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Development of Vat Polymerization Materials for Additive Manufacturing of Gun Propellant


The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: Develop techniques to incorporate energetic solid filler such as HMX, RDX, or Nitroguanidine (NQ) with feedstock for additive manufacturing of gun propellant. DESCRIPTION: This development effort focuses on materials to enable 3D printing of gun propellants. Additive manufacturing presents the opportunity for performance gains through highly engineered complex structures. These structures offer the potential for increased loading densities and higher surface area progressivity. These properties, in turn, translate to extended range for existing weapon platforms. The developmental materials must match the high-strain-rate mechanical properties of JA2 propellant while providing propellant performance characteristics that match or exceed those of M31A2. The threshold energy level is a calculated impetus of 950 J/g with an objective level of 1100 J/g. The materials should also have superior low-temperature properties to avoid brittle fracture (glass transition below -50 Deg F, Tg) and should retain shape up to 145 deg F. This level of will likely be achieved through the addition of the energetic fillers. Materials can be a mixture of various polymers and additives. The proposed solution must not produce toxic combustion products and those that result in excessive residue and erosion. Oxygen balance and ignition properties must also be considered up front for this solution to be viable for defense applications. PHASE I: Demonstration of achieving greater than or equal to 75% solids loading by mass of filler with 1.7 - 1.9 g/cc density and nominal particle size of 10 micrometers. Second and equally weighted deliverable is demonstration of utilizing a commercial off the shelf or custom 3D printer that uses vat photopolymerization methods to obtain samples for testing. Third is characterization of preliminary mechanical properties including uniaxial compression results at high strain rates (1/100 seconds) and associated material characterization (density, microscopy, physical, chemical, etc.). If the capability to demonstrate at 1/100 seconds is unavailable in the private sector, lower strain rates with accompanying analysis may be used to extrapolate results. Alternatively, proposer may submit the material for evaluation at US government facilities at no charge. Additionally, cure/penetration depth of development materials must demonstrated and provided. PHASE II: Required Phase II deliverables would be scale-up of feedstock and delivery of said feedstock in a quantity greater than 500 ml. to a government and/or contractor facility for further performance evaluation. Subscale evaluation of said materials in both mechanical and combustion testing would be required to corroborate the results of phase I. The contractor stablished resolution limits, delivering sample calibration prints of said materials (and associated analysis) with proposed printing methods utilizing vat photopolymerization (selected during phase I). PHASE III DUAL USE APPLICATIONS: The end state of this research would be a material feedstock that balances high-performance combustion characteristics and superior mechanical properties in the extreme gun environment during the interior ballistic event. The target US Army application would be the 155mm Artillery platform due to the need for extended range. This technology will be transitioned to GOCO ammunition plants such as Radford Army Ammunition Plant, and will benefit from early engagement with the prime contractors operating these facilities. Commercial applications of this material include dental use (highly dense and highly filled materials), high performance composites, clean burning pyrotechnics (fireworks), and any application where a consumable 3d Printed object is needed. REFERENCES: 1. Photopolymerization processes of thick films and in shadow areas: a review for the access to composites; Patxi Garra, Céline Dietlin, Fabrice Morlet-Savary, Frédéric Dumur, Didier Gigmes, Jean-Pierre Fouassier and Jacques Lalevée; Polymer Chemistry - Royal Society of Chemistry 2017; Polym. Chem., 2017, 8, 7088; 2. Office of Naval Research ONR Scientific Officer: Steven G. Fishman; 01 January 1993- December 31, 1994; Final Technical Report August 25, 1997; 3. Preparation and Properties of Dental Composite Resin Cured under Near Infrared Irradiation; Motohiro Uo, Eiki Kudo, Aya Okada, Kohei Soga and Yasuo KOGO; Department of Biomedical Materials & Engineering, Hokkaido University, Sapporo 060-8586, Japan, Department of Material Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan;; 4. CHARACTERIZATION OF CURING KINETICS AND POLYMERIZATION SHRINKAGE IN CERAMIC-LOADED PHOTOCURABLE RESINS FOR LARGE AREA MASKLESS PHOTOPOLYMERIZATION (LAMP) A Thesis Presented to The Academic Faculty by Kiran Kambly In Partial Fulfillment Of the Requirements for the Degree Master of Science in Mechanical Engineering Georgia Institute of Technology Dec, 2009 KEYWORDS: 3D printing, additive manufacture, gun propellant, gun propulsion, combustion, highly filled material, highly filled composite, high performance photopolymer, photopolymer, toughness
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