How powerful is a pound of aluminum powder gunpowder
The main ingredients in gunpowder are potassium chlorate, magnesium powder and aluminum powder. When they have external energy, they will burn quickly and regularly on their own.
Both aluminum powder and magnesium powder can increase explosion heat, but how can we analyze it theoretically?
Below we consider the ionization energy
Aluminum powder combustion changed from 0 price to positive 3 price
Ionization energy (kJ/ mol)
  M-M+ 577.4
  M+-M2+ 1816.6
  M2+-M3+ 2744.6
Magnesium powder combustion changes from 0 valence to positive 2 valence
Ionization energy (kJ/ mol)
  M-M+ 737.7
  M+-M2+ 1450.7
It is calculated that the ionization energy of aluminum powder with the same molar mass is obviously greater than that of magnesium powder, and the heat released is correspondingly higher. Therefore, it is better to use aluminum powder in theory.
In practical applications, aluminum powder is also used as a substance to increase explosive heat. Aluminum powder is also added in explosives. Magnesium powder is also more expensive than aluminum powder, so aluminum powder is more suitable for explosives.
Why do most explosives and firecrackers use aluminum powder as a reducing agent instead of the more active magnesium powder?
Several reasons have determined that aluminum is a superior additive than magnesium. Some people have already answered questions about storage and safety. I mainly talk about several other important reasons. The first is the energy density: full combustion of aluminum will release 83.73kJ/cm^3 of energy, while magnesium is 44.21kJ/cm^3. Obviously, the energy density of aluminum is close to twice that of magnesium. If the reaction rate of magnesium powder does not reach twice that of aluminum powder, then the output power of magnesium will not reach the level of aluminum. Even if the output power of magnesium reaches that of aluminum, magnesium will have a disadvantage because its total energy is inferior to aluminum. The reaction rate of the metal powder is mainly determined by the particle size, and it has a natural advantage to make the aluminum powder finer. This is the second reason. The second reason is the manufacturing process. Everyone should know that magnesium can burn in nitrogen. The preparation of propellant and energy material grade aluminum powder is made by spray cooling. The spray cooling method uses a very thin nozzle to drive the liquid metal out with a high-pressure gas, thereby forming very fine metal particles, which are then cooled down to obtain the product. The working principle is very similar to the spray nozzle of Avène and the nozzle for watering flowers. Since aluminum powder does not react with nitrogen at the melting point temperature, nitrogen can be used as driving gas and cooling gas to make aluminum powder. Air can be used in the early days, but now in order to improve the specific impulse of the propellant, it needs to use a few microns or even nanometers. The aluminum powder is not safe to use air, so nitrogen is used. And if nitrogen is used to make magnesium powder, it will wait for a big explosion. Therefore, the magnesium powder processing does not require spray cooling. Even if this method is used, argon gas must be used, which is much more expensive than air and nitrogen. Therefore, the magnesium powder is generally made by ball milling, which is the violent collision of several large steel mills to grind the magnesium chips. It is conceivable that the quality of the magnesium powder obtained is very poor. Third, the issue of compatibility. The activity of magnesium is higher than that of aluminum, and the compatibility of magnesium and aluminum with other substances is poor. Propellant energy materials These are systems where oxidizers and reductants are mixed. We need something that is not so active but can emit huge energy. Aluminum is very suitable. For example, mixing ammonium perchlorate and aluminum powder is safer than mixing ammonium perchlorate and magnesium powder. In summary, aluminum powder is far superior to magnesium powder.