|his method is notoriously unreliable: magnesium itself is hard to ignite, and in windy or wet conditions the strip may be extinguished. Also, magnesium strips do not contain their own oxygen source so ignition cannot occur through a small hole. A significant danger of magnesium ignition is the fact that the metal is an excellent conductor of heat; heating one end of the ribbon may cause the other end to transfer enough heat to the thermite to cause premature ignition. Despite these issues, magnesium ignition remains popular amongst amateur thermite users.|
The reaction between potassium permanganate and glycerine is used as an alternative to the magnesium method. When these two substances mix, a spontaneous reaction will begin, slowly increasing the temperature of the mixture until flames are produced. The heat released by the oxidation of glycerine is sufficient to initiate a thermite reaction. However, this method can also be unreliable and the delay between mixing and ignition can vary greatly due to factors such as particle size and ambient temperature.
Another method of igniting is to use a common sparkler to ignite the mix. These reach the necessary temperatures and provide a sufficient amount of time before the burning point reaches the sample.
Oh and theres more.
Thermite reaction proceeding for a railway welding. Shortly after this, the liquid iron flows into the mold around the rail gap.
The violent effects of thermite demonstrated in the Utah desert
Thermite reactions have many uses. Thermite was originally used for repair welding in-place such things as locomotive axle-frames where the repair can take place without removing the part from its installed location. It can also be used for quickly cutting or welding metal such as rail tracks, without requiring complex or heavy equipment.
A thermite reaction, when used to purify the ores of some metals, is called the Thermite process. An adaptation of the reaction, used to obtain pure uranium, was developed as part of the Manhattan Project at Ames Laboratory under the direction of Frank Spedding. It is sometimes called the Ames process.
When thermite is made using iron (III) oxide, for maximum efficiency it should contain, by mass, 25.3% aluminum and 74.7% iron oxide. (This mixture is sold under the brand name Thermit as a heat source for welding.) The complete formula for the reaction using iron (III) oxide is as follows:
Fe2O3(s) + 2Al(s) ? Al2O3(s) + 2Fe(s); ?H = -851.5 kJ/mol
When thermite is made using iron (II,III) oxide, for maximum efficiency it should contain, by mass, 23.7% aluminium and 76.3% iron oxide. The formula for the reaction using iron (II,III) oxide:
3Fe3O4(s) + 8Al(s) ? 4Al2O3(s) + 9Fe(s); ?H = -3347.6 kJ/mol
The reaction using Fe3O4 produces a substantially larger amount of energy pr. mol reaction than the reaction using Fe2O3, which produces more energy pr. gram of thermite mixture.
Thermite should not be confused with a thermal lance.
Thermite grenades are used as incendiary devices to quickly destroy items or equipment when there is imminent danger of them being captured by enemy forces. Because of the difficulty in igniting standard iron-thermite, plus the fact that it burns with practically no flame and has a small radius of action, standard thermite is rarely used on its own as an incendiary composition. It is more usually employed with other ingredients added to enhance its incendiary effects. Thermate-TH3 is a mixture of thermite and pyrotechnic additives which have been found to be superior to standard thermite for incendiary purposes. Its composition by weight is generally thermite 68.7%, barium nitrate 29.0%, sulphur 2.0% and binder 0.3%. Addition of barium nitrate to thermite increases its thermal effect, creates flame in burning and significantly reduces the ignition temperature. Although the primary purpose of Thermate-TH3 is as an incendiary, it will also weld metal surfaces together.
A classic military use for Thermite is disabling artillery pieces. Thermite can be used to permanently disable artillery pieces without the use of explosive charges and therefore operate with a reasonable amount of stealth. The 2nd Ranger Battalion used Thermite grenades against the Nazi artillery at Pointe du Hoc during the Allied invasion of Normandy. There are several ways to do this. One method is to weld the breach of the weapon closed by inserting an armed thermite grenade into it and then quickly closing the breech. This makes the weapon impossible to load. An alternative method is to insert an armed thermite grenade down the muzzle of the artillery piece, fouling the barrel. This makes the piece very dangerous to fire. Yet another method is to use Thermite to destroy the traversing and elevation mechanism on the cannon, making it impossible to properly aim the gun..
As someone who aged 15 had access to the Anarchist cookbook and a docile chemistry teacher who gave me a set of keys to the lab one afternoon, I stole the ingredients to make thermite (and some kick ass smoke bombs). It isn't an explosive its a aluminothermic reaction, for a start. And a moderately slow moving one at that. To use that to make the quick "pancake fall" of the twin towers?. To quote Ricky Gervais, "you're having a laugh"