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 Post subject: Re: Need Technical Data For Induction Heating Process
PostPosted: Wed Oct 10, 2012 3:43 pm 
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In my not usually very humble opinion,,it really is time to call in a Registered Professional Electrical Engineer. Someone who has about twenty years of experience in exactly this field.

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 Post subject: Re: Need Technical Data For Induction Heating Process
PostPosted: Wed Oct 10, 2012 11:16 pm 
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Joined: Sat Sep 22, 2012 2:30 pm
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Yes...I believe your right...I'm already in over my head here dealing with the electrical/electronic aspects of this project...But I knew that before I started...It becomes more and more obvious the more I research this those aspects of the project....

I may fry/vaporize my rough if not myself...

I want to understand this science so I will continue to try and acquire as much info as possible til December when I'm finally back in Cali but will need an experienced someone to hold my hand going forward...

At least this exercise has given me some direction...Thanks for the input...

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 Post subject: Re: Need Technical Data For Induction Heating Process
PostPosted: Tue Nov 26, 2013 10:39 am 
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Joined: Fri Nov 22, 2013 3:22 am
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G4Lab wrote:
"Does the Graphite itself heat from the Induction process or just the metals the that crucible contains??" ... playnext=2
Here a Graphite Rod is heated white hot...

But graphite requires a reducing atmosphere. If you flood it with Oxygen it will simply burn off as CO2 and probably instantaneously. It may even reduce the sapphire to metallic aluminum. I don't know offhand which is more electronegative. You may be able to look that up in a chart of electronegativity.
Your link did not transcribe correctly and does not work. But if there is metal you can be sure it and not the crucible is grabbing the energy!

Edit: Yes if you heat the corundum in a graphite crucible the oxygen will transfer to the graphite making CO2 and leaving metallic aluminum.

See the table of solar panel ... alues.html

So if other ceramics such as Chromite...Chromium Oxide don't respond to the induction process than I can use a Graphite tube as a casing which than heats everything contained within...The Graphite can withstand any potential temperature required with repeated applications and is readily available for replacement...

Graphite is used for all kinds of crucibles and hight temp furnace furniture. Other ceramics and refractories are available too. I think Judith Osmer used to use platinum crucibles when she did flux grown rubies. And Kanthal heaters too I think.

I think a silicon carbide crucible might be better. It probably will catch the RF (High frequency AC and RF are synonymous) and can resist very high temps and maybe oxygen too

I have another question I would like answered if possible:
"My question is are the higher watts used to make the heating process faster or to reach specific temperatures???...Could the same temperatures be reached with lower wattage over time??"

When you heat things they lose heat. the more watts you put in the faster they get hot. The hotter they get the more watts they need to maintain thermal equilibrium with the environment. So more watts equals faster heating and also higher ultimate temp.
(say you had a one thousand watt heater. think of a 1200 watt electric heater you can buy for nothing these days. The Nichrome wire heating element or quartz heating element is connected directly across the AC line and is engineered to draw the correct number of watts. The all stop at dull orange red heat because the rate of energy input equals the rate of heat energy loss (ie heating the room which is what they are designed to do)
The better you can insulate your chamber the higher temp you can achieve with a given number of watts. That is why the furnaces the aforementioned Judith Osmer used had very thick walls of foamed ceramic insulation and probably most of the systems that Ted Themelis engineers probably do too.(haven't been to his website in a long time)

Slower heating is a desirable application and lower wattage would be more cost effective/smaller more portable equipment...

There is some minimum wattage you will have to exceed to reach the temp require in the volume required. Each different type of solid matter in addition to whether or not it can snag the energy from the coils, also has a specific heat which is how many calories it takes to raise it one degree. (choose your units)

But I also stumbled upon this:
Frozen H2O??...
Water does conduct electricity...That is a known...But I have to admit to being rather surprised by this and wonder why??

This strikes me at best as a cool parlor trick and at worst an advertising fraud. Perhaps the ice had been cooled down to liquid nitrogen temperature first so that the interior could get white. Maybe the part actually white was a small part in the center maybe with some chemical additives. I want to know why the ice was not melting faster , nor cracking nor exploding. It may be they have been working on this and tuning the parameters of the system to get it just right. You have to do that with all induction heating applications. Notice the specialized coil.

I am not at all an expert on this but I am sure Ted Themelis has looked at whether or not induction methods would work for gem heating. It is after all the exact subject to which he has devoted his life. What do you suppose you will discover that he does not already know???

There is nothing whatsoever magic about induction heating. It can do some tricks that are harder to do with regular heating because it does allow very high energy densities.
So in the analytical instruments that I take care of a sprayer makes a mist of the solutions to be analyzed. These are carried in a stream of Argon gas into a set of ICP coils where the gas turns into a plasma of such high temperature that all the molecules are broken down into their component atoms.(this alone is like something out of a sci fi movie. Straight up Matter Disruption. I love it.!!!) The plasma then makes these atoms emit their characteristic light wavelength (ICP OES Inductively coupled plasma optical emission spectrosopy) to then be analysed OR sends the plasma into a mass spectrometer where the atoms can be sorted and detected according to atomic weight (ICP MS Inductively couple plasma Mass Spectroscopy) So it can get real hot like the surface of the sun, but very low mass and density. Still surrounded by very dark glass because there is hellacious UV radiation emitted that would give you sunburn FAST. The chambers are quartz glass and synthetic sapphire. There is laminar flow gas to keep the plasma well away from the chamber wall. Sort of a gaseous skull.

Similar techniques are also used in CVD diamond growth. They are also related to microwave oven technology too but microwave don't use coils. They are higher frequency (shorter wavelength why they are called microwaves) and heat the water in food directly. But they can be used to run temps way up if there is a suitable containment vessel. Have you considered a microwave powered furnace? Might be do-able.

Thanks for sharing detailed information. You have solved must of my queries but still I need to search bit more..

Last edited by HarryWells on Wed Nov 27, 2013 11:49 am, edited 1 time in total.

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 Post subject: Re: Need Technical Data For Induction Heating Process
PostPosted: Wed Nov 27, 2013 5:58 am 
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Joined: Sat Jul 14, 2012 5:11 pm
Posts: 657
Ohh great, another bloody Thai based heating scam?
A heat treatment system you can carry around the world with you?
C'mon how long do you think you would survive in most gem mining areas/countries?
"Hey guys, there's some guy coming to visit us dumb miners, buy our low grade rough, go back to his hotel, and turn it into 'sparkling beauties', just like an Alchemist. And Ohh, by the way, you may lose power for a few hours!" HaHa.
Then, if the story follows the old line, take the new Sparkling rough, back to Thailand, and unload it as top grade Thai stone?
Forgive me for venting, but I've seen my area destroyed during the big 1970's/80's boom, when thousands of Kg's of rough left Queensland for Thailand, to be heated, gassed and otherwise modified, with the finest stones sold as Thai, and the poor quality, dumped on an unsuspecting world as Australian/Queensland stone. 30 years later, we still struggle to overcome the damage done by the Asian "cooking factories".
Maybe one day soon, we will all be able to educate more people that natural is beautiful, and overcome the obsession with perfection.
Sorry man, but I'm with Ted on this one.

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