A system and method for producing fuel grain for a rocket engine horizontally with an additive manufacturing machine is disclosed. To begin, a fuel grain model is received. The fuel grain model is oriented in a direction of a central core axis and divided into two-dimensional layers with defined footprint areas. In accordance with the fuel grain model, a first layer is printed by applying successive fuel beads in a direction primarily parallel to the central core axis.

A device may include an electrically-operated propellant or energetic gas-generating material, additively manufactured together with electrodes for producing a reaction in the material. The device may also include a casing that is additively manufactured with the other components. The additive manufacturing may be accomplished by extruding or otherwise depositing raw materials for the different components where desired. The electrodes may be made of a conductive polymer material, for example using an electrically-conductive fill in a polymer.

An energetic thermoplastic filament comprising an energetic material bound within a thermoplastic matrix and methods for the fabrication of an energetic thermoplastic filament are disclosed. The energetic material comprises an energetic material selected from an explosive, a propellant, a pyrotechnic, an oxidizer, or combinations thereof. The thermoplastic comprises a TPE, ETPE, or combinations thereof. The thermoplastic filaments may be formed by extrusion. The energetic thermoplastic filaments are particularly suitable for additive manufacturing by thermal FDM style 3D printing systems.

A method of producing a propellant material element, such as an electrically-operated propellant material, includes extruding a propellant material through a heated nozzle. The nozzle may be heated to a temperature that is above the boiling point of a solvent that is part of the propellant material, yet is below a decomposition temperature of the propellant material. This allows some of the solvent to be driven off during the extruding process, while still preventing initiation of an energy-creating reaction within the material. The heating of the material in the extruding process, and especially the heating of the nozzle that the material is extruded through, may be controlled to remove an amount of solvent that results in the extruded material having desirable properties.

An additively manufactured solid fuel grain for a hybrid rocket engine having a cylindrical shape, defining a center combustion port and comprising a stack of fused layers of polymeric material suitable for hybrid rocket fuel. Each layer is formed as a plurality of fused abutting concentric beads of solidified material arrayed around the center port. An oxidizer is introduced into the solid fuel grain through the center port, with combustion occurring along the exposed surface area of the solid fuel grain center port wall. Each concentric bead possesses a surface pattern that increases the combustion surface area and when stacked forms a rifling pattern of undulations that induces oxidizer-fuel gas axial flow to improve combustion efficiency. The port wall surface pattern persists during the rocket engine's operation as the fuel phase changes from solid to gas and is ablated.

A hybrid rocket solid fuel grain having a cylindrical shape and defining a center port is additive manufactured from a compound of thermoplastic fuel and passivated nanocomposite aluminum additive. The fuel grain comprises a stack of fused layers, each formed as a plurality of fused abutting concentric circular beaded structures of different radii arrayed defining a center port. During operation, an oxidizer is introduced along the center port, with combustion occurring along the exposed port wall. Each circular beaded structure possesses geometry that increases the surface area available for combustion. As each layer ablates the next abutting layer, exhibiting a similar geometry is revealed, undergoes a gas phase change, and ablates. This process repeats and persists until oxidizer flow is terminated or the fuel grain material is exhausted. To safety achieve this construction, a fused deposition additive manufacturing apparatus, modified to shield the nanocomposite material from the atmosphere is used.

A hybrid rocket solid fuel grain having a cylindrical shape and defining a center port is additive manufactured from a compound of thermoplastic fuel and passivated nanocomposite aluminum additive. The fuel grain comprises a stack of fused layers, each formed as a plurality of fused abutting concentric circular beaded structures of different radii arrayed defining a center port. During operation, an oxidizer is introduced along the center port, with combustion occurring along the exposed port wall. Each circular beaded structure possesses geometry that increases the surface area available for combustion. As each layer ablates the next abutting layer, exhibiting a similar geometry is revealed, undergoes a gas phase change, and ablates. This process repeats and persists until oxidizer flow is terminated or the fuel grain material is exhausted. To safety achieve this construction, a fused deposition additive manufacturing apparatus, modified to shield the nanocomposite material from the atmosphere is used.

An additively manufactured energetic material, a method of producing an additively manufactured energetic material, and a method of making an injection moldable plastic bonded energetic material are provided. The energetic material comprises a liquid optically curable binder and an energetic material suspended in the optically curable binder.

The invention is directed to a method for the preparation of an energetic material product such as a propellant or explosive charge or grain. The method includes additive manufacturing with co-extrusion of at least two materials to form a multi-layered filament and layer-by-layer deposition of the multi-layered filament. The multi-layered filament has a first material layer and a second material layer and at least one layer includes an energetic material. In another aspect, the invention is directed to an apparatus for use in this method, the apparatus comprising a co-extrusion nozzle.

A system and methods for additively manufacturing energetic particles such as polymer-free nanothermite aerogels are provided. An ink containing graphene oxide (GO), Al, and Bi.sub.2O.sub.3 nanoparticles in propylene carbonate is prepared. The method includes in-situ reduction of graphene oxide (GO), by ethylenediamine, during extrusion and printing of the ink onto a substrate with a simple printing system. The printed aerogels include reduced GO as a porous scaffold for the aerogel with Al and Bi.sub.2O.sub.3 clusters embedded therein. The linear burning rate of the printed aerogels reached a higher rate (10 m/s) that reported for typical polymer-assisted 3D printed nanothermite products. Also provided is a framework for optimizing a nanothermite fuel grain structure to match a desired combustion profile. The framework was used to model optimal fuel layer thicknesses, radii and bum rates for simple thrust, complex thrust and pressure matching cases.