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Hello,<br>
<br>
The Titanium is a chemical active element used in high vacuum Ion
Getter Pumps; it could accumulate<br>
a high volume of gas, which by a sudden expansion could generate
the necessary flame temperature <br>
for some gases.<br>
The scraped material from the e-beam walls could have contained in
addition to Ti some other highly<br>
oxidizing elements like Al, Cr ( actually they were used in Napalm
fabrication) and also Pt which coverts<br>
the molecular H2 into atomic Hydrogen ( with low temperature
ignition point), etc<br>
I think the flame is triggered by a such thermodynamic/ chemical
process; not by static electricity, as<br>
it happened in a metal garbage can, too.<br>
Thanks, Bernard<br>
<br>
<br>
On 5/7/13 9:47 AM, Joe Palmer wrote:<br>
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All,<br>
<br>
When fine particles of a metal that can oxidize (Ti, Al, Cr, Fe,
Ag, etc) are suddenly exposed to air, they of course do oxidize,
and because their surface area to volume ratio is so great they
can reach the ignition temperature of acetone, methanol, or
isopropanol, and in some cases their own ignition temperature.
This is similar, but not identical to the mechanism behind
grainery explosions. While water is generally anathema to vacuum
systems, in this case wiping the material down with water or a
mixture of water and isopropanol, is not a bad idea.<br>
<br>
Regards,<br>
<br>
Joe Palmer<br>
PRISM MNFL <br>
Ops Manager<br>
<br>
<div class="moz-cite-prefix">On 5/6/2013 4:08 PM, Leif Johansen
wrote:<br>
</div>
<blockquote
cite="mid:879AEF5002D70747B136D02BC86A9C980E0647@ait-pex02mbx05.win.dtu.dk"
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<p class="MsoNormal"><span style="color:#1F497D">Hello Rick, <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB">At
DTU Danchip we have an e-beam evaporation system in which
we deposit Titanuim. We have had at least three incidents
of wipes or other parts catching fire during maintenance
work. I do believe that the root cause is that Titanuim
oxidizes very fast, especially when a large, fresh surface
is exposed to oxygen. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB">I
have tried to translate our safety precautions from Danish
into some sort of English: <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB">“Before
the work is started, DI water is filled in a bucket and
placed next to the machine. Surface cleaning of various
chamber parts must take place over the water bucket. All
used cloths, with or without Ethanol/IPA are also to be
deposited in the bucket, so they can absorb water. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB">Absorption
of water in the cloths will prevent ignition. Some metals,
like Titanum, when exposed to mechanical stress like
hammering or scraping, form small particles which ignite
as a result of fast oxidation”<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB">Hope
this could help. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB">Best
regards, <o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-GB">Leif</span><span
style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif""
lang="EN-US">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif""
lang="EN-US"> <a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:labnetwork-bounces@mtl.mit.edu">labnetwork-bounces@mtl.mit.edu</a>
[<a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="mailto:labnetwork-bounces@mtl.mit.edu">mailto:labnetwork-bounces@mtl.mit.edu</a>]
<b>On Behalf Of </b>Morrison, Richard H., Jr.<br>
<b>Sent:</b> 6. maj 2013 15:50<br>
<b>To:</b> <a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a><br>
<b>Subject:</b> [labnetwork] Titanium hazard<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US">Hi Everyone,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Last week one of the
staff was wiping off some evaporator parts that were
covered with Titanium metal. He was using texwipes soaked
with IPA. He tossed the texwipes in the trash then
accidentally dropped some wipes saturated with IPA on top
of them and a fire started. It self extinguished after 1
minute but it melted the bottom of a plastic trash can.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Have any of you had
that happen or something similar? Needless to say this is
very alarming and I need to understand what could have
caused this and develop a corrective action plan.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Rick<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Draper Laboratory<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Group Leader
Microfabrication Operations<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">555 Technology Square<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Cambridge Ma,
02139-3563<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><a
moz-do-not-send="true" href="http://www.draper.com">www.draper.com</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><a
moz-do-not-send="true"
href="mailto:rmorrison@draper.com">rmorrison@draper.com</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">W 617-258-3420<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">C 508-930-3461<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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