Effects of Environmental Factors on Additive Manufactured Materials

NPS NRP Executive SummaryEffects of Environmental Factors on Additive Manufactured MaterialsN4 - Fleet Readiness & LogisticsThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Impacts Of Hot Isostatic Pressing 3D Printed Parts

NPS NRP Executive SummaryImpacts Of Hot Isostatic Pressing 3D Printed PartsMarine Corps Logistic Command (MCLC)This research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Ultrahigh Temperature Materials for Hypersonic Systems Readiness

NPS NRP Project PosterThe proposed study aims to support the Hypersonics RDT&E efforts at the Strategic Systems Programs (SSP) by developing and validating materials that have potential to withstand the high temperatures encountered by systems used in hypersonic flight. Multilayered architectures that combine the high melting temperatures and oxidation resistance of ultrahigh temperature ceramics (UHTC) (top) and graphitic composites (bottom) are proposed along with the technical assessment of their performance. The approach to fabricate the UHTC will employ a low power atmospheric microwave plasma system operating under atmospheric conditions to generate a combination of borides and carbides known for their thermal and/or oxidation resistance. The UHTC particulates generated will be integrated into a layered structure containing a graphitic base. The composite samples produced will be analyzed by X-ray diffraction, electron microscopy, energy dispersive spectroscopy to determine crystalline structure, microstructural features, and composition. Thermogravimetric and differential scanning calorimeter analyses will be employed to study the oxidation resistance of the new composites up to 1400 degrees C. The ablation resistance will be tested by exposing the materials to temperatures of about 2000 degrees C achieved by an oxyacetylene flame and evaluating its effects. Some of the research questions that this research will answer include: Could we generate strategic and operational alternatives/formulations to the materials currently employed for hypersonic applications? What variables in the plasma system will provide the ideal conditions (power, flow rates, precursor composition) to generate the targeted compositions? What are the properties of the new materials? How do the novel materials compare to current benchmarks? Deliverables include technical report, student thesis or publications produced in the frame of this research.Strategic Systems Programs (SSP)ASN(RDA) - Research, Development, and AcquisitionThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Ultrahigh Temperature Materials for Hypersonic Systems Readiness

NPS NRP Technical ReportThe proposed study aims to support the Hypersonics RDT&E efforts at the Strategic Systems Programs (SSP) by developing and validating materials that have potential to withstand the high temperatures encountered by systems used in hypersonic flight. Multilayered architectures that combine the high melting temperatures and oxidation resistance of ultrahigh temperature ceramics (UHTC) (top) and graphitic composites (bottom) are proposed along with the technical assessment of their performance. The approach to fabricate the UHTC will employ a low power atmospheric microwave plasma system operating under atmospheric conditions to generate a combination of borides and carbides known for their thermal and/or oxidation resistance. The UHTC particulates generated will be integrated into a layered structure containing a graphitic base. The composite samples produced will be analyzed by X-ray diffraction, electron microscopy, energy dispersive spectroscopy to determine crystalline structure, microstructural features, and composition. Thermogravimetric and differential scanning calorimeter analyses will be employed to study the oxidation resistance of the new composites up to 1400 degrees C. The ablation resistance will be tested by exposing the materials to temperatures of about 2000 degrees C achieved by an oxyacetylene flame and evaluating its effects. Some of the research questions that this research will answer include: Could we generate strategic and operational alternatives/formulations to the materials currently employed for hypersonic applications? What variables in the plasma system will provide the ideal conditions (power, flow rates, precursor composition) to generate the targeted compositions? What are the properties of the new materials? How do the novel materials compare to current benchmarks? Deliverables include technical report, student thesis or publications produced in the frame of this research.Strategic Systems Programs (SSP)ASN(RDA) - Research, Development, and AcquisitionThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Ultrahigh Temperature Materials for Hypersonic Systems Readiness

NPS NRP Executive SummaryThe proposed study aims to support the Hypersonics RDT&E efforts at the Strategic Systems Programs (SSP) by developing and validating materials that have potential to withstand the high temperatures encountered by systems used in hypersonic flight. Multilayered architectures that combine the high melting temperatures and oxidation resistance of ultrahigh temperature ceramics (UHTC) (top) and graphitic composites (bottom) are proposed along with the technical assessment of their performance. The approach to fabricate the UHTC will employ a low power atmospheric microwave plasma system operating under atmospheric conditions to generate a combination of borides and carbides known for their thermal and/or oxidation resistance. The UHTC particulates generated will be integrated into a layered structure containing a graphitic base. The composite samples produced will be analyzed by X-ray diffraction, electron microscopy, energy dispersive spectroscopy to determine crystalline structure, microstructural features, and composition. Thermogravimetric and differential scanning calorimeter analyses will be employed to study the oxidation resistance of the new composites up to 1400 degrees C. The ablation resistance will be tested by exposing the materials to temperatures of about 2000 degrees C achieved by an oxyacetylene flame and evaluating its effects. Some of the research questions that this research will answer include: Could we generate strategic and operational alternatives/formulations to the materials currently employed for hypersonic applications? What variables in the plasma system will provide the ideal conditions (power, flow rates, precursor composition) to generate the targeted compositions? What are the properties of the new materials? How do the novel materials compare to current benchmarks? Deliverables include technical report, student thesis or publications produced in the frame of this research.Strategic Systems Programs (SSP)ASN(RDA) - Research, Development, and AcquisitionThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Novel Metal Oxide Aerogel / Graphitic Hybrids for Supercapacitive Energy Storage

Energy Academic Group Science and Technology ProjectGoal: Create the foundation to develop hybrid metal oxide aerogel/graphitic materials for supercapacitor devices, by preserving high surface area, while presenting significantly higher specific capacitance than carbon by itself due to pseudocapacitive effects

Modeling of Energy Demand and Savings Associated with the Use of Epoxy-Phase Change Material Formulations

The article of record as published may be found at http://dx.doi.org/10.3390/ma13030639This manuscript integrates the experimental findings of recently developed epoxy-phase change material (PCM) formulations with modeling efforts aimed to determine the energy demands and savings derived from their use. The basic PCM system employed was composed of an epoxy resin, a thickening agent, and nonadecane, where the latter was the hydrocarbon undergoing the phase transformation. Carbon nanofibers (CNF) and boron nitride (BN) particulates were used as heat flow enhancers. The thermal conductivities, densities, and latent heat determined in laboratory settings were introduced in a model that calculated, using EnergyPlus software, the energy demands, savings and temperature profiles of the interior and the walls of a shelter for six different locations on Earth. A shipping container was utilized as exemplary dwelling. Results indicated that all the epoxy-PCM formulations had a positive impact on the total energy savings (between 16% and 23%) for the locations selected. The use of CNF and BN showed an increase in performance when compared with the formulation with no thermal filler additives. The formulations selected showed great potential to reduce the energy demands, increase savings, and result in more adequate temperatures for living and storage spaces applications.This research was funded by Office of Naval Research Energy System Technology Evaluation Program. Richa Agrawal acknowledges the National Academies of Sciences, Engineering, and Medicine (NASEM) for support through National Research Council Research Associateship Program (NRC-RAP).This research was funded by Office of Naval Research Energy System Technology Evaluation Program. Richa Agrawal acknowledges the National Academies of Sciences, Engineering, and Medicine (NASEM) for support through National Research Council Research Associateship Program (NRC-RAP)

Nitrogen Doped Graphene Generated by Microwave Plasma and Reduction Expansion Synthesis

The article of record as published may be found at http://dx.doi.org/10.1166/nnl.2016.2055This work aimed to produce nitrogen doped graphene from Graphite Oxide (GO) by combining the Expansion Reduction Synthesis (RES) approach, which utilizes urea as doping/reducing agent, with the use of an Atmospheric Plasma torch (Plasma), which provides the high temperature reactor environment known to thermally exfoliate it. The use of this combined strategy (Plasma-RES) was tried in an attempt to increase the surface area of the products. The amount of nitrogen doping was controlled by varying the urea/GO mass ratios in the precursor powders. X-ray diffraction analysis, SEM, TEM, BET surface areas and conductivity measurements of the diverse products are presented. Nitrogen inclusion in the graphene samples was corroborated by the mass spectral signal of the evolved gases generated during thermal programmed oxidation experiments of the products and by EDX analysis. We found that the Plasma-RES method can successfully generate doped graphene in situ as the urea and GO precursors simultaneously decompose and reduce in the discharge zone. When using the same amount of urea in the precursor mixture, samples obtained by Plasma-RES have higher surface area than those generated by RES, however, they contain a smaller nitrogen content

Electrically Conductive CNT Composites at Loadings below Theoretical Percolation Values

The article of record as published may be found at https://doi.org/10.3390/nano9040491It is well established that dramatic increases in conductivity occur upon the addition of conductive filler materials to highly resistive polymeric matrices in experimental settings. However, the mechanisms responsible for the observed behavior at low filler loadings, below theoretical percolation limits, of even high aspect ratio fillers such as carbon nanotubes (CNT) are not completely understood. In this study, conductive composites were fabricated using CNT bundles dispersed in epoxy resins at diverse loadings, using different dispersion and curing protocols. Based on electron microscopy observation of the CNTs strands distribution in the polymeric matrices and the corresponding electrical conductivities of those specimens, we concluded that no single electron transfer model can accurately explain the conductive behavior for all the loading values. We propose the existence of two different conductive mechanisms; one that exists close to the percolation limit, from ‘low loadings’ to higher CNT contents (CNT % wt > 0.1) and a second for ‘extremely low loadings’, near the percolation threshold (CNT % wt < 0.1). The high conductivity observed for composites at low CNT loading values can be explained by the existence of a percolative CNT network that coexists with micron size regions of non-conductive material. In contrast, samples with extremely low CNT loading values, which present no connectivity or close proximity between CNT bundles, show an electrical conductivity characterized by a current/voltage dependence. Data suggests that at these loadings, conduction may occur via a material breakdown mechanism, similar to dielectric breakdown in a capacitor. The lessons learned from the data gathered in here could guide future experimental research aimed to control the conductivity of CNT composites

Breaking Functional Connectivity into Components: A Novel Approach Using an Individual-Based Model, and First Outcomes

Landscape connectivity is a key factor determining the viability of populations in fragmented landscapes. Predicting ‘functional connectivity’, namely whether a patch or a landscape functions as connected from the perspective of a focal species, poses various challenges. First, empirical data on the movement behaviour of species is often scarce. Second, animal-landscape interactions are bound to yield complex patterns. Lastly, functional connectivity involves various components that are rarely assessed separately. We introduce the spatially explicit, individual-based model FunCon as means to distinguish between components of functional connectivity and to assess how each of them affects the sensitivity of species and communities to landscape structures. We then present the results of exploratory simulations over six landscapes of different fragmentation levels and across a range of hypothetical bird species that differ in their response to habitat edges. i) Our results demonstrate that estimations of functional connectivity depend not only on the response of species to edges (avoidance versus penetration into the matrix), the movement mode investigated (home range movements versus dispersal), and the way in which the matrix is being crossed (random walk versus gap crossing), but also on the choice of connectivity measure (in this case, the model output examined). ii) We further show a strong effect of the mortality scenario applied, indicating that movement decisions that do not fully match the mortality risks are likely to reduce connectivity and enhance sensitivity to fragmentation. iii) Despite these complexities, some consistent patterns emerged. For instance, the ranking order of landscapes in terms of functional connectivity was mostly consistent across the entire range of hypothetical species, indicating that simple landscape indices can potentially serve as valuable surrogates for functional connectivity. Yet such simplifications must be carefully evaluated in terms of the components of functional connectivity they actually predict