metalresearcher - 17-9-2018 at 11:55
I tried to ignite KClO3 + sugar under vacuum (i.e. < 50 mbar) by a laser pointer.
In open air it ignites, even through a glass jar, but when the same jar is evacuated and shine the well-focused laser on it (covered with a bit of
cahcoal to absorb the heat better) it does not ignite.
It appears that it requires air to ignite, while KClO3 is already an oxidizer on its own.
What is going on here ?
wg48 - 17-9-2018 at 12:51
Assuming you can ignite the same mixture through the glass when the air is present, I guess the oxygen released from the thermal decomposition of the
chlorate is pumped away before it can react with the sugar. Meaning its an oxygen gas sugar reaction as opposed to a molten chlorate molten sugar
reaction.
Metacelsus - 17-9-2018 at 12:53
I know that the Rosetta/Philae spacecraft had an issue with harpoons not firing because the pyrotechnics didn't work in vacuum. Maybe a similar thing
is going on.
Edit to add sources:
https://www.wired.com/2013/10/in-space-no-one-can-hear-your-...
http://txchnologist.com/post/102624788755/philae-harpoon-fai...
[Edited on 2018-9-17 by Metacelsus]
BromicAcid - 17-9-2018 at 14:58
I remember seeing something on a similar combustion reaction occurring under vacuum. Their issue there is that the boiling point of the byproducts
and starters were low enough that they sapped the energy the reaction needed to be self sustaining under vacuum.