=46rom Arocket list. There are other sites on this. I suspect iron sand may work. Sounds like great fun. Stand over on end to get a sensible shape for many things. RM ___________________________________________________________ ----- Original Message -----=20 =46rom: "Jeff Grady" < > To: Sent: Wednesday, January 07, 2004 8:28 PM Subject: [AR] Melting metals with a microwave (long post) This was recently posted on another list (hobbicast@yahoogroups.com) = and thought it may interest many on this list: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D Some of you may know that I make a living by developing new products = and processes for the metal casting and steel making industries. About 6 months ago, we started looking seriously at using microwave energy fo= r melting metals. About $40,000 later, we have done an immense amount of lab work. We h= ave successfully melted Aluminum, Bronze, Iron, Steel and even Glass in a simple 1000 watt microwave oven. The key points in doing this are as follows. 1. You need do have either a special crucible that absorbs microwaves= , or, you will need to have microwave absorbing materials nearby to a microwave transparent crucible. So far, we have made all of our own crucibles. I can't tell you what = we are using, because we fully intend to offer these crucibles for sale = to the public, sometime this year. What I can tell you is that Silica (fused silica) is microwave transparent. Alumina becomes a microwave absorber at elevated temperatures. Once you get it hot, it will get v= ery hot, very quickly in microwave energy. We have developed a mixture of refractories that can be shaped into a crucible that will reach over 2,000=B0F. in less than 5 minutes of microwave heating. 2. You will need to use some fairly fancy refractory insulation to ke= ep =66rom burning up the inside of the microwave. We use a very low dens= ity solid or fibrous material that is about 70% Alumina and 30% Silica. Y= ou can either build a box and then put the crucible inside of it, or, yo= u can line the whole inside of the microwave. Just remember that the radiant heat from a glowing crucible needs to be contained, or you wi= ll quickly burn the inside of the oven. Remove any plastic covers inside the microwave, or they will melt. 3. You really need to keep close tabs on the temperature of the metal= in order to avoid some serious over heating disasters. Last month, we ov= er heated some Iron, which then melted through an Alumina crucible (that takes 3700=B0F), and then we vaporized the Iron (that takes about 500= 0=B0F). Things can get really hot really fast. Be prepared to shut down the power if you get into runaway heating. Have some really well insulate= d gloves or tongs to handle the crucible. 4. Now, here's the neat part. We know that metals behave as microwave reflectors. They won't heat up in a microwave. BUT, we have learned t= hat all metals will become microwave absorbers at elevated temperatures. = We suspect that the temperature at which this occurs is about half of th= e melting point of the metal. We will know what the exact temperatures = are later in January. Once you reach this magical temperature, the metals will absorb the microwaves and you can melt lickety split! Virtually all of the energ= y that you put into the oven is going directly into the metal and causi= ng molecular vibration (heating). DON'T DO ANY OF THIS KIND OF STUFF IN YOUR WIFE'S MICROWAVE! I have toasted 3 microwaves in the past 3 months, mainly because they got too hot from runaway heating. I melted through the bottom of one = and the Iron ran out onto the table, along with a fair amount of microwav= e energy, which can be quite dangerous. If you are serious about doing this, you need to constantly measure for microwave leakage from the unit. I expect to make a public announcement about the availability of thes= e special crucibles and the refractory insulation for holding them, sometime in the next 3 months. This is no BS. We are quite serious ab= out designing a microwave that will have the capability of melting at lea= st one ton per hour, by the end of 2004. The eventual goal is to design = and build a system that can melt several hundred tons a day. I will keep all of my Hobbicast friends posted on our progress. Tom Cobett Cleveland, OH --^---------------------------------------------------------------- This email was sent to: apptech@PARADISE.NET.NZ EASY UNSUBSCRIBE click here: http://topica.com/u/?a2i9pz.a7ON2I.YXBwd= GVj Or send an email to: arocket-unsubscribe@topica.com TOPICA - Start your own email discussion group. FREE! http://www.topica.com/partner/tag02/create/index2.html --^---------------------------------------------------------------- -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads