IrC - 15-3-2006 at 13:25
I have 4 NdFeB N-48 1/2" square magnets together, with a square of Pyrolytic Graphite floating in space in the center just above it, suspended in mid
air by nothing but the magnetic fields. After staring at it for a long time and having several flashbacks from the 60's, it occured to me this would
be a cool sensor for something or other, maybe magnetic fields or gravity waves. If I can silver one side keeping weight extremely low and bounce a
laser off it into a beamsplitter and photodetector, I would be able to measure movement of the Pyrolytic Graphite of less than a quarter wavelength of
the laser light. Needless to say air would have to be kept from blowing on it. I gives me some really cool ideas of making some kind of sensor, if
only I knew how to perfectly coat the square of Pyrolytic Graphite with a reflecting layer. Anyone have any ideas?
I still have no real good ideas on my laser rod polishing-silvering question either, and have both Yag and Ruby rods to do so feel free to answer that
question here as well.
Twospoons - 15-3-2006 at 13:30
Vacuum metalisation?
Fleaker - 15-3-2006 at 13:43
I agree with Twospoons: vacuum deposition of silver. I've never done it before so I can't personally attest to how well it will work. If you have a
good vacuum pump, you might be able to do it at a somewhat reasonable temperature. If, however, you have an arc furnace, you could always evacuate and
purge with argon then boil silver in that.
I doubt it'll work/adhere, but try making a silver nitrate solution and adding to it a dextrose solution, then pour this onto your graphite and add
KOH solution. This reduces silver onto glass and some plastics, but I'm not sure about graphite. I'm also not sure how much solution concentrations
matter in this, but I can check it out later this weekend. If I have enough time, I'll get a piece of graphite, and test it out using borax glaze
(which will adhere to graphite) as a substrate for the silver.
HTH
IrC - 15-3-2006 at 13:44
Likely best but I would have to build some kind of exotic machine. Think I will study on that one as that could lead to other cool projects! Anyway,
check out the link below for Emo's auction:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=61296...
You will have to copy and paste, for some reason the board software chops links beyond a certain length?
Good idea, but keep in mind anything soaking in may mess up the structure which makes it so diamagnetic, and weight is critical for it to float with
available magnetic field strength.
[Edited on 15-3-2006 by IrC]
Odyssèus - 15-3-2006 at 14:01
Why not just put a very small/thin mirror on top of it? I have a piece of PG that I can float on 4 supermagnets and its somewhat resistant to being
pushed down by my finger.
neutrino - 15-3-2006 at 15:27
One thing to remember when buying pyrolitic graphite is that not all pyrolytic graphites can levitate. This piece obviously can, but I felt this was
useful information so I decided to throw it in.
If you want to buy PG, there is only one website that sells it to hobbyists in small quantities:
Scitoys
Why not just cut a very thin piece of PG and attach a mirror?
Seismic activity will interfere with your results here. Even earthquakes on the other side of the planet can be picked up by a sensitive enough
instrument, such as what you are planning on building here.
IrC - 15-3-2006 at 16:28
Actually earthquake detection was my first thought after I realized this would probably not detect UFO's. Bummer.
The_Davster - 15-3-2006 at 18:11
Melt some regular wax onto one side of the graphite, then submerge the entire thing into some tollens reagent, add aldehyde of choice, ocne the mirror
has appeared remove the silvered graphite and melt off the wax.
IrC - 15-3-2006 at 23:22
Thanks, this seems like a way to go. Since the plate floats an eighth inch now with N-48 magnets, it seems I can just silver the entire plate and make
it easier (not needing the wax). Tarnishing is my last concern (and whether or not the solution will soak into the plate seeing as how it is just thin
graphite). Clear acrylic spray may aid in this but I wonder how much weight this will add to it. I guess I could look around for 4 N-50 magnets to
boost the lifting force. Do you think this would work for my laser rods, and what about tarnish? I don't think the acrylic would be a good idea for
those. Overall a great idea rogue, I will try it. The worst that can happen is it soaks in and somehow messes up the lattice structure wrecking the
diamagnetism. Possibly if this does happen slight heating would take care of it without altering the graphite.
http://chemlearn.chem.indiana.edu/demos/Tollens.htm
In checking out this page, I already have all the chemicals mentioned in the above link except the Dextrose, but this is easy enough to get.
Questions: I know this may seem lame to ask but what is the purpose of the KOH and could it be ommited? It seems the reaction is between the AgNO3 and
NH4OH, with Dextrose reducing the Ag? Also, how important is the washing with nitric acid and acetone steps in relation to what I am doing? It seems
that this is merely to clean the glass to aid in plating, but in my case it is the graphite plate involved and neither chemical seems wise to use on
it. Lastly, how likely is this chance of the mixture becoming explosive they mention, if I make some of this chemical up, seeing as how this is
mentioned in the link?
The_Davster - 16-3-2006 at 05:55
I have tried in the past to make it go explosive, it was not so easy. Just really dilute and acidify the tollens after use and you should be fine.
If you get a black precipitate, this is the explosive they speak of Ag3N, silver nitride or fulminating silver. If you get it formed the best way to
get rid of it in my opinion is simply to flush it.
Twospoons - 16-3-2006 at 13:34
I've just realised that since graphite is conductive, you may be able to electroplate it. I think that with any of the methods described adhesion of
the silver will be your biggest problem. If you keep the layer really thin you should be OK. If you are worried about tarnishing either plate with
aluminium instead, or just keep the whole contraption under argon.