>Will said:
>Althought Terman shows this same thing on page 315 of the
>1st edition, 1943, here is a link to a website below about
>getters;
(1) http://www.thevalvepage.com/valvetek/getter/getter.htm
>It's impossible to run one temperature on zirconium. It's
>optimum temp according to Terman is 1400 deg C to absorb
>oxygen, nitrogen, carbon dioxide, and carbon monoxide in
> >vacuum power tubes.
Will, I wonder if you aren't a little confused on this
topic. You said above " It's impossible to run one
temperature on zirconium. It's optimum temp according to
Terman is 1400 deg C to absorb oxygen, nitrogen, carbon
dioxide, and carbon monoxide in vacuum power tubes."
You then sited a link.
http://www.thevalvepage.com/valvetek/getter/getter.htm
The very link you sited says this:
"Zirconium
Zirconium has valuable gettering characteristics and has
come into wide use during the past decade. It forms very
stable solid solutions (or compounds) with such gases as O,
N, CO and CO2. Zirconium metal is cheaper than tantalum and
requires somewhat lower operating temperatures. Zirconium is
available either in solid metal form (sheets or wires) or it
may be applied in the form of a powder to base metals
(molybdenum) as described above. The proper outgassing
temperature for zirconium lies between 1,000 and 1,700 C,
which is attained by either direct or indirect heating of
the zirconium metal or of the base metal to which zir-conium
metal or zirconium powder has been applied. Wherever it is
deemed inadvisable to heat the getter material to this
temperature range, an outgassing temperature of 700 C must
be considered minimum for activating the surface of the
zirconium getter. While zirconium is effective as a getter
from about 400 C on, it is most active at temperatures up to
1,600 C if used, for example, on molybdenum and carbon
anodes."
The very text you referenced says "While zirconium is
effective as a getter from about 400 C on, it is most active
at temperatures up to 1,600 C if used,"
It appears the text you referenced says "400deg C up is
effective". Can you explain why that means it is useless
below 1700 degrees C, when that isn't what they say? Can you
also explain why Eimac was successful in using that very
common gettering material, when you say it is impossible to
use?
Thanks,
73 Tom
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