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Mike Tiner,<br>
<br>
Before making a decision of what form of acetylene to use for carbon
nanotube production it is worth reviewing issues with this gas. The
well known issue of acetylene being explosive and unstable at
pressure over ~30 psig is one issue. This is why it is disolved in
acetone and an inert matrix in a welding cylinder. There are other
issues worth considering. <br>
<br>
Acetylene derived from calcium carbide has some level of phosphine
contamination. This will be high enough PH3 to affect the dopant
properties of the nanotubes produced. <br>
<br>
As a result of this PH3 contaminant the Microlab used calcium
carbide as a convenient surrogate when doing "bump" tests on our
toxic gas monitoring system and our hand-held monitor. CaC2 also
provided a way to let engineers know what phosphine smelled like. A
small chunk of calcium carbide in a beaker plus a little water
produces that characteristic odor. It was good instruction, in those
less-litigious times, a time when one could get away with a
common-sense demonstrations. <br>
<br>
Regards,<br>
Bob Hamilton<br>
<br>
<br>
<div class="moz-cite-prefix">On 7/14/2013 9:57 PM, Mike Tiner wrote:<br>
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<p class="MsoNormal">Dear All,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I can’t remember if this has been addressed
before, but we are installing a CVD reactor for CNTs and
graphene which uses Acetylene as one of the feed gasses. I am
trying to decide whether to use a cylinder with or without
acetone. Can anyone give insight into this? Do we require
acetone?, is there a contamination issue to be aware of?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Any advice will be appreciated.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best regards,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Mike<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<pre class="moz-signature" cols="72">--
Robert Hamilton
University of California at Berkeley
Marvell NanoLab
Room 520 Sutardja Dai Hall
Berkeley, CA 94720-1754
<a class="moz-txt-link-abbreviated" href="mailto:bob@eecs.berkeley.edu">bob@eecs.berkeley.edu</a>
Phone: 510-809-8600
Mobile: 510-325-7557 (emergencies)
e-mail preferred
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