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All sources NASA NTRS DOE OSTI

DOE OSTI2019

Comparison of Experimental Measurements of Thermal Conductivity of Fe{sub 2}O{sub 3} Nanofluids Against Standard Theoretical Models and Artificial Neural Network Approach

In the present work, the practicability of Fe{sub 2}O{sub 3} nanofluids for heat transfer applications has been examined. Nanofluids performance, in terms of modulation of thermal conductivity, has been investigated with increasing concentration of Fe{sub 2}O{sub 3} nanoparticles in water and ethylene glycol base fluids at 10, 20, 30, 40, 50, 60 and 70 °C. Fe{sub 2}O{sub 3} nanoparticles have been synthesized using the wet chemical method and characterized using TEM, SEM, XRD and UV–Vis. The characterization results revealed a face-centered cubic structure having alpha phase and particle size in the range of 40-55 nm for the synthesized Fe{sub 2}O{sub 3} nanoparticles. Thermal conductivity measurement results show increases in thermal conductivity with the increase in concentration and temperature of nanofluids. 16.45 and 19.76% enhancement in thermal conductivity have been observed for Fe{sub 2}O{sub 3}–water and Fe{sub 2}O{sub 3}–ethylene glycol nanofluids of 2 vol.% at 70 °C compared to water and ethylene glycol base fluids at 10 °C, respectively. Results of the ANN approach are in good agreement with experimental results, and H–C model gives better predictions compared to other standard models. The study gives clear insights into improved heat transfer performance by material engineering.

36 MATERIALS SCIENCE↗

DOE OSTI2011

EFFECTS OF GAMMA IRRADIATION ON EPDM ELASTOMERS

Two formulations of EPDM elastomer, one substituting a UV stabilizer for the normal antioxidant in this polymer, and the other the normal formulation, were synthesized and samples of each were exposed to gamma irradiation in initially pure deuterium gas to compare their radiation stability. Stainless steel containers having rupture disks were designed for this task. After 130 MRad dose of cobalt-60 radiation in the SRNL Gamma Irradiation Facility, a significant amount of gas was created by radiolysis; however the composition indicated by mass spectroscopy indicated an unexpected increase in the total amount deuterium in both formulations. The irradiated samples retained their ductility in a bend test. No change of sample weight, dimensions, or density was observed. No change of the glass transition temperature as measured by dynamic mechanical analysis was observed, and most of the other dynamic mechanical properties remained unchanged. There appeared to be an increase in the storage modulus of the irradiated samples containing the UV stabilizer above the glass transition, which may indicate hardening of the material by radiation damage. Polymeric materials become damaged by exposure over time to ionizing radiation. Despite the limited lifetime, polymers have unique engineering material properties and polymers continue to be used in tritium handling systems. In tritium handling systems, polymers are employed mainly in joining applications such as valve sealing surfaces (eg. Stem tips, valve packing, and O-rings). Because of the continued need to employ polymers in tritium systems, over the past several years, programs at the Savannah River National Laboratory have been studying the effect of tritium on various polymers of interest. In these studies, samples of materials of interest to the SRS Tritium Facilities (ultra-high molecular weight polyethylene (UHMW-PE), polytetrafluoroethylene (PTFE, Teflon{reg_sign}), Vespel{reg_sign} polyimide, and the elastomer ethylene propylene diene monomer (EPDM)) have been exposed in closed containers to tritium gas initially at 1 atmosphere pressure. These studies have demonstrated the degradation of properties when exposed to tritium gas. Also, the radiolytic production of significant amounts of hydrogen has been observed for UHMW-PE and EPDM. The study documented in this report exposes two similar formulations of EPDM elastomer to gamma irradiation in a closed container backfilled with deuterium. Deuterium is chemically identical to protium and tritium, but allows the identification of protium that is radiolytically produced from the samples. The goal of this program is to compare and contrast the response of EPDM exposure to two different types of ionizing radiation in a similar chemical environment.

36 MATERIALS SCIENCE↗

DOE OSTI2015

Literature Review: Assessment of DWPF Melter and Melter Off-gas System Lifetime

A glass melter for use in processing radioactive waste is a challenging environment for the materials of construction (MOC) resulting from a combination of high temperatures, chemical attack, and erosion/corrosion; therefore, highly engineered materials must be selected for this application. The focus of this report is to review the testing and evaluations used in the selection of the Defense Waste Processing Facility (DWPF), glass contact MOC specifically the Monofrax ® K-3 refractory and Inconel ® 690 alloy. The degradation or corrosion mechanisms of these materials during pilot scale testing and in-service operation were analyzed over a range of oxidizing and reducing flowsheets; however, DWPF has primarily processed a reducing flowsheet (i.e., Fe 2+ /ΣFe of 0.09 to 0.33) since the start of radioactive operations. This report also discusses the materials selection for the DWPF off-gas system and the corrosion evaluation of these materials during pilot scale testing and non-radioactive operations of DWPF Melter #1. Inspection of the off-gas components has not been performed during radioactive operations with the exception of maintenance because of plugging.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2015

Literature Review: Assessment of DWPF Melter and Melter Off-gas System Lifetime

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRS1985

Properties of coated and modified surfaces

The ability to create surface and near-surface properties distinct from the bulk properties of a material by means of coating or surface modification techniques is an important new field of development for engineering materials, encompassing ion implantation, plasma processing, reactive deposition methods, ion beam deposition and modification, molecular beam epitaxy, and fast quench thermal processing. Attention is given to specific areas of process control which illustrate (1) the use of process development to control material properties, (2) the importance of surface modification and coating to the tribology and ion-surface interactions of semiconductor film growth, and (3) recent findings in surface science which exemplify potential applications of ion-surface interactions that generate novel material qualities.

Mattox, D. M.↗

NASA NTRS1996

Materials All Around Us

The purpose of this journal exercise is to determine the properties of the materials in the environment around us, and to relate these properties to the materials systems for which they are used. Students will develop a strong rationale for gaining knowledge of engineering materials. The journal entries will serve as a starting point classroom discussion. Along with the journal, students are required to bring samples to class of 'found' materials and products composed of materials systems. Students are encouraged to be materials observers.

Jacobs, James A.↗

DOE OSTI2020

High-pressure strengthening in ultrafine-grained metals

The Hall–Petch relationship, according to which the strength of a metal increases as the grain size decreases, has been reported to break down at a critical grain size of around 10 to 15 nanometres. As the grain size decreases beyond this point, the dominant mechanism of deformation switches from a dislocation-mediated process to grain boundary sliding, leading to material softening. In one previous approach, stabilization of grain boundaries through relaxation and molybdenum segregation was used to prevent this softening effect in nickel–molybdenum alloys with grain sizes below 10 nanometres. Here we track in situ the yield stress and deformation texturing of pure nickel samples of various average grain sizes using a diamond anvil cell coupled with radial X-ray diffraction. Our high-pressure experiments reveal continuous strengthening in samples with grain sizes from 200 nanometres down to 3 nanometres, with the strengthening enhanced (rather than reduced) at grain sizes smaller than 20 nanometres. Here, we achieve a yield strength of approximately 4.2 gigapascals in our 3-nanometre-grain-size samples, ten times stronger than that of a commercial nickel material. A maximum flow stress of 10.2 gigapascals is obtained in nickel of grain size 3 nanometres for the pressure range studied here. We see similar patterns of compression strengthening in gold and palladium samples down to the smallest grain sizes. Simulations and transmission electron microscopy reveal that the high strength observed in nickel of grain size 3 nanometres is caused by the superposition of strengthening mechanisms: both partial and full dislocation hardening plus suppression of grain boundary plasticity. These insights contribute the ongoing search for ultrastrong metals via materials engineering.

36 MATERIALS SCIENCE↗

NASA NTRS2005

An Examination of Materials in Launch Vehicle Propulsion

The primary activities carried out for this effort used Mr. Glasgow's communication skills and materials expertise. He worked closely with both the Space Transportation Project Office and the Materials Division, preparing summaries of the weekly Space Transportation Project Office activities for use by the Materials and the Structures Divisions and for distribution to other portions of the GRC. Mr. Glasgow participated in systems analysis and planning sessions of the Program Office, serving as both a representative of the microtechnologists and as a reviewer of the macrotechnologies involved in proposed new launch vehicles. He helped define the technology readiness level of those new vehicle concepts and provided especially critical expertise to provide realistic technical assessments to various vehicle proponents. While a major portion of his work was performed at the GRC site, travel was required to Langley and to Nashville. In addition to the written contributions mentioned above, he presented summaries of Materials Division activities and interests in industry briefings. Mr. Glasgow continued his interest in the copper-chromium-niobium alloy system, a system originally identified by him as a potential rocket engine material and now chosen as baseline for two new rocket engine designs by the leading US builder of rocket engines.

Source record↗

DOE OSTI2024

Predicting non-linear stress–strain response of mesostructured cellular materials using supervised autoencoder

Recent breakthroughs in advanced manufacturing capabilities have made it possible to design and print sophisticated topologies of cellular structures using diverse engineering materials such as metals, polymers, and ceramics. In these architectured materials, it is often desirable to tailor the mechanical properties by altering the unit cell topology. This necessitates an in-depth understanding of how the topology of the unit cell structure affects the macroscopic behavior of the material in both the linear and the non-linear regimes encountered under large compression. Here, we have developed a machine learning (ML) approach capable of accelerating the prediction of the stress–strain response of a polymer-based cellular structure under uniaxial confined compression. As part of generating the training data for ML, 60,000 mesostructures were generated using a relatively novel approach based on cellular automata, and their corresponding stress–strain responses were obtained from the finite element simulations. Principal component analysis (PCA) was used to reduce the dimensionality of the stress–strain curves. With only 20 principal components, PCA captured 99.89% of the variance in the stress–strain curves while reducing the dimensionality by 5X. ML using supervised autoencoder was able to successfully speed up the prediction of the non-linear stress–strain response of a unit cell by up to 4600X. The proposed method can serve as an efficient data generation tool and a rapid means for predicting the structure–property relationship through accelerated forward modeling of cellular materials under compaction, in cases where the macroscopic stress–strain response is governed by the unit-cell topology.

36 MATERIALS SCIENCE↗

NASA NTRS1986

Experimental evaluation of candidate carbon-carbon materials for OTV engine nozzle extensions

Advanced carbon-carbon nozzle materials can reduce the weight and improve the efficiency of the proposed reusable Orbit Transfer Vehicle (OTV) liquid rocket engine. Experimental evaluations of eight carbon-carbon materials in an O2/H2 rocket nozzle environment have been performed. The hot fire testing will support the choice of the materials for the OTV nozzle design. The OTV nozzle requirements and operating environment are defined. The rocket device used to simulate the OTV hot-fire nozzle environment for material specimen evaluation is described. The results of hot-fire testing for eight carbon-carbon materials are discussed. Results for coated and uncoated materials, evaluated in side-by-side testing, are compared. Plans for further testing of the leading materials are described.

Suhoza, J. P.↗

DOE OSTI2019

Growth interactions between icosahedral quasicrystals

We investigate the solidification pathways of a population of icosahedral quasicrystals in a liquid through in situ synchrotron x-ray tomography. The wealth of three-dimensional space- and time-resolved data enables us to test the predictions of various models and theories of crystallization on a quasi-crystal-forming alloy. Remarkably, we find the general evolution equation—that accounts for the competing effects of growth, coalescence, and coarsening—fits well our experimental data on surface area concentration. Furthermore, we quantify the orientation selection, screening length, and coarsening rate of the dodecahedra, and compare these results to that of periodic crystals. The latter is a full order of magnitude smaller than that of elemental metal dendrites in the limit of zero volume fraction, a reflection of the low solid-liquid interfacial energy of the icosahedral phase. Furthermore, our paper provides the critical input data for microstructural models used for integrated computational materials engineering of complex intermetallics, including quasicrystals.

36 MATERIALS SCIENCE↗

NASA NTRS1984

Interaction of atomic oxygen with solid surfaces at orbital altitudes (A0114)

The basic approach to this experiment is to expose a wide variety of material surfaces to the atomic flux in orbit. The experiment is passive and depends on preflight and postflight measurements of the test surfaces in the laboratory. The experiment will also include a reflectometer device to measure atomic beam reflection angles and thus momentum accommodations, and a unique passive spacecraft attitude sensor. Samples consisting of solid disks or thin film coatings on substrate disks will be mounted in a panel. The face of this panel will be flown on Long Duration Exposure Facility normal to the incident stream of oxygen atoms. Each disk will have part of its front surface masked so exposure to the atomic-oxygen reaction will be limited to selected areas, the shadowed areas being used as control surfaces in the measurements. A typical sample is an optically flat quartz disk overcoated with a film of the material of interest. These include Ag, Au, Pt, Nb, Ni, Al, C, Si, Ge, LiF, and a few engineering materials. Some materials for which the expected removal rate is high, such as carbon, will be solid disks rather than thin films.

Gregory, J. C.↗

NASA NTRS2018

2040 Vision: A Roadmap for Integrated, Multiscale Materials and System Modeling and Simulation

Over the last few decades, advances in high-performance computing, new materials characterization methods, and, more recently, an emphasis on integrated computational materials engineering (ICME) and additive manufacturing have been a catalyst for multiscale modeling and simulation-based design of materials and structures in the aerospace industry. While these advances have driven significant progress in the development of aerospace components and systems, that progress has been limited by persistent technology and infrastructure challenges that must be overcome to realize the full potential of integrated materials and systems design and simulation modeling throughout the supply chain. As a result, NASA's Transformational Tools and Technology (TTT) Project sponsored a study (performed by a team led by Pratt & Whitney) to define the potential 25-year future state required for integrated multiscale modeling of materials and systems (e.g., load-bearing structures) to accelerate the pace and reduce the expense of innovation in future aerospace and aeronautical systems. This talk will describe the findings of this 2040 Vision study (e.g., the 2040 vision state; the required interdependent core technical work areas, Key Element (KE); associated critical gaps and actions to close those gaps; and major recommendations). This roadmap is a community consensus document and is a result of over 450 professionals input obtain via: i) four society workshops (AIAA, NAFEMS, and two TMS), ii) community-wide survey, and iii) the establishment of 9 expert panels (one per key element) consisting on average 10 non-team members from academia, government and industry to review, update content, and prioritize gaps and actions. It is NASA's hope and desire that this roadmap provides the strategic guidance to both public and private research and development decision makers to make the proposed 2040 vision state a reality and thereby provide a significant advancement in the United States global competitiveness.

Multiscale Modeling↗

DOE OSTI2016

Pool Boiling CHF Experiment for Cr-alloy-coated Accident Tolerant Fuel Cladding

The severe accident at the Fukushima nuclear power plants forced the nuclear communities to revise and reinforce their safety technology, especially accident tolerance. The main problem of Zr-based alloys is hydrogen generation owing to steam oxidation in a very high temperature environment. Currently, several types of Accident Tolerant Fuel (ATF) claddings that eliminate the steam oxidation problem have been presented as alternatives. Although the ATFs have shown appropriate performances in terms of material engineering, thorough tests including thermal hydraulic concerns are still required to ensure the design compatibilities. In this study, we conducted pool boiling critical heat flux (CHF) experiments using Cr-alloy-coated ATF claddings to verify basic thermal hydraulic performances. (authors)

36 MATERIALS SCIENCE↗

DOE OSTI2026

Towards Commercialization of Low-Cost, Crack-Tolerant, Screen-Printable Metallization by Full-Size Module Testing and Field Characterization

This project is motivated by the need to develop a materials engineering solution to reduce solar module degradation caused by cell cracks. The cell-crack-induced power loss is a long-term degradation mechanism and one of the main causes of solar panel field failures. Cell cracks can occur during module fabrication, transportation, installation, and long-term operation due to thermomechanical stressors. Our team’s internal estimation – based on the national weather pattern, frequency of severe weather, and 39- GW asset survey by Heliolytics – reveals that the cell-crack-induced module degradation translates to lost revenues >$17B over an average 5-year period for solar farm owners and to reduced reliability (<25 years panel lifetime) for solar energy consumers. In response to this challenge, the prime recipient offers a metal matrix composite (MMC) silver paste that is tailor-engineered for screen-printing gridlines and busbars, which serve as the electrical contacts on solar cells. We formulate our MMC paste by adding low-cost (∼0.02¢/WDC for research grade), surface-engineered carbon nanotubes to commercially available silver paste. The MMC paste offers a drop-in, cost-effective solution to cell cracks for solar cell and module manufacturers. The main goal of this project was to conduct field-relevant, module-level analysis and qualification of MMC metallization.

14 SOLAR ENERGY↗

NASA NTRS1971

Impact sensitivity of materials in contact with liquid and gaseous oxygen at high pressures.

An apparatus developed by Marshall Space Flight Center for use in determining the impact sensitivity of engineering materials in liquid and gaseous oxygen at pressures greater than one atmosphere is described. This apparatus uses the impact tester described in ASTM D2512, ?Compatibility of Materials with Liquid Oxygen,' with the addition of a pressurized sample holder in place of the D2512 anvil region.

Key, C. F.↗

DOE OSTI2021

3D printing of lignin: Challenges, opportunities and roads onward

Abstract As the second most abundant biopolymer on earth, and as a resource recently becoming more available in separated and purified form on an industrial scale due to the development of new isolation technologies, lignin has a key role to play in transitioning our material industry towards sustainability. Additive manufacturing (AM), the most efficient‐material processing technology to date, has likewise made great strides to promote sustainable industrial solutions to our needs in engineered products. Bringing lignin research to AM has prompted the emergence of the nascent “lignin 3D printing” field. This review presents the recent state of art of this promising field and highlights its challenges and opportunities. Following a review of the industrial availability, molecular attributes, and associated properties of technical lignins, we review R&D efforts at implementing lignin systems in extrusion‐based and stereolithography (SLA) printing technologies. Doing so underlines the adage of lignin research that “all lignins are not created equal,” and stresses the opportunity nested in this chemical diversity created mostly by differences in isolation conditions to molecularly select and tune the attributes of technical lignin systems towards desirable properties, be it by modification or polymer blending. Considering the AM design process in its entirety, we finally propose onward routes to bring the full potential to this emerging field. We hope that this review can help promote the unique value and overdue industrial role of lignin in sustainable engineered materials and products.

36 MATERIALS SCIENCE↗

DOE OSTI2013

SLAC National Accelerator Laboratory FACET & TEST BEAM FACILITIES PROPOSAL: Development of Electron Radiography for Material Science

The material science community is presently limited by diagnostics in both the fabrication of materials and measuring the resulting materials characteristics of these new fabrication techniques. Because of this limitation the community is forced into an empirical mode of material fabrication, where expert judgment is used to guide manufacturing processes and the resulting materials are inspected and tested for the desired characteristics. This development approach can be time consuming and costly. The solution to this problem is to improve our fundamental understanding of materials, which requires the development of new diagnostics capable of measurement at the micron length scale, during both processing and during testing. These new measurements will enable a fundamental understanding of material characteristics allowing the development of predictive models, which will in turn enable material engineering by design rather than today’s empirical approach. Solving this problem has become a grand challenge for the materials science community. Los Alamos plans to address this challenge through the development of new diagnostics capable of measurements at the smallest length scales through the Multi-Probe Diagnostic Hall (MPDH) at the planned MaRIE (Material and Radiation In Extremes) Facility. One of the probes will be a coherent photon beam generated by an FEL driven by a multi-GeV electron beam. The photons will be used for diffraction measurements as well as radiography of relatively thin samples (nearly single grains). The same multi-GeV electron beam can be used to directly radiograph thicker systems (many grains or “bulk” material), providing high resolution measurements of the density distribution of materials during both fabrication and dynamic testing. This technique, electron radiography or eRad, that has been identified by LANL as one of the probes required to meet this grand challenge has never been demonstrated with high energy electrons. We propose to begin development of this technique with the electron beam available at FACET.

47 OTHER INSTRUMENTATION↗