"Flash"light

Polar_Hops

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Hello folks, i am set on making a reuseable flash, by burning aluminum with O2. An aluminum wire, will be placed in 90-95% pure oxygen, heated by a short.

That's the basic idea. It comes down to the jar now- I need to find a heat resistant glass jar, with two holes for ceramic beads to be inserted. Does anyone know where i could find a glass jar, that can be topped off, without sealing completely, with two small holes?

Or maybe one that already has ceramic beads for wire insertion? Any help would be much appreciated!

Also, are there any conductive(electrically) metal oxides with high melting temperatures (with high temperature of thermal decomposition)that are not toxic?
 

yuandrew

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Sounds like you're trying to make a Photoflash bulb. Hopefully; the combustion does not cause your container to shatter. Mason jars may be thick enough but stand back to be safe.

Oh, and I'm sure it will be very bright for a short time
 

Polar_Hops

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I was thinking of drilling holes, but i was worried it would make the glass more prone to crack from thermal expansion. Is there any good way to drill glass? Is there any place that could disolve 2 holes with HF? I woudlnt want to mess around with HF at all.

I guess if the jars are cheap enough, it really dosnt matter.

So... what's everyone's favorite technique for drilling glass?
 

bwaites

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Why not use an Erlenmyer flask?

Pyrex, tough, narrow neck.

You could close it with a hard rubber stopper, and run the wires through the beads placed in holes drilled in the stopper. Much easier to drill that way.

Bill
 

Polar_Hops

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In pure oxygen, rubber, as well as most other hydrocarbons, are very flamable, if not explosive. maybe a hard teflon stopper may do.

I aggree it would be easier. I doubt the rubber would cause an explosion, and the heat may not be enough to even crack the flask, but a hard teflon stopper should last much longer.
 
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HarryN

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If you have the budget, there are ceramic seals in the vacuum industry which have electrical feedthroughs.

Glass can be drilled with the proper bits, but it is weakened considerably locally from small cracks.

I would put in some kind of pressure venting method, at least in the prototype.

It might sound strange, but one of your best seals might be to float the glass upside down in water, bring in the wires through the water into the glass, and let 'er rip. Al will work, but actually, Mg would be a possible alternate.
 

Polar_Hops

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Thank you harry! But... what are they adapted for? Probably a tube? What are they called, i'll google them.

I plan to fill the container under water, on the first versions of it, atleast, and insert a desiccator packet.

Are you saying you think water could work as a venting seal? I coudlnt agree more!

Batterycharger: two holes in a metal lid would probably cause shorts without insulation. This would deprive the aluminum energy required to attain the activation energy/ignition energy. Tugnsten with fiberglass insulation MAY work, but it may not. We see how fast it burns up if you pop a bulb.

If the aluminum was to burn, it would probably have enough activation energy to ignite the metal lid in an O2 rich enviroment.

If the lid is burning, that is taking the oxygen the aluminum wire would need to burn. I was going to design the "bulb" to hold 10% more oxygen than required @ 1 atm based on stoichiometric figuring. So if the metal at the top is burning, that means less aluminum would burn. But given aluminum's reactivity, the rate of the aluminum should be much quicker, and get most of the o2 before any other metal consumes it.

I hope to be able to use this thing enough to fill my blasting cabinet with some new Al2O3 :)

But not on one prototype.

I'm not going to watch it burn, rather film it. I am unaware of the levels of UVA and UVB it may produce. My prototype version should have a filter for the two, and i think just normal glass should be sufficent for any UVC that may be produced.

While we're at it, can one think of a practical application of this? besides being fun? Maybe something for frequent users of Hi-speed cameras could make use of?
 
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Vee3

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Pyrex tubing is available in many diameters and wall thicknesses. Maybe you could use that somehow.

Glass can be drilled fairly easily using a brass tube and diamond or carbide lapping compound in a drill press. I did this one time when I had to install Schrader valves in beer bottles for testing different cap pressures for bottling inspection equipment...
 
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greenLED

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Is there a collegue with a chemistry program nearby? Some have glass-blowers on staff... or you can try to find a glass blower to make you one.
 

HarryN

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Hi Polar

An example ceramic feedthrough is at mdcvacuum.com. They mostly are used as electrical feedthroughs for vacuum systems. Rather expensive when new, btw.

You can also make your own with silicone sealant.

I do not really understand your end use of the Al2O3, but I assume you know that you can purchase this in almost any purity and size grade at reasonable prices ?

Al is quite reactive, but it has another property working against you - it forms an inert skin (AlOx) which does not react so well. If you actually need to rapidly oxidize Al, then you need finely divided Al powder as your starting point, not Al wire. BTW, finely divided Al powder must be handled carefully, as it truly is quite reactive. Full protection of face, hands, and body are a must.
 

Polar_Hops

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Vee3, I dont understand the application of the brass tube. Does it fit over the bit?

Greenled: That is something i should look into. My courses were blogged with many other things this semester, and i didnt really have time to fit in a chem lab. I could ask my chem prof, as he is also the lab instructor, but he seems to like me less for not taking the lab the same semester as the lecture.

Harry: Thank you for the link. That is what i was looking for.

On some other points:

I have burned aluminum foil completely in an o2 rich enviroment (i ignited it with a oxy/acetylene torch with low flow pressure) This could have been hot enough for the foil to melt, turning into a liquid, and take up a larger surface area.

Another option should be aluminum wool, if i could find it. I should be able to create very high temperatures in aluminum foil with electrical discharge.

I remember that i did learn basic things, that i have to brush up on to figure out how much power must be put through a wire to increase it's temperature. However, i suspect that if i can heat the aluminum to a hot enough temperature by shorting a powerful battery, resulting in the melting temperature, the wire should melt and have the same effect as the foil.

I do know that Al203 is easy to get, but it'd be neat having enough, that i personally made (in a fun way), to fill up a blasting cabinent.

The initial heat created in the secondary surface oxidization (if it occurs), plus the heat from the power of the battery may be enough to cause the aluminum to melt.

I supose if i put a high enough current through it, the aluminum would vaporize. That should do it for sure.

I just want to remind you, alothough it is probably already at the top of your head when it comes to this topic, is that things burn much faster, at much higher temperatures.

It does vary, i'd assume, on the mechinisims of the reaction. But a good estimate is 5-10 times faster, with a siginificantly higher temperature.

Once i get my oxygen concentrator (ships monday), i will test more. I would test now, but i'm out of sodium carbonate peroxyhydrate, which is what i usually use, along with MnO2 as a catalist, to produce O2.

There are still a few thing i need to buy before i even get started with the testing- like various gauges of aluminum wire, a 8 AA cell holder, and accessories that may not have came with the oxygen concentrator (like an "oxygen hose")

Thanks for all the input so far folks, it has greatly increased my motivation to get this up and running. I know i have seemingly tried to shoot down everyone's suggestions, but it's not like that. I just didnt look up all the information i need to know yet, however, i have listed it. Lets face it though, even the simple burning of a wire has a lot of factors that go into it. One thing is a secondary oxidization stage, which may occur when the aluminum oxide, depends upon the thermal expansion. If the thermal expansion is not high enough, it may not occur at all.

Keep the input coming along, please =) It is a great help, and is very much appreciated!
 

Vee3

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The brass tube "is" the drill bit for this application. You put the tube in the chuck like you would a drill bit.

What you do is put your glass piece in a vise so it doesn't move (I used a mill, but a drill press will work). Get a piece of brass tubing with an outside diameter of the hole you want to make. Smear a blob of lapping compound on the glass under the tube. Turn the drill press on the lowest speed. Bring the spinning brass tube down (Slowly and carefully) to contact the glass and (Slowly and carefully) "grind" a hole in the glass. Be very careful when breaking through the far side (More slowly and carefully required here). Works great (If you go slowly and carefully, that is).
 

Polar_Hops

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Aah, i get it now vee, thanks! I'm suprised the brass dosnt wear before the glass.

I just bought an oxygen concentrator because o2 is generally expensive if you dont have the tanks. By the time you get everything, it will be a lot more than the $78 i got my oxygen concentrator for, however it does have the advantage of being under high psi.
 

Polar_Hops

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Wow. I got the oxygen concentrator, and i think it actually puts out an excess of 5 liters/minute.

If you put a hose in a 2 liter bottle filled 3/4 with water, it looks like it is boiling at superheated temperatures, and rocks the 2 liter bottle.

I am having some problems to get the aluminum to burn- so far i have used little pieces of charcoal and graphite with success. The aluminum foil MUST melt first before it will burn. I had a sustained reaction for ~1 second, consuming nowhere near the bulk of the foil.

I'll have some time to figure out the power needed in the wire tommarow to heat it to it's melting point.

I'm glad i researched about photobulbs- They can explode, and i dont want shrapnel. To avoid the shrapnel, i could wrap the glass in some type of clear tape, or paint it with fingernail polish (clear kind).

Bottled oxygen may be good because it is dry. Aluminum burns slow compared to hydrogen, which would be produced my humidity in the air oxidizing the aluminum. Another note about this is that water as an oxidizer is only equivlant to about ~65-68% that of pure oxygen, so brightness would be reduced as well. I can probably make a fitting for the oxygen concentrater using cacl2 as a dessicator, but it would be a series of jars. Oh well, I dont supose it would be that bad... Anyone have any ideas to dry the air? I'm trying to avoid H2SO4, because metal contaminants could produce hydrogen, which is another thing i am trying to avoid.

On the bright side, i found out they can produce around 180,000 lumen seconds.
 
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