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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

STS-121: Discovery Pre-Launch Mission Management Team Press Briefing

The briefing began with Allard Buetel (NASA Public Affairs) introducing Bill Gerstenmaier (Associate Administrator for Space Operations) who provided an update of the Mission Management team meeting. The 3 criteria reviewed by the team were: a) ascent heating; b) ice formation and c) remaining foam still intact. The ascent heating had a safety factor of 5 and posed no concern. Ice formation was not a concern. In order to insure there was no damage to the remaining foam, an 8ft. pipe with a camera attached was used to provide pictures. The boroscope pictures showed there was no damage to the brackets or foam. The inspection went very well and the foam was acceptable and ready to fly. Then the floor was open to questions from the press.

Source record↗
NASA NTRS1993

Optimization of Hot-Pressed n-Type SiGe/GaP and p-Type SiGe/B Thermoelectric Materials

A comprehensive experimental and theoretical work has been conducted in order to optimize the thermoelectric properties of Si_(80)Ge_(20) materials and reach the goal of a combined figure of merit value of 0.85x10^(-3) K^(-1) averaged over a 600-1000 C temperature range. Improvement for the n-type material has been obtained by determining the optimum amounts of gallium and phosphorus dopants necessary to achieve optimum carrier mobility and concentration. The emphasis is now on the consistent reproducibility of these results through understanding and control of the hot-pressing parameters relating microstructure and composition to the transport properties. The optimum doping level has now been firmly established for p-type materials, and work is concentrating on the reduction in thermal conductivity. BN ultra fine particles have been successfully incorporated into fully dense samples and have resulted in desired improvement of the figure of merit...

Fleurial, Jean-Pierre↗
NASA NTRS2010

Oxidation Characterization of Hafnium-Based Ceramics Fabricated by Hot Pressing and Electric Field-Assisted Sintering

Ceramic borides, such as hafnium diboride (HfB2) and zirconium diboride (ZrB2), are members of a family of materials with extremely high melting temperatures referred to as Ultra High Temperature Ceramics (UHTCs). UHTCs constitute a class of promising materials for use in high temperature applications, such as sharp leading edges on future-generation hypersonic flight vehicles, because of their high melting points. The controlled development of microstructure has become important to the processing of UHTCs, with the prospect of improving their mechanical and thermal properties. The improved oxidation resistance of HfB2 has also become important if this material is to be successfully used at temperatures above 2000 C. Furthermore, the use of UHTCs on the leading edges of vehicles traveling at hypersonic speeds will mean exposure to a mixed oxidation environment comprised of both molecular and atomic oxygen. The current study has investigated the high-temperature oxidation behavior of HfB2-based materials in a pure O2 environment, as well as in environments containing different levels of dissociated oxygen (O/O2). Materials were processed by two techniques: conventional hot pressing (HP) and electric field-assisted sintering (FAS). Their oxidation behavior was evaluated in both a tube furnace at 1250 C for 3 hours and in a simulated re-entry environment in the Advanced Heating Facility (AHF) arcjet at NASA Ames Research Center, during a 10-minute exposure to a cold wall heat flux of 250W/sq cm and stagnation pressure of 0.1-0.2 atm. The microstructure of the different materials was characterized before and after oxidation using scanning electron microscopy (SEM).

Gasch, Matt↗
NASA NTRS2011

Femoral Blood Flow and Cardiac Output During Blood Flow Restricted Leg Press Exercise

Low load blood flow restricted resistance exercise (LBFR) causes muscle hypertrophy that may be stimulated by the local ischemic environment created by the cuff pressure. However, local blood flow (BF) during such exercise is not well understood. PURPOSE: To characterize femoral artery BF and cardiac output (CO) during leg press exercise (LP) performed at a high load (HL) and low load (LL) with different levels of cuff pressure. METHODS: Eleven subjects (men/women 4/7, age 31.4+/-12.8 y, weight 68.9+/-13.2 kg, mean+/-SD) performed 3 sets of supine left LP to fatigue with 90 s of rest in 4 conditions: HL (%1-RM/cuff pressure: 80%/0); LL (20%/0); LBFR(sub DBP) (20%/1.3 x diastolic blood pressure, BP); LBFR(sub SBP) (20%/1.3 x supine systolic BP). The cuff remained inflated throughout the LBFR exercise sessions. Artery diameter, velocity time integral (VTI), and stroke volume (SV) were measured using Doppler ultrasound at rest and immediately after each set of exercise. Heart rate (HR) was monitored using a 3-lead ECG. BF was calculated as VTI x vessel cross-sectional area. CO was calculated as HR x SV. The data obtained after each set of exercise were averaged and used for analyses. Multi-level modeling was used to determine the effect of exercise condition on dependent variables. Statistical significance was set a priori at p< 0.05. RESULTS: Artery diameter did not change from baseline. BF increased (p<0.05) after exercise in each condition except LBFR(sub SBP) in the order of HL (12.73+/-1.42 cm3,mean+/-SE) > LL (9.92+/-0.82 cm3) > LBFR(sub dBP)(6.47+/-0.79 cm3) > LBFR(sub SBP) (3.51+/-0.59 cm3). Blunted exercise induced increases occurred in HR, SV, and CO after LBFR compared to HL and LL. HR increased 45% after HL and LL and 28% after LBFR (p<0.05), but SV increased (p<0.05) only after HL. Consequently, the increase (p<0.05) in CO was greater in HL and LL (approximately 3 L/min) than in LBFR (approximately 1 L/min). CONCLUSION: BF during LBFR(sub SBP) was 1/3 of that observed in LL, which supports the hypothesis that local ischemia stimulates the LBFR hypertrophic response. As the cuff did not compress the artery, the ischemia may have occurred because of the blunted rise in CO or because arterial BP cannot overcome the cuff pressure. As LBFR(sub DBP) effectively reduced BF and CO with cuff pressures less than systolic BP, future studies should investigate the hypertrophic potential of LBFR at even lower cuff pressures.

Everett, M. E.↗
NASA NTRS2014

KSC Press Site Transformer Bldg. (K7-1205c) SWMU 074 Interim Measure Work Plan

This document presents and discusses the Interim Measure (IM) Work Plan for the Press Site Transformer Building (K7-1205C). The purpose of the proposed IM activities is to remove soil affected with polychlorinated biphenyls (PCBs) greater than the Florida Department of Environmental Protection (FDEP) residential direct-exposure Soil Cleanup Target Level (R-SCTL) of 0.5 milligrams per kilogram and encapsulate concrete exhibiting PCB concentration greater than the Toxic Substance Control Act (TSCA) threshold of 50 milligrams per kilogram.

Remediation↗
NASA NTRS2015

Superelastic Ball Bearings: Materials and Design to Avoid Mounting and Dismounting Brinell Damage in an Inaccessible Press-fit Application-: Detailed Analysis - II

Rolling element bearings utilized in precision rotating machines require proper alignment, preload, and interference fits to ensure overall optimum performance. Hence, careful attention must be given to bearing installation and disassembly procedures to ensure the above conditions are met. Usually, machines are designed in such a way that bearings can be pressed into housings or onto shafts through the races without loading the rolling elements. However, in some instances, either due to limited size or access, a bearing must be installed or removed in such a way that the load path travels through the rolling elements. This can cause high contact stresses between the rolling elements and the races and introduces the potential for Brinell denting of the races. This paper is a companion to the Part I paper by the authors that discusses material selection and the general design philosophy for the bearing. Here, a more in-depth treatment is given to the design of a dent-resistant bearing utilizing a superelastic alloy, 60NiTi, for the races. A common bearing analysis tool based on rigid body dynamics is used in combination with finite element simulations to design the superelastic bearing. The primary design constraints are prevention of denting and avoiding the balls riding over the edge of the race groove during a blind disassembly process where the load passes through the rolling elements. Through an iterative process, the resulting bearing geometry is tailored to improve axial static load capability compared to a deep-groove ball bearing of the same size. The results suggest that careful selection of materials and bearing geometry can enable blind disassembly without damage to the raceways, which is necessary in the current application (a compressor in the International Space Station Environmental Control and Life Support System), and results in potential design flexibility for other applications, especially small machines with miniature bearings.

metals↗
NASA NTRS2011

Support Assembly for Composite Laminate Materials During Roll Press Processing

A composite laminate material is supported during the roll press processing thereof by an assembly having: first and second perforated films disposed adjacent to first and second opposing surfaces of a mixture of uncured resin and fibers defining the composite laminate material, a gas permeable encasement surrounding the mixture and the first and second films, a gas impervious envelope sealed about the gas permeable encasement, and first and second rigid plates clamped about the gas impervious envelope.

Catella, Luke A.↗
NASA NTRSDate not supplied

Ultrahigh Mass Loading Batteries with Holey Graphene-Enabled Dry-Pressed Cathode Architectures

Holey graphene is a structural derivative of graphene with arrays of nanometer-sized, through-thickness holes across the lateral surface of the atomically thin nanosheet. It has been widely acknowledged that the presence of holes improves ion transport through the graphene planes, making holey graphene an ideal electrode material for electrochemical energy storage. We recently discovered another unique attribute of holey graphene in that it can be directly compressed from powder into electrode in a single step without the use of solvent or binder. In addition to neat holey graphene electrodes, composite electrodes with holey graphene as an ultralightweight scaffold host filled with various active materials can also be readily prepared in a similar solvent-free and binder-free fashion. The active materials can be metal-containing catalysts for lithium-oxygen batteries, lithium-ion battery electrode materials, or high energy density components such as sulfur. Compared to the conventional slurry-based process, the dry-press method is comparably much more suitable toward the facile and scalable preparation of ultrahigh mass loading electrodes with ultrahigh areal capacities.

holey graphene, cathode scaffold, lithium metal, h↗
NASA NTRS2021

Hot Isostatic Pressing for Reduction of Defects in Additively Manufactured Inconel-718 Preliminary Simulation Approach and Results

Selective laser melting (SLM) of Inconel-718 (IN718) is a promising advanced manufacturing technology; however, challenges exist for fracture-critical parts where pores induced during the manufacturing process reduce fatigue life of the material. Hot isostatic pressing (HIP) is a common post processing technique used to reduce the part porosity by exposing parts to high temperature and pressures. Pore closure depends on the pore shape, trapped gas, and HIP parameters, and the process can only be optimized by understanding the effect of these variables. An analysis capability is described to better understand the conditions necessary for pore closure, and the effect of several variables on porosity are explored and compared to a baseline case. The importance of valid material response models is identified as a significant factor in model accuracy; especially the creep material response model which, in the baseline case, predicts that creep strain accounts for 87.7% of the total strain at the conclusion of the HIP cycle. Lessons learned are described, in addition to future work including model validation.

Joshua M Fody↗
DOE OSTI2012

Hot Isostatic Press Manufacturing Process Development for Fabrication of RERTR Monolithic Fuel Plates

We use experimentation and finite element modeling to study a Hot Isostatic Press (HIP) manufacturing process for U-10Mo Monolithic Fuel Plates. Finite element simulations are used to identify the material properties affecting the process and improve the process geometry. Accounting for the high temperature material properties and plasticity is important to obtain qualitative agreement between model and experimental results. The model allows us to improve the process geometry and provide guidance on selection of material and finish conditions for the process strongbacks. We conclude that the HIP can must be fully filled to provide uniform normal stress across the bonding interface.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

B2 Grain Growth Behavior of a Ti-22Al-25Nb Alloy Fabricated by Hot Pressing Sintering

Grain growth behavior of a powder metallurgy (P/M) Ti-22Al-25Nb alloy was investigated by applying a series of isothermal treatment tests over a wide range of temperatures and holding times. An isothermal treatment scheme was conducted in the B2 phase region (1070-1110 °C) and α{sub 2} + B2 phase region (1010-1050 °C) at holding times of 10, 30 min, 1, 2, and 3 h, respectively. The effects of temperature and holding time on the microstructure evolution and microhardness of the P/M Ti-22Al-25Nb alloy at elevated temperatures were evaluated using optical microscope, scanning electron microscope, x-ray diffraction, and Vickers hardness test techniques. The results revealed that the alloy’s treated microstructure was closely linked to temperature and holding time, respectively. The change law of B2 grain growth with holding time and temperature can be well interpreted by the Beck equation and Hillert equation, respectively. The B2 grain growth exponent n and activation energy Q were acquired based on experimental data in the α{sub 2} + B2 and B2 phase regions. In addition, the grain growth contour map for the P/M Ti-22Al-25Nb alloy was constructed to depict variations in B2 grain size based on holding time and temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Characterization and crystallographic analyses of new three-fold Ti(O,C) nanotwins in a hot-pressed Nb-Ti-al alloy

Highlights: • Two new types of three-fold Ti(O,C) twins were observed in Nb-Ti-Al alloy. • Crystallographic relationships of the twins were analyzed in detail. • Different intersection angles derive from crystallographic operation forming twins. • Ambiguity of a 3-fold twin was clarified by the analysis of the common [011] axis. - Abstract: In this article, two new types of three-fold Ti(O,C) twins were observed, and the crystallographic relationships of the twins have been analyzed in depth. The difference in the intersection angles of primary twin boundaries derives from different crystallographic operations forming the face-centered cubic Ti(O,C) twins: two consecutive rotations of 70.5° counter-clockwise or clockwise around the [011] axis. Using double and triple Thompson tetrahedrons, the ambiguity of a three-fold twin in TEM observation is clarified by the analysis of the common [011] axis. These findings might bring about substantial insights to the crystallographic understanding of three-fold twins.

36 MATERIALS SCIENCE↗
DOE OSTI2016

FY16 Annual Accomplishments - Waste Form Development and Performance: Evaluation Of Ceramic Waste Forms - Comparison Of Hot Isostatic Pressed And Melt Processed Fabrication Methods

FY16 efforts were focused on direct comparison of multi-phase ceramic waste forms produced via melt processing and HIP methods. Based on promising waste form compositions previously devised at SRNL, simulant material was prepared at SRNL and a portion was sent to the Australian Nuclear Science and Technology Organization (ANSTO) for HIP treatments, while the remainder of the material was melt processed at SRNL. The microstructure, phase formation, elemental speciation, and leach behavior, and radiation stability of the fabricated ceramics was performed. In addition, melt-processed ceramics designed with different fractions of hollandite, zirconolite, perovskite, and pyrochlore phases were investigated. for performance and properties.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

The Consolidation of Glass-Ceramic Waste forms by Hot Isostatic Pressing: Sample Optimisation - 16581

Zirconolite based glass-ceramics were developed for the disposition of plutonium residues at the UK's Sellafield site. Glass-ceramics act as double barrier systems, separating Pu into a durable ceramic phase and retaining miscellaneous material in the amorphous phase. Here we discuss the optimisation of processing parameters and formulations of these alternative waste-forms. All samples were HIPed at 1250 deg. C, 100 MPa for 4 hrs. By investigating the effects of different pre-HIP heat treatments on sample quality and throughput, and glass phase compositions on the crystalline phase assemblage, an optimised method and wasteform composition were achieved. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

MRP: Qualification of Powder Metallurgy Hot Isostatic Pressed (PM HIP) Materials for Elevated-Temperature Nuclear Construction

PM HIP is a mature technology that offers many advantages that are attractive to the microreactor industry. The elevated-temperature creep-fatigue properties of the PM HIP 316H SS bar that has been characterized are reduced compared to the wrought material. Work will be carried out in fiscal year 2022 to identify the mechanisms responsible for the reduced creep-fatigue properties. Confirmatory testing of optimized material will be conducted to demonstrate long-term PM HIP properties comparable to the wrought-product form. The lessons learned for PM HIP 316H SS will be applied to the procurement and confirmatory testing of PM HIP Alloy 800H.

316H stainless steel↗
DOE OSTI2013

Resolving the grain boundary and lattice impedance of hot-pressed Li 7 La 3 Zr 2 O 12 garnet electrolytes

Here, the cubic-stabilized garnet solid electrolyte with a nominal composition of Li 6.28 Al 0.24 La 3 Zr 2 O 12 is thoroughly characterized by impedance spectroscopy. By varying the frequency of the applied AC signal over 11 orders of magnitude for characterizations from –100 to +60 °C, the relative contributions of grain and grain boundary conduction are unambiguously resolved.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Chemical composition of cold‐pressed blackberry seed flour extract and its potential health‐beneficial properties

Abstract The blackberry seed flour was cold‐extracted using 50% acetone and examined for its phytochemical composition and health‐beneficial properties including in vitro gut microbiota modulatory, free radical scavenging, anti‐inflammatory, and antiproliferative capacities. Among identified thirteen components of blackberry seed flour extract through UHPLC‐MS analysis, sanguiin H6 was the primary component and followed by ellagic acid and pedunculagin. For health‐beneficial properties, the blackberry seed flour extract increased the total number of gut bacteria and shifted the abundance of specific bacterial phylum, family, or genus. The extract had RDSC, ORAC, HOSC, and ABTS •+ scavenging capacities of 362, 304, 2,531, and 267 μmol Trolox equivalents (TE)/g, respectively. In addition, the blackberry seed flour extract showed capacities for anti‐inflammation and antiproliferation by suppressing LPS induced IL‐1β mRNA expressions in the cultured J774A.1 mouse macrophages and the proliferation of LNCaP prostate cancer cells. The results suggest potential health benefits and further utilization of blackberry seed flour as functional foods.

Choe, Uyory↗