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Diana Santiago

Publications and source records attributed to Diana Santiago.

12 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

High Yield Exfoliation of a Sub-Micron Hexagonal Boron Nitride Using a Solvent Free Method

Sodium fluoride (NaF) has been found to be an activation agent in exfoliating a hexagonal boron nitride (hBN) platelet, using solvent free method. The procedure was carried out by enhancing the intercalation of ferric chloride (FeCl3) in an intermediate step, up to 330 °C, followed by removal of the by-product at room temperature. In this research, five additional common salts including lithium fluoride, potassium fluoride, lithium chloride, sodium chloride, and potassium chloride, were examined and compared to NaF for their effectiveness in producing the most exfoliation of a commercially available sub-micron-size hBN. It was found that, all fluoride and chloride salts significantly activated the intercalation of FeCl3 into this hBN. Analyses and characterization from X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscoy revealed NaCl to be one of most effective agents without further heat treatment and the least expensive salt in the intercalating reaction and exfoliation process. The synthetic route of this solvent free method is straightforward with 89% yield and above which can be produced on a large scale.

boron nitride↗
NASA NTRS2023

Scaling Electric Machines to a Megawatt and Material Options

Megawatt (MW) electric aircraft propulsion (EAP) is seen as a significant contributor toward achieving the goals set forth by the Sustainable Flight National Partnership. A large part of enabling MW EAP is developing specific-power-dense electric machines. As specific-power-dense electric machines are scaled up from kW to MW power levels, the thermal stresses on the machines increase in both magnitude and performance-affecting characteristics. This is particularly true for the stators of these machines. Analysis via thermal resistance network modeling and multiscale modeling reveals that increasing amounts of heat will be trapped in the stator windings as the power levels increase. The challenges this presents can be addressed through material advancements whereby materials gain multifunctionality. Specifically, the electrical insulation and potting materials, along with the electrical conductor, that compose the stator slot must work together (gain multifunctionality) to relieve the increased thermal stress. Materials research at the NASA Glenn Research Center points to some useful solutions in this trade space.

Electric Machine↗
NASA NTRSDate not supplied

Scaling Electric Machines to a Megawatt and Material Options

Megawatt (MW) electric aircraft propulsion (EAP) is seen as a significant contributor toward achieving the goals set forth by the Sustainable Flight National Partnership. A large part of enabling MW EAP is developing specific-power-dense electric machines. As specific-power-dense electric machines are scaled up from kW to MW power levels, the thermal stresses on the machines increase in both magnitude and performance-affecting characteristics. This is particularly true for the stators of these machines. Analysis via thermal resistance network modeling and multiscale modeling reveals that increasing amounts of heat will be trapped in the stator windings as the power levels increase. The challenges this presents can be addressed through material advancements whereby materials gain multifunctionality. Specifically, the electrical insulation and potting materials, along with the electrical conductor, that compose the stator slot must work together (gain multifunctionality) to relieve the increased thermal stress. Materials research at the NASA Glenn Research Center points to some useful solutions in this trade space.

Electric Machine↗
NASA NTRSDate not supplied

NASA-GRC High Voltage Materials Development and Test Capabilities Portfolio

This presentation provides the background information on NASA-GRC high voltage (HV) materials team research efforts towards electrified propulsion systems since 2016 . Additionally, it covers polymer and ceramic filler materials development for HV electrical insulation composites, copper/ carbon nanotube hybrid conductors, modeling efforts, HV test capabilities, and future material processing capabilities.

Boron Nitride↗
NASA NTRSDate not supplied

Forcespun Polymers as Precursors to Boron Nitride Fibers

The need for multifunctional materials in aerospace technologies is currently driving the development of new novel composite materials. Specifically, insulation materials with high thermal conductivity, high electrical resistivity, and are chemically inert are needed for high voltage power applications. Boron nitride (BN) nanomaterials fit these criteria and can be incorporated into composites for further material design. The synthesis of boron nitride through a polymer derived ceramic route allows for the morphology of the resulting BN to be tailored. This is especially beneficial since the polymers can be shaped or spun into fibers prior to the ceramic conversion. This project utilizes the Forcespinning technique to produce boron-containing polymer fibers that are converted to boron nitride through a heat treatment. The chemical compositions and fiber morphologies were studied and reported here.

Boron nitride, Fibers, Forcespinning↗
NASA NTRSDate not supplied

Modification of Hexagonal Boron Nitride with Metal Oxides

The development of multifunctional hexagonal boron nitride (hBN) materials aims to capitalize on the intrinsic properties of hBN which include being electrically insulating, thermally conductive, and chemically and thermally stable at high temperatures. The creation of novel composite materials that include these properties is required to address our current aerospace and space engineering challenges. Researchers at NASA Glenn have done significant prior work which has produced processes to intercalate, exfoliate, coat, and functionalize various hBN materials. This presentation covers our recent progress towards the integration of titanium oxides into hBN utilizing our previous methods along with optimizing and producing new methods to create novel functional hBN nanomaterials.

boron nitride↗
NASA NTRSDate not supplied

Engineered Hexagonal Boron Nitride:Titanium Dioxide Composites for High Voltage Insulation

Hexagonal boron nitride (hBN) and Titanium dioxide are both ceramic materials with widespread use in commercial and consumer applications in everything from cosmetics and paint to deep space satellite components. As a dielectric material, hBN is electrically insulating, thermally conductive, and stable to most temperatures and environments. Titanium dioxide is also a good electrical insulator with a wide bandgap and large dielectric constant, as well as high temperature tolerance and chemical stability. This presentation covers our recent efforts to combine the best properties of hBN and titanium dioxide to produce an intercalated hBN:titanium dioxide composite which was then further processed and incorporated into polymer composites, as well as a standalone ceramic material for testing as a novel insulation material.

boron nitride↗
NASA NTRSDate not supplied

Materials for Power Transmission in Extreme Environments

NASA’s goal for a sustained human presence on the Moon and a future Lunar economy requires the development of novel power transmission materials for extreme environments. As an increasing number of public and private entities set their sights towards a future on the Moon, the demand for surface power will dramatically increase – potentially up to megawatt levels. A Lunar economy is envisioned to include a human habitat, manned and unmanned science exploration assets, excavation rovers and systems, and large-scale infrastructure construction such as solar arrays and power grids. A NASA trade study estimated that 1 to 3 km of power transmission lines (1 to 3 KV ac and dc) will be needed over time. Current high power and voltage SOA cables/wire can easily exceed 1 kg/m where mass is not as critical. Connectors, deployment spools and robots further increase the subsystem mass significantly increasing costs. On the other hand, advances in aeronautics provides path towards space missions. The operating environment on the Moon presents substantial risk to safe and reliable power transmission due to space weathering and degradation. These challenges include cosmic and UV radiation, extreme temperatures swings, the electrostatic Lunar exosphere, and the electrostatic and abrasive lunar regolith. The critical need for lightweight, safe and reliable power cables/wires materials is evident. In this presentation, the extreme high altitude and lunar environments and recent materials development from NASA Glenn Research Center’s High Voltage Materials team towards meeting NASA’s objectives and goals for aeronautics and space missions.

Cu/CNT conductors↗