On Nov 21, 2009, at 3:03 AM, Erik Christiansen wrote: > On Fri, Nov 20, 2009 at 05:10:18PM +0000, Leslie Newell wrote: >> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it >> will >> strip oxygen out of the CO2. That is also the reason why you should >> never use a CO2 fire extinguisher on magnesium fires. > > However, it is extensively used in fire extinguishers precisely > because > it does not give up its oxygen even at hundreds of degrees C. I'm not > sure of how many thousand degrees magnesium burns at, but it is more > than 1500, because thermite (magnesium and iron oxide) combustion > melts > the iron produced by the reduction of the iron oxide.
Correction: "Thermite" is actually a name brand which is a mixture of aluminum and iron oxide. Generically speaking, Thermite is referred to an "aluminothermic" reaction. It is aluminum's high infinity for oxygen that strips the oxygen away from the iron oxide. I am sure you could also burn (exothermic reaction) magnesium with iron oxide, however, that would result in such rapid combustion it would cause an explosion. I have actually casted iron, steel, nickel, chromium, ferrotitanium, and even titanium using aluminothermic reactions (you use the oxide for the metal that you want - like titanium dioxide for titanium). It is fascinating stuff! Note that titanium dioxide takes a great deal more energy to sustain an exothermic reaction compared to iron oxide, so the use of a catalyst is required. Cheers, Jeshua Lacock Founder/Programmer 3DTOPO Incorporated <http://3DTOPO.com> Phone: 208.462.4171 ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
