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NASA NTRS2013

Flame Suppression Agent, System and Uses

Aqueous droplets encapsulated in a flame retardant polymer are useful in suppressing combustion. Upon exposure to a flame, the encapsulated aqueous droplets rupture and vaporize, removing heat and displacing oxygen to retard the combustion process. The polymer encapsulant, through decomposition, may further add free radicals to the combustion atmosphere, thereby further retarding the combustion process. The encapsulated aqueous droplets may be used as a replacement to halon, water mist and dry powder flame suppression systems.

Parrish, Clyde F.↗
NASA NTRSDate not supplied

Microbial Pigments and Their Degradation Products as Biosignatures

Carotenoids are a class of vibrant biological pigments that have a characteristic chemical structure centered around a polyene core (Lu et al. 2018). Carotenoids and their derivatives are candidate biosignatures because they can persist in the terrestrial geologic record for up to 1.73 billion years (Vinnichenko et al. 2020), have specific structures that are likely the result of complex pathways, mediate the survival of many microorganisms in Mars and Ocean Worlds analog environments, and are detectable with multiple techniques, including Raman spectroscopy. In this project, we aim to investigate the detectability of carotenoid pigments with different spectroscopic methods to inform future instrument selection. We compare the spectra of five unaltered carotenoids, two model compounds, and carotenoid-forming archaeon with visible and deep UV Raman spectroscopy and UVVis absorption spectrophotometry. We then use one model pigment, beta-carotene, to evaluate the likelihood that unique spectral properties of carotenoids, or their refractory byproducts, would be preserved and detectable on a remote planetary surface by exposing it to simulated conditions for Mars. Sample Acquisition. Pigments betacarotene, lutein, zeaxanthin, astaxanthin, and lycopene were purchased from Sigma Aldrich. Halobacterium salinarum NRC-1 was acquired from Carlina Biological and grown in Halobacterium media. Mineral salts including sodium sulfate, sodium carbonate, and halite were used to form matrices in which the beta-carotene was embedded before exposure. Pigment-mineral mixes were at a 1:10 ratio in water. Analytical Techniques. Deep UV Raman data were collected on a custom laboratory mapping spectrometer called MOBIUS (Mineral and Organic Based Investigations using Ultraviolet Spectroscopy), which is an analog to the SHERLOC instrument on the Mars 2020 Perseverance rover (Bhartia et al. 2021). It features a 248.56 nm NeCu pulsed laser, liquid nitrogen-cooled detector, and tunable optical setup. Visible Raman data were collected using a Horiba Jobin Yvon LabRam HR spectrometer with a frequencydoubled Nd:YAG laser (532 nm) and a HeNe laser (633 nm). A VWR 6300 PC UV/Visible Spectrophotometer was used to collect absorption data for carotenoid solutions, model compounds, and solvents in UVpermissible capped cuvettes. Data were collected from 190-1100 nm at 1 nm increments. All spectral data were analyzed using Igor Pro 9 (Wavemetrics). Irradiation. We used a vacuum chamber equipped with a cryostat and a flood electron gun to simulate Martian surface temperatures, low pressures, and ionizing radiation (10keV, 10μA for 6h at 200K for our initial tests). The samples were prepared by drying the pigment-mineral mix onto polished metal tabs, then mounted on the cryostat for processing. Samples were then analyzed directly on the tabs after exposure. Results: In comparing the visible and deep UV Raman spectra of unaltered pigments, we found that they differed drastically. Carotenoids are often studied with visible Raman and typically have peaks at 1525 cm-1 and 1157 cm-1, due to the stretching of the C=C and C-C bonds in the polyene structure. However, in deep UV, the strongest feature is at ~1630 cm-1 and is broad, possibly indicating that multiple peaks are forming this feature. This stark difference is likely due to different preresonant enhancement effects. The UV-Vis results show that there is an absorption band in the deep UV <300 nm, which supports the hypothesis that the 248.6 nm excitation is interrogating another aspect of carotenoids than visible Raman. Our preliminary exposure tests indicated that pigments – even without minerals present - were largely unaltered in the applied conditions, with only a slight broadening in the primary polyene peaks apparent in the visible Raman data. Figure 1. A) Visible vs. deep UV Raman spectra of unaltered beta carotene. B) Schematic of exposure. Conclusions: Our results to date indicate that deep UV and visible Raman spectroscopy, both techniques with planetary mission heritage from Mars 2020 (Wiens et al. 2021, Bhartia et al. 2021), may be used in a complementary manner to observe carotenoids. In addition, we find that beta-carotene is largely resistant to our current exposure conditions, though there may be some amount of amorphization of the material which could cause the broadening of the peaks at 1525 and 1157 cm-1. As a next step, we aim to increase the dosage and duration of exposure to observe degradation of the parent pigment, possibly add UV as a factor via an Ar mini-arc UV lamp and use GC-MS to characterize possible degradation products.

pigments↗
NASA NTRS2015

Forward Osmosis Brine Drying

The Forward Osmosis Brine Drying (FOBD) system is based on a technique called forward osmosis (FO). FO is a membrane-based process where the osmotic potential between brine and a salt solution is equalized by the movement of water from the brine to the salt solution. The FOBD system is composed of two main elements, the FO bag and the salt regeneration system. This paper discusses the results of testing of the FO bag to determine the maximum water recovery ratio that can be attained using this technology. Testing demonstrated that the FO bag is capable of achieving a maximum brine water recovery ratio of the brine of 95%. The equivalent system mass was calculated to be 95 kg for a feed similar to the concentrated brine generated on the International Space Station and 86 kg for an Exploration brine. The results have indicated that the FOBD can process all the brine for a one year mission for between 11% to 10% mass required to bring the water needed to make up for water lost in the brine if not recycled. The FOBD saves 685 kg and when treating the International Space Station brine and it saves 829 kg when treating the Exploration brine. It was also demonstrated that saturated salt solutions achieve a higher water recovery ratios than solids salts do and that lithium chloride achieved a higher water recovery ratio than sodium chloride.

Brine↗
NASA NTRS1984

Monitoring Lignin Content in Paper Processing

Feedstock and finished pulp analyzed and controlled automatically. System acquires samples from feed hopper, digestor, and blow tank. Sample homogenized, washed, and dried while conveyed to flash pyrolyzer. In pyrolyzer material converted into basic constituent, mostly compounds of molecular weight less than 200.

Boettger, H. G.↗
NASA NTRS2012

Diagnosing the Nature of Land-Atmosphere Coupling: A Case Study of Dry/Wet Extremes

Land-atmosphere (L-A) interactions play a critical role in determining the diurnal evolution of land surface and planetary boundary layer (PBL) temperature and moisture states and fluxes. In turn, these interactions regulate the strength of the connection between surface moisture and precipitation in a coupled system. To address deficiencies in numerical weather prediction and climate models due to improper treatment of L-A interactions, recent studies have focused on development of diagnostics to quantify the strength and accuracy of the land-PBL coupling at the process-level. In this study, a diagnosis of the nature and impacts oflocalland-atmosphere coupling (LoCo) during dry and wet extreme conditions is presented using a combination of models and observations during the summers of2006-7 in the U.S. Southern Great Plains. Specifically, the Weather Research and Forecasting (WRF) model has been coupled to NASA's Land Information System (LIS), which provides a flexible and high-resolution representation and initialization of land surface physics and states. A range of diagnostics exploring the links and feedbacks between soil moisture and precipitation are examined for the dry/wet regimes of this region, along with the behavior and accuracy of different land-PBL scheme couplings under these conditions. In addition, we examine the impact of improved specification ofland surface states, anomalies, and fluxes that are obtained through the use of a hew optimization and uncertainty module in LIS, on the L-A coupling in WRF forecasts. Results demonstrate how LoCo diagnostics can be applied to coupled model components in the context of their integrated impacts on the process-chain connecting the land surface to the PBL and support of hydrological anomalies.

Santanello, Joseph A., Jr.↗
NASA NTRS2005

Reactive Additives for Phenylethynyl-Containing Resins

Phenylethynyl-containing reactive additive (PERA) compounds and mixtures have been found to be useful for improving the processability of oligomers, polymers, co-oligomers, and copolymers that contain phenylethynyl groups. The additives can be incorporated in different forms: A solution of an amide acid or an imide of a PERA can be added to a solution of phenylethynyl-containing oligomer, polymer, co-oligomer, or copolymer; or An imide powder of a PERA can be mixed with a dry powder of a phenylethynyl-containing oligomer, polymer, co-oligomer, or copolymer. The effect of a given PERA on the processability and other properties of the resin system depends on whether the PERA is used in the amide acid or an imide form. With proper formulation, the PERA reduces the melt viscosity of the resin and thereby reduces the processing pressures needed to form the adhesive bonds, consolidate filled or unfilled moldings, or fabricate fiber-reinforced composite laminates. During thermal cure, a PERA reacts with itself as well as with the phenylethynyl-containing host resin and thereby becomes chemically incorporated into the resin system. The effects of the PERA on mechanical properties, relative to those of the host resin, depend on the amount of PERA used. Typically, the incorporation of the PERA results in (1) increases in the glass-transition temperature (Tg), modulus of elasticity, and parameters that characterize behavior under compression, and (2) greater retention of the aforementioned mechanical properties at elevated temperatures without (3) significant reduction of toughness or damage tolerance. Of the formulations tested thus far, the ones found to yield the best overall results were those for which the host resin was the amide acid form of a phenylethynyl-terminated imide (PETI) co-oligomer having a molecular weight of 5,000 g/mole [hence, designated PETI-5] and a PERA denoted as PERA-1. PETI-5 was made from 3,3',4'4'-biphenyltetracarboxylic dianhydride, 3,4'-oxydianiline (3,4'-ODA), 1,3-bis(3-aminophenoxy) benzene (1,3-APB), and 4-phenylethynylphthalic anhydride (PEPA). PERA-1 was made from 3,5-diamino- 4.-phenylethynylbenzophenon and equimolar amounts of phthalic anhydride and PEPA. To make PERA-1 in the imide form, the aforementioned ingredients were processed by refluxing in glacial acetic acid. To make the amide form of PERA-1, the ingredients were reacted in N-methyl-2-pyrrolidinone (NMP) under nitrogen at a temperature of 23 C (see figure). On the basis of the processability and other properties, a blend comprising 20 weight percent of PERA-1 and 80 weight percent PETI-5 was selected for further evaluation. Relative to neat PETI-5, the blend exhibited an increase in Tg; improved processability; and comparable values of shear strength in adhesion to titanium panels, open-hole compressive properties, compression properties after impact, and resistance to microcracking.

Connell, John W.↗
NASA NTRS2024

Critical Load Exceedances for North America and Europe using an Ensemble of Models and an Investigation of Causes for Environmental Impact Estimate Variability: An AQMEII4 Study

Exceedances of critical loads for deposition of sulphur (S) and nitrogen (N) to different ecosystems were estimated using European and North American ensembles of air quality models, under Phase 4 of the Air Quality Model Evaluation International Initiative (AQMEII4), to identify where risk of ecosystem harm is expected to occur based on model deposition estimates. The ensembles were driven by common emissions and lateral boundary condition inputs. Model output was regridded to common North American and Europe 0.125° resolution domains, which were then used to calculate critical load exceedances. New, targeted deposition diagnostics implemented in AQMEII4 allowed an unprecedented level of post-simulation analysis to be carried out and facilitated the identification of specific causes of model-to-model variability in critical load exceedance estimates. New datasets for North American critical loads for acidity for forest soil water and aquatic ecosystems were combined with the ensemble deposition predictions to show a substantial decrease in the area and number of locations in exceedance between 2010 and 2016 (forest soils: 13.2 % to 6.1 %; aquatic ecosystems: 21.2 % to 11.4 %). All models agreed in the direction of the ensemble exceedance change between 2010 and 2016. The North American ensemble also predicted a decrease in both severity and total area in exceedance between the years 2010 and 2016 for eutrophication-impacted ecosystems in the USA (sensitive epiphytic lichen: 81.5 % to 75.8 %). The exceedances for herbaceous community richness also decreased between 2010 and 2016, from 13.9 % to 3.9 %. The uncertainty associated with the North American eutrophication results is high; there were sharp differences between the models in both predictions of total N deposition and the change in N deposition, and hence in the predicted eutrophication exceedances between the two years. The European ensemble was used to predict relatively static exceedances of critical loads with respect to acidification (4.48 % to 4.32 % from 2009 to 2010) while eutrophication exceedance increased slightly (60.2 % to 62.2 %). While most models showed the same changes in critical load exceedances as the ensemble between the two years, the spatial extent and magnitude of exceedances varied significantly between the models. The reasons for this variation were examined in detail by first ranking the relative contribution of different sources of sulphur and nitrogen deposition in terms of deposited mass and model-to-model variability in that deposited mass, followed by their analysis using AQMEII4 diagnostics, along with evaluation of the most recent literature. All models in both the North American and European ensembles had net annual negative biases with respect to observed wet deposition of sulphate, nitrate and ammonium. Diagnostics and recent literature suggest that this bias may stem from insufficient cloud scavenging of aerosols and gases, and may be improved through the incorporation of multiphase hydrometeor scavenging within the modelling frameworks. The inability of North American models to predict the timing of the seasonal peak in wet ammonium ion deposition (observed maximum was in April, while all models predicted a June maximum) may also relate to the need for multiphase hydrometeor scavenging (absence of snow scavenging in all models employed here). High variability in the relative importance of particulate sulphate, nitrate and ammonium deposition fluxes between models was linked to the use of updated particle dry deposition parameterizations in some models. However, recent literature and further development of some of the models within the ensemble suggests these particulate biases may also be ameliorated via the incorporation of multiphase hydrometeor scavenging. Annual sulphur and nitrogen deposition prediction variability was linked to SO 2 and HNO 3 dry deposition parameterizations, and diagnostic analysis showed that the cuticle and soil deposition pathways dominate the deposition mass flux of these species. Further work improving parameterizations for these deposition pathways should reduce variability in model acidifying gas deposition estimates. The absence of base cation chemistry in some models was shown to be a major factor in positive biases in fine mode particulate ammonium and particle nitrate concentrations. Models employing ammonia bidirectional fluxes had both the largest and the smallest magnitude biases, depending on the model and bidirectional flux algorithm employed. A careful analysis of bidirectional flux models suggests that those with poor NH 3 performance may underestimate the extent of NH 3 emissions fluxes from forested areas. Based on these results, an increased process-research focus is therefore recommended for the following model processes and on observations which may assist in model evaluation and improvement: multiphase hydrometeor scavenging combined with updated particle dry deposition, cuticle and soil deposition pathway algorithms for acidifying gases, base cation chemistry and emissions, and NH 3 bidirectional fluxes. Comparisons with satellite observations suggest that oceanic NH 3 emissions sources should be included in regional chemical transport models. The choice of land use database employed within any given model was shown to significantly influence deposition totals in several instances, and employing a common land use database across chemical transport models and critical load calculations is recommended for future work.

critical loads↗
NASA NTRS2003

Lyophilization for Water Recovery From Solid Waste

This abstract describes the development of a solid waste treatment system designed for a near term human exploration mission. The technology being developed is an energy- efficient lyophilization technique that recovers water from spacecraft solid waste. In the lyophilization process water in an aqueous waste is frozen and then sublimed, resulting in the separation of the waste into a dried solid material and liquid water. This technology is ideally suited to applications where water recovery rates approaching 100% are desirable but production of CO, is not. Water contained within solid wastes accounts for approximately 3% of the total water balance. If 100% closure of the water loop is desired the water contained within this waste would need to be recovered. To facilitate operation in microgravity thermoelectric heat pumps have be used in place of traditional fluid cycle heat pumps. A mathematical model of a thermoelectric lyophilizer has been developed and used to generate energy use and processing rate parameters. The results of laboratory investigations and discussions with ALS program management have been used to iteratively arrive at a prototype design. This design address operational limitations which were identified in the laboratory studies and handling and health concerns raised by ALS program management. The current prototype design is capable of integration into the ISS Waste Collection System.

Flynn, Michael↗
NASA NTRS1993

Evaluation of Enzymatic Hydrolysis of CELSS Wheat Residue Cellulose at a Scale Environment to NASA's KSC Breadboard Project

Biomass processing at the Kennedy Space Center CELSS breadboard project has focused on the evaluation of breadboard-scale enzymatic hydrolysis of wheat residue cellulose (25%, w/w). Five replicate runs of cellulase production by Trichoderma reesei (QM9414) and enzymatic hydrolysis of residue cellulose were completed. Enzymes were produced in 1 0 days (5 L, 25 g (dry weight) residue). Cellulose hydrolysis (12 L, 50 g (dry weight) residue) using these enzymes produced 5.5 to 6.0 g glucose liter(exp -1) in 7 days. Cellulose conversion efficiency was 29%. These processes are feasible technically on a breadboard scale, but would only increase the edible wheat yield 10%.

Strayer, Richard F.↗
NASA NTRS1981

Combustion of solid carbon rods in zero and normal gravity

In order to investigate the mechanism of carbon combustion and to assess the importance of gravitational induced convection on the process, zero and normal gravity experiments were conducted in which spectroscopic carbon rods were resistance ignitied and burned in dry oxygen environments. In the zero-gravity drop tower tests, a blue flame surrounded the rod, showing that a gas phase reaction in which carbon monoxide was oxidized to carbon dioxide was taking place. The ratio of flame diameter to rod diameter was obtained as a function of time. It was found that this ratio was inversely proportional to both the oxygen pressure and the rod diameter. In the normal gravity tests, direct mass spectrometric sampling was used to measure gas phase concentrations. The gas sampling probe was positioned near the circumference of a horizontally mounted 0.615 cm diameter carbon rod, either at the top or at angles of 45 deg to 90 deg from the top, and yielded concentration profiles of CO2, CO, and O2 as a function of distance from the surface. The mechanism controlling the combustion process was found to change from chemical process control at the 90 deg and 45 deg probe positions to mass transfer control at the 0 deg probe position at the top of the rod. Under the experimental conditions used, carbon combustion was characterized by two surface reactions, 2C + O2 yields 2CO and CO2 + C yields 2CO, and a gas phase reaction, 2CO + O2 yields 2CO2.

Spuckler, C. M.↗
NASA NTRS2006

Application of Aerosol Hygroscopicity Measured at the Atmospheric Radiation Measurement Program's Southern Great Plains Site to Examine Composition and Evolution

A Differential Mobility Analyzer/Tandem Differential Mobility Analyzer (DMA/TDMA) was used to measure submicron aerosol size distributions, hygroscopicity, and occasionally volatility during the May 2003 Aerosol Intensive Operational Period (IOP) at the Central Facility of the Atmospheric Radiation Measurement Program's Southern Great Plains (ARM SGP) site. Hygroscopic growth factor distributions for particles at eight dry diameters ranging from 0.012 micrometers to 0.600 micrometers were measured throughout the study. For a subset of particle sizes, more detailed measurements were occasionally made in which the relative humidity or temperature to which the aerosol was exposed was varied over a wide range. These measurements, in conjunction with backtrajectory clustering, were used to infer aerosol composition and to gain insight into the processes responsible for evolution. The hygroscopic growth of both the smallest and largest particles analyzed was typically less than that of particles with dry diameters of about 0.100 micrometers. It is speculated that condensation of secondary organic aerosol on nucleation mode particles is largely responsible for the minimal hygroscopic growth observed at the smallest sizes considered. Growth factor distributions of the largest particles characterized typically contained a nonhygroscopic mode believed to be composed primarily of dust. A model was developed to characterize the hygroscopic properties of particles within a size distribution mode through analysis of the fixed size hygroscopic growth measurements. The performance of this model was quantified through comparison of the measured fixed size hygroscopic growth factor distributions with those simulated through convolution of the size-resolved concentration contributed by each of the size modes and the mode-resolved hygroscopicity. This transformation from sizeresolved hygroscopicity to mode-resolved hygroscopicity facilitated examination of changes in the hygroscopic properties of particles within a size distribution mode that accompanied changes in the sizes of those particles. This model was used to examine three specific cases in which the sampled aerosol evolved slowly over a period of hours or days.

Gasparini, Roberto↗
NASA NTRS2020

Modeling the smoky troposphere of the southeast Atlantic: a comparison to ORACLES airborne observations from September of 2016

In the southeast Atlantic, well-defined smoke plumes from Africa advect over marine boundary layer cloud decks; both are most extensive around September, when most of the smoke resides in the free troposphere. A framework is put forth for evaluating the performance of a range of global and regional atmospheric composition models against observations made during the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) airborne mission in September 2016. A strength of the comparison is a focus on the spatial distribution of a wider range of aerosol composition and optical properties than has been done previously. The sparse airborne observations are aggregated into approximately 2° grid boxes and into three vertical layers: 3–6 km, the layer from cloud top to 3 km, and the cloud-topped marine boundary layer. Simulated aerosol extensive properties suggest that the flight-day observations are reasonably representative of the regional monthly average, with systematic deviations of 30 % or less. Evaluation against observations indicates that all models have strengths and weaknesses, and there is no single model that is superior to all the others in all metrics evaluated. Whereas all six models typically place the top of the smoke layer within 0–500 m of the airborne lidar observations, the models tend to place the smoke layer bottom 300–1400 m lower than the observations. A spatial pattern emerges, in which most models underestimate the mean of most smoke quantities (black carbon, extinction, carbon monoxide) on the diagonal corridor between 16° S, 6° E, and 10° S, 0° E, in the 3–6 km layer, and overestimate them further south, closer to the coast, where less aerosol is present. Model representations of the above-cloud aerosol optical depth differ more widely. Most models overestimate the organic aerosol mass concentrations relative to those of black carbon, and with less skill, indicating model uncertainties in secondary organic aerosol processes. Regional-mean free-tropospheric model ambient single scattering albedos vary widely, between 0.83 and 0.93 compared with in situ dry measurements centered at 0.86, despite minimal impact of humidification on particulate scattering. The modeled ratios of the particulate extinction to the sum of the black carbon and organic aerosol mass concentrations (a mass extinction efficiency proxy) are typically too low and vary too little spatially, with significant inter-model differences. Most models overestimate the carbonaceous mass within the offshore boundary layer. Overall, the diversity in the model biases suggests that different model processes are responsible. The wide range of model optical properties requires further scrutiny because of their importance for radiative effect estimates.

Yohei Shinozuka↗
NASA NTRS2013

Subsurface Salts in Antarctic Dry Valley Soils

The distribution of water-soluble ions, major and minor elements, and other parameters were examined to determine the extent and effects of chemical weathering on cold desert soils. Patterns at the study sites support theories of multiple salt forming processes, including marine aerosols and chemical weathering of mafic minerals. Periodic solar-mediated ionization of atmospheric nitrogen might also produce high nitrate concentrations found in older sediments. Chemical weathering, however, was the major contributor of salts in Antarctic Dry Valleys. The Antarctic Dry Valleys represent a unique analog for Mars, as they are extremely cold and dry desert environments. Similarities in the climate, surface geology, and chemical properties of the Dry Valleys to that of Mars imply the possible presence of these soil formation mechanisms on Mars, other planets and icy satellites.

Englert, P.↗
NASA NTRS1975

Mechanisms of deterioration of nutrients

The retention of flavor during freeze drying was studied with model systems. Mechanisms by which flavor retention phenomena is explained were developed and process conditions specified so that flavor retention is optimized. The literature is reviewed and results of studies of the flavor retention behavior of a number of real food products, including both liquid and solid foods are evaluated. Process parameters predicted by the mechanisms to be of greatest significance are freezing rate, initial solids content, and conditions which result in maintenance of sample structure. Flavor quality for the real food showed the same behavior relative to process conditions as predicted by the mechanisms based on model system studies.

Karel, M.↗
NASA NTRS1980

Preliminary analysis of the potential of LANDSAT imagery to study desertification

The use of LANDSAT imagery to define and delimit areas under process of desertification was investigated. Imagery for two different years (1973 and 1978) and two different seasons (dry and rainy seasons in 1976), were used to identify terrain morphology and vegetation cover. The analysis of LANDSAT interpretation, combined with geological and soil information obtained from published literature, allowed the identification of eleven ecological units which were classified corresponding to the degree of the Xique Xique region of Rio Sao Francisco.

Dejesusparada, N.↗
NASA NTRS1983

Description of the containerless melting of glass in low gravity

A brief description is given of a single-axis, acoustic levitator/furnace apparatus used to position, heat, melt, and quench multicomponent oxide, glass-forming compositions in low gravity. This apparatus is capable of processing eight approximately spherical samples (about 6 mm diameter) at temperatures up to 1550 C in a dry air atmosphere. Results are also presented for a containerless melting experiment conducted on SPAR VI where a ternary CaO-Ga2O3-SiO2 composition was levitated and quenched to a glass. Selected properties of the glass prepared on SPAR VI are compared with the properties of glass samples of identical composition prepared on earth.

Ray, C. S.↗
NASA NTRS1984

New innovations in composites

Procedures for manufacturing metal clad graphite resin structural elements applicable to optical systems requiring precisely controlled thermal and mechanical properties are described. Analytical estimates were made of the material properties that can be obtained for various ratios of graphite epoxy and aluminum cladding. Three graphite fiber systems were evaluated. Two manufacturing processes are described. One method is a procedure for manufacturing long tubes by wrapping aluminum foil over dry graphite fiber. Resin was applied by spreading before applying the aluminum wrap. A second approach, offering the opportunity for precise tuning of the coefficient of expansion, is by die flattening metal tubing through which a measured amount of fiber has been drawn. Prior to flattening, resin is injected, and after flattening or shaping the part is cured. This latter procedure offers the opportunity to fine tune the structure to achieve a CTE with a precision equal to that of the measuring systems-by modifying the number of fiber tows prior to manufacturing or by etching the metal after manufacturing. Experimental verification and demonstration data are presented for Gr/E bars with aluminum and steel skins.

Bluck, R. M.↗
NASA NTRS1991

Fabrication Of Ceramic Mats

Process to make mats of fine zirconia filaments proposed. Ceramic mats formed by sintering mats of partially dried filaments extruded from slurry of ceramic powder, binder, and solvent. Mats of fine zirconia fibers easier to ball-mill than commercially available zirconia powder.

Collins, Earl R., Jr.↗