crucible, there is a company who has a process to turn a graphite shape into SiC, but I bet their method is a closely
guarded secret.  Of course, if anyone does know the process, I'm sure
we'd all like to know.
Also, for information on small arc furnaces, try http://arcmelt.velp.info/ , or http://www.popsci.com/popsci/how2/article/0,20967,726308,00.... . If you're like me and don't have an arc welder, try using old AT
computer power supplies to put a high current through a graphite rod (as a resistive furnace). With this setup, I heated up a small amount of CaO up
to the point that it reacted with the carbon rod and made calcium carbide, but I didn't try making silicon carbide. Anyway, you'll have a
big job making enough SiC for a crucible in this way, if you even get any.
|
|
|
Cyrus
Hazard to Others
Posts: 397
Registered: 24-4-2004
Location: Ancient Persia
Member Is Offline
Mood: No Mood
|
|
Thanks for the links.
Graphite to silicon carbide is doable.
2C + SiO2 -> SiC + CO2 (maybe CO)
One interesting use for this is to make wood ceramics- carbonize wood, dip the wood in colloidal silica, and then heat- a porous SiC ceramic shape is
made. There's so much to do and so little time.
Yes, I know that I'll need lots of SiC, but this is more for "fun" than for a practical purpose- it would be more useful for small
crucibles and other small high temperature things- stirring rods, etc... (I'm also working on slip casting clay graphite and clay crucibles,
which would be more economical. I've gotten ok results so far, but I know what to fix. )
BromicAcid, a while back you mentioned NASICON ceramics, I think I have all of the materials needed, I may have a go at slip-casting some pieces for
Na production.
Gotta get that Na.
[Edited on 18-12-2004 by Cyrus]
|
|
|
Cyrus
Hazard to Others
Posts: 397
Registered: 24-4-2004
Location: Ancient Persia
Member Is Offline
Mood: No Mood
|
|
Edit- I have found some more information on phenolic resins.
They are made by a reaction with phenol(ahh! I see the light) and formaldehyde, in the presence of either an alkaline or an acidic catalyst. If
it's alkaline, they are called resoles, and are self curing, but if it's acidic, they are novolacs and take a catalyst to cure.
A commercial use for phenolic resins is in the production of glassy carbon/graphite electrodes for arc furnaces.
|
|
|
Texium
|
Thread Moved
19-11-2023 at 10:17 |
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
