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DillonCo 12-18-2003 03:28 AM

Tungsten at High Temperatures
 
How reactive is tungsten at high temperatures (around 2500*C)? I will be
exposing it to carbon, CO2 and air. While I know it will react with the
carbon, I have read this can be prevented by using a thin rhenium seperator
between the tungsten and carbon. Currently, I have read conflicting reports
on tungsten's reactivity in air. If it is reactive, will a rhenium coating
stop corrosion (and not corrode itself)? Also, is CO2 (and maybe CO) any
concern at any temperature?
Thanks for any help.



Repeating Rifle 12-18-2003 04:01 AM

Tungsten at High Temperatures
 
in article S99Eb.74751$8y1.279211@attbi_s52, DillonCo at
[Only registered and activated users can see links. Click Here To Register...] wrote on 12/17/03 7:28 PM:

My experience with this is limited to light bulbs. When I have broken an
incandescandescant tungsten lamp accidently, the tungsten filament gets
turned into a yellow oxide.

Bill


DillonCo 12-19-2003 02:06 AM

Tungsten at High Temperatures
 
> You're dead.

Would rhenium resist such reactions at those temperatures?



G. R. L. Cowan 12-19-2003 03:08 AM

Tungsten at High Temperatures
 
DillonCo wrote:

No. [Only registered and activated users can see links. Click Here To Register...] used to have pictures of a laminar
HfC/SiC structure that would stand up for a little while.
(Hafnium becomes the pleasant refractory HfO2.)


--- Graham Cowan
[Only registered and activated users can see links. Click Here To Register...] --
fireproof fuel, real-car range, no emissions

DillonCo 12-19-2003 07:24 PM

Tungsten at High Temperatures
 

"G. R. L. Cowan" <[Only registered and activated users can see links. Click Here To Register...]> wrote in message
news:[Only registered and activated users can see links. Click Here To Register...]...
protective

Great site, thanks!
So, basically, anything will oxidize (in air) at elevated temperatures? To
bad ;).
Do you know if tungsten (wuth certainty), rhenium, or TaC/NbC will react
with CO2?
Thanks for all your help!



G. R. L. Cowan 12-20-2003 04:31 PM

Tungsten at High Temperatures
 
DillonCo included:

Things that won't oxidize, and may not evaporate too quickly,
include BeO, M2O3, MO2 where M=Y, Zr, Th, Hf, and for M2O3 maybe a few
others.


No, but I'd be surprised if they didn't.
If the solid does not include carbon,
oxygen atoms take the metal away.
If it does have carbon, the extra O in CO2 takes that,
and then both oxygens take the metal away.



--- Graham Cowan
[Only registered and activated users can see links. Click Here To Register...] --
how cars gain nuclear cachet

Pelerin Galimatias 12-21-2003 05:45 PM

Tungsten at High Temperatures
 
Vapor deposited silicon might produce some protection
for tungsten--it does for molybdenum. When oxidized a
moly disilicide coating produces a protective SiO2 layer.
--
00000010000001000001100010000110100011111100101110 11101000010000


G. R. L. Cowan 12-21-2003 06:05 PM

Tungsten at High Temperatures
 
Pelerin Galimatias wrote:

Silica becomes volatile well below the OP's desired temperature
of 2,500 Celsius.


--- Graham Cowan
[Only registered and activated users can see links. Click Here To Register...] --
fireproof fuel, real-car range, no emissions

Pelerin Galimatias 12-21-2003 10:07 PM

Tungsten at High Temperatures
 
In article <[Only registered and activated users can see links. Click Here To Register...]>, [Only registered and activated users can see links. Click Here To Register...] says...

Ok, nothing will work in an oxidizing atmosphere at that temperature.
--
00000010000001000001100010000110100011111100101110 11101000010000


Jaak Suurpere 12-22-2003 10:49 AM

Tungsten at High Temperatures
 
[Only registered and activated users can see links. Click Here To Register...] (Pelerin Galimatias) wrote in message news:<bs55jt$7pc8a$[Only registered and activated users can see links. Click Here To Register...].uni-berlin.de>...


You might consider thoria. Melts at 3400 degrees. (Not sure of
volatility, but does not boil yet.) Impossible to oxidize and hard to
reduce.

Among other oxides, I think uranium dioxide melts at 2880 degrees. At
lower temperatures it can be oxidized, though.


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