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At least 433 records · Page 24

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DOE OSTI2020

Method of fabricating rigid radiation reflectors

A rigid radiation reflector is fabricated from a powdered material transparent to light in a wavelength band extending from approximately 0.2 micrometers to at least 8 micrometers. The powdered material is dispersed in a liquid wherein the powdered material is at least 95% insoluble in the liquid. The resulting mixture is molded under pressure at room temperature and then sintered to generate a porous solid. The porous solid is cooled to room temperature. A surface of the porous solid is then coated with a light-reflecting metal.

Youngquist, Robert C.↗

DOE OSTI2021

Improvements to the Powder Processing of near-Final Shape alnico Magnets

Alnico permanent magnets (PMs), a recent PM system of interest as an attractive rare earth-free PM alternative, have advantageous high operating temperature and magnetic saturation with the potential for utilization in electric machines, e.g. interior-PM motors found in electric vehicles, if current directional solidification methods can be replaced by a true mass production approach. Recently, two unique alnico compositions, termed Full-Co and Co-lean, with improved coercivity, were gas atomized, compression molded, and vacuum sintered (4h at 1240°C) to high densities of 97.8% and 99.3%, respectively. However, the Co-lean remained fine grained isotropic magnets and the Full-Co grains were not textured, lowering magnetic strength in spite of attempts to grow large textured grains by a stress-biased solid state grain alignment method to convert them to high energy anisotropic magnets. It was hypothesized that oxidation during de-binding in air left many prior particle boundary oxides within the sintered microstructure that hindered grain growth and texturing during the stress-biased texturing procedure and prevented the desired abnormal grain growth (AGG). Here we explored a vacuum de-binding step that was linked (in-place) to vacuum sintering and found that the Co-lean exhibited faster uniform grain growth that doubled the average grain size (40 μm to 80 μm). Linked vacuum de-binding and sintering of Full-Co produced some AGG after only 1 h of 1240°C sintering. A new direction for promoting AGG (and stress-biased texturing) in alnico is being explored that utilizes a fundamental analysis of systems with second phase particles that either inhibit or boost grain growth. This effort explores the influence of vacuum de-binding linked to a series of lower sintering temperatures at a fixed time (4h) to see if oxide particle size and volume fraction can be changed to promote AGG conditions in alnico. Surprising qualitative results indicate that AGG may be promoted for vacuum sintering at less than 1200°C.

Rinko, Emily↗

DOE OSTI2021

Inkjet-Based 3D Printing: From Quantum Dots to Steel Tools

Inkjet-based additive manufacturing (AM) technologies are highly versatile among manufacturing processes due to their ability to shape any material in powder or ink form. The two inkjet-based AM technologies are binder jetting and material jetting, and as each of their names suggest, the former uses inkjet to deposit binder into the actual build material and the latter uses inkjet to deposit the actual build material. With each of these technologies comes unique opportunities in the form of embedding functional components within the build, creating material gradients within parts by selectively layering feedstocks, shaping non-weldable materials, and creating low-cost tooling with conformal cooling channels. Dr. Amy Elliott at Oak Ridge National Laboratory has explored a variety of materials and approaches with inkjet-based manufacturing technologies, focusing on industry-relevant applications such as injection molding tooling and mining drills.

Elliott, Amy↗

DOE OSTI2021

Air Dehumidification using Ionic Liquid-Based Fiber Bundle Membrane Contactor

Air dehumidification is essential since excess moisture in the buildings causes discomfort to the occupants, encourages the production of air pathogens such as mold or mildew, and causes corrosion and rotting that degrade building materials. Existing moisture removal processes are mainly focused on condensation and desiccant (liquid or solid) techniques with direct contact between air and desiccant. However, these methods are energy-intensive, or desiccant might be lost or cause corrosion in the process. The main objective of this study is to investigate an ionic liquid-based liquid desiccant absorber based on a membrane fiber bundle. The novel system consists of membrane contactors containing bundles of 10,000 polypropylene fibers. The fiber bundles have 0.3 micron diameter, with ionic liquid flowing inside, and air flowing outside. The fibers provide a high contact area among phases: 1.4 m2 contact surface area in a 0.00015 m3 volume. The ionic liquid as a sorbent stipulates the selectivity for air, prevents the loss of solvent in the operation due to negligible volatility, provides fast diffusion due to low viscosity compared to common ionic liquids, and has high affinity and solubility in water. The dehumidification capacity of the membrane technology was experimentally investigated. The experimental results show that the ionic-liquid based membrane system can effectively remove excess moisture from the air. The novel fiber bundle dehumidification system has a system volume of 0.00798 m3 (7.98 L) and active heat and mass transfer surface area of 8.4 m2. It achieved an average dehumidification of 320 ± 25 W with a volumetric air flowrate of 3.1 m3/min (108 ft3/min).

Turnaoglu, Tugba↗

DOE OSTI2021

Helical superconducting undulator for 3rd and 4th generation of synchrotron light source and FELs

A helical superconducting undulator includes a cylindrical magnetic core through which a bore hole allows the passage of charged particles. A single superconducting wire wraps the magnetic core guided by helical flights and cylindrical protrusions, to create interleaved helical windings on the magnetic core. An electrical current may be supplied to the superconducting wire to generate a periodic helical magnetic field in the bore. The helical superconducting undulator also includes a strong-back enclosure that acts as an epoxy mold during epoxy impregnation, a structural support to ensure straightness of the undulator after epoxy impregnation, and assists in cooling and thermal control of the magnetic core and superconducting wire during device operation.

Gluskin, Efim↗

DOE OSTI2022

Methods, systems, and apparatuses for in-line variably porous surfaces

Variably porous panels and panel assemblies incorporating shape memory alloy components along with methods for actuating the shape memory alloys are disclosed to predictably alter the porosity of a substrate surface, with the shape memory alloy maintained in an orientation relative to the panel that is in-plane with a mold-line of the panel outer surface.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Rapid manufacturing of tailored preforms

A method for rapid manufacturing of three dimensional discontinuous fiber preforms is provided. The method includes the deposition of a polymeric material containing fibers on a surface to form a tailored charge for compression molding. The reinforced polymeric material may be a thermoplastic or a reactive polymer with viscosity low enough to allow flow through an orifice during deposition, yet high enough zero shear viscosity to retain the approximate shape of the deposited charge. The material can be deposited in a predetermined pattern to induce the desired mechanical properties through alignment of the fibers. This deposition can be performed in a single layer or in multiple layers. The alignment is achieved passively by shear alignment of the fibers or actively through fiber orientation control or mixing. The fibers can be of the desired material, length, and morphology, including short and long filaments.

Kunc, Vlastimil↗

DOE OSTI2022

What does it take to “see” air leakage through a building envelope?

Unwanted air leakage in buildings can cause health and comfort issues for the building occupants and contribute to rot and mold growth in building materials. Leakage also contributes to unnecessary energy consumption ~4 quads (1172 TWh) per year in the buildings sector in the United States. Finding and repairing leaks through the building envelope can improve the energy efficiency, comfort, air-quality, and moisture durability of the building stock. Typical methods of locating air leakage, such as infrared imaging or smoke tracing, rely on concurrent blower door operation which also measures the total leakage rate of the building. These methods can be disruptive to occupants and can’t measure the contribution of individual leaks to prioritize sealing efforts. ORNL is working on a refraction-based fluid flow imaging technique that can measure the leakage rate of individual leaks from the outside of the building. The working principle of this device is based on the refraction of light caused by the exfiltration because there is a small difference in density between the exfiltration and ambient air. We will discuss the operation of the air leak detector and key variables that affect its performance. We will also present preliminary results showing the visualization capability of this new air leak detector under different conditions. Experiments were completed with different claddings, air temperatures, and lighting conditions.

Boudreaux, Philip↗

DOE OSTI2023

System and method of making a crankshaft with alternate materials

A crankshaft for an internal combustion engine is provided. The crankshaft comprises at least four main journals aligned on a crankshaft axis of rotation defining a centerline. The crankshaft further comprises at least three pin journals. Each pin journal is disposed about a respective pin journal axis and positioned between the main journals. Each of the pin journals is joined to a pair of crank arms. Each pair of crank arms is joined to a respective main journal. Each of the main journals, pin journals, and crank arms is made of a first metallic material. Each crank arm has an over-molded counterweight metallurgically bonded thereto. Each counterweight is disposed opposite a respective pin journal relative to the centerline for balance and stability. Each counterweight is made of a second metallic material. The crankshaft has a weight ratio of the second metallic material to the first metallic material of between 0.20 to 0.50.

Klemstine, David C.↗

DOE OSTI2022

Thin Triples Expand the Affordable High-Performance Window Options For Retrofit

Sales of high-performance triple-pane windows make up only a small fraction (~3%) of total window sales in the United States with relatively stagnant market growth over the past 20 years. High costs have been the most commonly cited barrier to adoption. The emergence of thin triples that can fit into the glazing pocket of existing double pane windows has the potential to revolutionize the high-performance window market in particular the retrofit market by enabling glass only upgrades for situations where the frames are still in good condition. The retrofit market has other unique challenges not found in new construction that can be solved or reduced by thin triple pane windows. Insert replacements are often pursued instead of full frame replacement, in retrofits, this method reduces the net free area of a window and can turn an egress window into one that no longer meets the net free area requirements for egress. Thin frames minimize such occurrences. However, these thin frames can often not accommodate the weight of a traditional triple pane, thin triples can bring high performance to this situation. Thicker frames can also increase retrofit labor costs because the interior drywall and/or trim molding needs to be cut back to accommodate a thicker frame while thin triples can fit into frames that match the thickness of the existing window. This paper presents information about field test experiences the highlight these retrofit advantages from experiencing the challenges associated with retrofitting a thick frame as well as the supply chain, purchasability, material and labor costs, and real-world energy and non-energy performance associated with the IGU only replacement method.

window retrofits, thin triple-pane windows, high p↗

DOE OSTI2023

Coating composition embodiments for use in investment casting methods

Disclosed herein are embodiments of a coating composition for use in investment casting. The coating composition embodiments provide a solidified coat that can be as a mold for casting castable materials and that is easily removed from the casted material using water. The coating composition embodiments disclosed herein are reusable and are non-toxic and exhibit high thermal stability.

Cluff, Kyle↗

DOE OSTI2022

Forming Complex Nuclear Fuel Shapes in High-Loaded Silicide Surrogates

This work provides proof of the concept that high silicide loading nuclear fuel meat surrogates with complicated geometries can be produced with uniform density through an application of cold isostatic pressing (CIP). Dispersion fuels with high volumetric loading of U_3 Si_2 have challenges in fabrication. Fabrication involves a series of processes including powder compaction, rolling pack assembly, and roll forming. PNNL has undertaken extensive experimental work using MoSi2 and WSi2 as surrogates for U3Si2 to explore the feasibility of reducing or eliminating the issues through the application of CIP in the powder pressing step prior to rolling pack assembly. The composites were prepared at >40 vol% silicide loading, which was representative of 4.8 gU/cm^3 and formed via CIP at 50 KSI (Kilopound per Square Inch) pressure. The CIP mold design was taken through a design process which aimed to reduce defects and increase precision. The application of CIP here provides a broad strategy for producing highly loaded dispersion fuels with complex geometries and uniform density.

Clelland, Dustin T.↗

DOE OSTI2023

Developing a Roadmap for Bio-Derivable and Recyclable Composites: Re-Design and Scale-Up Considerations

Composites, often in the form of fiber reinforced plastics, are used in multiple facets of modern life from snowboards to vehicles, to wind turbines and beyond. Despite their prolific, and often renewable energy related uses, they are currently subject to a linear material economy from emission intensive precursors; thus, there is an opportunity to re-design these materials to be both bio-derivable and recyclable. In the present work, we provide a roadmap of what application considerations must be considered for vacuum assisted resin transfer molding (VARTM) processes for large composites materials at scale (e.g. infusible viscosities, moderate cure times, proper fiber adhesion, low cost, and maximum peak exotherm) when implementing bio-derivable and recyclable materials. We also provide illustrative concepts utilizing polyester covalently adaptable networks, from epoxy-anhydride chemistry, to achieve these goals. We further provide considerations when developing recycling process (e.g. maintenance of fiber sizing and orientation) and demonstrate these practices using low temperature methanolysis. Accompanying technoeconomic and life cycle analysis further illustrate the decarbonization benefits to bio-derivable and recyclable thermosets while informing future research and recycling processes. Finally, we provide a brief introduction to synergistic work within our team exploring how to further decarbonize the manufacturing of these materials.

BIOMASS FUELS,ENERGY CONSERVATION, CONSUMPTION, AN↗

DOE OSTI2024

Nuclear Data Sensitivity/Uncertainty Studies of Tantalum-Reflected Systems

Tantalum (Ta) is a refractory metal with high melting point and high corrosion resistance. This makes it useful as a mold material for plutonium casting operations. Unfortunately, there are few criticality benchmarks with high nuclear data sensitivities. Given that, it is desirable to design new experiments to provide additional validation data for nuclear criticality safety, which is the objective of the Thales project. Multiple application models were used to represent process conditions (either normal conditions or credible upset conditions) both at Los Alamos National Laboratory (LANL) and Savannah River Site (SRS). A total of 40 application models were obtained. Given this, it was useful to down-select the number of needed application models. This work documents the down-selection based on several nuclear data sensitivity/uncertainty metrics. In addition to showing the result of the specific down-selection used for the Thales project, this work discusses potential ways to represent a large number of application models with a smaller number of proposed experiment designs.

42 ENGINEERING↗

DOE OSTI2023

New Materials and an Efficient Processing Approach for Materials for Harsh Environments – Continuous Electric Field Assisted Sintering

Electric-field assisted sintering (EFAS) is an advanced manufacturing method for the consolidation and processing of ceramic and metal materials. It is a particularly excellent candidate for efficient materials processing as it has greater than 90% energy cost savings and improved CO2 emissions compared to traditional sintering in a furnace. This is due to direct rapid heating of the materials and molds leveraging an electrification phenomenon called Joule heating where electrical current is passed through the sample/mold assemblies causing direct heating. The technique does have limitations though as it is traditionally a batch-process and suffers from scale up difficulties. To overcome this, researchers at Idaho National Laboratory changed the form factor of traditional EFAS instruments to develop and construct a continuous rolling electric-field assisted sintering (CEFAS) device. Its unique design creates highly localized electrical, thermal, and mechanical process parameters for continuous samples of limitless length. Advanced core shell powder materials were also created using fluidized powder bed atomic layer deposition of core/shell solid oxide electrochemical electrode/electrolyte BaCe0.7Zr0.1Y0.1Yb0.1O3 (BCZYYb) and yttrium doped BaZrO3 (BZY) to be a feedstock for the new CEFAS instrument. The innovative core/shell powder is hypothesized to have high protonic conductivity with enhanced environmental resistance. The completed project covers innovations in process control and design enabled by control theory, finite element modeling and mechanical design, three dimensionally printed carbon-carbon composite manufacturing and utilization, and green materials processing techniques.

36 MATERIALS SCIENCE↗

DOE OSTI2024

CEFAS Poster for Advanced Manufacturing Workshop 3/26/24

36 MATERIALS SCIENCE↗

DOE OSTI2024

Effect of Heat Treatment on Microstructure and Mechanical Property of 316L Stainless Steel Produced by Laser Powder Bed Fusion

The advanced non-light water reactor designs (Gen IV reactors), including molten salt/ very high temperature/ sodium-cooled and lead-cooled fast reactors, typically operate at higher temperatures and more extreme radiation conditions than light water reactors. An intrinsic part of the deployment and progress of Gen IV reactor designs is selecting the most suitable structural material for a specific application. Additive manufacturing (AM), a fairly new process of making physical, three-dimensional objects from a computer design file, is going to completely change the way of design, build and certify nuclear systems. It offers a range of opportunities to produce complex geometries from existing materials, offers new routes for processing of previously difficult to process materials, allows for design of new high-performance materials, and finally facilitates hybridization of dissimilar materials. This emerging technology has successfully produced cars, wind turbine blade molds and even live cells. It could also open up big opportunities for the nuclear industry to quickly deploy technologies at a fraction of the cost. So far, AM techniques have been preliminarily applied in the field of nuclear reactors, including the classical parts such as the pressure vessel of a small reactor with 508-III steel, the bottom nozzle of a fuel assembly with 304L steel, the fuel cladding with zirconium alloy and the integrated impeller of a pump and the multi-channel valve body with 316L steel [6,7]. The AM applications for operating nuclear reactors started in auxiliary plant components and have slowly migrated to metallic reactors and core components, but many of these are not safety critical components. Although many parts used for nuclear reactors have been fabricated by AM techniques, practical applications in engineering are still a long way off due to the uncertainty factors focused on the processing, material properties, analysis methods and application standards, which feeds the safety and life-cycle of the nuclear reactor. Due to rapid, repeated heating and cooling during production, a high dislocation density was present in the AM material. This microstructure feature is unstable at elevated temperature while high temperature is one of the typical operation environments for nuclear reactors. Thus, it is important to understand the thermal effect on the microstructure of AM material. The objectives of this study are to investigate the effect of heat treatment on the microstructure and mechanical properties of 316L stainless steel produced by laser powder bed fusion additive manufacturing, and to determine an appropriate heat treatment practice that will be applied to the lightweight AM lattice-structured material with the same chemistry. The heat treatment study consisted of annealing the samples at a temperature range of 800 to 1200 oC with a 50 oC increment for different times (1-24 hours), followed by vacuum or air cooling. Microstructural characterization was carried out by Scanning Electron Microscope (SEM). Grain size and crystallographic orientation were investigated by Electron Backscatter Diffraction (EBSD). Vickers hardness tests with a 0.5 kg load were employed to determine the hardness of samples after different heat treatments. After heat treatment, the random crystallographic orientation was preserved, and the volume fraction of high-angle grain boundaries (grain boundary misorientation =15 oC) remained the same. The dislocation density decreased with annealing temperature due to recovery. The fine subgrain structures in the as-printed specimen were quite stable up to 1200 oC. Minimal recrystallization was observed up to 1200 oC. Recrystallization initiated only after 8.5 hours at 1200 oC. The SEM images did not show obvious dependence of microstructure on cooling rate. The hardness of the specimens decreased with increasing annealing temperature as a result of the decrease in dislocation density. It is interesting to note that the AM material showed very similar hardness to the wrought material when annealing at similar temperature, although the microstructures are very different. Annealing at 1050 oC for 1 hour followed by air cooling was selected as the heat treatment procedure for the lattice designed lightweight AM 316L material.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Data Acquisition System Selection and Calibration of Resistive Moisture Content Measurements for Large-Scale Field Studies in Cold Climate Residential Building Envelope Performance

The residential building stock built before the energy codes were enforced has several significant inefficiency problems in terms of insulation and air leakage. To decrease these inefficiencies, building retrofits are necessary. However, if the envelope is not appropriately designed, excessive accumulation of moisture content and thus mold formation and decay inside the envelope layers can be a vital problem. This risk becomes higher, especially in extreme climate conditions such as cold winters and hot and humid summers as in some northern regions of the U.S. Field studies are essential to test the long-term hygrothermal performance of building envelopes. Although in-situ temperature, RH, and heat flux measurements are straightforward, moisture content measurements are cumbersome. Mainly, because of the heterogeneous nature of the wood materials, deviations and nonuniformities within the materials are unavoidable. Resistance measurements are one of the oldest methods used to measure the moisture content of wood and other building materials. In large-scale studies, it is commonly preferred to use multi-purpose data acquisition systems (DAQ) and custom-made or prefabricated moisture pins to measure the electrical resistance (and thus moisture content) of critical building materials. These multi-purpose DAQ systems generally provide lower costs and offer more flexibility. However, these systems require calibration and fine-tuning to achieve accurate moisture content measurements. A large-scale, two-year-long field study was conducted in northern Minnesota to monitor the hygrothermal performance of residential retrofit wall systems in cold climates. Two base case walls and sixteen different wall treatments were tested. Moisture contents were measured at various layers in each wall treatment using 85 sets of moisture pins. This paper focuses on the overall approach, fabrication, and calibration methodology for the combination of custom-made moisture pins and a multi-purpose DAQ. The aim is to directly use the low-excitation multi-purpose DAQ without any extra voltage regulator. A half-bridge circuit is used to measure wood resistance with 4V excitation voltage and 100 kΩ and 500 kΩ reference resistors. The system is calibrated for four different materials: Douglas fir, lodgepole pine, western red cedar, and oriented strand board (OSB). Calibration experiments were done under controlled conditions in 50% and 65% RH test chambers. Resistance-based moisture content calibration curves are obtained for each species. Results show that higher reference resistors provided better calibration curves for lower excitation voltages.

Desjarlais, Andre Omer↗