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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,081 records · Page 60

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NASA NTRS2014

Method for Making a Fuel Cell

The invention is a novel solid oxide fuel cell (SOFC) stack comprising individual bi-electrode supported fuel cells in which an electrolyte layer is supported between porous electrodes. The porous electrodes may be made from graded pore ceramic tape that has been created by the freeze cast method followed by freeze-drying. Each piece of graded pore tape later becomes a graded pore electrode scaffold that, subsequent to sintering, is made into either an anode or a cathode. The electrode scaffold comprising the anode includes a layer of liquid metal. The pores of the electrode scaffolds gradually increase in diameter as the layer extends away from the electrolyte layer. As a result of this diameter increase, any forces that would tend to pull the liquid metal away from the electrolyte are reduced while maintaining a diffusion path for the fuel. Advantageously, the fuel cell of the invention may utilize a hydrocarbon fuel without pre-processing to remove sulfur.

Cable, Thomas L.↗

NASA NTRS2006

Impact Damage and Strain Rate Effects for Toughened Epoxy Composite Structures

Structural integrity of composite systems under dynamic impact loading is investigated herein. The GENOA virtual testing software environment is used to implement the effects of dynamic loading on fracture progression and damage tolerance. Combinations of graphite and glass fibers with a toughened epoxy matrix are investigated. The effect of a ceramic coating for the absorption of impact energy is also included. Impact and post impact simulations include verification and prediction of (1) Load and Impact Energy, (2) Impact Damage Size, (3) Maximum Impact Peak Load, (4) Residual Strength, (5) Maximum Displacement, (6) Contribution of Failure Modes to Failure Mechanisms, (7) Prediction of Impact Load Versus Time, and (8) Damage, and Fracture Pattern. A computer model is utilized for the assessment of structural response, progressive fracture, and defect/damage tolerance characteristics. Results show the damage progression sequence and the changes in the structural response characteristics due to dynamic impact. The fundamental premise of computational simulation is that the complete evaluation of composite fracture requires an assessment of ply and subply level damage/fracture processes as the structure is subjected to loads. Simulation results for the graphite/epoxy composite were compared with the impact and tension failure test data, correlation and verification was obtained that included: (1) impact energy, (2) damage size, (3) maximum impact peak load, (4) residual strength, (5) maximum displacement, and (6) failure mechanisms of the composite structure.

Chamis, Christos C.↗

NASA NTRSDate not supplied

Progress Towards Prolonged Deployment of SiC JFET-R ICs Into Previously Inaccessible Hostile Environments

This invited presentation describes demonstration of semiconductor integrated circuits (ICs) and ceramic packaging that are arguably the most environmentally durable transistor electronics ever demonstrated. SiC junction field effect transistor-resistor (JFET-R) ICs with two-level interconnect have successfully operated for over 1 year in 500 °C air-ambient [1], 60 days in 460 °C and 9.3 MPa pressure caustic Venus surface environment test chamber [2], and radiation exposure through 7 Mrad(Si) total ionizing dose (TID) and 86 MeV-cm2/mg heavy ion strikes [3]. Furthermore, these ICs have also demonstrated operation from -190 °C to +812 °C (over 1000 °C T-span) without significant change in signal (input /output) or power supply voltages [4]. With modest adjustments, the SiC JFET-R fabrication process is compatible with semiconductor mass-production tools and materials. As an initial step towards this end, the processing that forms the SiC JFETs and resistors (without interconnect) for the NASA Glenn “Generation 12” design prototype JFET-R ICs was conducted at GE Research. Once the COVID-delayed IC interconnect and bond pad fabrication processing on these wafers is completed at NASA Glenn, the resulting chips will be packaged and oven-tested [5]. It is expected that further technology transfer to complete commercial production will lower investment and risk barriers to useful application deployment. For NASA, an initial high-value deployment is opening the Venus surface to extended missions for robotic scientific exploration.

Silicon Carbide↗

NASA NTRS1995

Supporting technology for the development of Controlled Ecological Life Support Systems (CELSS)

To support the development of Controlled Ecological Life Support Systems (CELSS) in the space program, a metabolic simulator has been selected for use in a closed chamber to test functions of the CELSS. This metabolic simulator is a catalytic reactor which oxidizes the methyl acetate to produce carbon dioxide and water vapor. In this project, kinetic studies of catalytic oxidation of methyl acetate were conducted using monolithic and pellet catalysts with 0.5% (by weight) platinum (Pt) on aluminum oxide (Al2O3). The reaction was studied at a pressure of one atmosphere and at temperatures varying from 160 C to 420 C. By-products were identified at the exit of the preheater and reactor. For the kinetic study with the monolithic catalyst, a linear regression method was used to correlate the kinetic data with zero-order, first-order and Langmuir-Hinshelwood models. Results indicate that the first-order model represents the data adequately at low concentrations of methyl acetate. For higher concentrations of methyl acetate, the Langmuir-Hinshelwood model best represents the kinetic data. Both rate constant and adsorption equilibrium constants were estimated from the regression. A Taguchi orthogonal array (L(sub 9)) was used to investigate the effects of temperature, flow rate, and concentration on the catalytic oxidation of methyl acetate. For the monolithic catalyst, temperature exerts the most significant effect, followed by concentration of methyl acetate. For the pellet catalyst, reaction temperature is the most significant factor, followed by gas flow rate and methyl acetate concentration. Concentrations of either carbon dioxide or oxygen were seen to have insignificant effect on the methyl acetate conversion process. Experimental results indicate that the preheater with glass beads can accomplish thermal cracking and catalytic reaction of methyl acetate to produce acetic acid, methanol, methyl formate, and 1-propanol. The concentration of all by-products was measured in ppmv (parts per million by volume). At higher temperatures, greater amounts of these products are produced, as expected. In all cases, methanol was the predominant concentration detected, followed by methyl formate. At temperatures lower than 320 C for the P-type monolithic catalyst, methanol, acetic acid, and acetone were detected, whereas, for the E-type monolithic catalyst, only methanol was detected at 160 C. Both P and E types of the monolithic catalyst were specified with the same substrates (ceramic), washcoat (Al2O3), and promoter (Pt). However, the manufacturing and treatment procedures were quite different. It was therefore concluded that the performance of the E-type monolithic catalyst is superior to that of the P-type for oxidation of methyl acetate. At higher reaction temperatures, e.g., above 420 C, all reactants and byproducts were completely oxidized using these two types of monolithic catalyst to produce carbon dioxide and water vapor. A complex heterogenous catalytic reaction mechanism was proposed to explain the formation of the byproducts (methanol, acetic acid, and methyl formate) as the methyl acetate traveled through the preheater packed with glass beads. The by-product, 1-propanol, may be formed only through a homogeneous reaction, since it is difficult to develop a reasonable sequence of heterogeneous reaction steps to explain its formation. The homogeneous thermal decomposition of methyl acetate to form free radicals was proposed to explain the formation of 1-propanol, and also methanol, in the preheater. A dual-site catalytic reaction mechanism was proposed for the oxidation of methyl acetate over Pt/Al2O3 monolithic catalyst. The dual-site mechanism describes the chemisorption of oxygen molecules as well as a physical adsorption of methyl acetate on the active sites. On the active sites, methyl acetate is oxidized rapidly to form carbon dioxide and water vapor. A rate equation derived from this mechanism gives the Langmuir-Hinshelwood rate formula which has been observed from the experimental data obtained in this project for high methyl acetate concentration (greater than 1000 ppmv) over a monolithic catalyst. If the oxygen concentration is very high and methyl acetate concentration is very low, the reaction rate equation is then reduced to a first-order with respect to methyl acetate concentration. The first-order model has also been observed from the experimental data obtained in this project for low methyl acetate concentration (less than 1000 ppmv).

Li, Ku-Yen↗

NASA NTRS2005

Factors Controlling Elevated Temperature Strength Degradation of Silicon Carbide Composites

For 5 years, the cooperative agreement NCC3-763 has focused on the development and understanding of Sic-based composites. Most of the work was performed in the area of SiC fiber-reinforced composites for UEET and NGLT and in collaboration with Goodrich Corporation under a partially reimbursable Space Act Agreement. A smaller amount of work was performed on C fiber-reinforced SiC matrix composites for NGLT. Major accomplishments during this agreement included: Improvements to the interphase used in melt-infiltrated (MI) SiC/SiC composites which increases the life under stressed-oxidation at intermediate temperatures referred to as "outside-debonding". This concept is currently in the patent process and received a Space Act Award. Mechanistic-based models of intermediate temperature degradation for MI SiC/SiC Quantification and relatively robust relationships for matrix crack evolution under stress in SiC/SiC composites which serve as the basis for stress-strain and elevated temperature life models The furthering of acoustic emission as a useful tool in composite damage evolution and the extension of the technique to other composite systems Development of hybrid C-SiC fiber-reinforced SiC matrix composites Numerous presentations at conferences, industry partners, and government centers and publications in recognized proceedings and journals. Other recognition of the author's accomplishments by NASA with a TGIR award (2004), NASA's Medal for Public Service (2004), and The American Ceramic Society s Richard M. Fulrath Award (2005). The following will briefly describe the work of the past five years in the three areas of interest: SiC/SiC composite development, mechanistic understanding and modeling of SiC/SiC composites, and environmental durability of C/SiC composites. More detail can be found in the publications cited at the end of this report.

Source record↗

NASA NTRS1991

Multilayer ceramic oxide solid electrolyte for fuel cells and electrolysis cells

A unitary layered ceramic structure is disclosed which comprises co-sintered layers. The co-sintered structure comprises a sintered central layer of yttria stabilized zirconia (YSZ) which is about 8 mole percent yttria and having a density of at least about 95% of theoretical, and sintered outer layers of strontium lanthanum manganite (LSM) having the approximate molecular composition La.sub.0.8 Sr.sub.0.2 MnO.sub.3, having a density from about 50 to about 60% of theoretical, and having interconnected porosity from about 40 to 50% with an interconnected pore diameter from about one micron to about five microns. The sintered central layer is sandwiched by and bonded and sintered to the outer layers and is essentially free of significant amounts of manganese. A process for making the unitary composition-of-matter is also disclosed which involves tape casting a LSM tape and then on top thereof casting a YSZ tape. The process comprises presintering LSM powder at 1250.degree. F., crushing the presintered commercially available LSM powder, forming a slurry with the crushed LSM, a binder and solvent, tape casting the slurry and allowing the slurry to air dry. A mixture of commercially available submicron size particle YSZ powder is milled with a dispersant and solvent to disperse the YSZ particles thereby forming a dispersed YSZ slurry. The YSZ slurry is then tape cast on the dried LSM tape. If desired, a third layer of LSM can be cast on top of the dried YSZ layer. After drying the composite LSM/YSZ and LSM/YSZ/LSM tapes are fired at 1300.degree. C. No migration of manganese into the YSZ layer was observed with scanning electron microscope/edax in the sintered multilayer tape.

Schroeder, James E.↗

NASA NTRS1990

Multilayer ceramic oxide solid electrolyte for fuel cells and electrolysis cells and method for fabrication thereof

An unitary layered ceramic structure is disclosed which comprises co-sintered layers. The co-sintered structure comprises a sintered central layer of yttria stabilized zirconia (YSZ) which is about 8 mole percent yttria and having a density of at least about 95% of theoretical, and sintered outer layers of strontium lanthanum manganite (LSM) having the approximate molecular composition La.sub.0.8 Sr.sub.0.2 MnO.sub.3, having a density from about 50 to about 60% of theoretical, and having interconnected porosity from about 40 to 50% with an interconnected pore diameter from about one micron to about five microns. The sintered central layer is sandwiched by and bonded and sintered to the outer layers and is essentially free of significant amounts of manganese. A process for making the unitary composition-of-matter is also disclosed which involves tape casting a LSM tape and then on top thereof casting a YSZ tape. The process comprises presintering LSM powder at 1250.degree. F., crushing the presintered commercially available LSM powder, forming a slurry with the crushed LSM, a binder and solvent, tape casting the slurry and allowing the slurry to air dry. A mixture of commercially available submicron size particle YSZ powder is milled with a dispersant and solvent to disperse the YSZ particles thereby forming a dispersed YSZ slurry. The YSZ slurry is then tape cast on the dried LSM tape. If desired, a third layer of LSM can be cast on top of the dried YSZ layer. After drying the composite LSM/YSZ and LSM/YSZ/LSM tapes are fired at 1300.degree. C. No migration of manganese into the YSZ layer was observed with scanning electron microscope/edax in the sintered multilayer tape.

Schroeder, James E.↗

NASA NTRS2003

NASA Tech Briefs, June 2003

Topics covered include: Nulling Infrared Radiometer for Measuring Temperature; The Ames Power Monitoring System; Hot Films on Ceramic Substrates for Measuring Skin Friction; Probe Without Moving Parts Measures Flow Angle; Detecting Conductive Liquid Leaking from Nonconductive Pipe; Adaptive Suppression of Noise in Voice Communications; High-Performance Solid-State W-Band Power Amplifiers; Microbatteries for Combinatorial Studies of Conventional Lithium-Ion Batteries; Correcting for Beam Aberrations in a Beam-Waveguide Antenna; Advanced Rainbow Solar Photovoltaic Arrays; Metal Side Reflectors for Trapping Light in QWIPs; Software for Collaborative Engineering of Launch Rockets; Software Assists in Extensive Environmental Auditing; Software Supports Distributed Operations via the Internet; Software Estimates Costs of Testing Rocket Engines; yourSky: Custom Sky-Image Mosaics via the Internet; Software for Managing Inventory of Flight Hardware; Lower-Conductivity Thermal-Barrier Coatings; Process for Smoothing an Si Substrate after Etching of SiO2; Flexible Composite-Material Pressure Vessel; Treatment to Destroy Chlorohydrocarbon Liquids in the Ground; Noncircular Cross Sections Could Enhance Mixing in Sprays; Small, Untethered, Mobile Roots for Inspecting Gas Pipes; Paint-Overspray Catcher; Preparation of Regular Specimens for Atom Probes; Inverse Tomo-Lithography for Making Microscopic 3D Parts; Predicting and Preventing Incipient Flameout in Combustors; MEMS-Based Piezoelectric/Electrostatic Inchworm Actuator; Metallized Capillaries as Probes for Raman Spectroscopy; Adaptation of Mesoscale Weather Models to Local Forecasting; Aerodynamic Design using Neural Networks; Combining Multiple Gyroscope Outputs for Increased Accuracy; and Improved Collision-Detection Method for Robotic Manipulator.

Source record↗

NASA NTRS1994

Copper-containing ceramic precursor synthesis: Solid-state transformations and materials technology

Three copper systems with relevance to materials technology are discussed. In the first, a CuS precursor, Cu4S1O (4-methylpyridine)(sub 4)- (4-MePy), was prepared by three routes: reaction of Cu2S, reaction of CuBr-SMe2, and oxidation of copper powder with excess sulfur in 4-methylpyridine by sulfur. In the second, copper powder was found to react with excess thiourea (H2NC(S)NH2) in 4-methylpyridine to produce thiocyanate (NCS(-)) complexes. Three isolated and characterized compounds are: Cu(NCS)(4-MePy)(sub 2), a polymer, (4-MePy-H)(Cu(NCS)(sub 3)(4-MePy)(sub 2)), a salt, and t-Cu(NCS)(sub 2)(4-MePy)(sub 4). Finally, an attempt to produce a mixed-metal sulfide precursor of Cu and Ga in N-methylimidazole (N-MeIm) resulted in the synthesis of a Cu-containing polymer, Cu(SO4)(N-MeIm). The structures are presented; the chemistry will be briefly discussed in the context of preparation and processing of copper-containing materials for aerospace applications.

Hepp, Aloysius F.↗

NASA NTRS2011

Sustainably Sourced, Thermally Resistant, Radiation Hard Biopolymer

This material represents a breakthrough in the production, manufacturing, and application of thermal protection system (TPS) materials and radiation shielding, as this represents the first effort to develop a non-metallic, non-ceramic, biomaterial-based, sustainable TPS with the capability to also act as radiation shielding. Until now, the standing philosophy for radiation shielding involved carrying the shielding at liftoff or utilizing onboard water sources. This shielding material could be grown onboard and applied as needed prior to different radiation landscapes (commonly seen during missions involving gravitational assists). The material is a bioplastic material. Bioplastics are any combination of a biopolymer and a plasticizer. In this case, the biopolymer is a starch-based material and a commonly accessible plasticizer. Starch molecules are composed of two major polymers: amylase and amylopectin. The biopolymer phenolic compounds are common to the ablative thermal protection system family of materials. With similar constituents come similar chemical ablation processes, with the potential to have comparable, if not better, ablation characteristics. It can also be used as a flame-resistant barrier for commercial applications in buildings, homes, cars, and heater firewall material. The biopolymer is observed to undergo chemical transformations (oxidative and structural degradation) at radiation doses that are 1,000 times the maximum dose of an unmanned mission (10-25 Mrad), indicating that it would be a viable candidate for robust radiation shielding. As a comparison, the total integrated radiation dose for a three-year manned mission to Mars is 0.1 krad, far below the radiation limit at which starch molecules degrade. For electron radiation, the biopolymer starches show minimal deterioration when exposed to energies greater than 180 keV. This flame-resistant, thermal-insulating material is non-hazardous and may be sustainably sourced. It poses no hazardous waste threats during its lifecycle. The material composition is radiation-tolerant up to megarad doses, indicating its use as a radiation shielding material. It is lightweight, non-metallic, and able to be mechanically densified, permitting a tunable gradient of thermal and radiation protection as needed. The dual-use (thermal and radiation shielding), sustainable nature of this material makes it suitable for both industrial applications as a sustainable/green building material, and for space applications as thermal protection material and radiation shield.

Pugel, Diane↗

NASA NTRS2002

NASA Glenn/AADC Collaboration Optimized Erosion Coatings for Inlet Guide Vanes

There is a need for lightweight, durable materials and structures to reduce the weight of propulsion systems. Polymer matrix composites (PMC's) are promising materials for aerospace applications because of their high strength-to-weight ratio relative to metals. Unfortunately, they are limited to applications where they are not exposed to hightemperature oxidizing atmospheres and/or particulates from ingested air. This is because oxidation and erosion occur on the surface, leading to weight loss, nodulation, and/or cracking on the surface, and a consequent decline of mechanical properties over time. Although prior research has shown that oxidation can be slowed when metallic or ceramic coatings are applied onto PMC's, there remains a need for erosion-resistant coatings that protect PMC's from high-velocity particulates in the engine flow path. These erosionresistant coatings could extend the life of polymer composites. Polymer composites are heavily damaged without an erosion-resistant coating because they are not as hard as metallic engine structures. The effectiveness and life of the coatings depends on their inherent properties as well as on the interaction between the coating and the PMC. Since polymers, in general, have high thermal expansion coefficients in comparison to metals and ceramics, failure of the coatings often occurs at this interface. The objective of this research is to develop strategies to improve this interface and tailor overlays for erosion resistance. The bondcoat, which was developed at the NASA Glenn Research Center, is composed of zinc blended with polyimides to improve the compatibility between the PMC and the overlay material. Initial coating trials at AADC produced vanes that had poor bonding between the overlay and bondcoats. Subsequently, Glenn successfully demonstrated that high-quality plasma-sprayed erosion coating systems could be applied to these guide vanes. Inlet guide vanes from AE 3007 engines fiber composites were coated using a coating system composed of a bondcoat and a hard topcoat. Optimization of the plasma spray process has led to plans for future erosion testing in gas turbine engine environments.

Sutter, James K.↗

NASA NTRS1990

Grain orientation studies in superconductors

Grain oriented fabrication of ceramics utilizes the presence of some form of anisotropy in the particles of the starting material to obtain textured microstructures. The molten salt, or flux method, a popular technique for growing crystals and particles with anisotropic morphology, is utilized in this study. The formation of Ba2YCu3O(7-x) in the presence of molten salts of Na, K, Li belonging to chloride and sulfate systems does not appear feasible in the temperature range up to 900 C. Researchers also present the results of studies in using BaY2CuO5 as seed crystals in the formation of Ba2YCu3O(7-x) wherein BaY2CuO5 has been observed to have better stability in water and against most of the salts as compared to Ba2YCu3O(7-x). Additional results of molten salt processing of bismuth systems are also presented.

Gopalakrishnan, Sudhakar↗

NASA NTRS2004

Liquid-Metal-Fed Pulsed Plasma Thrusters

A short document proposes liquid-metal-fed pulsed plasma thrusters for small spacecraft. The propellant liquid for such a thruster would be a low-melting-temperature metal that would be stored molten in an unpressurized, heated reservoir and would be pumped to the thruster by a magnetohydrodynamic coupler. The liquid would enter the thruster via a metal tube inside an electrically insulating ceramic tube. A capacitor would be connected between the outlet of the metal tube and the outer electrode of the thruster. The pumping would cause a drop of liquid to form at the outlet, eventually growing large enough to make contact with the outer electrode. Contact would close the circuit through the capacitor, causing the capacitor to discharge through the drop. The capacitor would have been charged with enough energy that the discharge would vaporize, ionize, and electromagnetically accelerate the contents of the metal drop. The resulting plasma would be ejected at a speed of about 50 km/s. The vaporization of the drop would reopen the circuit through the capacitor, enabling recharging of the capacitor. As pumping continued, a new drop would grow and the process would repeat.

Markusic, Thomas↗

NASA NTRS2013

NASA Tech Briefs, Februrary 2013

Topics covered include: Measurements of Ultra-Stable Oscillator (USO) Allan Deviations in Space; Gaseous Nitrogen Orifice Mass Flow Calculator; Validation of Proposed Metrics for Two-Body Abrasion Scratch Test Analysis Standards; Rover Low Gain Antenna Qualification for Deep Space Thermal Environments; Automated, Ultra-Sterile Solid Sample Handling and Analysis on a Chip; Measuring and Estimating Normalized Contrast in Infrared Flash Thermography; Spectrally and Radiometrically Stable, Wideband, Onboard Calibration Source; High-Reliability Waveguide Vacuum/Pressure Window; Methods of Fabricating Scintillators With Radioisotopes for Beta Battery Applications; Magnetic Shield for Adiabatic Demagnetization Refrigerators (ADR); CMOS-Compatible SOI MESFETS for Radiation-Hardened DC-to-DC Converters; Silicon Heat Pipe Array; Adaptive Phase Delay Generator; High-Temperature, Lightweight, Self-Healing Ceramic Composites for Aircraft Engine Applications; Treatment to Control Adhesion of Silicone-Based Elastomers; High-Temperature Adhesives for Thermally Stable Aero-Assist Technologies; Rockballer Sample Acquisition Tool; Rock Gripper for Sampling, Mobility, Anchoring, and Manipulation; Advanced Magnetic Materials Methods and Numerical Models for Fluidization in Microgravity and Hypogravity; Data Transfer for Multiple Sensor Networks Over a Broad Temperature Range; Using Combustion Synthesis to Reinforce Berms and Other Regolith Structures; Visible-Infrared Hyperspectral Image Projector; Three-Axis Attitude Estimation With a High-Bandwidth Angular Rate Sensor Change_Detection.m; AGATE: Adversarial Game Analysis for Tactical Evaluation; Ionospheric Simulation System for Satellite Observations and Global Assimilative; Modeling Experiments (ISOGAME); An Extensible, User- Modifiable Framework for Planning Activities; Mission Operations Center (MOC) - Precipitation Processing System (PPS) Interface Software System (MPISS); Automated 3D Damaged Cavity Model Builder for Lower Surface Acreage Tile on Orbiter; Mixed Linear/Square-Root Encoded Single-Slope Ramp Provides Low-Noise ADC with High Linearity for Focal Plane Arrays; RUSHMAPS: Real-Time Uploadable Spherical Harmonic Moment Analysis for Particle Spectrometers; Powered Descent Guidance with General Thrust-Pointing Constraints; X-Ray Detection and Processing Models for Spacecraft Navigation and Timing; and Extreme Ionizing-Radiation-Resistant Bacterium

Source record↗

NASA NTRS1992

Space Station Furnace Facility. Volume 1: Requirements definition and conceptual design study, executive summary

The Space Station Freedom Furnace (SSFF) Study was awarded on June 2, 1989, to Teledyne Brown Engineering (TBE) to define an advanced facility for materials research in the microgravity environment of Space Station Freedom (SSF). The SSFF will be designed for research in the solidification of metals and alloys, the crystal growth of electronic and electro-optical materials, and research in glasses and ceramics. The SSFF is one of the first 'facility' class payloads planned by the Microgravity Science and Applications Division (MSAD) of the Office of Space Science and Applications of NASA Headquarters. This facility is planned for early deployment during man-tended operations of the SSF with continuing operations through the Permanently Manned Configuration (PMC). The SSFF will be built around a general 'Core' facility which provides common support functions not provided by SSF, common subsystems which are best centralized, and common subsystems which are best distributed with each experiment module. The intent of the facility approach is to reduce the overall cost associated with implementing and operating a variety of experiments. This is achieved by reducing the launch mass and simplifying the hardware development and qualification processes associated with each experiment. The Core will remain on orbit and will require only periodic maintenance and upgrading while new Furnace Modules, samples, and consumables are developed, qualified, and transported to the SSF. The SSFF Study was divided into two phases: phase 1, a definition study phase, and phase 2, a design and development phase. The definition phase 1 is addressed. Phase 1 was divided into two parts. In the first part, the basic part of the effort, covered the preliminary definition and assessment of requirements; conceptual design of the SSFF; fabrication of mockups; and the preparation for and support of the Conceptual Design Review (CoDR). The second part, the option part, covered requirements update and documentation; refinement of the selected conceptual design through additional trades and analyses; design, fabrication, and test of the Development Model; and design, fabrication, and test of the Interrack Demonstration Unit; and support of the requirements definition review (RDR). The purpose of part 2 was to prove concept feasibility.

Source record↗

NASA NTRS1995

CVD silicon carbide monofilament reinforced SrO-Al2O3-2SiO2 (SAS) glass-ceramic composites

Unidirectional CVD SiC fiber-reinforced SrO.Al2O3.2SiO2 (SAS) glass-ceramic matrix composites have been fabricated by hot pressing at various combinations of temperature, pressure and time. Both carbon-rich surface coated SCS-6 and uncoated SCS-0 fibers were used as reinforcements. Almost fully dense composites have been obtained. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase observed in the matrix from x-ray diffraction. During three point flexure testing of composites, a test span to thickness ratio of approximately 25 or greater was necessary to avoid sample delamination. Strong and tough SCS-6/SAS composites having a first matrix crack stress of approximately 300 MPa and an ultimate bend strength of approximately 825 MPa were fabricated. No chemical reaction between the SCS-6 fibers and the SAS matrix was observed after high temperature processing. The uncoated SCS-0 fiber-reinforced SAS composites showed only limited improvement in strength over SAS monolithic. The SCS-0/SAS composite having a fiber volume fraction of 0.24 and hot pressed at 1400 deg C exhibited a first matrix cracking stress of approximately 231 +/- 20 MPa and ultimate strength of 265 +/- 17 MPa. From fiber push-out tests, the fiber/matrix interfacial debonding strength (tau(sub debond)) and frictional sliding stress (tau(sub friction)) in the SCS-6/SAS system were evaluated to be approximately 6.7 +/- 2.3 MPa and 4.3 +/- 0.6 MPa, respectively, indicating a weak interface. However, for the SCS-0/SAS composite, much higher values of approximately 17.5 +/- 2.7 MPa for tau(sub debond) and 11.3 +/- 1.6 MPa for tau(sub friction) respectively, were observed; some of the fibers were so strongly bonded to the matrix that they could not be pushed out. Examination of fracture surfaces revealed limited short pull-out length of SCS-0 fibers. The applicability of various micromechanical models for predicting the values of first matrix cracking stress and ultimate strength of these composites were examined.

Bansal, Narottam P.↗

NASA NTRSDate not supplied

From Regolith to Living Off the Land: Formulating a Data Model to Catalog Lunar Construction Materials

Artemis Program objectives for sustainable, long-term presence on the Moon and more distant planetary surfaces will require learning to “Live off the Land”, relying on in-situ resource utilization to produce infrastructure and building materials from lunar regolith, icy subsurface deposits, and residual waste materials. Meeting demand for consumables while scaling development with resources found within the landing zone will require detailed data on the geology and environment of the lunar surface. Lunar infrastructure development will generate vast amounts of new engineering data regarding availability of processed feedstocks and their performance in building materials. Lunar engineering data accessible to program partners, research institutions and industry may help situate processes and specifications within the in-situ GIS context. Lunar missions to date have generated geological and ice favorability maps of the lunar surface, and recent technology studies have tested automated construction systems and novel material formulations using regolith simulants and binders. Current discussions focus on identifying key feedstocks, quantities required for nominal mission scenarios and infrastructure plans, and mapping the value chain from regolith to feedstock to consumables and construction materials.

lunar construction↗

NASA NTRSDate not supplied

From Regolith to Living Off the Land: Formulating a Data Model to Catalog Lunar Construction Materials

lunar construction↗