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Apparently titanium is used as getter in vacuum systems....interesting, titanium is relatively cheap.
and, I managed to finally deposit "something" actually deposit, with good adhesion, but 0 electrical conductance.
but not with evaporation, just plain DC sputtering, with 2 copper electrodes and a glass piece next to them. it looked rather nice, goldish...shiny, far from opaque, probably because of the short deposition time.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Daedronus wrote ...
Apparently titanium is used as getter in vacuum systems....interesting, titanium is relatively cheap.
Titanium is used in 'ion pumps' for removing 'hard to pump' gases like helium.
Ion pumps have two charged plates, which ionise any gas molecules that 'happen' to drift in between them, the +ve ion (He2+ or alphas) are attracted to the cathode, where they become implanted, eventually resulting in 'helium embrittlement', and the electrons are attracted to the anode plate. Ion pumps therefore have a limited lifespan and are only used for ultra high vacuums.
1. deposit gold, should work with just the mechanical pump, but, it's expensive, I will have problems to etch it (did I mention I also need to etch the metalization? :)
2. deposit copper in argon gas but I don't have a argon bottle and it's quite a bit of a initial investment...but it will also come in handy when I get a tig welder...I do want one...someday.
3. get a diffusion pump, should be fun for more then just the metalisation, simple enough to operate...but I kinda hate the water cooling, but I should be able to do any metalisation process with any materials.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Daedronus wrote ...
right now I see 3 options...
1. deposit gold, should work with just the mechanical pump, but, it's expensive, I will have problems to etch it (did I mention I also need to etch the metalization? :)
2. deposit copper in argon gas but I don't have a argon bottle and it's quite a bit of a initial investment...but it will also come in handy when I get a tig welder...I do want one...someday.
3. get a diffusion pump, should be fun for more then just the metalisation, simple enough to operate...but I kinda hate the water cooling, but I should be able to do any metalisation process with any materials.
You can get small bottles of argon for around £10:
You can get air cooled diff. pumps, just rig up a cooling fan
But, I tried again today with silver, and it works very nice. it's almost a perfect mirror. Silver seems to be inert enough.
I will also have a micron pressure gauge later this week so I will see the actual working vacuum level.
Also, probably next week I will have some viton material, to replace the silicon seals.
The problem with silver however is that it seems to have really bad adherence, I can clean it off with a finger. Is silver that soft or maybe it's my coating?
And, what do you guys think will serve me better? a diffusion pump or argon gas?
I have a chance to get a seemingly nice diffusion pump:
Registered Member #65
Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155
Typically an inert gas like pure Argon (not the welding gas mix with CO2) will allow this to occur at higher pressures and KV.
The effect can be nuisance issue that can erode Nickel plates in electronic tubes, or completely cook the shells off of neon tubes during "burn-in".
Note at one time optical coating for mirrors used temporary Gallium based amalgams, tin based chemical coating processes, and Silver based toxic plating processes.
Zirconium based coatings tend to keep things "shiny" these days.
OK, so, my obsession continues, I got both a diffusion pump and argon (in the small bottles, it turns out some locals stores do sell them, they had like 2 bottles, too bad if someone else needs some...and oh...they don't have the regulators, doh! but I got one never the less).
I don't have the diffusion pump ... yet (or the oil, cooling and connections, for that matter) so this will have to wait for a while
but I did try the argon, and it makes a BIG difference for copper.
In argon the copper sputtering is starting to look right, I got the oh so nice distinct green glow of copper ions (copper self sputtering, free copper atoms ionize and eject more copper atoms, or decay and make the nice green glow):
And since I now have a pressure gauge, I can tell you it was at about 100 microns in flowing argon.
And yes, controlling the flow from 2bars to 100 microns is a pain, I'm using a restriction (pinched hypodermic needle) a vacuum line regulator for a intermediate pressure and the bottle regulator, that basically I can just open a little and close back.
I also tried silver again, in argon, and it pretty much is a perfect mirror, it was pretty good without argon to begin with...
Copper deposition seems like a tough nut to crack. Ether I don't have a clean enough vacuum or I need 5N oxygen free copper.
Right now I have only viton seals, and i can get down to 1 or 2 microns, maybe even lower, I zero out my pressure gauge. The pressure is so low my high voltage flyback transformer has problems igniting a plasma. I don't play too much in this regime as I probably get x-rays.
Aluminium doesn't seem to deposit anything at all, or maybe it's Al2O3 that is transparent... On the aluminium sputter target I got some white power, that's definitely Al2O3.
Titanium works, after it gets hot enough/bright enough plasma, the color of the plasma changes drastically and the pressure takes a nose dive. The deposition is quite shiny and conductive, so it's not titanium oxide (white) or nitride (gold).
For fun I will try to run titanium with plain air instead of argon, and see if I get the oxide or the nitride.
I will try to get a titanium filament as a getter. Tungsten doesn't work, there is actually a water cycle that just moves tungsten from the filament to everything else.
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Inert metals? / PVD process
