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3D printing brings more efficient ways to make rocket propellants
How energetic materials are made affects the shapes that they come in and how they release energy over time. For example, solid rocket propellants are made similar to a cake where a stand mixer stirs the “batter,” which is mostly made of ammonium perchlorate, aluminum, and a rubbery binder, before it’s poured into a pan. The “cake” solidifies in the pan while it bakes in the oven.
However, it is very challenging to 3D-print energetic materials for several reasons. Some energetic materials are very viscous, which means it is very hard to squeeze that mixture out of a tube with a small nozzle. Imagine squeezing clay out of a small syringe—the material is too thick to easily move through the small hole. In addition, energetic materials can be dangerous if handled improperly. They can ignite if there is too much heat during the manufacturing process or during storage, or if they are exposed to a static electric shock.
While much of this research is in its infancy, companies such as X-Bow have been 3D-printing propellants and conducting successful flight tests with these motors.