If you look back upon my previous work you will find that I have been experimenting with vacuum metal deposition.
I have been attempting to vaporize metal and have it coat glass under a vacuum. There will be more on this once I get the process working flawlessly.
Ideally this is done under a very deep vacuum using a diffusion vacuum pump.
I am attempting to do this without the use of a diffusion pump.
The vacuum chamber that I have been using is showing signs of melting and burning which to say the least is less than ideal for the task at hand.
The first problem is the type of material used for the chamber base. The second is in dealing with the heat generated and the third is the vacuum seal.
I have come up with a solution to all three in the most unlikeliest of places...
I have been attempting to vaporize metal and have it coat glass under a vacuum. There will be more on this once I get the process working flawlessly.
Ideally this is done under a very deep vacuum using a diffusion vacuum pump.
I am attempting to do this without the use of a diffusion pump.
The vacuum chamber that I have been using is showing signs of melting and burning which to say the least is less than ideal for the task at hand.
The first problem is the type of material used for the chamber base. The second is in dealing with the heat generated and the third is the vacuum seal.
I have come up with a solution to all three in the most unlikeliest of places...
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This experiment has some risks that you should be aware of!
The first is that it is not electrically grounded. It is best to not touch the chamber assembly while it is operating. This experiment uses a variable transformer connected to a step up transformer(240V 15A).( these are not shown here but will be discussed in another Instructable)
The second is that the glass jar shown is not safety rated for a vacuum. It is a very thick wall preserving jar. If you want to try these experiments it is best to have a vacuum shield while running under a vacuum. Mine was removed for the pictures.
The third is that the first time you see metal actually bonded to glass you may become addicted!
The first is that it is not electrically grounded. It is best to not touch the chamber assembly while it is operating. This experiment uses a variable transformer connected to a step up transformer(240V 15A).( these are not shown here but will be discussed in another Instructable)
The second is that the glass jar shown is not safety rated for a vacuum. It is a very thick wall preserving jar. If you want to try these experiments it is best to have a vacuum shield while running under a vacuum. Mine was removed for the pictures.
The third is that the first time you see metal actually bonded to glass you may become addicted!
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and for how long of time.
For those without access to brazing/welding equipment, it might be possible to thread a metal spacer onto the electrode of the sparkplug. Then a screw in the other end of the spacer would be the mounting point for the heating elements.
1. If you are using tempered glass be sure to use new, completely unscratched glass. Scratches in tempered glass cause really significant weaknesses, and the vacuum will exacerbate this problem.
2. In our lab we use borosilicate glass for this because of all of the heat you are putting into the system. Keep in mind Pyrex kitchenware isn't actually borosilicate anymore, it's tempered. Tempered glass will work, with the added benefit that when it implodes it will form tiny little squares of glass that may be slightly less dangerous than long sharp blades.
3. If you can, it would be good to find a bell jar that is parabolic in shape. It's much stronger than the shape of canning jars.
4. I realize how expensive actual vacuum rated glass is (I just had to order a new one for our lab, and it was over $1000!). If you're going use less expensive glass, it would be easy to build a little wooden box with a thick, 2" diameter plastic porthole to monitor if everything is working properly. This way if/when it implodes you and your workspace are protected.
Great 'ible, keep it up!
and on page 292 there are details of how to make a small scale aluminizer.
It might give you some help with what you are trying to do. please note that you need a high voltage 5Kv transformer but you could probably use a microwave transformer.
What materials you depositing?
- Don't weld both sides of the connections. For deep vacuum work you only want a single weld so that there is no possibility of trapped air that can migrate out through very small cracks. These virtual leaks can prevent a system from ever reaching low vacuum. If you have a 1 liter chamber at 0.01 T then a 10 microliter trapped volume (at 760 torr) has about the same amount of gas in it. Since it is leaking through a small crack your pressure won't get below .01 T for weeks. It's better to avoid the trapped volume and make sure that the single weld doesn't leak.
- If you have a pretty good vacuum gauge you may find you can find leaks by using rubbing alcohol. Be very careful that you don't have any sources of ignition near by while you are doing this, of course! Wait for your pressure reading to be pretty stable before starting. Use an eyedropper to put alcohol near junctions where leaks may be occurring. The alcohol has low enough viscosity to be sucked through small leaks. Once on the low pressure side it vaporizes and the pressure gauge will show a noticeable bump. This technique works best below about 0.05 T so you might not see much at 0.1. I'm assuming also, that your pump is capable of deeper vacuum when it is connected only to the gauge.
Keep up the good work. I'm really excited to see your next results.
Depending upon the situation, a good basic draw down pump, followed by a simple ball valved, very long stroke single piston pump.
20 - 25mm bore - with a 500 - 1000mm stroke.....
Greased leather / teflon impregnated sealing washer, on the piston.
Since some years I am ruminating the idea to make that that you are doing. My purpose is to aluminize little pieces of plastic (PVC, Polyurethane or other) to make a lightweight mirrors array for a solar cooker. I will follow your attempts, Please be "verbose" in explanations. If you add some video, please put captions, in order we non anglophone can understand.
I've bean wanting try for ages, but my vacuum pump won't do it.