is it possible to make conductive epoxy by adding copper powder?
i have copper powder but it does not seem to be conductive?
the graphite powder i have is conductive.
do i need to somehow wash (reduce) the copper powder to make it conductive?
i apologise for asking such simple questions.
thanks
john Mr. Wizard - 28-1-2012 at 22:39
Theoretically, yes it is possible. You can make copper powder by reducing a copper sulfate solution with vitamin c. I dissolved both in a small
amount of water and mixed the clear liquids only. It gave a very fine copper powder. What will happen though is it will corrode or turn dark over time
when exposed to air. You powder may have some kind of coating on it to keep it shiny. You seem to suspect this, as you asked about washing it. Some
simple evaporating solvent like acetone might work. Be careful of the inflammable fumes. Nothing ruins a day like having your hands catch fire and
dropping a bucket of burning solvent. Yes maybe overdramatic, but it happens all the time.
The most common metals used for conductive paints are silver and nickel; the silver being more expensive. I have a jar of each, and they are in a
clear liquid that has a faint smell. They both tend to settle out and form a lump in the bottom of the jar.
I recently saw an advertisement for a conductive silver epoxy, so I know it can be made. I don't know what the carrier is for conductive paints.
There is also a zinc powder spray paint sold as 'Cold Galvanizing'. It is very useful for protecting galvanized steel that has been welded. When you
weld the zinc galvanizing gets removed and leaves bare steel. A coating of this paint protects it very well. It is conductive when sprayed on paper. I
made a dry battery http://en.wikipedia.org/wiki/Zamboni_pile
by spraying graphite on one side of a sheet of paper and zinc on the other. I used a regular sheet of printer paper with a criss-cross pattern of
paper to keep the conductors from getting to the edge. I did this as a test and got measurable voltage when I cut and stacked 10 of the 'cells'
together. I tossed the stuff out in a clean up one day and haven't been able to reproduce it again. It may have been moisture in the air, or maybe I
changed graphite spray.
[Edited on 29-1-2012 by Mr. Wizard]Pulverulescent - 29-1-2012 at 05:08
Quote:
. . . i have copper powder but it does not seem to be conductive?
The cupric oxide that forms on copper exposed to air is an insulator ─ cuprous oxide is a semiconductor and was used as such in
older-type rectifiers . . .
does the mixing with acrylic varnish and a very small amount of water help to make the copper conductve ?Pulverulescent - 29-1-2012 at 17:14
Quote:
. . . does the mixing with acrylic varnish and a very small amount of water help to make the copper conductve ?
Welcome to SciMad Laura ─ artists here are thin on the ground despite what the slogan up top says!
But science and art really are two sides of the same coin . . .
The scientist, ironically enough, when a breakthrough is made, marvels at the sheer beauty of the thing, while for the artist, it's 'rightness' that
counts above all else!
You may, though, find your conductive copper project peppered with problems.
PVA is itself an insulator and water will oxidise the semiconducting cuprous oxide to the insulating cupric oxide!
I think you may have set yourself a very onerous task . . .
Don't give up just yet, though?
Hydrogen reduces cupric oxide to the metal, so presumably preparation of these conductive polymers possibly involves the use of a glove-box containing
pure H<sub>2</sub>!
