Can Microwave Furnaces Be Used to Melt Iron?

AAAAAAAAAAARGH! NOOOOOOOOOOO!

I think you might be referring to "inductive heating", which is competely different. Inductive heating consists of placing the iron inside an alternating magnetic field and over-saturating it. Heat is dissipated within the metal as the magnetic field changes and reverses. The technique can be used in drum heaters for those 45gal drums.

Microwave ovens' frequencies are 'tuned' to the hydrogen-oxygen bonds in the water molecule, and literally 'cook' the food from within by vibrating them. Put anything metallic inside the oven and you are very likely to become very unpopular both with others living at home, and your fire insurance company. DON'T DO IT!

I got this comprehensive information off the WEB. I know all about inductive heating.and plastic welding. RF generators etc.

But this system was fully described , The iron was inside a graphite enclosure which inturn, was enclosed in refractory insulation, the oven was run for 25 minuts to obtain the temperature, the insulation was inplace, to protect the oven.

After the prescribed time.

The door was opened. a small crucible was removed from the graphite enclosure and metal was poured.

So what about this other item I read regarding: reactivating carbon on water filteration systems? by cooking it in a micro wave oven.

Are you telling me that cooking carbon will blow my oven?

Perhaps the guy de tuned his magnetron? he was making jewelery.

GF

Microwave ovens' frequencies are tuned to the hydrogen-oxygen bonds in the water molecule. Gas jets are probably safer on jewelry.

Why these individuals are doing anything else is most abstruse!

<Are you telling me that cooking carbon will blow my oven? Perhaps the guy de tuned his magnetron?>

Look, I've, er, found this spare microwave oven lurking in the tea room at Argos. If you want to blow yourself up its yours for £10. <Splutter>

Mmmm, was the web site wikipedia?

Can I copy and paste your :

AAAAAAAAAAARGH! NOOOOOOOOOOO!

&

DON'T DO IT!

May I help Crabtree?

<A domestic microwave oven melting metal at 1000 degrees Celsius

Research is nearing completion on a system that will allow the melting and casting of bronze, silver, gold, and even cast iron, using an unmodified domestic microwave oven as the energy source.
A potential foundry in every kitchen !! >

Probably 1 gm. of Silver was melted with difficulty.( CI melts at ~1050C)

Domestic Microwave OVEN is Hardly a Melting MICROWAVE FURNACE!

To melt Iron there are a hundred easier ways.

Microwave ovens can heat up not only water but for example some ceramics or any material with high dielectric loss, so it may work

Stealth technology is really all about absorbing microwaves (eliminate radar reflections). most stealth coatings are made with either ferrite or carbon powders, so the "carbon boat" would probably work well.

Just to see what would happen, I once put a small square of the conductive carbon foam (the kind used to protect IC's in shipping) in our microwave. It absorbed the microwaves very well! The smell of the exploding foam was so bad, my wife wouldn't let me near our microwave oven for weeks.

A colleague of mine once put an MMC mixture of Alumina and titanium inside my new microwave oven to see if it would melt and bond properly.

The flipside was that they put the lot onto a paper plate they found laying around .

Result, burnt plate but nothing extreme. The stuff did heat up so the working principle might be there for other bonds than just the ones joining H and O in water.

you can melt iron in your microwave oven, if the iron is a very small piece and thin.

If your oven's power is big enough, it can melt large iron. no doult.

but the ordinary oven cannt do it. the eddy will burn your transformer and megnetron in oven. bvecause its power is not strong enough.

When my youngest daughter was in cullinary school she mentioned they put metal in the commercial microwaves all the time.

she can recall their commercial oven was always burned then.

About the activated carbon question:

Carbons remove organics by affinity and ion bonding. You can reactivate the carbon with heating, but only the organics will come off.

Remember to do it someplace well ventilated, or you'll breath what you didn't drink.

Anyone who's bought a microwave pizza or a hot pocket can attest that metal is put in the microwave all the time. That grey area on the supplied plate/sleeve contains metal, although Im not sure if thats really ment to reflect heat or the actual microwaves back into the food. My guess is the carbon (probably graphite) boat is doing the heating for what you describe. Carbon does some pretty interesting things in the kitchen microwave. In college I used to demonstrate (I was a physic student) for my drunken frat buddies by placing a lit wooden match in the microwave and setting it on high. After about 3 seconds the microwaves would strike a purpleish ball of plasma, which I can tell you was probably pretty hot. Later on in life I worked at a research lab where we used various carbon containing substances to strike plasmas in a microwave device for the purposes of growing synthetic diamond. Plasma temp was well in excess of 3000 C at 4.9 kW. Oh, and everything inside that microwave chamber was also metal, so I might like to add that tuning your resonant cavity plays a huge role in what gets hot and what doesnt, and arc mitigation.

Industrial Microwave ovens are being used for extreme high temperature applications. A domestic appliance is not "tuned" to do the job, and would probably melt from the inside out as your target began to get hot.

Hi,

if you use an automatic 3stub-tuner and an isolator this is possible, provided you have enough energy to overcome the heat losses and you have accurate coupling to put the energy into your specimen.

As metals are more or less good conductors, the electric field at the surface will generate big currents (given by temperature dependent resistance). These currenst will heat the metal.

As the frequencies are pretty high (some GHz) the currents are limited to a very shallow surface (micrometer) where there may be an oxide that can be heated also by dielectric losses (nonideal capacitors).

The magnetic field will directly induce voltages by its fast changing magnetic flux. The currents that are generated (also by Ohms law thus temperature dependent) will contribute to heating.

Microwave heated cearmic firing is a matter of fact in industrial processes.

Microvawe brazing at temperatures up to 1200°C also.

So why not metal melting?

You need the automatic tuner to tune the incoming microwave to the losses of your sample. This is similar to impedance matching .

You need isolation of your generator from the backwards traveling wave else you will burn the generator if the tuner is not perfect.

RHABE

The microwave oven is a tuned RF circuit (or cavity). Think of the heated material as an antenna inserted into this cavity... If your heated material will cause a very high SWR (standing wave ratio) the losses at the Magnetron tube and hence the power supply, will be so high that, it will end up in smoke very quickly. There is a certain amount of SWR that will not burn the the MW oven and might bring a piece of metal to high enough temperature and melt it. A domestic model will protest very loudly at a very small piece.

There are dozen easier ways to melt metal. Why would mess with this dangerous idea? or is this just an academic interest ?

Wangito

Wangito.

I have an interest in the fact that micro waves will turn a flame containing incandescent particles of carbon into a plasma.

This being the case, it should be possible to produce CO + H2 within the plasma in the presence of steam. this reaction is endothermic, and the plasma needs to supply energy,The tuning of the cavity and its shape, is a worthy challenge.

If this can be attained, it should be possible, to gasify low grade fuels, "smokelesly" and economically, by using this device as an after burner. the energy released in this manner, will of set ,the high grade energy needs, (electricity), being used to create the plasma.

The focusing and reflection of micro waves, is a known science, I do not believe the challenge is insurmountable for the needs of this process. cleaning up the exhaust of heat engines might also be applicable. I am not sure what effect micro waves have on the pure gas CO2, other than, it probably will warm up?

I like your comments

GF

Very intriguing... and I can see where you are going...

Let me do some reading.

However I don't think that this is the right forum to develop the idea. Did you try to bring this to a serious R+D group for evaluation?

Wangito.

_I

Wangito.

I sketched out the idea on the gasification blog.these guys seem to be locked into tried and true methods going back to Fischer Trop and Kalle' charcoal fueled devices.

Didn't get much enthusiasm for the idea. It is probably to Technological as most like to weld up hot water tanks modified to make tarry gas.

GF

Looked for the gasification blog, couldn't find it.( blog index.) It is probably in another chat room? or, can you give the link.

Ira

"If this can be attained, it should be possible, to gasify low grade fuels, "smokelesly" and economically, by using this device as an after burner. the energy released in this manner, will of set ,the high grade energy needs, (electricity), being used to create the plasma."

I'm pretty sure that it's already been done. However, it was set up more as a way of cleaning up the exhaust gasses of diesel powered busses. It was a long time ago (5 years +) but there was an article about it in a science type program on the ABC (Australian Broadcasting Corporation, Aussie version of BBC).

Sorry I can't remember the specific details and I haven't got time at the moment to search the web for it. If you have time try searching for "microwave", "exhaust " and "cleaning" and see what comes up.