Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Eutectic”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Self Assembled Structures by Directional Solidification of Eutectics

Interest in ordered porous structures has grown because of there unique properties such as photonic bandgaps, high backing packing density and high surface to volume ratio. Inspired by nature, biometric strategies using self assembled organic molecules dominate the development of hierarchical inorganic structures. Directional solidification of eutectics (DSE) also exhibit self assembly characteristics to form hierarchical metallic and inorganic structures. Crystallization of diphasic materials by DSE can produce two dimensional ordered structures consisting of rods or lamella. By selective removal of phases, DSE is capable to fabricate ordered pore arrays or ordered pin arrays. Criteria and limitations to fabricate hierarchical structures will be presented. Porous structures in silicon base alloys and ceramic systems will be reported.

Dynys, Frederick W.↗
DOE OSTI2012

Heat Capacity Uncertainty Calculation for the Eutectic Mixture of Biphenyl/Diphenyl Ether Used as Heat Transfer Fluid: Preprint

The main objective of this study was to calculate the uncertainty at 95% confidence for the experimental values of heat capacity of the eutectic mixture of biphenyl/diphenyl ether (Therminol VP-1) determined from 300 to 370 degrees C. Twenty-five samples were evaluated using differential scanning calorimetry (DSC) to obtain the sample heat flow as a function of temperature. The ASTM E-1269-05 standard was used to determine the heat capacity using DSC evaluations. High-pressure crucibles were employed to contain the sample in the liquid state without vaporizing. Sample handling has a significant impact on the random uncertainty. It was determined that the fluid is difficult to handle, and a high variability of the data was produced. The heat capacity of Therminol VP-1 between 300 and 370 degrees C was measured to be equal to 0.0025T+0.8672 with an uncertainty of +/- 0.074 J/g.K (3.09%) at 95% confidence with T (temperature) in Kelvin.

14 SOLAR ENERGY↗
DOE OSTI2019

Additive manufacturing via direct writing of pure metal and eutectics through latent heat position control

An additive manufacturing system for producing metal parts from pure metal or eutectic alloys. The system includes an additive manufacturing print head, a print head heater system, an agitation system, a nozzle in the additive manufacturing print head, a reservoir for melting the metal, and a long heated tube for conditioning the alloy for extrusion in the semi-solid state through a nozzle.

Pascall, Andrew J.↗
DOE OSTI2020

Low-temperature bonding with spaced nanorods and eutectic alloys

Bonded surfaces are formed by adhering first nanorods and second nanorods to respective first and second surfaces. The first shell is formed on the first nanorods and the second shell is formed on the second nanorods, wherein at least one of the first nanorods and second nanorods, and the first shell and the second shell are formed of distinct metals. The surfaces are then exposed to at least one condition that causes the distinct metals to form an alloy, such as eutectic alloy having a melting point below the temperature at which the alloy is formed, thereby bonding the surfaces upon which solidification of the alloy.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Deep Learning Potential For Investigation of Chemical Conversion of CO2 at Air-Reactive Deep Eutectic Solvent Interface

Capturing CO2 from air is urgent to battle against the climate change. Traditional CO2 capture by alkaline solution or aqueous amine has high regeneration cost, equipment corrosion, and amine leakage. Deep eutectic solvents (DESs) are promising alternatives with low corrosion, non-toxicity, and biodegradable nature. Functionalized DESs can capture and convert CO2 at low partial pressures. Developing reactive DESs for efficient CO2 capture needs a foundational understanding of the reaction-transport coupling of CO2 at the air-DES interface. In this study, we develop a deep learning potential (DLP) to investigate the absorption and reaction of CO2 at the air-DES interface (DES: 1-ethyl-3-methylimidazolium 2-cyanopyrrolide ([Emim][2-CNpyr]) and ethylene glycol (EG)). The DLP model allows us to simulate chemical reactions at a lower computational cost with ab initio accuracy. By analyzing reaction free energy surfaces, molecular interactions among CO2, DES components and reaction products, and transport of CO2 through the interface, we identify three main reaction pathways of CO2 at the interface: forming carboxylate with [Emim], carbamate with [2-CNpyr], and carbonate with EG. The mechanistic understanding of CO2 chemisorption at the interface will facilitate the development of novel direct air capture technology using DESs.

Nguyen, Manh Tien↗
DOE OSTI2016

Determination of Activity of Neodymium(III) in Molten Eutectic LiCl-KCl using Electrochemical Methods

The pyrochemical recycling of actinides is a promising option for closing the nuclear fuel cycle. The technology is particularly attractive for recycle of metallic and molten salt fuels. The Republic of Korea is also taking a serious look at the application of pyrochemical treatment of used oxide fuel from Pressurized Water Reactors (PWR). The science behind pyrochemical recycling is being actively studied at the various national labs and universities. The Rare Earth Drawdown process is proposed to be included in a commercial pyrochemical recycling facility in order to minimize the amount of waste generated from the processing that will require permanent disposal in a geological repository. This process involves selective extraction of rare earth elements from electro-refiner salt. The salt can then be further processed to selectively remove Group I-II active metals and eventually be recycled back to the electro-refiner. The preferred method of separation of the rare earths from the salt is using electrolysis due to its inherent selectivity and ease of operation. The purpose of this study is to evaluate the effects of the presence of cesium (Group I) on the electrochemical behavior of neodymium in a molten eutectic LiCl-KCl salt. The activity and by extension the activity coefficient of a species determines many of the key electrochemical properties such as apparent reduction potential. In this study, we have undertaken a series of experiments to experimentally determine the activity coefficient of the dissolved neodymium(III) ions as a function of concentration, both in the presence and absence of cesium. This was done using a first of its kind electrochemical cell. Previously, activity of dissolved species has been determined using electrochemical cells in which equilibrium potentials are measured for the Nd/Nd(III) versus a Ag/AgCl reference electrode. There are several issues associated with such an approach. These electrodes are associated with several sources of errors; indeterminate values of Standard Reduction Potentials of (E{sup θ}) for Ag and Nd in molten salts, unknown liquid junction potentials and potential drifts. These uncertainties contribute errors to the experimental measurements. For this study, we employed a Nd/LiCl-KCl-NdCl{sub 3(Saturatedelectrode)}. There are several advantages with using such an electrode. If the expanded Nernst Equation is written for the aforementioned electrochemical cell, all of the terms cancel out except the activity term. This enables us to directly experimentally measure the activity of the species in solution. When we use a saturated NdCl{sub 3} reference electrode, the activity that is measured is defined as the activity versus a 'Saturated Solid State'. To determine the activity coefficients, we need to determine the activity versus the 'Liquid Standard Sate'. To convert the activity from solid standard state to liquid standard state, we correct for it using the hypothetical Gibbs free energy of fusion for neodymium chloride. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Conceptual design of inverted core lead bismuth eutectic fast reactor for marine applications

The development of an inverted core fast reactor aims to generate 60 MWth for about 30 Effective Full Power Years without refueling. The reactor design is a transportable reactor using UO{sub 2} fuel and lead-bismuth-eutectic cooled designed for marine applications and is intended to improve the reactor performances compared to the normal core design: better condition for passive cooling system capability by lower core pressure drop, taking advantage of potential power uprate from the lower maximum fuel temperature. Systematic design processes are presented in this work: fuel pin geometry selection, fuel assembly (FA) design, and core design. A relationship between pressure drops, coolant velocity, maximum fuel temperature, coolant channel diameter, and fuel volume fraction was introduced in a single graph used as a tool to select fuel pin geometry. Fuel fabrication capability also took place in consideration of FA design which led to 7 holes per FA, and two-dimensional temperature distribution studies were also carried out. Core design processes including radial zoning, axial zoning, and core optimization were conducted using Monte Carlo code MCS, which is UNIST CORE laboratory in-house code. The current core design uses 3 fuel enrichment levels and 3 FA types to control the local power distribution and power shift during its lifetime. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2020

Multi-Step Crystallization of Self-Organized Spiral Eutectics

A method for the solidification of metallic alloys involving spiral self-organization is presented as a new strategy for producing large-area chiral patterns with emergent structural and optical properties, with attention to the underlying mechanism and dynamics. This study reports the discovery of a new growth mode for metastable, two-phase spiral patterns from a liquid metal. Crystallization proceeds via a non-classical, two-step pathway consisting of the initial formation of a polytetrahedral seed crystal, followed by ordering of two solid phases that nucleate heterogeneously on the seed and grow in a strongly coupled fashion. Crystallographic defects within the seed provide a template for spiral self-organization. These observations demonstrate the ubiquity of defect-mediated growth in multi-phase materials and establish a pathway toward bottom-up synthesis of chiral materials with an inter-phase spacing comparable to the wavelength of infrared light. Given that liquids often possess polytetrahedral short-range order, our results are applicable to many systems undergoing multi-step crystallization.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of Ceramic Rolling and Annealing on Mechanical Properties of AlCoCrFeNi{sub 2.1} Eutectic High-Entropy Alloys

It was firstly proved that AlCoCrFeNi{sub 2.1} could optimize the strength-ductility combination by ceramic rolling at room temperature. The technique greatly enhanced the strength of the materials at the price of slight ductility, which is different from the previous studies. When the thickness reduction was 23.06%, the yield strength and compressive strength were 1611.42 and 2212.99 MPa, respectively, with the plastic strain of 28.36%. Such an excellent combination of strength and ductility was attributed to the distribution of the residual stress, the high hydrostatic stress and the shear bands in ceramic rolling process. The plastic strain of the material increased to 38.54%, and the strength reduced to 1900.73 MPa after annealing at 800 °C for 1 h. A lot of like-flower patterns of recrystallized ultrafine grain were observed after annealing at 800 °C due to the sluggish diffusion in HEAs and the effect of ceramic rolling. In addition, after annealing at 800 °C, the fracture mode changed to shearing fracture of microvoid aggregation from cleavage/quasi-cleavage fracture of as-rolled sample due to the deposition of the second phase in the tested sample.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Ion transport in non-aqueous electrolyte mixtures of zinc chloride deep eutectic solvent (DES) and molecular solvents

For this work, the ion dynamics of null solvents 1ZnCl 2 :4EtG and 1ChCl:1ZnCl 2 :6EtG incorporating 1M water, propylene carbonate (PC) or acetonitrile (AcN) were investigated using 1 H NMR spectra and spin-lattice relaxation time (T 1 ) measurements combined with ionic conductivity, density, and viscosity, all as a function of temperature. Results show that the inclusion of all co-solvents increased the available free volume of the mixtures and followed the trend H 2 O ≤ PC < AcN. 1 H NMR spectra and T 1 inferred the presence of multiple ionic species with varying rates of mobilities. These dynamic heterogeneities were displayed by the broad T 1 minima – especially for the 1ZnCl 2 :4EtG mixtures – and asymmetrically broadened linewidths. T 1 results also revealed selective interaction sites between the hydrogen bond donors and acceptors, as well as with the co-solvents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Thermodynamic Assessment of Hot Corrosion Mechanisms of Superalloys Hastelloy N and Haynes 242 in Eutectic Mixture of Molten Salts KF and ZrF4

The KF - ZrF4 system was considered for the application as a heat exchange agent in molten salt nuclear reactors (MSRs) beginning with the work carried out at ORNL in early fifties. Based on a combination of excellent properties such as thermal conductivity, viscosity in the molten state, and other thermo-physical and rheological properties, it was selected as one of possible candidates for the nuclear reactor secondary heat exchanger loop.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Deep Eutectic Salt Formulations Suitable as Advanced Heat Transfer Fluids

Concentrating solar power (CSP) facilities are comprised of many miles of fluid-filled pipes arranged in large grids with reflective mirrors used to capture radiation from the sun. Solar radiation heats the fluid which is used to produce steam necessary to power large electricity generation turbines. Currently, organic, oil-based fluid in the pipes has a maximum temperature threshold of 400 °C, allowing for the production of electricity at approximately 15 cents per kilowatt hour. The DOE hopes to foster the development of an advanced heat transfer fluid that can operate within higher temperature ranges. The new heat transfer fluid, when used with other advanced technologies, could significantly decrease solar electricity cost. Lower costs would make solar thermal electricity competitive with gas and coal and would offer a clean, renewable source of energy. Molten salts exhibit many desirable heat transfer qualities within the range of the project objectives. Halotechnics developed advanced heat transfer fluids (HTFs) for application in solar thermal power generation. This project focused on complex mixtures of inorganic salts that exhibited a high thermal stability, a low melting point, and other favorable characteristics. A high-throughput combinatorial research and development program was conducted in order to achieve the project objective. Over 19,000 candidate formulations were screened. The workflow developed to screen various chemical systems to discover salt formulations led to mixtures suitable for use as HTFs in both parabolic trough and heliostat CSP plants. Furthermore, salt mixtures which will not interfere with fertilizer based nitrates were discovered. In addition for use in CSP, the discovered salt mixtures can be applied to electricity storage, heat treatment of alloys and other industrial processes.

25 ENERGY STORAGE↗