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NASA NTRS1996

Cost Models for MMC Manufacturing Processes

The quality cost modeling (QCM) tool is intended to be a relatively simple-to-use device for obtaining a first-order assessment of the quality-cost relationship for a given process-material combination. The QCM curve is a plot of cost versus quality (an index indicating microstructural quality), which is unique for a given process-material combination. The QCM curve indicates the tradeoff between cost and performance, thus enabling one to evaluate affordability. Additionally, the effect of changes in process design, raw materials, and process conditions on the cost-quality relationship can be evaluated. Such results might indicate the most efficient means to obtain improved quality at reduced cost by process design refinements, the implementation of sensors and models for closed loop process control, or improvement in the properties of raw materials being fed into the process. QCM also allows alternative processes for producing the same or similar material to be compared in terms of their potential for producing competitively priced, high quality material. Aside from demonstrating the usefulness of the QCM concept, this is one of the main foci of the present research program, namely to compare processes for making continuous fiber reinforced, metal matrix composites (MMC's). Two processes, low pressure plasma spray deposition and tape casting are considered for QCM development. This document consists of a detailed look at the design of the QCM approach, followed by discussion of the application of QCM to each of the selected MMC manufacturing processes along with results, comparison of processes, and finally, a summary of findings and recommendations.

Elzey, Dana M.↗

NASA NTRS1978

High-purity silicon for solar cell applications

The article discusses the production of solar cells from high-purity silicon. The process consists of reducing the level of impurities in the raw materials, preventing material contamination before and after entering the furnace, and performing orders-of-magnitude reduction of metal impurity concentrations. The high-purity raw materials are considered with reference to carbon reductants, silica, and graphite electrodes. Attention is also given to smelting experiments used to demonstrate, in an experimental-scale furnace, the production of high-purity SoG-Si. It is found that high-purity silicon may be produced from high-purity quartz and chemically purified charcoal in a 50-kVA arc furnace. The major contamination source is shown to be impurities from the carbon reducing materials.

Dosaj, V. D.↗

NASA NTRS1979

Solar silicon via the Dow Corning process

Technical feasibility for high volume production of solar cell-grade silicon is investigated. The process consists of producing silicon from pure raw materials via the carbothermic reduction of quartz. This silicon was then purified to solar grade by impurity segregation during Czochralski crystal growth. Commercially available raw materials were used to produce 100 kg quantities of silicon during 60 hour periods in a direct arc reactor. This silicon produced single crystalline ingot, during a second Czochralski pull, that was fabricated into solar cells having efficiencies ranging from 8.2 percent to greater than 14 percent. An energy analysis of the entire process indicated a 5 month payback time.

Hunt, L. P.↗

NASA NTRSDate not supplied

Reusable TPS Materials Development Activities at NASA Ames

Recent developments in low-cost access to low-earth orbit (LEO) and hypersonic flight are driving renewed demand in reusable thermal protection systems (RTPS) that have not had broad application since the Space Shuttle era. Modern systems will need to consider full cycle cost (lower cost raw materials, manufacturing, integration, and refurbishment) in addition to improved performance to enable this new generation of space flight. NASA Ames Research Center (ARC) has a long history of RTPS development including modern state-of-the-art materials like Alumina Enhanced Thermal Barrier (AETB), and multi-component systems like Toughened Uni-piece Fibrous Reinforced Oxidation-resistant Composite (TUFROC). Now, ARC is supporting the growing commercial space field through internal research and development efforts for high-risk low TRL materials and collaboration with commercial partners including technology transfer. This talk will discuss the current development efforts at ARC that span updating legacy insulating systems with modern raw materials and processes to totally novel designs for heat pipes with various low-TRL activities in between. It will also discuss Ames’ recent re-investment in experimental capabilities to enable characterization and material testing.

Adam Caldwell↗

NASA NTRS1985

Characterization of ZrO2-Y2O3 thermal spray powder systems

The overall objective is to establish the interrelation between the raw material in the coating process and the performance of the coating deposit. It is anticipated that these interrelations will help establish more precise specifications for the procurement of the raw materials. Some of the preliminary results of the program are presented.

Mantkowski, Thomas E.↗

NASA NTRSDate not supplied

New Development Activities at NASA Ames in Reusable TPS Materials

Over the last few years, new activities in rapid, low-cost access to low-earth orbit (LEO) and hypersonic flight have refreshed interest in reusable thermal protection systems (RTPS) that have not had broad application since the Space Shuttle era. Development of novel systems having a greater consideration of full cycle cost (lower cost raw materials, manufacturing, integration, and refurbishment) in addition to improved performance are needed to enable this new generation of space flight. NASA Ames has a long history of RTPS development including invention of flexible blankets such as Advanced Flexible Reusable Surface Insulation (AFRSI), rigid ceramic tiles like Fibrous Refractory Composite Insulation (FRCI) and Alumina Enhanced Thermal Barrier (AETB), and multi-component systems like Toughened Uni-piece Fibrous Reinforced Oxidation-resistant Composite (TUFROC). In much more recent times, NASA Ames is supporting the growing commercial space field through internal research and development efforts for high-risk low TRL materials and collaboration with commercial partners including technology transfer. This talk will discuss the current development efforts that span broadly from updating legacy insulating systems with modern raw materials and processes to totally novel designs for heat pipes with various low-TRL activities in between. It will also discuss Ames’ recent re-investment in experimental capabilities to enable characterization and material testing.

Reusable thermal protection materials↗

NASA NTRSDate not supplied

New Development Activities at NASA Ames in Reusable TPS Materials

Reusable thermal protection materials↗

NASA NTRS1980

Coal gasification systems engineering and analysis. Appendix A: Coal gasification catalog

The scope of work in preparing the Coal Gasification Data Catalog included the following subtasks: (1) candidate system subsystem definition, (2) raw materials analysis, (3) market analysis for by-products, (4) alternate products analysis, (5) preliminary integrated facility requirements. Definition of candidate systems/subsystems includes the identity of and alternates for each process unit, raw material requirements, and the cost and design drivers for each process design.

Source record↗

NASA NTRS1994

Preparation and Dielectric Measurements of the Rare Earth Green Phases R2BaCuO(5-x) (R = Y, Sm, Gd, Dy, Ho, Er, Yb)

It has been demonstrated that R2BaCuO(5-x) (R = Y, Sm, Gd, Dy, Ho, Er, Yb) does not undergo significant densification unless the sintering temperatures are near the incongruent melting point or the sintering times are long. Good quality powders of Y2BaCuO(5-x) have been synthesized by using oxide raw materials or precursors such as acetates and nitrates. The acetates- and the nitrates-derived yttrium green phase resulted in finer particle sizes, acceptable dielectric properties and lower melting temperatures than those processed via oxide raw materials. The hot pressing technique has been employed to produce a dense R2BaCuO(5-x) (R=Y,Gd) substrate with satisfactory dielectric properties. Reactivity to reducing conditions, i.e. graphite die, limited the optimization of the properties. A high sensitivity to the annealing atmosphere has been demonstrated in Y2BaCuO,.,,. Oxygen treatment at 950 OC has been shown to improve the dielectric properties while treatment in nitrogen, at the same temperature, degraded desirable properties. A high sensitivity to the annealing atmosphere has been demonstrated in Y2BaCuO(5-x). Oxygen treatment at 950 C has been shown to improve the dielectric properties while treatment in nitrogen, at the same temperature, degraded desirable properties. The dielectric constants of the rare earth green phases R2BaCuO(5-x) were found to be low. Relaxation peaks were detected at low temperatures (T less than 150 K) and at high temperatures (150 less than T greater than 420 K). The dielectric losses and conductivities at 77 K were measured to be in the range of 10(exp -4) and 10(exp -12) (Omega-cm)(exp -1), respectively. Many parameters were found to exhibit dependencies on the rare earth cation sizes.

Gonzalez-Titman, Carlos↗

NASA NTRS1978

Process feasibility study in support of silicon material task 1

Initial results for gas thermal conductivity of silicon tetrafluoride and trichlorosilane are reported in respective temperature ranges of 25 to 400 C and 50 to 400 C. For chemical engineering analyses, the preliminary process design for the original silane process of Union Carbide was completed for Cases A and B, Regular and Minimum Process Storage. Included are raw material usage, utility requirements, major process equipment lists, and production labor requirements. Because of the large differences in surge tankage between major unit operations the fixed capital investment varied from $19,094,000 to $11,138,000 for Cases A and B, respectively. For the silane process the original flowsheet was revised for a more optimum arrangement of major equipment, raw materials and operating conditions. The initial issue of the revised flowsheet (Case C) for the silane process indicated favorable cost benefits over the original scheme.

Fang, C. S.↗

NASA NTRS1982

Ultrapure glass optical waveguide development in microgravity by the sol-gel process

Containerless melting of glasses in space for the preparation of ultrapure homogeneous glass for optical waveguides is discussed. The homogenization of the glass using conventional raw materials is normally achieved on Earth either by the gravity induced convection currents or by the mechanical stirring of the melt. Because of the absence of gravity induced convection currents, the homogenization of glass using convectional raw materials is difficult in the space environment. Multicomponent, homogeneous, noncrystalline oxide gels can be prepared by the sol-gel process and these gels are promising starting materials for melting glasses in the space environment. The sol-gel process is based on the polymerization reaction of alkoxysilane with other metal alkoxy compounds or suitable metal salts. Many of the alkoxysilanes or other metal alkoxides are liquids and thus can be purified by distillation.

Source record↗

NASA NTRS1986

A metallurgical route to solar-grade silicon

The aim of the process is to produce silicon for crystallization into ingots that can be sliced to wafers for processing into photovoltaic cells. If the potential purity can be realized, the silicon will also be applicable for ribbon pulling techniques where the purification during crystallization is negligible. The process consists of several steps: selection and purification of raw materials, carbothermic reduction of silica, ladle treatment, casting, crushing, leaching, and melting. The leaching step is crucial for high purity, and the obtainable purity is determined by the solidification before leaching. The most difficult specifications to fulfill are the low contents of boron, phosphorus, and carbon. Boron and phosphorus can be excluded from the raw materials, but the carbothermic reduction will unavoidably saturate the silicon with carbon at high temperature. During cooling carbon will precipitate as silicon carbide crystals, which will be harmful in solar cells. The cost of this solar silicon will depend strongly on the scale of production. It is as yet premature to give exact figures, but with a scale of some thousand tons per year, the cost will only be a few times the cost of ordinary metallurgical silicon.

Schei, A.↗

NASA NTRS1998

An Experimental Investigation of Transverse Tension Fatigue Characterization of IM6/3501-6 Composite Materials Using a Three-Point Bend Test

As composites are introduced into more complex structures with out-of-plane loadings, a better understanding is needed of the out-of-plane, matrix-dominated failure mechanisms. This work investigates the transverse tension fatigue characteristics of IM6/3501 composite materials. To test the 90 degree laminae, a three-point bend test was chosen, potentially minimizing handling and gripping issues associated with tension tests. A finite element analysis was performed of a particular specimen configuration to investigate the influence of specimen size on the stress distribution for a three-point bend test. Static testing of 50 specimens of 9 different sized configurations produced a mean transverse tensile strength of 61.3 Mpa (8.0 ksi). The smallest configuration (10.2 mm wide, Span-to-thickness ratio of 3) consistently exhibited transverse tensile failures. A volume scale effect was difficult to discern due to the large scatter of the data. Static testing of 10 different specimens taken from a second panel produced a mean transverse tensile strength of 82.7 Mpa (12.0 ksi). Weibull parameterization of the data was possible, but due to variability in raw material and/or manufacturing, more replicates are needed for greater confidence. Three-point flex fatigue testing of the smallest configuration was performed on 59 specimens at various levels of the mean static transverse tensile strength using an R ratio of 0.1 and a frequency of 20 Hz. A great deal of scatter was seen in the data. The majority of specimens failed near the center loading roller. To determine whether the scatter in the fatigue data is due to variability in raw material and/or the manufacturing process, additional testing should be performed on panels manufactured from different sources.

Peck, Ann W.↗

NASA NTRS2005

Reuse International Space Station (ISS) Modules as Lunar Habitat

NASA currently projects ending the ISS mission in approximately 2016, due primarily to the expense of re-boost and re-supply. Lunar outposts are expected to be in place in the same timeframe. In support of these mission goals, a scheme to reuse ISS modules on the moon has been identified. These modules could function as pressurized volumes for human habitation in a lunar vacuum as they have done in low-earth orbit. The ISS hull is structurally capable of withstanding a lunar landing because there is no atmospheric turbulence or friction. A compelling reason to send ISS modules to the moon is their large mass; a large portion of the ISS would survive re-entry if allowed to de-orbit to Earth. ISS debris could pose a serious risk to people or structures on Earth unless a controlled re-entry is performed. If a propulsive unit is devised to be attached to the ISS and control re-entry, a propulsion system could be used to propel the modules to the moon and land them there. ISS modules on the lunar surface would not require re-boost. Radiation protection can be attained by burying the module in lunar regolith. Power and a heat removal system would be required for the lunar modules which would need little support structure other than the lunar surface. With planetary mass surrounding the module, heat flux may be controlled by conductance. The remaining requirement is the re-supply of life-support expendables. There are raw materials on the moon to supplement these vital resources. The lunar maria is known to contain approximately 40% oxygen by mass in inorganic mineral compounds. Chemical conversion of moon rocks to release gaseous oxygen is known science. Recycling and cleaning of air and water are currently planned to be accomplished with ISS Environmental Control & Life Support Systems (ECLSS). By developing a Propulsion and Landing Module (PLM) to dock to the Common Berthing Mechanism (CBM), several identical PLMs could be produced to rescue and transfer the ISS modules to the lunar surface, one by one. The propulsion does not need to be as swift as Apollo, nor would the modules need to be manned during transportation to the moon. The trajectory from low-Earth to lunar orbit would avoid or quickly pass through the Van Allen belts to minimize radiation exposure to electronics onboard. A landing technology similar to Apollo's could be utilized to land an ISS module on the moon. Since the mission will be unmanned, system redundancy could be minimized to keep the cost down. If the mission failed and a module crashed landed on the moon, the risk of debris landing on Earth would be avoided and the raw materials could be used in future lunar missions.

Miernik, Janie↗

NASA NTRS1982

Materials processing in space

Processing-refining of raw materials from extraterrestrial sources is detailed for a space materials handling facility. The discussion is constrained to those steps necessary to separate desired components from raw or altered input ores, semi-purified feedstocks, or process scrap and convert the material into elements, alloys, and consumables. The materials are regarded as originating from dead satellites and boosters, lunar materials, and asteroids. Strong attention will be given to recycling reagent substances to avoid the necessity of transporting replacements. It is assumed that since no aqueous processes exist on the moon, the distribution of minerals will be homogeneous. The processing-refining scenario will include hydrochemical, pyrochemical, electrochemical, and physical techniques selected for the output mass rate/unit plant mass ratio. Flow charts of the various materials processing operations which could be performed with lunar materials are provided, noting the necessity of delivering several alloying elements from the earth due to scarcities on the moon.

Waldron, R. D.↗

NASA NTRS1977

Lunar resources and their utilization

Lunar surface materials offer a source of raw materials for space processing to produce structural metals, oxygen, silicon, glass, and ceramic products. Significant difference exist, however, between lunar surface materials in the highlands and those in the maria. In the highlands the soil depth is at least an order of magnitude greater, the Al:Fe ratio is ten times greater, the content of plagioclase as a source of clear glass is three times as great, and the content of Ti is at least an order of magnitude lower. Evaluation of the extractive metallurgy and chemical operations associated with carbothermic and silicothermic refinement of lunar regolith suggests that Fe, Al, Si, Mg and probably Ti, Cr and Mn can be recovered, while oxygen is produced as a by-product. A conservative plant design yields its own weight in oxygen, silicon, and structural metals in less than six days. Power requirements for a throughput of 300,000 tons per year is less than 500 megawatts. The processing is done more economically in space than on the lunar surface.

Phinney, W. C.↗

NASA NTRS1979

Design, durability and low cost processing technology for composite fan exit guide vanes

A lightweight composite fan exit guide vane for high bypass ratio gas turbine engine application was investigated. Eight candidate material/design combinations were evaluated by NASTRAN finite element analyses. A total of four combinations were selected for further analytical evaluation, part fabrication by two ventors, and fatigue test in dry and wet condition. A core and shell vane design was chosen in which the unidirectional graphite core fiber was the same for all candidates. The shell material, fiber orientation, and ply configuration were varied. Material tests were performed on raw material and composite specimens to establish specification requirements. Pre-test and post-test microstructural examination and nondestructive analyses were conducted to determine the effect of material variations on fatigue durability and failure mode. Relevant data were acquired with respect to design analysis, materials properties, inspection standards, improved durability, weight benefits, and part price of the composite fan exit guide vane.

Blecherman, S. S.↗

NASA NTRS1980

Design, durability and low cost processing technology for composite fan exit guide vanes

A program was conducted to design, fabricate and test a durable, low cost, lightweight composite fan exit guide vane for high bypass ratio gas turbine engine application. Eight candidate material/design combinations were evaluated by NASTRAN finite element analysis. Four of these candidate systems were selected for composite vane fabrication by two vendors. A core and shell vane design was chosen in which the unidirectional graphite core fiber was the same for all candidates. The shell material, fiber orientation and ply configuration were varied. Material tests were performed on raw material and composite specimens to establish specification requirements. Composite vanes were nondestructively inspected and subsequently fatigue tested in both dry and 'wet' conditions. The program provided relevant data with respect to design analysis, materials properties, inspection standards, improved durability, weight benefits and part price of the composite fan exit guide vane.

Blecherman, S. S.↗