sunnymoon - 2-2-2006 at 12:35
Hello
How can I calculate effect of Aluminium on power in a explosive composition?
Can this be calculate like effect of CHNO compounds?
Swany - 2-2-2006 at 18:47
There isn't a way. You can calculate the extra energy for the formation of Al2O3(assuming thats what you want), though it is formed after the initial
detonation, I am told.
Chris The Great - 2-2-2006 at 20:57
I would think that the detonation properites of explosives with Al can be calculated... somehow. I have not seen a simple pen-and-paper type
calculation like there is for CHNO type explosives (several calculations for those). I think computer codes can calculate it, but no clue where you
would get that and programming it would certainly be on the difficult side.
Swany - 3-2-2006 at 06:37
I belive it would be quite difficult to be accurate. Extensive testing would have to be done just to generate consistant resuts. I don't think it
would be very feasable for anyone like us.
On the brighter side, I have some german dark Al, and I am testing it in a ETN/NG plastique, against straight ETN/NG plastique. It seems such a waste
of all of the extra oxygen... even with 10% Al, which is what the plastique will hold comfortably, it is still oxygen positive. If nothing, it will
add a nice flash to the explosion.
sylla - 4-2-2006 at 15:22
There is an underlying question in "how to calculate the al ratio" that is "how does aluminium interract with the molecules ?". We can consider that
we have some gases CO, CO2, N2, H2O and H2. How is aluminium likely to react with these ?
There is several possible reactions :
CO + Al -> Al2O3 + C
CO2 + Al -> Al2O3 + CO
H2O + Al -> Al2O3 + H2
Only the very first reaction causes problem because the amount of gazes is reduced. The others are really fine because they do not reduce the number
of mols of gaz but increase the energy. But, temperature depends not only on energy but also on the kind of gaz presents. (Thermal Coefficients).
So, it all boils down to "What is the oxygen affinity of each components ?" Eh that's a good question ! I've already worked with this aluminium
addition problem and so far, all I did was using 1/3 of the first, 1/3 of the second and 1/3 of the last one. It gaves pretty good results.
From memory, it said 15% aluminium 75% TNT while the empirical data says 18% aluminium 72% TNT...
Good luck for your calculations and if you have some news, tell me because I'm really interrested in these kind of theoretical reasearch 
12AX7 - 4-2-2006 at 16:43
FWIW, 2Al2O3 + 9C <--> Al4C3 + 6CO proceeds to the right at high temperatures. AFAIK, Al is unable to fully reduce carbon, but magnesium can.
The remaining equations you wrote should proceed as indicated, though as mentioned the rate is probably more for overall power than VOD or something.
Sp: "gas", not "gaz".
Tim
vulture - 5-2-2006 at 02:21
Interesting, hadn't thought about aluminiumcarbide formation. Although it is said that the reaction needs a reducing atmosphere to work, so it depends
on the OB of the explosive.
I once uploaded a PDF from JoPEP which had a discussion of the effect of several sizes and concentrations of aluminium powder on different explosive
compositions. I believe it should still be on the FTP.
[Edited on 5-2-2006 by vulture]
Aluminum
MadHatter - 5-2-2006 at 11:10
Vulture, there is indeed a section in the PEP series on the effects of aluminum in pyro.
It's on the FTP under EXPLOSIVES.
Sunnymoon, check your U2U. It contains the information necessary to access the FTP.
Do some downloading and reading. You'll find lots of information there.