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Author: Subject: Making rubies using microwave
Parakeet
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[*] posted on 1-5-2023 at 05:25


Sure! Let me see…
Spread a mixture of 95% aluminum oxide and 5% chromium oxide in a microwave oven. (4:15)
Place a small piece of aluminum foil, and put a heated charcoal on it. (4:32)
Cover the charcoal with more oxide mixture. On top of this mound, put a mechanical pencil lead. (4:40)
Turn on the microwave oven to 700W.
If a fire breaks out, turn off the microwave and cover the place where the fire broke out with a layer of oxide mixture. (5:20)
After 7 hours of heating, collect the rubies.

For his second attempt, he put the mechanical pencil lead directly on the aluminum foil and placed a charcoal next to the lead. (Make sure that the lead touches the charcoal) (7:50)
Then after covering it with Al/Cr oxide powder, turn on the microwave and the rest was similar to the first attempt.

However, some details are not explained in the video. For example, I can see something like a sheet in the microwave oven (4:15), but it was not mentioned. Also, in the video they say safeguards are in place, but there is no specific explanation.
So just be careful if you actually do this.

If you have any questions, please feel free to ask!
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Admagistr
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[*] posted on 1-5-2023 at 07:37


Quote: Originally posted by Parakeet  
Sure! Let me see…
Spread a mixture of 95% aluminum oxide and 5% chromium oxide in a microwave oven. (4:15)
Place a small piece of aluminum foil, and put a heated charcoal on it. (4:32)
Cover the charcoal with more oxide mixture. On top of this mound, put a mechanical pencil lead. (4:40)
Turn on the microwave oven to 700W.
If a fire breaks out, turn off the microwave and cover the place where the fire broke out with a layer of oxide mixture. (5:20)
After 7 hours of heating, collect the rubies.

For his second attempt, he put the mechanical pencil lead directly on the aluminum foil and placed a charcoal next to the lead. (Make sure that the lead touches the charcoal) (7:50)
Then after covering it with Al/Cr oxide powder, turn on the microwave and the rest was similar to the first attempt.

However, some details are not explained in the video. For example, I can see something like a sheet in the microwave oven (4:15), but it was not mentioned. Also, in the video they say safeguards are in place, but there is no specific explanation.
So just be careful if you actually do this.

If you have any questions, please feel free to ask!


Thank you so much, Parakeet! When I try it and something isn't quite clear, I'll ask you. I have experience with similar experiments in the microwave,I burned two artist pencils,which are made of pure graphite without any impurities and I stuck their carbon rods close together in the Al2O3+Cr2O3 mixture.The reaction was terrifying with explosions and ball lightning,so I couldn't even film it,I was tempted to end it prematurely,but I overcame my fear and let the reaction run in the set mode for 30 seconds until the end. I got the biggest ruby I have made so far,but of course it doesn't have gem quality,it is opaque,the size is between 0.5cm to 1cm.Do they do the reaction continuously for 7 hours,or do they always turn the microwave off and then keep repeating it until they reach a total time of 7 hours?Thanks!
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Parakeet
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[*] posted on 1-5-2023 at 14:40


Quote: Originally posted by Admagistr  
Do they do the reaction continuously for 7 hours,or do they always turn the microwave off and then keep repeating it until they reach a total time of 7 hours?Thanks!

He does not clearly explains that. There is little explanation of how the microwave oven was operated.
However, the dial on his microwave oven only has a scale up to 15 minutes, so he probably repeated turning it on and off for 7 hours.
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[*] posted on 15-10-2023 at 19:32
Microwave Corundum


Quote: Originally posted by Bedlasky  
Hi,

I came across this interesting method of making synthethic rubies.

https://www.youtube.com/watch?v=ybcdRQmQcHQ


I just tried this yesterday with my younger daughter using a microwave (USD 60) I got for the purpose. Amazingly, the microwave oven isn't broken yet, and has produced things that'll glow. We used 1% (w/w) Cr₂O₃ in aluminum oxide. Because I was already at a pottery supply place getting the materials, I also got a couple of refractory plates, one for the bottom, a smaller one for the top, and a clay bit with a hole in it to use as a crucible.

We didn't have aluminum wool, so we tried copper, which didn't work right away, and parts cut from a steel scrubber (more flat coils than thin fibers). To everybody's delight, we got things that glowed under UV light, and are working up to making bigger ones.

I saw that program in Japanese on making way bigger bits of corundum in the microwave, but it was very light on details. Are there written ones somewhere else, ideally in English?

[Edited on 2023/10/16 by davidfetter]
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Admagistr
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[*] posted on 16-10-2023 at 12:39


I just tried this yesterday with my younger daughter using a microwave (USD 60) I got for the purpose. Amazingly, the microwave oven isn't broken yet, and has produced things that'll glow. We used 1% (w/w) Cr₂O₃ in aluminum oxide. Because I was already at a pottery supply place getting the materials, I also got a couple of refractory plates, one for the bottom, a smaller one for the top, and a clay bit with a hole in it to use as a crucible.

We didn't have aluminum wool, so we tried copper, which didn't work right away, and parts cut from a steel scrubber (more flat coils than thin fibers). To everybody's delight, we got things that glowed under UV light, and are working up to making bigger ones.

I saw that program in Japanese on making way bigger bits of corundum in the microwave, but it was very light on details. Are there written ones somewhere else, ideally in English?

[Edited on 2023/10/16 by davidfetter][/rquote]
I haven't tried the Japanese process yet, but I'm about to.Do you have any pictures of the experiment?If you use copper or steel to start the reaction, I'm worried that you might contaminate the rubies.Have you observed anything like this?Higher concentrations of iron in the crystal lattice of ruby interfere with its luminescence. I have tried tungsten and molybdenum.Its oxides promote ruby crystallization,but the arc did not ignite,probably because the energy required to create a plasma from these materials exceeds that available in a microwave oven.The solution would probably be to coat Mo or W with a layer of graphite or aluminum.
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[*] posted on 17-10-2023 at 12:35


Quote: Originally posted by Admagistr  
I just tried this yesterday with my younger daughter using a microwave (USD 60) I got for the purpose. Amazingly, the microwave oven isn't broken yet, and has produced things that'll glow. We used 1% (w/w) Cr₂O₃ in aluminum oxide. Because I was already at a pottery supply place getting the materials, I also got a couple of refractory plates, one for the bottom, a smaller one for the top, and a clay bit with a hole in it to use as a crucible.

We didn't have aluminum wool, so we tried copper, which didn't work right away, and parts cut from a steel scrubber (more flat coils than thin fibers). To everybody's delight, we got things that glowed under UV light, and are working up to making bigger ones.

I saw that program in Japanese on making way bigger bits of corundum in the microwave, but it was very light on details. Are there written ones somewhere else, ideally in English?

[Edited on 2023/10/16 by davidfetter][/rquote]
I haven't tried the Japanese process yet, but I'm about to.Do you have any pictures of the experiment?If you use copper or steel to start the reaction, I'm worried that you might contaminate the rubies.Have you observed anything like this?Higher concentrations of iron in the crystal lattice of ruby interfere with its luminescence. I have tried tungsten and molybdenum.Its oxides promote ruby crystallization,but the arc did not ignite,probably because the energy required to create a plasma from these materials exceeds that available in a microwave oven.The solution would probably be to coat Mo or W with a layer of graphite or aluminum.


I tried to take a few with my phone camera, but the UV light I was using to see whether rubies had come out did terrible things to the images it captured. What sorts of cameras are people using for this kind of thing?

The steel scrubber bits definitely get wound into the ruby we've made so far. I'm looking for sources of Al wool to try as...microwave antennae? I guess that's kinda what they're doing.
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[*] posted on 17-10-2023 at 13:58


The steel scrubber bits definitely get wound into the ruby we've made so far. I'm looking for sources of Al wool to try as...microwave antennae? I guess that's kinda what they're doing.[/rquote]

I have had success with thin aluminum wire, which I made into a ring, which had a gap of several millimeters between the opposite ends of the wire.I also have a problem with shooting in UV light, I have not been able to take a picture chromium doped Ga2O3, which in UV light had several beautiful colors depending on the angle at which the UV light fell. I wrote a thread about it,here on SM with photos,but only in natural light.In natural light it is green,in UV it is blue-green,blue,grey,purple and red,like the gemstone alexandrite!But alexandrite is more likely to be green in sunlight and purple-red in UV,it doesn't have as many colors in UV as Ga2O3:Cr3+.

[Edited on 17-10-2023 by Admagistr]
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[*] posted on 17-4-2024 at 07:14


I would like to get a small ruby vee-bearing for a very low friction DIY pulsemotor.
I wonder if making some synthetic ruby pieces and somehow grind a vee hole in the middle can be done.
Grinding such a vee-dent in a ruby would require some grind powder of equal or harder substance, that means ruby or diamond dust.
Or a tool already coated with such powder.
But when thinking about it for a while i think there is a far easier source of such ruby bearings, old HQ watches.
I probaly can find an old HQ watch at some second hand store and i bet they have some of those bearings inside somewhere.
I looked online for such ruby bearings and havent found a good source so old watches is probably what i try next.
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Admagistr
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[*] posted on 17-4-2024 at 11:03


Quote: Originally posted by Mateo_swe  
I would like to get a small ruby vee-bearing for a very low friction DIY pulsemotor.
I wonder if making some synthetic ruby pieces and somehow grind a vee hole in the middle can be done.
Grinding such a vee-dent in a ruby would require some grind powder of equal or harder substance, that means ruby or diamond dust.
Or a tool already coated with such powder.
But when thinking about it for a while i think there is a far easier source of such ruby bearings, old HQ watches.
I probaly can find an old HQ watch at some second hand store and i bet they have some of those bearings inside somewhere.
I looked online for such ruby bearings and havent found a good source so old watches is probably what i try next.


A long time ago, when I was a kid, I ground miniature screwdrivers out of sewing needles on an electric grinder and took apart a few old watches and got a lot of ruby bearings;-)! A medical plaster for minor injuries, which I wrapped around the top of the needles, served as a handle for the screwdrivers. I don't have those ruby bearings anymore, they got lost somewhere in the many years that have passed. Otherwise, rubies can be ground with a carborundum SiC wheel.
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[*] posted on 17-4-2024 at 15:28


You do know you can just buy them, mounted and unmounted, along with matching bearing pins? Making your own seems like a very difficult route to go down.
https://www.swissjewel.com/products/jewel-bearings/




Helicopter: "helico" -> spiral, "pter" -> with wings
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