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<nmz787_>
macor for making electrical feedthroughs into a vacuum chamber? howso? I was planning on getting some torr-seal epoxy, or maybe trying to shove piano wire through a chunk of Viton or something
<_Sync_>
well, actually making good ones vs making makeshift ones
<SpeedEvil>
Doens't indium wet macor?
<SpeedEvil>
It's not really very expensive
<_Sync_>
indium wets some ceramics
<whitequark>
that sounds very mechanically flimsy...
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<SpeedEvil>
you preload the fixture adequately so the indium is not doing any clamping
<whitequark>
m
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<nmz787_>
_Sync_: if I got some macor, drilled a hole and shoved a wire through, would I just seal with torr-seal epoxy or is there a better way?
<whitequark>
You still need to seal macor to the flange
<whitequark>
You could, idk, make a thread on it and fill it with indium
<whitequark>
Thread to keep it inside, indium to make it sealed
<whitequark>
Not sure if that could work
<nmz787_>
don't most feedthroughs use some rubber o-ring too?
<nmz787_>
around the flange?
<nmz787_>
or can they be metal to metal as well?
<whitequark>
um, what?
<whitequark>
do you want to seal ceramic to metal using an o-ring?
<whitequark>
that won't work, it's too porous to form a seal
<nmz787_>
well you said coat it with indium first
<whitequark>
probably won't even reach -1
<nmz787_>
so then without an o-ring it would be metal to metal
<whitequark>
indium wets metal and maybe ceramic
<whitequark>
um, what?
<nmz787_>
take a block of ceramiic, drill holes, add wires, seal the wires with epoxy, then coat the entire thing in indium? (it sounds like you're saying to do that)
<superkuh>
ER, growth on surface electrolytically.
<superkuh>
Sorry.
<whitequark>
hrm
<whitequark>
what?
<superkuh>
I guess I can just use the common words. Anodizing.
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<whitequark>
well, I got that. can you write down the redox half-reaction you expect there?
<superkuh>
Not of the top of my head, no. I was hoping to find something in a literature search so I could avoid doing actual thinking.
<whitequark>
ok, what /at all/ do you expect there?
<whitequark>
alumina is non-conductive
<whitequark>
MgO is not something you can deposit electrolytically at all in... water
<whitequark>
or Mg for that matter
<superkuh>
Well, I suppose that answers that question then.
<whitequark>
do you mean like in some kind of molten salt? that will probably attack the ceramic, and definitely attack whatever's you're trying to attach to the ceramic
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<superkuh>
I just wanted to avoid having to find and buy an alumina tube to fit my conductor (http://superkuh.com/dfp_annotated_anode_hole.png). I figured growing alumina on aluminum would be easier than finding a perfect fitting alumina tube. But then I found out about the problem of pores.
<SpeedEvil>
Pores are good.
<SpeedEvil>
you can fill them with dye, and make it pretty
<whitequark>
growing alumina on aluminium?..
<SpeedEvil>
What is that?
<superkuh>
Aluminum oxide.
<superkuh>
What is always coating aluminum in air.
<superkuh>
Er, Aluminium.
<whitequark>
both spellings are correct :p
<SpeedEvil>
superkuh: yes - I mean - what is the thing you are trying to make.
<superkuh>
Anyway, not relevant to homecmos. Just thought the Lucalox was neat and wildly extrapolated.
<whitequark>
Lucalox is very neat.
<whitequark>
It's halfway between sapphire and small-grain-alumina.
<whitequark>
haha you also have a bunch of files like that
<whitequark>
oh, yeah, have you seen the plasma window stuff?
<whitequark>
you can make a direct non-solid-state vacuum-atmosphere interface
<whitequark>
and put e.g. electron or proton beam through it with so little attenuation it is not measurable
<SpeedEvil>
superkuh: ah
<superkuh>
I've heard of plasma windows but I don't understand how it works.
<whitequark>
very simple
<whitequark>
pV=nRT
<whitequark>
T is large enough for p to rise to 1 atm
<whitequark>
at the same time it is mostly confined within the window by the field
<whitequark>
and where it is not, an additional pump gets it away
<_Sync_>
superkuh: that's old news
<_Sync_>
nmz787_: if you use torrseal you might as well just use some kind of plastic
<_Sync_>
or just embed the wires in it isolated form some kind of metal body
<whitequark>
actually, yes
<nmz787_i>
"The only limit to the size of the plasma window are current energy limitations as generating the window consumes around 20 kilowatts per inch (8 kW/cm) in the diameter of a round window.[citation needed]"
<whitequark>
I did flanges from acrylic
<whitequark>
they're ok if by ok you mean complete shit
<whitequark>
they do hold -2 or so though (have not tested lower)
<nmz787_i>
I was thinking get a slab of Viton, jam piano wire throug (very stiff) then compress with metal plates on both sides, one of which would be the flange
<_Sync_>
it always just depends on what you want to do
<whitequark>
gross but might work ok
<nmz787_i>
this would be for feeding into a FIB or SEM... so would need between -5 and -8
<nmz787_i>
a FIB/TEM guy said torr-seal works fine for his equipment when he's rigged things up before