Combining mesoscale thermal transport and x-ray diffraction measurements to characterize early-stage evolution of irradiation-induced defects in ceramics
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Khafizov, Marat (ORCID:0000000181713528)↗
SEARCH · Engineering Papers
Results for “Thermal characterization”
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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Assessment of Technologies for the Space Shuttle External Tank Thermal Protection System and Recommendations for Technology Improvement: Materials Characterization and Analysis - Part 1
The use of foam insulation on the External Tank (ET) was necessitated by the potentially hazardous build up of ice on the vehicle prior to and during launch. This use of foam was initiated on the Saturn V rocket, which, like the Space Shuttle, used cryogenic fuel. Two major types of foam have been used on the ET. The first type is NCFI 24-124, an acreage material that is automatically sprayed on in a controlled environment. It replaced CPR 488 in 1998 and has been used since that time. The other major foams, BX-250 or BX-265, are handsprayed foams that are used to close out regions where the various sections of the ET are attached. The objectives of the present report are to study the chemistries of the various foam materials and to determine how physical and mechanical anomalies might occur during the spray and curing process. To accomplish these objectives, the report is organized as follows. First, the chemistries of the raw materials will be discussed. This will be followed by a discussion of how chemistry relates to void formation. Finally, a TGA-MS will be used to help understand the various foams and how they degrade with the evolution of chemical by-products.
Weiser, Erik S.↗
Lamb wave characterization of the effects of long-term thermal-mechanical aging on composite stiffness
Lamb waves offer a promising method of evaluating damage in composite materials. The Lamb wave velocity is directly related to the material parameters, so an effective tool exists to monitor damage in composites by measuring the velocity of these waves. The Lamb Wave Imager (LWI) uses a pulse/receive technique that excites an antisymmetric Lamb mode and measures the time-of-flight over a wide frequency range. Given the material density and plate thickness, the bending and out-of-plane shear stiffnesses are calculated from a reconstruction of the dispersion curve. In this study, the time-of-flight as well as the elastic stiffnesses D11, D22, A44, and A55 for composite samples which have undergone combined thermal and mechanical aging are obtained. The samples examined include a baseline specimen with 0 cycles, specimens which have been aged 2350 and 3530 cycles at high strain levels, and one specimen aged 3530 cycles at low strain levels.
Aircraft↗
Development of high temperature silicone adhesive formulations for thermal protection system applications
Trade-off studies and screening evaluations were made of commercial polymers and silicone foam sheet stock. A low modulus, low density 0.26 gm/cc modification was developed of the GE-RESD PD-200 system based upon GE RTV-560 silicone polymer. The bond system modification was initially characterized for mechanical and thermal properties, evaluated for application methods, and its capability demonstrated as a strain arrestor bond system.
Hockridge, R. R.↗
Tutorial - Electric Motor and Integrated Traction Drive Thermal Management
The share of vehicles with fully electric propulsion systems is constantly increasing, and so is their traction drive power. The continuous push to increase power of electric vehicle (EV) traction drives necessitates their efficient cooling to prevent damage to temperature sensitive components of the drive system and achieving higher power outputs in a smaller footprint. With increasing power and power density of electric traction drives, their thermal management is becoming increasingly challenging. This tutorial will provide an overview of thermal management approaches for electric motors and power electronics in EV applications. It will review examples of current industry solutions for power-dense electric motor cooling, power electronics (inverter) cooling, their integration concepts and thermal management system solutions. We'll look at the advantages and challenges of power electronics integration into a single traction drive unit and respective thermal management system concepts. We'll talk about barriers to implementation of a unified thermal management system. The tutorial will also review key aspects of thermal management system design: modeling and simulation using FEA and CFD tools, experimental characterization, and general workflow for thermal management system evaluation.
ADVANCED PROPULSION SYSTEMS,DIRECT ENERGY CONVERSI↗
Saturn's Equatorial Oscillation: Evidence of Descending Thermal Structure from Cassini Radio Occultations
Ground-based and Cassini CIRS thermal-infrared data have characterized the spatial and temporal characteristics of an equatorial oscillation in Saturn's middle atmosphere above the 100-mbar level. The CIRS data indicate a vertical pattern of alternating warm and cold anomalies at the equator. From the thermal wind equation this implies a concomitant reversal of zonal winds with attitude, relative to the cloud-top winds, with peak-to-peak amplitude approximately 200 meters per second. The ground-based observations do not having the altitude range or vertical resolution of the CIRS observations, but they cover several years and indicate an oscillation cycle of 1 years, roughly half of Saturn's year. Equatorial oscillations in Earth's middle atmosphere have primarily exhibited either quasi-biennial or semi-annual "periodicities," and both types have been extensively observed and modeled. They exhibit a vertical pattern of alternating warmer and cooler zonal-mean temperatures and zonal winds analogous to that described above for Saturn. Moreover, the pattern of winds and temperatures descends with time. Momentum deposition by damped vertically propagating easterly and westerly waves is thought to play a key role in forcing both types of oscillation, and it can plausibly account for the descent. Here we report the direct observation of this descent in Saturn's equatorial atmosphere from Cassini radio occultation soundings in 2005 and 2009. The retrieved temperatures are consistent with a descent of 0.6 x the pressure scale height over this time period. The descent rate is related to the magnitude of the wave forcing, radiative damping, and induced meridional circulations. A simple calculation implies that vertical wave fluxes of zonal momentum approximately 0.05 square meters per square second could account for the observed vertical descent on Saturn, which is comparable to the magnitude of the wave fluxes associated with the terrestrial quasi-biennial oscillation.
Flasar, F. M.↗
Uncovering the Size-dependent Thermal Solid Transformation of Akaganéite
Investigating the structural evolution and phase transformation of iron oxides is crucial for gaining a deeper understanding of geological changes on diverse planets and preparing oxide materials suitable for industrial applications. In this study, we employed in-situ heating techniques in conjunction with transmission electron microscopy (TEM) observations and ex-situ characterization to thoroughly analyze the thermal solid-phase transformation of akaganéite one-dimensional (1D) nanostructures with varying diameters. Our findings offer compelling evidence for a size-dependent morphology evolution in akaganéite 1D nanostructures, which can be attributed to the transformation from akaganéite to maghemite (?-Fe2O3) and subsequent crystal growth. Specifically, we observed that akaganéite nanorods with a diameter of around 50 nm transformed into hollow polycrystalline maghemite nanorods, which demonstrated remarkable stability without arresting crystal growth under continuous heating. In contrast, smaller akaganéite nanoneedles or nanowires with a diameter ranging from 20 to 8 nm displayed a propensity for forming single-crystal nanoneedles or nanowires through phase transformation and densification. By manipulating the size of the precursors, we have developed a straightforward method for the synthesis of single-crystal and polycrystalline maghemite nanowires through solid-phase transformation. These significant findings provide new insights into the size-dependent structural evolution and phase transformation of iron oxides at the nanoscale.
Wang, Xiang↗
Prethermalization in coupled one-dimensional quantum gases
We consider the problem of the development of steady states in one-dimensional Bose gas tubes that are weakly coupled to one another through a density-density interaction. We analyze this development through a Boltzmann collision integral approach. We argue that when the leading order of the collision integral, where single particle-hole excitations are created in individual gases, is dominant, the state of the gas evolves first to a non-thermal fixed point, i.e. a prethermalization plateau. This order is dominant when a pair of tubes are inequivalent with, say, different temperatures or different effective interaction parameters, \gamma γ . When both tubes are in the strongly interacting regime we additionally characterize this non-thermal prethermalization plateau by constructing the quasi-conserved quantities that control the existence of this plateau as well as the associated generalized Gibbs ensemble.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Heat Transfer of Supercritical Carbon Dioxide in 3D-Printed Tubes with Internal Ribs and Yttria Stabilized Zirconia Coating
This technical report describes measurements performed in NETL’s Heat Exchanger Experimental Test (HEET) facility using supercritical carbon dioxide as the working fluid. 3D printed tubes with internal ribs and yttria stabilized zirconia (YSZ) exterior coatings were employed in the heat exchanger. Heat transfer and friction factor enhancements from the internal ribs were characterized over a range of flow conditions. Additionally, the thermal resistance from the YSZ coating was characterized for both a freshly applied coating and a coating subjected to thermal aging.
36 MATERIALS SCIENCE↗
Characterization of Two Fast-Turnaround Dry Dilution Refrigerators for Scanning Probe Microscopy
Low-temperature scanning probe microscopes (SPMs) are critical for the study of quantum materials and quantum information science. Due to the rising costs of helium, cryogen-free cryostats have become increasingly desirable. However, they typically suffer from comparatively worse vibrations than cryogen-based systems, necessitating the understanding and mitigation of vibrations for SPM applications. Here, in this work, we demonstrate the construction of two cryogen-free dilution refrigerator SPMs with minimal modifications to the factory default and we systematically characterize their vibrational performance. We measure the absolute vibrations at the microscope stage with geophones and use both microwave impedance microscopy and a scanning single-electron transistor to independently measure tip-sample vibrations. Additionally, we implement customized filtering and thermal anchoring schemes and characterize the cooling power at the scanning stage and the tip electron temperature. This work serves as a reference to researchers interested in cryogen-free SPMs, as such characterization is not standardized in the literature or available from manufacturers.
36 MATERIALS SCIENCE↗
Characterization of geometric isomers of Norbornene end-capped imides
Three geometric isomers from the thermal isomerization of methylene-4,4' bis(endo-N-phenylbicyclo/2.2.1/hept-2-ene-5,6-di carboximide) (I) were chromatographically separated and isolated in order to investigate the thermal cure of norbornene end-capped imide oligomers, which display considerable promise for use in various aerospace adhesive and composite applications. Endo-endo (I), endo-exo (II), and exo-exo (III) configurations were assigned to each compound based on the results of NMR spectroscopy. Several chromatographic, spectroscopic, and thermal techniques were then used to characterize these three isomers which serve as model compounds for norbornene end-capped polyimides. It was found that each compound thermally isomerized to an equilibrium mixture of all three compounds prior to cure. It is proposed that these compounds react by different mechanisms in air and nitrogen.
Young, P. R.↗
Charpy Impact Characterization of Surveillance Specimens Harvested from Palisades High Fluence A-60 Capsule
Located on the shores of Lake Michigan, the Palisades Nuclear Generating Station (PNGS) was a nuclear power plant that operated in Covert Township, Michigan. The plant had a single pressurized water reactor that produced electricity for the region. The PNGS was shut down in 2022 after more than four decades of service. The PNGS included in its surveillance program a surveillance capsule, designated A-60, containing specimens of a weld metal with nickel content of about 1.36 wt% and copper content of about 0.25 wt%. The capsule was removed from its surveillance position in early 1995 and has been resident in the spent fuel pool since that time. This capsule was irradiated to a fluence of 1.96×10 20 n/cm 2 (E>1MeV) that is equivalent for more than 150 effective full power years (EFPYs) for the US reactor pressure vessel (RPV) fleet. The material is also of special interest because of its very high nickel content and potential for development of NiMnSi (nickel-manganese-silicon) precipitates. Combination of very high fluence and very high Ni and Cu content makes the material in this capsule of great interest as benchmark for currently developing embrittlement trend curves (ETC) aiming to predict embrittlement at high fluences. Multi-year efforts by the Light Water Reactor Sustainability (LWRS) Program personnel from the Materials Research Pathway (MRP) to harvest this capsule finally succeeded in 2023. As a result, the Westinghouse Electric Company (WEC) through contract with Oak Ridge National Laboratory (ORNL) came to PNGS site, retrieved the A-60 capsule, brought it to WEC Churchill hot cell facility, opened the capsule and sent all surveillance specimens in the capsule to ORNL for future characterization by July 2023. Total of 9 tensile and 48 Charpy specimens were inventoried in the ORNL hot cells. Testing plan has been developed based on available specimens. It includes hardness, tensile, Charpy impact, Mini-CT fracture toughness testing, in-situ thermal annealing, and microstructural characterization, including Atom Probe Tomography (APT). Charpy impact testing has been completed and results are presented in this report. Moreover, negotiations with Pressurized Water Reactors Owners Group (PWROG) and Westinghouse resulted in Westinghouse donating to ORNL a piece of archive weld and base metal such that unirradiated characterization of these materials can be performed as part of this project. Comparison of measured hardening and embrittlement has been performed and data are compared to available large database.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Thermally Conductive Metal-Tube/Carbon-Composite Joints
An improved method of fabricating joints between metal and carbon-fiber-based composite materials in lightweight radiators and heat sinks has been devised. Carbon-fiber-based composite materials have been used in such heat-transfer devices because they offer a combination of high thermal conductivity and low mass density. Metal tubes are typically used to carry heat-transfer fluids to and from such heat-transfer devices. The present fabrication method helps to ensure that the joints between the metal tubes and the composite-material parts in such heat-transfer devices have both (1) the relatively high thermal conductances needed for efficient transfer of heat and (2) the flexibility needed to accommodate differences among thermal expansions of dissimilar materials in operation over wide temperature ranges. Techniques used previously to join metal tubes with carbon-fiber-based composite parts have included press fitting and bonding with epoxy. Both of these prior techniques have been found to yield joints characterized by relatively high thermal resistances. The present method involves the use of a solder (63 percent Sn, 37 percent Pb) to form a highly thermally conductive joint between a metal tube and a carbon-fiber-based composite structure. Ordinarily, the large differences among the coefficients of thermal expansion of the metal tube, solder, and carbon-fiber-based composite would cause the solder to pull away from the composite upon post-fabrication cooldown from the molten state. In the present method, the structure of the solder is modified (see figure) to enable it to deform readily to accommodate the differential thermal expansion.
Copeland, Robert J.↗
Thermal expansion behavior of LDEF metal matrix composites
The thermal expansion behavior of Long Duration Exposure Facility (LDEF) metal matrix composite materials was studied by (1) analyzing the flight data that was recorded on orbit to determine the effects of orbital time and heating/cooling rates on the performance of the composite materials, and (2) characterizing and comparing the thermal expansion behavior of post-flight LDEF and lab-control samples. The flight data revealed that structures in space are subjected to nonuniform temperature distributions, and thermal conductivity of a material is an important factor in establishing a uniform temperature distribution and avoiding thermal distortion. The flight and laboratory data showed that both Gr/Al and Gr/Mg composites were stabilized after prolonged thermal cycling on orbit. However, Gr/Al composites showed more stable thermal expansion behavior than Gr/Mg composites and offer advantages for space structures particularly where very tight thermal stability requirements in addition to high material performance must be met.
Le, Tuyen D.↗
Li-ion cells for terrestrial robots
SAFT prismatic wound 5 Ahr MP series cells were evaluated for potential application in a lithium ion battery designed for Tactical Mobile Robots (TMR). In order to satisfy battery design requirements, a 10 Ahr battery containing two parallel 8-cell strings was proposed. The proposed battery has a weight and volume of approximately 3.2kg and 1.6 liters, respectively. Cell qualification procedures include initial characterization, followed by charge/discharge cycling at 100% DOD with intermittent EIS measurements at various state of charge. Certain cells were also subjected to extreme operational temperatures for worst-case analysis. Excellent specific energy (>130 Whr/kg) was obtained with initial characterization cycles. Even at abusive thermal conditions, the cell capacity fade was less than Ahr after 300 cycles. Rate characterization showed good cell discharge behavior with minimal decrease in capacity. At various state of charge, impedance measurements suggest that the cathode play a more significant role in capacity. At various state of charge impedance measurements suggest that the cathode play a more significant role in capacity fade than the anode.
robots↗
Crosslinked Matrimid®-like polyimide membranes with unimodal network structure for enhanced stability and gas separation performance
Gas separation membranes have attracted academic and industrial attention, and crosslinking has been identified to be one of the most effective ways to enhance membrane stability. In this paper, a series of crosslinked Matrimid®-like films with unimodal network structures are prepared via thermally end-linking phenylethnyl-terminated BTDA-DAPI oligomers with well-controlled molecular weight (i.e., 3000–15,000 g/mol), wherein the crosslink density (the inter-crosslink chain length) of resulting unimodal networks is systematically varied by using oligomers with various molecular weight. Comprehensive characterizations of chemical structure, thermal properties, microstructures are performed. Pure-gas permeation measurements are performed focusing on H 2 /CH 4 and CO 2 /CH 4 separations as a function of crosslink density. In sharp contrast to the commonly observed permeability reduction in randomly crosslinked networks, all the crosslinked unimodal films, even when densely crosslinked, present markedly enhanced permeability and well-maintained ideal selectivity relative to the uncrosslinked linear counterpart, leading to almost horizontal movements towards upper bounds along with expectedly enhanced membrane stability. In conclusion, it is concluded that introducing bulky groups at the crosslink sites provide a practical means to counteract the densification effect induced by crosslinking and the construction of unimodal networks exemplifies a fundamentally new strategy to regulate the microstructure and property of crosslinked membranes for gas separations.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Characterization of the Heat Extraction Capability of a Compliant, Sliding, Thermal Interface for Use in a High Temperature, Vacuum Microgravity Furnace
Much of the material science gained in microgravity research requires processing a sample in a high performance furnace. One such furnace currently being designed is the Quench Module Insert (QMI). The Principle Investigators, for whom the furnace is proposed, require high temperature gradients in their cylindrical samples to achieve the science objectives. One of the components critical to achieving high sample axial temperature gradients in the Quench Module Insert is a high performance cold zone to extract the heat from the sample. This cold zone employs a compliant, sliding thermal interface based on a Vel-Therm felt. This felt provides a conductive path between the Sample Cartridge Assembly (SCA) exterior surface and the interior surface of the water cooled chill block while allowing movement of the sample relative to the chill block. The Vel-Therm felt is composed of long polymer-based fibers affixed to a thin flexible substrate layer. The fibers are oriented perpendicular to this substrate giving the felt the appearance of a velvet fabric. The Vel-Therm felt heat extraction capability was quantified in earlier tests performed in an inert gas environment. The current activity, described in this paper, is intended to characterize the extraction capability of Vel-Therm felt in a vacuum environment similar to the QMI environment. This testing is necessary to quantify the thermal performance of the Vel-Therm felt and the sensitivity of that performance to key variables. The data derived from these tests will be incorporated into the current thermal models to improve the quality of the models and reduce uncertainty of the analytical results. In addition, the data will be used to help select the appropriate Vel-Therm felt and set proper operating limits as well as assess the performance range of the furnace. The objective of this test is to measure the heat extraction rate of the Vel-Therm felt as specified by the effective heat transfer coefficient. Therefore, the test setup was designed to force the bulk of the heat transfer through the area where the Vel-Therm felt was applied. A heat source, consisting of a ceramic heating element encased in a Copper (Cu) housing is mounted on four isolated support rods. A 6-layer molybdenum radiation shield is used to insulate against heat loss from the heater and prevent heat exchange between the hot and cold sides of the test apparatus. The Vel-Therm felt is affixed to the surface of the cold sink, a water-cooled Cu chill block. An adjustable plate supports and isolates the cold sink from above and is used to control the amount of the deflection of the Vel- Therm when in contact with the Cu heating element housing. The primary means of establishing the power being conducted through the felt is to measure the energy being transferred to the water passing through the chill block. Analysis was performed to support the assumption that the source and sink surfaces were approximately isothermal under the specific test conditions. As a check on the amount of power passing through the felt, the power supplied to the heater was also measured. Thermocouples were strategically located throughout the test apparatus for measurement purposes. A bell jar was lowered over the assembly to impose vacuum conditions. Currently, variables tested have been fiber compression and fiber type and surface temperatures (both the hot and cold side temperatures are hypothesized to be important to the performance of the Vel-Therm.) Selected runs were repeated to ensure consistency and repeatability. Results obtained thus far reveal that Vel-Therm performance is significantly degraded by fibers being exposed to high compression. It also shows that performance is somewhat negatively impacted by previous compression, thereby, raising the question of repeatability. In addition, early results show a significant dependence on temperature. A computer aided mathematical analysis of the test setup is ongoing. The results will be correlated to actual results. The correlation will examine such details as parasitic loses, conduction down the power leads and many other concerns.
Bellomy-Ezell, Jenny↗
Characterization and durability testing of plasma-sprayed zirconia-yttria and hafnia-yttria thermal barrier coatings. Part 2: Effect of spray parameters on the performance of several hafnia-yttria and zirconia-yttria coatings
This is the second of two reports which discuss initial experiments on thermal barrier coatings prepared and tested in newly upgraded plasma spray and burner rig test facilities at LeRC. The first report, part 1, describes experiments designed to establish the spray parameters for the baseline zirconia-yttria coating. Coating quality was judged primarily by the response to burner rig exposure, together with a variety of other characterization approaches including thermal diffusivity measurements. That portion of the study showed that the performance of the baseline NASA coating was not strongly sensitive to processing parameters. In this second part of the study, new hafnia-yttria coatings were evaluated with respect to both baseline and alternate zirconia-yttria coatings. The hafnia-yttria and the alternate zirconia-yttria coatings were very sensitive to plasma-spray parameters in that high-quality coatings were obtained only when specific parameters were used. The reasons for this important observation are not understood.
Miller, Robert A.↗