[labnetwork] acetone in Acetylene

[Bob Hamilton]

Mike Tiner,

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.

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.

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.

Regards,
Bob Hamilton


On 7/14/2013 9:57 PM, Mike Tiner wrote:
>
> Dear All,
>
> 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?
>
> Any advice will be appreciated.
>
> Best regards,
>
> Mike
>
> *Mike Tiner
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-- 
Robert Hamilton
University of California at Berkeley
Marvell NanoLab
Room 520 Sutardja Dai Hall
Berkeley, CA 94720-1754
bob at eecs.berkeley.edu
Phone: 510-809-8600
Mobile: 510-325-7557 (emergencies)
e-mail preferred

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