A Foundry in Every Kitchen

WolfWithoutAClause writes "Bored with making the same old food or plasma in your microwave? David Reid sounds like he is. He's using his domestic microwave oven to melt iron, silver and bronze! Over 900C! I don't know about you, but I'm going to be checking the temperature of my pizza rather more carefully in future..."

Comments

For more cool Microwave science...

[DeafDumbBlind]

Try putting in a CD (Yet another use for those AOL 7.0 discs that they keep sending)

A burned out light-bulb causes some interesting things to happen as well :-)

Re:For more cool Microwave science...

[Anonymous Coward]

Since we're in a well labelled offtopic thread anyway, put a lit cigarette on a dish, and microwave it on high. My guess is that it is about the same thing as ball lightning that results. This is not a joke, but I'll 90% guarantee that you'll find yourself laughing when it works just as I promised.

Re:Microwave Pizza??

[Anonymous Coward]

Ah my son. You've traveled from the past, from back in 1989 when microwave technology still frightened most food manufacturers and no one looked at all the wonderful things synthetic materials can do as food adatives. Pop a few in and your pizza microwaves perfectly!

Fahrenheit 451

[KeelSpawn]

This somehow reminds me of the famous sci-fi book - Fahrenheit 415 - the degree (451) which books burn!! but the story never said anything about microwave melting metal! one thing that was similar to that microwave was the "wall incinerator" in F451. It's a microwaved-sized object in a wall, you can put anything in it and it burns to nothing. I think we'er pretty darn close to that already.. =)

Re:Hmm

[klevin]

Try actually reading the article. One: they've already done it. Two: it's not the entire inside area of the microwave that's reaching those tempuratures, just the area inside several layers of material that convert microwaves to heat, plus the interior surfaces of the microwave have been layered with insulation to protect them.

Microwaves are potentially dangerous---no shit.

[dc.wander]

I feel obliged to say something, before some 13 or 14 year-old kills themselves:

microwaves are high voltage, high current devices. they can kill you EVEN IF THE POWER IS OFF AND THE DEVICE IS UNPLUGGED (ex: by discharging of a large capacitor). Unless you really know what you are doing, don't open one up. i've been trained in servicing electronics, and even i wouln't go near one of these things.

see: Notes on the Troubleshooting and Repair of Microwave Ovens for more information.

Re:Microwaves are potentially dangerous---no shit.

[Anonymous Coward]

microwaves are high voltage, high current devices. they can kill you EVEN IF THE POWER IS OFF AND THE DEVICE IS UNPLUGGED (ex: by discharging of a large capacitor). Unless you really know what you are doing, don't open one up. i've been trained in servicing electronics, and even i wouln't go near one of these things.

Good call. If you still feel the urge to work on them, good work habits include wearing good insulated shoes and working with ONE HAND only (other behind your back!), which limits most current paths to just your hand. Usually the worse thing that happens is your hand is tossed off of what you're working, but you're less likely to have a path through your heart, which is when it gets dangerous... Another safety precaution is to discharge the caps with a screwdriver (but be careful, might damage something with a dead short!)

Re:Microwaves are potentially dangerous---no shit.

[Brymouse]

First of all, most large caps is a microwave have 10 meg-ohm resistors on them to bleed off the charge. All you have to do is put a large screw driver across the cap to test if it is safe to handle. If the resistor is in good condition, nothing should happen, if not, you get one hell of a spark. No harm done to you, but maybe the screw driver!

Now as for servicing a microwave, 9 time out of 10 they have a partial diagram in them, that shows the major componits. Once you have this, it is easy to work on one, as long as you know the basics of how a microwave works.

Short version of how a microwave works (for food!). First, power comes into the unit, goes through a set-up transformer, is rectified, and smoothed though the cap(s). Then this high voltage is applied to the magnatron (the thing that makes microwaves), and the resulting radiation is couppled into a waveguide. In this waveguide is a metal disk with holes in it, that "stirs" the microve energy. From here it goes into the chamber, and heats your food. It accomplices because the water in food absorbs the 2.4 GHz radiation.

That's how it works.

Re:Microwaves are potentially dangerous---no shit.

[juhaz]

Almost all, if not all big capasitors are electrolytic, those things are very sensitive to overvoltage, as well as plugging them backwards. They probably do not like shorting, either. It may not kill you like shock, but being blind because a exploding capasitor threw some metal case fragments into your eyes is not very nice either.

Just to be sure, as you can't be too careful, discharge those damn things _TROUGH A RESISTOR, NOT BY SHORTING_.

It's to protect the plastic floor of oven.

[Blaede]

There's nothing wrong with heating up a metal in a microwave, that in itself will not ruin the unit. What is a big problem is the heated item melting the inside floor of the oven due to (drum roll, please), HEAT! The item gets hot, and melts a big hole in the floor, therefore ruining it. So go ahead and heat metals in your microwave, just don't let it touch the insides directly. That means using a plate, cover, etc.

metal clays are easier to work with

[g4dget]

If you want to make small pieces of jewelry or other parts, there are metal clays (search on Google): almost pure precious metal (silver, gold) with a little bit of binder. When you heat them, the binder burns away and the metal sticks together.

Other than that, the technique sounds unnecessarily laborious and complex. There are easier ways to melt metal, even at home. Thermite, for example, should appeal to people who like fireworks. Basic textbooks on inorganic chemistry, mineralogy, and metallurgy can tell you how. (Don't people learn this stuff in high school chemistry anymore?)

Do not try this at home!

[Anonymous Coward]

I've cast aluminum (1200F) and iron (2200F) and am truly concerned about the total lack of safety equipment that this guy presented. When I cast the molten metal, we wore complete body leathers and used tongs to keep the hot metal at least 1-2 feet away. To pick up a container using bare hands and sleeves is nuts. Molten metal will burn through unprotected skin.

A serious problem with pouring molten metals is the risk of moisture in the moulds. For example, if a fly happened to be in the mould when the metal was poured, the metal would explode from the moisture with enough force to hit the ceiling. I sure don't want to be in a room when its raining molten metal!

Re:Do not try this at home!

[Austenite]

I had two really sad thoughts after reading this post....

Firstly, I have been told that molten steel is hot enough that the moisture content in your skin vaporises and causes it to (mostly) skitter away from your skin, a bit like water in a hot frypan. Molten aluminium, on the other hand (pun intended!), isn't hot enough to cause this effect, and so transfers a greater proportion of its heat to your body. Despite the overall amount of heat in the aluminium being lower, the damage to you is much, much worse.

The other sad thought was the chorus from "It's raining men" changed to "It's raining mol-ten". I'll never get it out of my head now!

Microwave to heat � best container material

[Saggi]

Microwaves in a microwave oven are using a frequency that matches the vibration frequency of the O-H bond in water. Now if a microwave should be converted into heat, it must hit a molecule, where it can leave the correct energy. This is quantum mechanics, so only the precise amount of energy can be transferred to the vibration. If the wavelength of the microwave doesn't match, energy will not be transferred.

Now the described experiment used several different containers for the metal. These containers absorb the microwave and convert them into heat. To obtain the best container material, you should look for materials whose vibration energy of some of its atom bonding matches that of the O-H bonding in water.

The O-H bond has been chosen as most food contains water. Materials without water will not heat in a microwave oven. (Unless it contains molecules that match the frequency in other ways).