[TheForge] chip shapes and materials

[Bruce Freeman]

Frosty,
Your idea on thermally conductive chips is excellent. 
What we need is small (maybe 3/4" dia) balls of a
highly refractory and thermally conductive material. 
Frankly, I'd be inclined to try commerical alumina
spheres first.  Failing that, then hand-rolled
rrammable refractory spheres.

But since such refractories are inherently not very
conductive, how about going back to the "rice in
porcelain" idea.  Take a wooden bead, 1/2" dia.  Wrap
it in castable refractory about 1/8" thick, making a
ball about 3/4" dia.  Push a punch though the bead
hole to clear away the "clay" at that point.  Let it
set, then fire it - burning out the wooden bead. 

Voila', a hollow refractory sphere.  Being hollow, it
would not "store" heat in the thermally inaccessible
center.  (This is roughly equivalent to having a high
thermal conductivity.)  Being roughly spherical, it
would be fairly strong, despite being hollow. 
Furthermore, the holes would allow heating from the
interior to some degree, for what that's worth.  

Sounds like a fair amount of trouble to go through,
but talk is cheap!

BTW, I disagree about the torus (lifesaver) shape. 
Such shapes are used for distillation columns.  They
pack quite tightly, and I think it would be tough
working with them.   Go get a gross of lifesavers and
give it a try :^)

I'm also intrigued by the idea of using carbon for the
chip.  Sure it would burn, but probably not very much.
 Graphite crucibles are practical, and they take much
more stress than these chips would have to.  I'm still
thinking of "marbles" made out of commercial (tough!)
coke.  Unfortunately, this stuff seems to be available
only in large (fist sized) chunks, and breaking it
apart is no simple trick.  Maybe use a hole saw on the
stuff to reduce it to cylinders?

Keep thinking...

Bruce
NJ








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