 |
 |
Silicone in Microwave
Name: Mike M.
Status: other
Age: 20s
Location: N/A
Country: N/A
Date: 10/15/2004
Question:
Without going into too much detail, a silicone-based
liquid was placed in a microwave and started sparking like aluminum. Why?
Replies:
A couple of possibilites-
1) Your silicone fluid is a good dielectric liquid with a fairly high
dielectric constant and a low breakdown field.
you got microwave standing waves in the large volume of it, which
eventually cause dielectric breakdowns (sparks).
2) Water is lucky. When it heats and turns to vapor, the breakdown
voltage is not low.
If it does breakdown and form a plasma, water plus the oxygen in air make
a plasma the tries to extinguish itself soon.
It does not become a very conductive plasma when it evaporates and ionizes.
Even so, a grape almost cut in half can make a brief electric arc, as the
bridge of skin between the two halves gets too much power.
Silicone is not so lucky. When it evaporates, it is a carbon-containing gas.
So if its steam ignites, it will consume all the oxygen near it, and the
plasma will self-sustain longer.
This idea may translate into easier formation of sparks.
One might get a pretty big eruption from this kind of thing, in
low-boiling liquids.
And a fire, if it is flammable.
All assuming your silicone liquid was clear.
If it was gray, it may have had metal powder in it.
If it was white or orange, it had inorganic oxides which also might make
it more susceptible to microwaves.
Jim Swenson
Click here to return to the Engineering Archives
| |
Update: June 2012
|
|
