I need to find a substance with the following physical properties:
December 11, 2013 1:23 PM Subscribe
I need to find a substance that is : a) transparent over the visible or infrared, b) melts between 10 and 100 degrees C c) has modest freeze/melt expansion e)is at least a bit volatile in the liquid phase.
posted by Nish ton to Science & Nature (9 answers total) 1 user marked this as a favorite
I need to find a material that is :
a) transparent over the visible and infrared, or at least infrared, both when solid and when liquid.
b) melts between 10 and 100 degrees C. The lower bound matters and is pretty firm, the upper bound is more flexible. Really it's just a matter of convenience and the desire to avoid complications caused by thermal expansion caused at higher temperatures.
c) Does not have a particularly large expansion or contraction upon melting or freezing, 0.7% or less is good, some paraffin waxes are roughly this (they are not transparent, though).
d)Is not terribly toxic, although I can manage some toxicity.
e)is volatile enough in the liquid phase that we can remove it by vacuum pumping to reduce the ambient pressure, then boiling it away.
What I want to do with it is to selectively melt out a void from a block of material using a cone of light to selectively heat areas inside the block under computer control, carefully remove the remaining liquid, and then fill the resulting void with plaster, allow the plaster to set, then remove the remaining transparent material, so you have a custom cast.
I will read comments on the viablility of this process and am of course interested in talking about it some other time, but right now I am really only looking for the material, as the details look promising in other regards, upon close inspection.
Water would be ok, except for the large freeze melt volume change, darn it. We can add calcium chloride to the plaster so it can set at a little bit below zero degrees... but it's better not to, because it affects the accuracy of the process, most likely.
There's gotta be some material or another that has this. Benzene might be ok. Camphor, oxalic acid. There's gotta be something better, though. Something like water that is relatively easy to handle and stuff.
I'm doing this out of the local hacker space here in Ottawa, it is a sort of art project, but if the accuracy of the process can be pushed, it could be used a bit like a 3d printer.