Military Propellant Auxiliary Ingredients
In military propellants, "auxiliary ingredients" do not refer to single, fixed components, but rather functional components added according to the propellant type (solid or liquid) and specific application. While these auxiliary ingredients are not the main fuel or oxidizer, they are crucial to the propellant's performance, stability, safety, and processability.
Common auxiliary ingredients in military propellants include:
**Binders (Adhesives):** Used to bind solid components such as oxidizers and fuels into uniform, stable propellant grains.
Common examples include: hydroxyl-terminated polybutadiene (HTPB), polyurethane, and polybutadiene acrylate acrylonitrile (PBAN).
**Curing Agents:** Used to cross-link and cure the propellant mixture containing binders, forming solid propellant grains.
Examples include: isocyanate compounds (such as toluene diisocyanate and hexamethylene diisocyanate).
Plasticizers: Improve propellant flexibility, lower glass transition temperature, and enhance cryogenic performance.
Metallic fuels: Increase specific impulse and combustion temperature.
Aluminum powder is the most commonly used, followed by magnesium, boron, etc.
Oxidizers: Although a major component, they constitute the largest proportion of solid propellants and often work synergistically with auxiliary ingredients.
Ammonium perchlorate (NH₄ClO₄) is the most mainstream solid propellant oxidizer; potassium perchlorate is also used in ignition propellants and signaling agents.
Stabilizers and anti-aging agents: Extend propellant storage life and prevent decomposition.
Burn rate modifiers (catalysts/decelerators): Control combustion rate, such as iron oxide and ferric oxide.
Special functional additives: such as urea derivatives, which can be used to prepare high-energy, low-toxicity propellant components (such as urea perchlorate); and dipentaerythritol derivatives, which are used to improve the high-temperature resistance and oxidation resistance of fuels.
