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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
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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>
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<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 class="moz-txt-link-abbreviated" href="mailto:labnetwork-bounces@mtl.mit.edu">labnetwork-bounces@mtl.mit.edu</a>
[<a 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 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>
</div>
<br>
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