Sciencemadness Discussion Board

Thermate (Rather thermite analogs) VS Thermite

Camroc37 - 5-10-2016 at 14:00

I would like to start a thread on the differences between thermite and thermate. Thermate more specifically refers to Thermate-TH3, a military recipe consisting of 68.7% Thermite mix (exact ratio of Aluminum and Iron Oxide is not said, but I went with a 1:3 ratio of Al:FeO3), 29% Barium Nitrate, and 2% Sulfur by weight. Seeing that Barium Nitrate is somewhat expensive compared to other oxidizers, I opted to create a Thermite analog or variant using the exact ratios. The new recipe is as follows: 68.7% thermite (51.525% Red Iron Oxide and 17.175% 30 micron Aluminum powder), 29% Potassium Nitrate, 2% Sulfur. Using the easiest sources I could find, the final cost per pound is $3.68. In the end, Thermite alone is more expensive than thermate as the cost comes from the Aluminum.
Anyways, what I would like to know is the temperature difference between my recipe and plain thermite. I haven't found a comparison on SM or online between the specs of these mixes. I have semi-educatedly guessed Thermate to burn about ~2,000 degrees F hotter than thermite alone. Am I close? Please continue this thread with any info you have.

blogfast25 - 5-10-2016 at 14:28

Quote: Originally posted by Camroc37  
The new recipe is as follows: 68.7% thermite (51.525% Red Iron Oxide and 17.175% 30 micron Aluminum powder), 29% Potassium Nitrate, 2% Sulfur. Using the easiest sources I could find, the final cost per pound is $3.68. In the end, Thermite alone is more expensive than thermate as the cost comes from the Aluminum.
Anyways, what I would like to know is the temperature difference between my recipe and plain thermite. I haven't found a comparison on SM or online between the specs of these mixes. I have semi-educatedly guessed Thermate to burn about ~2,000 degrees F hotter than thermite alone. Am I close? Please continue this thread with any info you have.


Your mixture is badly designed.

The molar ratio Fe2O3/Al is about 2, which is what's needed for:

Fe2O3 + 2 Al ==== > 2 Fe + Al2O3

You're not leaving any Al to be oxidised by the potassium nitrate. The result is that part of the iron oxide will not be reduced, lowering the overall heat output of the of mix.

For this mixture to be stoichiometric and pack maximum reaction heat, you should add about 15.5 g Al powder per 100 g of current mix. That would probably add another 500 C to the adiabatic end temperature.



[Edited on 5-10-2016 by blogfast25]

Camroc37 - 5-10-2016 at 16:38
Quote: Originally posted by blogfast25  
Your mixture is badly designed.

The molar ratio Fe2O3/Al is about 2, which is what's needed for:

Fe2O3 + 2 Al ==== > 2 Fe + Al2O3

You're not leaving any Al to be oxidised by the potassium nitrate. The result is that part of the iron oxide will not be reduced, lowering the overall heat output of the of mix.

For this mixture to be stoichiometric and pack maximum reaction heat, you should add about 15.5 g Al powder per 100 g of current mix. That would probably add another 500 C to the adiabatic end temperature.



[Edited on 5-10-2016 by blogfast25]

Thank you for the fix, I'll try it out.
x/100*15.5 is the formula for anyone else who has used my incorrect recipe. x=weight of thermate mix before adding the Aluminum, 15.5g extra for every 100g of mix.

[Edited on 6-10-2016 by Camroc37]

Edit: fixed broken quote

[Edited on 10-6-2016 by zts16]