Date of Award

12-2017

Degree Type

Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

Committee Chair

Jeffrey F. Rhoads

Committee Member 1

Steven F. Son

Committee Member 2

George T.-C. Chiu

Abstract

The work discussed in this document seeks to utilize traditional additive manufacturing techniques to selectively deposit energetic materials. The goal was to gain a fundamental understanding of how to use commonplace 2D inkjet printing and 3D fused deposition technology to selectively deposit reactive materials. Doing so provides the ability to manipulate the geometry, as well as composition, of the energetic material during the manufacturing process. Achieving this level manipulation and control has shown to be nontrivial, if not impossible, using traditional manufacturing methods. The ability to change the geometry of the energetic material at will greatly increases the ability of these energetic materials to be integrated with a wide range of systems, such as transient electronics. To create a transient electronic device, a destruction mechanism and an initiation system need to be integrated with electronic components. Experiments in this document investigate nanothermites for their ability to serve as this destruction mechanism. Nanothermites were prepared at various equivalence ratios and syringe deposited onto silicon substrates. The resultant destruction was shown to vary with the equivalence ratio of the material. A wide range of substrate destruction was demonstrated, varying from disintegration to only charring the wafer. Materials prepared near stoichiometric conditions were shown to disintegrate the silicon substrates completely. As the equivalence ratio was raised, less severe destruction was observed. The ability inkjet print these nanothermites provides the geometric control necessary to incorporate them into electronic components. An ink formulation process was explored in an attempt to create a fuel and an oxidizer ink, which could be inkjet printed simultaneously to create a nanothermite. Separate inks allow for the equivalence ratio, and therefore the resultant destruction, to be selectively tuned during the additive manufacturing process. Additionally, this gives the advantage of only needing two largely inert, shelf stable inks, instead of having to develop a new ink for every desired destruction level. Various candidate inks were formulated using different loadings and combinations of surfactants. Polyvinylpyrrolidone was shown to be the surfactant best suited for holding both aluminum and copper (II) oxide nanoparticles in suspension over time. These inks both showed reasonable shelf stability as well as viable reactivity when stoichiometric nanothermite samples were prepared using on-chip mixing. With respect to 3D printed energetic materials, fused deposition methods were used to print a fluoropolymer based energetic material which could be used as a multifunctional reactive structure. A reactive filament comprising of a polyvinylidene fluoride (PVDF) binder with 20% mass loading of aluminum (Al) was prepared using a commercial filament extruder and printed using a Makerbot Replicator 2X. The printing performance of the energetic samples was compared with standard 3D printing materials using metrics such as bead-to-bead adhesion and the surface quality of the printed samples. The reactivity and burning rates of the filaments and the printed samples were shown to be comparable. This result is imperative for fused deposition modeling to be used as a viable manufacturing method of energetic materials. In total, this document lays some of the groundwork necessary for additive manufacturing to be adopted as a viable method for the selective deposition of energetic materials. Going forward these methods can be used to integrate energetic materials in a manner not possible using traditional manufacturing methods.

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