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An apparatus and associated method are provided. A first silicon layer having at least one of an associated passivation layer and barrier is included. Also included is a composite anti-reflection layer including a stack of layers each with a different thickness and refractive index. Such composite anti-reflection layer is disposed adjacent to the first silicon layer.
Heat exchangers are used in many industries to transfer thermal energy between two or more objects with an associated thermal and hydraulic performance indicated by thermal effectiveness and pressure drop respectively. Many investigations have aimed to enhance the thermal effectiveness of heat exchangers by introducing turbulent flow inducers that increase the heat transfer rate at the expense of increasing pressure drop. Flow inducers like surface roughness can be controlled with advanced manufacturing methods like additive manufacturing for heat exchanger production. Selecting and manufacturing an optimal surface roughness for heat exchangers requires a more comprehensive approach that accounts for the surface roughness effect on the thermal and hydraulic performance of a sample. Since fabricating samples with additive manufacturing to a desired surface roughness can be an extensive experimental process, this study will fundamentally investigate the effect of surface roughness on the thermal and velocity boundary layers for various surface roughness profiles with physics-based computational modeling. To accurately model the surface roughness effect on thermohydraulic performance, correlations like roughness ratio, friction factor, and Nusselt number are investigated. This study expects to indicate correlations for different flow regimes which can successfully predict the effect of surface roughness on thermohydraulic performance. Results generated from modeling surface roughness effect with unique correlations are then compared to experimental data obtained from literature for validation. The results of this study will provide insight to understand the thermal fluid physics associated with surface roughness and design guidelines for heat exchangers produced with additive manufacturing.
Solvent-free manufacturing of battery components is a promising alternative to traditional slurry processing for reducing the cost and environmental impact. In this work, we used twin-screw melt extrusion to fabricate a polymer-based high voltage composite cathode. The melt-processed cathode is dense (near zero porosity) and thick (65 μm) and has high active material loading (80 wt %). The active particles are distributed uniformly throughout the melt-processed cathode, unlike the traditional slurry-cast cathode, which exhibits inhomogeneous particle distribution. In the melt-processed cathode, polymer and carbon form separate phases, whereas in the slurry-cast cathode they blend into a single phase. Due to these structural differences, the melt-processed cathode shows smooth charge–discharge profiles, while the slurry-cast cathode shows noisy charging and soft-shorting behavior. In conclusion, this work highlights that twin-screw extrusion as a scalable, solvent-free manufacturing method is advantageous in producing uniform cathodes, which mitigates anode instability.
This invention teaches the fiber optic sensors temperature sensors for cryogenic temperature range with improved sensitivity and resolution, and method of making said sensors. In more detail, the present invention is related to enhancement of temperature sensitivity of fiber optic temperature sensors at cryogenic temperatures by utilizing nanomaterials with a thermal expansion coefficient that is smaller than the thermal expansion coefficient of the optical fiber but larger in absolute value than the thermal expansion coefficient of the optical fiber at least over a range of temperatures.
Significant advances have been made in the past decade concerning silicon carbide fiber manufacturing methods resulting in near-stoichiometric small-diameter fibers that meet the property requirements for most of the ceramic matrix composites (CMC) and nuclear applications. The manufacturing cost, however, remained prohibitively high, preventing the use of it in different applications requiring much lower cost. Silicon carbide (SiC) fiber reinforced CMC is dominated by the cost of SiC fiber which comprises more than 50 % of the finished part cost. Here, this article provides insight into the SiC fiber manufacturing costs and highlights the need for an alternative SiC fiber precursor and manufacturing method. Analysis of the existing polycarbosilane (PCS)-based SiC fiber manufacturing shows that the crosslinking (curing) and raw material preparation steps are high-cost steps that need lower cost options. Alternative SiC fiber precursor should be sought for lowering the cost of SiC fibers.
A method for additively manufacturing a microstructure from a caloric material includes providing a geometry of the microstructure to a processor of an additive manufacturing device, the geometry defining a plurality of microfeatures of the microstructure. The method also includes generating, via the processor, a three-dimensional (3D) model representative of the geometry of the microstructure, wherein one or more of the plurality of microfeatures are represented in the 3D model by a non-arcuate profile. Further, the method includes printing, via the additive manufacturing device, the microstructure from the caloric material according to the 3D model. As such, the non-arcuate profile reduces a file size of the 3D model as compared to an arcuate profile.
Abstract Additive manufacturing (AM) allows agile, rapid manufacturing of geometrically complex components that would otherwise be impossible through traditional manufacturing methods. With this maturing manufacturing technology comes the need to adopt testing methods that are commensurate with the speed of additive manufacturing and take advantage of its geometric flexibility. High-throughput tensile testing (HTT) is a technique that allows a large number of tensile bars to be tested in a short amount of time. In the present study, HTT is used to evaluate AM AlSi10Mg produced using powder bed fusion with a Renishaw AM250 machine. Three parameters were varied in this study: (1) powder reuse history, (2) location on the build plate, and (3) size of the tensile specimen. For all parameter combinations, at least 22 specimens were tested; in several cases, over 40 were tested. This large dataset, consisting of over 500 tensile tests, permits Weibull statistical analysis and provides sufficient fidelity to isolate subtle trends that would have likely been missed in smaller, traditional datasets. The observed trends are rationalized in terms of the role of porosity and surface crust on mechanical response.
A critical challenge for the implementation of proton exchange membrane (PEM)-based water electrolyzers for the H2@Scale vision is the capital cost, which is largely driven by related factors of overdesign and highly manual legacy manufacturing methods. Typical electrolyzer cells have an order of magnitude higher membrane thickness and catalyst loading vs. fuel cells, in part because the manufacturing methods being used are not capable of producing uniform and reliable electrodes on thin membranes with low loading. Advanced electrode manufacturing is therefore the key enabler to reduce the cost of the electrolyzer stack, particularly roll-to-roll (R2R) manufacturing of catalyst coated layers (CCLs) and catalyst coated membranes (CCMs). The electrolyzer manufacturing process still relies on traditional sheet-to-sheet (S2S) processes, which requires intensive labor to make parts to meet the specification requirements. This project leverages fuel cell expertise (GM) with Proton’s knowledge of electrolyzer components to develop the electrocatalyst ink formulations and coating processes using slot die (ORNL) and gravure (NREL) coatings, with proof of concept at the pilot-scale (Kodak).
The back end of the fuel cycle focuses on the interim storage, transportation, and final disposition of the spent nuclear fuel from nuclear reactors. Commercial light water nuclear power stations across the United States operate with fuel assemblies being irradiated for up to 6 years (planned) in the reactor pressure vessel. After their planned irradiation, the fuel assemblies are moved to a spent fuel pool within the facility complex. After the spent nuclear fuel is removed from the fuel pool, it is typically inserted into a welded metal canister that can be transferred between overpacks for storage, transportation and possibly disposal. Most dry storage systems being used by industry today use dual purpose canisters (DPCs), designed for use in storage and transportation overpacks, but not specifically designed for disposal. Triple purpose-canisters, designed for disposal in addition to storage and transportation, have also been researched. Traditional manufacturing methods for spent fuel canisters involve fusion welding along the length or circumference of the canister which results in high tensile residual stresses in the joint weld zone (WZ) and heat affected zone (HAZ). In this paper, spent fuel canister designs were printed by wire arc additive manufacturing (AM) using the 316L SS welding wire to demonstrate: 1. Feasibility of spent nuclear fuel canister fabrication using this advanced manufacturing method, 2. Dynamic response of the additive manufacture canister design when subjected to the federally mandated Normal Conditions of Transport (NCT) and Hypothetical Accident Conditions (HAC) physical tests for Type B packages. This paper will focus on the canister printing design and structural tests. The AM 3D printed design, regulatory testing, and post-test evaluation of the canister tested to the 10 CFR 71.71 and 10 CFR 71.73 requirements will be presented. One AM canister design was subjected to the penetration, free drop, and puncture test. Before and after the dynamic structural tests, the AM canister design was scanned with a handheld scanner to capture a 3D CAD geometry to compare to the 3D printed canister design in the deformed shape. The scanned geometry was sectioned in areas with deformation and the cross-section profile was measured to determine accurate and repeated results of the deformed shape of the AM canister design.
Thermoelectric generators have strong potential for aerospace and aircraft applications. However, traditional manufacturing methods for thermoelectric devices severely limit device adaptability and consequently marketability. Laser powder bed fusion is an additive manufacturing method which shows promising potential for producing thermoelectric devices. Thermoelectric materials pose unique challenges compared to metals because of low thermal conductivity, brittle fracture characteristics, and irregular powder particle morphologies. Herein, we communicate processing procedures to fabricate thermoelectric parts of Bi 2 Te 3 through laser powder bed fusion. In this study, we identify the successful combination of key process parameters—laser power, scan speed, hatch distance, and powder layer thickness—to achieve high-quality parts in terms of density and physical properties, and we demonstrate the impact of process parameter variation on built part quality. While it cannot exclusively determine part quality, the volumetric energy density is a useful guide in deciding process parameters for thermoelectric materials, and the optimal value is between 9 and 11 J/mm 3 for Bi 2 Te 3 . We demonstrate successful fabrication of different freeform geometries of Bi 2 Te 3 powders. The results suggest it is possible to extend this method more broadly to other semiconductor materials, including thermoelectric power generation materials applicable for space applications.
The Pacific Northwest National Laboratory undertook the Materials Characterization, Prediction, and Control Laboratory Directed Research and Development Project to advance understanding of nuclear material processing and enable multifold acceleration in the development and qualification of new material systems produced via advanced manufacturing methods, such as solid phase processing, for use in national security and advanced energy applications (Smith 2021). A motivation of the Materials Characterization, Prediction, and Control Project was to demonstrate ultrasonic testing as a nondestructive evaluation method to complement traditional destructive methods for characterizing material microstructure with emphasis on grain size determination using a method that may have future applications for real-time inline process monitoring. The objective of the work described in this report is to establish the process and an analysis method for measuring grain sizes of polycrystalline metals with ultrafine grains using ultrasonic shear wave backscattering, building on prior studies on coarser-grained material. The work involves five tasks: Measured ultrasonic backscattering experimentally for a series of 316L stainless steel specimens with various grain sizes made by friction stir processing. Calculated ultrasonic backscattering coefficients from experimental data based on a physical measurement model. Measured ground truth grain sizes of the specimens from electron backscatter diffraction grain boundary images using a generalization of the ASTM E112 (ASTM 2021) intercept method. Built a curve of ultrasonic backscattering coefficients versus the ground truth intercept-based grain sizes to determine the correlation between mean grain sizes and ultrasonic measurements. Demonstrated the ability of using the correlation curve to deduce grain sizes with measured ultrasonic backscattering coefficients for a few 316L stainless steel specimens whose grain sizes were unknown beforehand but were targeted to be an extrapolation to larger grain sizes than used to formulate the correlation curves. Experimental procedures and computational algorithms are developed and validated for these tasks. This work establishes an ultrasonic technique for characterizing material microstructure with ultrafine grains that are often resulted by solid-phase processing. The technique is nondestructive, and it has the potential to be used for real time inline process monitoring. This work successfully demonstrates the viability of an ultrasonic nondestructive evaluation method for microstructural characterization of material having ultrafine grain structure (as small as 1?mm) and produced by an advanced manufacturing method. This includes a demonstration of the method to extrapolate to other conditions. While not demonstrated here, the method is expected to be viable for in-line, or near-inline, process monitoring in advanced manufacturing applications with suitable consideration for access of instrumentation to the material being manufactured.
Over the last several decades, additive manufacturing (AM) has been primarily used for rapid prototyping or to create novel geometries that would be difficult or impossible to create by normal manufacturing methods. More recently, research has been focused on expanding the list of materials that can be made through additive manufacturing, opening a greater range of material properties for this manufacturing method. Due to the unusual conditions during AM, including the high cooling rates and voxel by voxel method of production, AM parts often have anisotropic material microstructures and properties. In this investigation, the laser power, composition, and nozzle head speed during direct metal deposition of copper-iron alloys was varied to understand how the grain structure within the printed parts could be changed and controlled. The resulting dendrite spacing was measured and compared to calculated cooling rates from Gaussian beams on flat plates under similar material and laser properties, which resulted in a cooling rate to dendrite spacing relationship following an inverse square root, as is found in other dendritic systems [Young and Kerkwood, Metall. Trans. A 6, 197–205 (1975)]. Thus, it is demonstrated that in the Cu-Fe system, dendrite spacing can be controlled through manipulation of printing parameters.
NASA is committed to developing new materials and manufacturing methods that can enable new missions with ever increasing mission demands. Typically, the development and certification of new materials and manufacturing methods in the aerospace industry has required more than 20 years of development time with a costly testing and certification program. To reduce the cost and time to mature these emerging technologies, NASA is developing computational materials tools to improve understanding of the material and guide the certification process.
Scintillators are a fundamental technology that enables radiation detection. Their use has historically enabled the detection of incoming gamma radiation, with recent advances in plastic scintillator development enabling detection and discrimination of neutron and gamma radiation through pulse shape discrimination. However, scintillators have so far consisted of a single material, typically one primary dye and one secondary dye embedded in a plastic matrix. Based on the simulation studies described previously, mixed material scintillator systems with multiple secondary dyes arranged in alternating, periodic micro-sized regions opens the door for scintillators with a wide variety of different capability, such as directional sensing, positional reconstruction, particle identification, and pulse shape discrimination. However, fabrication of a mixed material scintillator system by conventional manufacturing methods is difficult to manufacture and scale, creating a barrier to their wide spread implementation. On the other hand, additive manufacturing additive manufacturing presents itself as the optimal method for fabricating mixed material scintillator systems based on its flexibility, ability to fabricate fine features, and potential for multimaterial fabrication.
The invention pertains to a high diffuse, reflective paint comprising an alcohol soluble binder, polytetrafluoroethylene (TFE) and an alcohol for coating a substrate and forming an optical reference with a superior Lambertian characteristic. A method for making the paint by first mixing the biner and alcohol, and thereafter by mixing in outgassed TFE is described. A wetting agent may be employed to aid the mixing process.
Idaho National Laboratory initiated examination of nickel-based alloys manufactured via three different additive manufacturing methods for potential applications in nuclear, high temperature structural components. The three methods analyzed included laser powder bed fusion, blown powder laser directed energy deposition, and wire-fed gas metal arc directed energy deposition. With the rapid push towards additive manufacturing, codes do not exist that definitively define what is or is not tolerable for each process and application, such as with conventional, wrought products. This report contains the initial work to understand possible manufacturing methods for high temperature alloys, and specifically, void formation, microstructure evolution, corrosion, and mechanical properties. To generate mechanical test data, specimens were tested irrespective of voids and microstructures were analyzed to better understand how to negate/improve these issues. The preliminary results showed major decreases in mechanical performance for material tested. Test specimens will continue to be produced to further improve each additive manufacturing processes, quantify void acceptance, and better understand the most suitable high temperature alloys receptive to additive manufacturing and high temperature nuclear applications.
Systems and methods for forming a magnetically-enabled part via additive manufacturing. The method includes depositing a layer of additive manufacturing material on a build plate, melting or sintering the layer of additive manufacturing material, depositing additional layers of additive manufacturing material on previous layers of additive manufacturing material, the additive manufacturing material of at least some of the additional layers being magnetically permeable, and melting or sintering the additional layers of additive manufacturing material such that the magnetically-enabled part has a transition region including at least some of the magnetically permeable additive manufacturing material.
Systems and methods for forming a magnetically-enabled part via additive manufacturing. The method includes depositing a layer of additive manufacturing material on a build plate, melting or sintering the layer of additive manufacturing material, depositing additional layers of additive manufacturing material on previous layers of additive manufacturing material, the additive manufacturing material of at least some of the additional layers being magnetically permeable, and melting or sintering the additional layers of additive manufacturing material such that the magnetically-enabled part has a transition region including at least some of the magnetically permeable additive manufacturing material.