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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

The Design of Mechanically Compatible Fasteners for Human Mandible Reconstruction

Mechanically compatible fasteners for use with thin or weakened bone sections in the human mandible are being developed to help reduce large strain discontinuities across the bone/implant interface. Materials being considered for these fasteners are a polyetherertherketone (PEEK) resin with continuous quartz or carbon fiber for the screw. The screws were designed to have a shear strength equivalent to that of compact/trabecular bone and to be used with a conventional nut, nut plate, or an expandable shank/blind nut made of a ceramic filled polymer. Physical and finite element models of the mandible were developed in order to help select the best material fastener design. The models replicate the softer inner core of trabecular bone and the hard outer shell of compact bone. The inner core of the physical model consisted of an expanding foam and the hard outer shell consisted of ceramic particles in an epoxy matrix. This model has some of the cutting and drilling attributes of bone and may be appropriate as an educational tool for surgeons and medical students. The finite element model was exercised to establish boundary conditions consistent with the stress profiles associated with mandible bite forces and muscle loads. Work is continuing to compare stress/strain profiles of a reconstructed mandible with the results from the finite element model. When optimized, these design and fastening techniques may be applicable, not only to other skeletal structures, but to any composite structure.

Roberts, Jack C.↗
NASA NTRS2004

The Office of the Materials Division

I was assigned to the Materials Division, which consists of the following branches; the Advanced Metallics Branch/5120-RMM, Ceramics Branch/5130-RMC, Polymers Branch/5150-RMP, and the Durability and Protective Coatings Branch/5160-RMD. Mrs. Pamela Spinosi is my assigned mentor. She was assisted by Ms.Raysa Rodriguez/5100-RM and Mrs.Denise Prestien/5100-RM, who are both employed by InDyne, Inc. My primary assignment this past summer was working directly with Ms. Rodriguez, assisting her with setting up the Integrated Financial Management Program (IFMP) 5130-RMC/Branch procedures and logs. These duties consisted of creating various spreadsheets for each individual branch member, which were updated daily. It was not hard to familiarize myself with these duties since this is my second summer working with Ms Rodriguez at NASA Glenn Research Center. RMC ordering laboratory, supplies and equipment for the Basic Materials Laboratory (Building 106) using the IF'MP/Purchase Card (P-card), a NASA-wide software program. I entered into the IFMP/Travel and Requisitions System, new Travel Authorizations for the 5130-RMC Civil Servant Branch Members. I also entered and completed Travel Vouchers for the 5130-RMC Ceramics Branch. I assisted in the Division Office creating new Emergency Contact list for the Materials Division. I worked with Dr. Hugh Gray, the Division Chief, and Dr. Ajay Misra, the 5130-RMC Branch Chief, on priority action items, with a close deadline, for a large NASA Proposal. Another project was working closely with Ms. Rodriguez in organizing and preparing for Dr. Ajay K. Misra's SESCDP (two year detail). This consisted of organizing files, file folders, personal information, and recording all data material onto CD's and printing all presentations for display in binders. I attended numerous Branch meetings, and observed many changes in the Branch Management organization.

Ramsey, amanda J.↗
NASA NTRS2003

New Method Developed To Purify Single Wall Carbon Nanotubes for Aerospace Applications

Single wall carbon nanotubes have attracted considerable attention because of their remarkable mechanical properties and electrical and thermal conductivities. Use of these materials as primary or secondary reinforcements in polymers or ceramics could lead to new materials with significantly enhanced mechanical strength and electrical and thermal conductivity. Use of carbon-nanotube-reinforced materials in aerospace components will enable substantial reductions in component weight and improvements in durability and safety. Potential applications for single wall carbon nanotubes include lightweight components for vehicle structures and propulsion systems, fuel cell components (bipolar plates and electrodes) and battery electrodes, and ultra-lightweight materials for use in solar sails. A major barrier to the successful use of carbon nanotubes in these components is the need for methods to economically produce pure carbon nanotubes in large enough quantities to not only evaluate their suitability for certain applications but also produce actual components. Most carbon nanotube synthesis methods, including the HiPCO (high pressure carbon monoxide) method developed by Smalley and others, employ metal catalysts that remain trapped in the final product. These catalyst impurities can affect nanotube properties and accelerate their decomposition. The development of techniques to remove most, if not all, of these impurities is essential to their successful use in practical applications. A new method has been developed at the NASA Glenn Research Center to purify gram-scale quantities of single wall carbon nanotubes. This method, a modification of a gas phase purification technique previously reported by Smalley and others, uses a combination of high-temperature oxidations and repeated extractions with nitric and hydrochloric acid. This improved procedure significantly reduces the amount of impurities (catalyst and nonnanotube forms of carbon) within the nanotubes, increasing their stability significantly. The onset of decomposition of the purified nanotubes (determined by thermal gravimetric analysis in air) is more than 300 C higher than that of the crude nanotubes. Transmission electron microscopy analysis of nanotubes purified by this method reveals near complete removal of iron catalyst particles. Analysis of the nanotubes using inductively coupled plasma spectroscopy revealed that the iron content of the nanotubes was reduced from 22.7 wt% in the crude nanotubes to less than 0.02 wt%. X-ray photoelectron spectroscopy revealed a decrease in iron content after purification as well as an increase in oxygen content due to the formation of carboxylic acid groups on the surface of the nanotubes. Nanotubes purified by this improved method can be readily dispersed in common organic solvents, in particular N,N-dimethylformamide, using prolonged ultrasonic treatment. These dispersions can then be used to incorporate single wall carbon nanotubes into polymer films.

Lebron, Marisabel↗
NASA NTRS1976

Space shuttle prototype check valve development

Contaminant-resistant seal designs and a dynamically stable prototype check valve for the orbital maneuvering and reaction control helium pressurization systems of the space shuttle were developed. Polymer and carbide seal models were designed and tested. Perfluoroelastomers compatible with N2O4 and N2H4 types were evaluated and compared with Teflon in flat and captive seal models. Low load sealing and contamination resistance tests demonstrated cutter seal superiority over polymer seals. Ceramic and carbide materials were evaluated for N2O4 service using exposure to RFNA as a worst case screen; chemically vapor deposited tungsten carbide was shown to be impervious to the acid after 6 months immersion. A unique carbide shell poppet/cutter seat check valve was designed and tested to demonstrate low cracking pressure ( 2.0 psid), dynamic stability under all test bench flow conditions, contamination resistance (0.001 inch CRES wires cut with 1.5 pound seat load) and long life of 100,000 cycles (leakage 1.0 scc/hr helium from 0.1 to 400 psig).

Tellier, G. F.↗
NASA NTRS1985

Accommodation requirements for microgravity science and applications research on space station

Scientific research conducted in the microgravity environment of space represents a unique opportunity to explore and exploit the benefits of materials processing in the virtual abscence of gravity induced forces. NASA has initiated the preliminary design of a permanently manned space station that will support technological advances in process science and stimulate the development of new and improved materials having applications across the commercial spectrum. A study is performed to define from the researchers' perspective, the requirements for laboratory equipment to accommodate microgravity experiments on the space station. The accommodation requirements focus on the microgravity science disciplines including combustion science, electronic materials, metals and alloys, fluids and transport phenomena, glasses and ceramics, and polymer science. User requirements have been identified in eleven research classes, each of which contain an envelope of functional requirements for related experiments having similar characteristics, objectives, and equipment needs. Based on these functional requirements seventeen items of experiment apparatus and twenty items of core supporting equipment have been defined which represent currently identified equipment requirements for a pressurized laboratory module at the initial operating capability of the NASA space station.

Uhran, M. L.↗
NASA NTRS1986

Adhesion and wear resistance of materials

Recent studies into the nature of bonding at the interface between two solids in contact or a solid and deposited film have provided a better understanding of those properties important to the adhesive wear resistance of materials. Analytical and experimental progress are reviewed. For simple metal systems the adhesive bond forces are related to electronic wave function overlap. With metals in contact with nonmetals, molecular-orbital energy, and density of states, respectively can provide insight into adhesion and wear. Experimental results are presented which correlate adhesive forces measured between solids and the electronic surface structures. Orientation, surface reconstruction, surface segregation, adsorption are all shown to influence adhesive interfacial strength. The interrelationship between adhesion and the wear of the various materials as well as the life of coatings applied to substrates are discussed. Metallic systems addressed include simple metals and alloys and these materials in contact with themselves, both oxide and nonoxide ceramics, diamond, polymers, and inorganic coating compounds, h as diamondlike carbon.

Buckley, D. H.↗
NASA NTRS1989

Materials properties numerical database system established and operational at CINDAS/Purdue University

A computerized comprehensive numerical database system on the mechanical, thermophysical, electronic, electrical, magnetic, optical, and other properties of various types of technologically important materials such as metals, alloys, composites, dielectrics, polymers, and ceramics has been established and operational at the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) of Purdue University. This is an on-line, interactive, menu-driven, user-friendly database system. Users can easily search, retrieve, and manipulate the data from the database system without learning special query language, special commands, standardized names of materials, properties, variables, etc. It enables both the direct mode of search/retrieval of data for specified materials, properties, independent variables, etc., and the inverted mode of search/retrieval of candidate materials that meet a set of specified requirements (which is the computer-aided materials selection). It enables also tabular and graphical displays and on-line data manipulations such as units conversion, variables transformation, statistical analysis, etc., of the retrieved data. The development, content, accessibility, etc., of the database system are presented and discussed.

Ho, C. Y.↗
NASA NTRS1989

An accurate analytic approximation to the non-linear change in volume of solids with applied pressure

An accurate analytic expression for the nonlinear change of the volume of a solid as a function of applied pressure is of great interest in high-pressure experimentation. It is found that a two-parameter analytic expression, fits the experimental volume-change data to within a few percent over the entire experimentally attainable pressure range. Results are presented for 24 different materials including metals, ceramic semiconductors, polymers, and ionic and rare-gas solids.

Schlosser, Herbert↗
NASA NTRS1990

NASA's HITEMP program for UHBR engines

NASA's High Temperature Engine Materials Program (HITEMP) is concerned with the laboratory-scale technology development and feasibility demonstration of high-temperature composite materials, in conjunction with the requisite structural analysis models and test methods for their validation. HITEMP encompasses research on metallic/intermetallic, ceramic, and polymer matrix composites, and is giving attention to high-temperature component composites applicable to future widebody commercial aircraft ultrahigh bypass ratio (UHBR) engines. The UHBR components for which advanced composites are envisioned are fan, compressor, and turbine rotor blades, stator vanes, disks, and shafts, thrust bearings, gearbox bearings and linings, combustor cases and linings, nacelles, and thrust-reversers.

Stephens, Joseph R.↗
NASA NTRS1991

Controlling panel flutter using adaptive materials

The effectiveness of using adaptive materials to control panel flutter is examined. Adaptive materials are those whose strain or mechanical properties can be controlled by the application of an external stimulus. Two such material types are piezoelectric (ceramics or polymers) and shape memory alloys. These materials experience controllable strain when subjected to applied voltage and heat, respectively. The present study investigates the use of both material types to modify the flutter characteristics of a simply supported panel in supersonic flow. Piezoelectric materials respond quickly to applied voltages and can be used with feedback control for active vibration suppression. The adaptive process of the shape memory alloy used in this study (geometry and stiffness change) is a relatively low frequency phenomenon; therefore, it is considered for passive (on/off) control schemes only. Nondimensional parameters for these adaptive materials are used with linear panel models, yielding results which allow for a better understanding of their capabilities in controlling aeroelastic responses.

Scott, R. C.↗
NASA NTRS1993

Long Duration Exposure Facility (LDEF) experiment M0003 meteoroid and debris survey

A survey of the meteoroid and space debris impacts on LDEF experiment M0003 was performed. The purpose of this survey was to document significant impact phenomenology and to obtain impact crater data for comparison to current space debris and micrometeoroid models. The survey consists of the following: photomicrographs of significant impacts in a variety of material types; accurate measurements of impact crater coordinates and dimensions for selected experiment surfaces; and databasing of the crater data for reduction, manipulation, and comparison to models. Large area surfaces that were studied include the experiment power and data system (EPDS) sunshields, environment exposure control canister (EECC) sunshields, and the M0003 signal conditioning unit (SCU) covers. Crater diameters down to 25 microns were measured and cataloged. Both leading (D8) and trailing (D4) edge surfaces were studied and compared. The EPDS sunshields are aluminum panels painted with Chemglaze A-276 white thermal control paint, the EECC sunshields are chromic acid-anodized aluminum, and the SCU covers are aluminum painted with S13GLO white thermal control paint. Typical materials that have documented impacts are metals, glasses and ceramics, composites, polymers, electronic materials, and paints. The results of this survey demonstrate the different response of materials to hypervelocity impacts. Comparison of the survey data to curves derived from the Kessler debris model and the Cour-Palais micrometeoroid model indicates that these models overpredict small impacts (less than 100 micron) and may underpredict large impacts (greater than 1000 micron) while having fair to good agreement for the intermediate impacts. Comparison of the impact distributions among the various surfaces indicates significant variations, which may be a function of material response effects, or in some cases surface roughness. Representative photographs and summary graphs of the impact data are presented.

Meshishnek, M. J.↗
NASA NTRS1993

Atomic oxygen erosion considerations for spacecraft materials selection

The Long Duration Exposure Facility (LDEF) satellite carried 57 experiments that were designed to define the low-Earth orbit (LEO) space environment and to evaluate the impact of this environment on potential engineering materials and material processes. Deployed by the Shuttle Challenger in April of 1984, LDEF made over 32,000 orbits before being retrieved nearly 6 years later by the Shuttle Columbia in January of 1990. The Solar Array Passive LDEF Experiment (SAMPLE) AO171 contained approximately 300 specimens, representing numerous material classes and material processes. AO171 was located on LDEF in position A8 at a yaw of 38.1 degrees from the ram direction and was subjected to an atomic oxygen (AO) fluence of 6.93 x 10(exp 21) atoms/sq cm. LDEF AO171 data, as well as short-term shuttle data, will be discussed in this paper as it applies to engineering design applications of composites, bulk and thin film polymers, glassy ceramics, thermal control paints, and metals subjected to AO erosion.

Whitaker, Ann F.↗
NASA NTRS1998

NASA's Microgravity Materials Science Program

Materials Science research programs are funded by NASA through the Microgravity Research Division. Such programs are normally designated as flight definition or ground based and can be awarded initially for up to four years. Selection is through a peer review process in response to a biennial NASA Research Announcement (NRA). The next announcement is due in November 1998 with proposals due in March 1999. Topics of special interest to NASA are described in the guidelines for proposal writing within the NRA. NASA's interest in materials is wide and covers a range which includes metals and alloys, ceramics, glasses, polymers, non-linear optics, aerogels and nanostructures. With increasing interest in the Human Exploration and Development of Space (HEDS) program, the materials research funded will not be exclusively devoted to processes dependent on microgravity, but will also support materials of strategic interest in meeting NASA's long range plans of interplanetary travel.

Gillies, Donald C.↗
NASA NTRS2004

Making Space Travel to Jupiter Possible

From man landing on the moon to a simple satellite being launched into orbit, many incredible space accomplishments have been witnessed by us all. However, what goes un-noticed to the common man is the extensive research and testing that lasts months, years, and even decades. Much of this required research just so happens to take place in the corridors of the Glen Research Center building number 49. In the Advanced Materials division of G.R.C., a number of researchers have the responsibility of discovering which metal, ceramic, or polymer is best for a specific application. Under the guidance of mentor extraordinaire Frank Ritzert, I am involved in many critical projects dealing with refractory metals, two of which I will mention in this report. The Jupiter Icy Moons Orbiter (JIMO) project actually was under full swing back in the 50's and early 60's. To enable the 14 year trek to the icy moons of Europa, Callisto, and Ganymede, nuclear propulsion methods were selected. Due to the extreme temperature of the reactor and the extended time period, a refractory metal would need to be implemented. After years of research and progress, the program was suddenly canceled. About a decade ago, the JIMO project was re-instated and now has a goal for departure around 2014. However, a few obstacles lie in our way concerning the use of refractory metals. In certain areas of the orbiter a joint is required between the refractories and other less dense metals. Two of these joints are with nickel based super alloys. Being an intern for Frank Ritzert, the refractory metals expert, I have the opportunity to develop the best method to braze refractory metals to Nickel 201. This involves the actual brazing, electron microscopy and reporting the results. My second project involves a certain part of the orbiter where Niobium 1Zirconium, a refractory metal, is joined with Hastelloy-X a Ni based metal. Small quantities of oxygen, helium and other impurities in the Ni alloy could diffuse into the Nb1Zr causing imbrittlement and possibly major failure. I will be testing the effects of Hast-X on Nb1Zr in a high temperature for 10, 50, 100, and 500 hours. After the samples are run through the heat treatment, strength and chemistry will be tested and reported. My appreciation for the research that goes behind every project has and will continue to grow. By digging through old documents written in the 50's and 60's, scouring through forgotten closets, and learning from those with experience in the refractory metals, I am bound to have an incredible learning experience here at NASA.

Barker, Samuel P.↗
NASA NTRS2001

Flame Synthesis Used to Create Metal-Catalyzed Carbon Nanotubes

Metal-catalyzed carbon nanotubes are highly ordered carbon structures of nanoscale dimensions. They may be thought of as hollow cylinders whose walls are formed by single atomic layers of graphite. Such cylinders may be composed of many nested, concentric atomic layers of carbon or only a single layer, the latter forming a single-walled carbon nanotube. This article reports unique results using a flame for their synthesis. Only recently were carbon nanotubes discovered within an arc discharge and recognized as fullerene derivatives. Today metal-catalyzed carbon nanotubes are of great interest for many reasons. They can be used as supports for the metal catalysts like those found in catalytic converters. Open-ended nanotubes are highly desirable because they can be filled by other elements, metals or gases, for battery and fuel cell applications. Because of their highly crystalline structure, they are significantly stronger than the commercial carbon fibers that are currently available (10 times as strong as steel but possessing one-sixth of the weight). This property makes them highly desirable for strengthening polymer and ceramic composite materials. Current methods of synthesizing carbon nanotubes include thermal pyrolysis of organometallics, laser ablation of metal targets within hydrocarbon atmospheres at high temperatures, and arc discharges. Each of these methods is costly, and it is unclear if they can be scaled for the commercial synthesis of carbon nanotubes. In contrast, flame synthesis is an economical means of bulk synthesis of a variety of aerosol materials such as carbon black. Flame synthesis of carbon nanotubes could potentially realize an economy of scale that would enable their use in common structural materials such as car-body panels. The top figure is a transmission electron micrograph of a multiwalled carbon nanotube. The image shows a cross section of the atomic structure of the nanotube. The dark lines are individual atomic layer planes of carbon, seen here in cross section. They form a nested series of concentric cylinders, much like the growth rings on a tree. This sample was obtained by the supported catalyst method, whereby the nanoscale catalysts are dispersed on a substrate providing their support. The substrate with catalyst particles was immersed within an acetylene diffusion flame to which nitrogen had been added to eliminate soot formation. Upon removal from the flame, the nanotubes were dispersed on a holder suitable for electron microscopy. Although not seen in the figure, the tube diameter reflects that of the catalyst particle.

VanderWal, Randy L.↗
NASA NTRS2006

Effect of Bending Stiffness of the Electroactive Polymer Element on the Performance of a Hybrid Actuator System (HYBAS)

An electroactive polymer (EAP)-ceramic hybrid actuation system (HYBAS) was developed recently at NASA Langley Research Center. This paper focuses on the effect of the bending stiffness of the EAP component on the performance of a HYBAS, in which the actuation of the EAP element can match the theoretical prediction at various length/thickness ratios for a constant elastic modulus of the EAP component. The effects on the bending stiffness of the elastic modulus and length/thickness ratio of the EAP component were studied. A critical bending stiffness to keep the actuation of the EAP element suitable for a rigid beam theory-based modeling was found for electron irradiated P(VDF-TrFE) copolymer. For example, the agreement of experimental data and theoretical modeling for a HYBAS with the length/thickness ratio of EAP element at 375 times is demonstrated. However, the beam based theoretical modeling becomes invalid (i.e., the profile of the HYBAS movement does not follow the prediction of theoretical modeling) when the bending stiffness is lower than a critical value.

Xu, Tian-Bing↗
NASA NTRS2004

Patterned Growth of Carbon Nanotubes or Nanofibers

A method and apparatus for the growth of carbon nanotubes or nanofibers in a desired pattern has been invented. The essence of the method is to grow the nanotubes or nanofibers by chemical vapor deposition (CVD) onto a patterned catalyst supported by a substrate. The figure schematically depicts salient aspects of the method and apparatus in a typical application. A substrate is placed in a chamber that contains both ion-beam sputtering and CVD equipment. The substrate can be made of any of a variety of materials that include several forms of silicon or carbon, and selected polymers, metals, ceramics, and even some natural minerals and similar materials. Optionally, the substrate is first coated with a noncatalytic metal layer (which could be a single layer or could comprise multiple different sublayers) by ion-beam sputtering. The choice of metal(s) and thickness(es) of the first layer (if any) and its sublayers (if any) depends on the chemical and electrical properties required for subsequent deposition of the catalyst and the subsequent CVD of the carbon nanotubes. A typical first-sublayer metal is Pt, Pd, Cr, Mo, Ti, W, or an alloy of two or more of these elements. A typical metal for the second sublayer or for an undivided first layer is Al at a thickness .1 nm or Ir at a thickness .5 nm. Proper choice of the metal for a second sublayer of a first layer makes it possible to use a catalyst that is chemically incompatible with the substrate. In the next step, a mask having holes in the desired pattern is placed over the coated substrate. The catalyst is then deposited on the coated substrate by ion-beam sputtering through the mask. Optionally, the catalyst could be deposited by a technique other than sputtering and/or patterned by use of photolithography, electron- beam lithography, or another suitable technique. The catalytic metal can be Fe, Co, Ni, or an alloy of two or more of these elements, deposited to a typical thickness in the range from 0.1 to 20 nm.

Delzeit, Lance D.↗
NASA NTRS2013

Motorized Beam Alignment of a Commercial X-ray Diffractometer

X-ray diffraction (XRD) is a powerful analysis method that allows researchers to noninvasively probe the crystalline structure of a material. This includes the ability to determine the crystalline phases present, quantify surface residual stresses, and measure the distribution of crystallographic orientations. The Structures and Materials Division at the NASA Glenn Research Center (GRC) heavily uses the on-site XRD lab to characterize advanced metal alloys, ceramics, and polymers. One of the x-ray diffractometers in the XRD lab (Bruker D8 Discover) uses three different x-ray tubes (Cu, Cr, and Mn) for optimal performance over numerous material types and various experimental techniques. This requires that the tubes be switched out and aligned between experiments. This alignment maximizes the x-ray tube s output through an iterative process involving four set screws. However, the output of the x-ray tube cannot be monitored during the adjustment process due to standard radiation safety engineering controls that prevent exposure to the x-ray beam when the diffractometer doors are open. Therefore, the adjustment process is a very tedious series of blind adjustments, each followed by measurement of the output beam using a PIN diode after the enclosure doors are shut. This process can take up to 4 hr to perform. This technical memorandum documents an in-house project to motorize this alignment process. Unlike a human, motors are not harmed by x-ray radiation of the energy range used in this instrument. Therefore, using motors to adjust the set screws will allow the researcher to monitor the x-ray tube s output while making interactive adjustments from outside the diffractometer. The motorized alignment system consists of four motors, a motor controller, and a hand-held user interface module. Our goal was to reduce the alignment time to less than 30 min. The time available was the 10-week span of the Lewis' Educational and Research Collaborative Internship Project (LERCIP) summer internship program and the budget goal was $1200. In this report, we will describe our motorization design and discuss the results of its implementation.

Van Zandt, Noah R.↗