On Tue, 14 Jun 2005 18:58:46 GMT, Rich Grise wrote:

On Tue, 14 Jun 2005 10:54:37 -0700, Dr.Polemic wrote:
On Tue, 14 Jun 2005 13:07:05 -0400, John Popelish wrote:
John Fields wrote:
On Tue, 14 Jun 2005 08:32:09 -0800, (Floyd L.
Davidson) wrote:
Dr. Polemic wrote:
On Tue, 14 Jun 2005 01:14:42 -0800, (Floyd L. Davidson) wrote:
Dr. Polemic wrote:
snip
No way did he "...get ni-cad to boil at room temperature (by) simply
reduc(ing) the pressure to something *significantly* below its vapor
pressure. We did it knowingly with gold too once..."

Gold has a vapor pressure of 10^-11 torr at about 800 degrees. I don't think gold will
boil even in interstellar space (10^-17 torr) at 20 degrees. It *will* evaporate, though;
so will tungsten! Slowly!

Takes a nice little vaccuum pump to do it though.

Yer fulla ****.

I think he is confusing boiling with sputtering.

But he says it *boiled*; he couldn't be mistaken, could he?

Or maybe just sublimation. And he didn't say the chamber was held at
room temperature.

What he said was: "Danged, several weeks of work shot because it just hadn't
occurred to him that ni-cad would boil at room temperature." I suppose I could say that
tungsten exaporates at room temperature and then say that I didn't say that the filament
wan't held at room temperature; I just meant that the room was at room temperature.


What's the vapor pressure of zinc at 20C?

10^-8 torr at 123 degrees C. And, of course it will evaporate at 10^-8 torr and 20
degrees, but it *won't* boil. At 10^-8 torr, it will *boil* at 123 degrees.

I once worked at a place
where their product used a UHV bell jar - that's "Ultrahigh vacuum".
They didn't even have an oil-based pump in the building. They started
with an ordinary sorption pump, then they had ion pumps and molecular
inertial pumps, and getter pumps, and the sexiest was the cryopump.

One day one of the vacuum engineers came into the shop from the line,
fit to be tied. It seems someone had supplied feedthroughs with brass
contacts. The zinc ruined some stuff, and wasted about a week from
having to clean out the bell jar.

Cheers!
Rich