Surface Determination of Additively Manufactured SS316-L Lattices Using Supervised Machine Learning.
Abstract not provided.
Moore, David G.↗
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Surface Determination of Additively Manufactured Lattices Using Supervised Learning.
Abstract not provided.
Moore, David G.↗
Surface Determination of Additively Manufactured Lattices Using Supervised Learning.
Abstract not provided.
Epstein, Collin↗
Image Stitching in Neutron Radiography for Surface Extraction of Additively Manufactured Parts
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Physics - Nuclear physics and radiation physics↗
Identifying the Accuracy of Surface Roughness for Metal Additive Manufacturing Parts Captured with Computed Tomography Scanning
Conventional surface roughness measurement techniques require direct access to internal surfaces, often necessitating destructive sectioning of test articles. Computed tomography (CT) offers a non-destructive alternative for internal surface characterization, but its application in metrology remains unstandardized and sensitive to machine resolution and operator technique. This study investigates the feasibility of using CT scanning to quantify areal surface roughness in metal AM heat exchanger tubes with three distinct internal geometries: ribbed, discrete W, and featureless. CT-derived surface parameters were extracted using custom Python scripts and compared to measurements obtained from a focus variation microscope calibrated against a known standard. Results show that CT-based roughness measurements closely matched microscope values for the discrete W specimen, deviations between CT and microscope measurements were minimal—less than 1 µm—indicating reliable reconstruction. In contrast, the ribbed and featureless specimens, with lower roughness values showed greater discrepancies. The findings suggest that CT scanning can be a viable non-destructive metrology tool for AM parts with surface roughness above approximately 8 µm. For smoother surfaces, current CT capabilities may not provide sufficient accuracy, highlighting the need for resolution-aware workflows and further standardization in CT-based surface metrology.
36 MATERIALS SCIENCE↗
Elucidating the assembly of Nanoparticle Organic Hybrid Materials (NOHMs) near an electrode interface with varying potential using Neutron Reflectivity
A critical concern regarding electrolyte formulation in an electrochemical environment is the impact of the interaction of the multiple components (i.e., supporting electrolyte or additive) with the electrode surface. Recently, liquid-like neat Nanoparticle Organic Hybrid Materials (NOHMs) have been considered as an electrolyte component to improve the transport of redox-active species to the electrode surface. However, the structure and assembly of the NOHMs near the electrode surface is unknown and could significantly impact the electrode-electrolyte interface. Hence, we have investigated the depth profile of polyetheramine (HPE) polymer and NOHM-I-HPE (nanoparticles with ionically bonded HPE polymer) in deuterated water (D2O) in the presence of two different salts (KHCO3 and ZnCl2) near two different electrode surfaces using neutron reflectometry. Moreover, the depth profile of the NOHM-I-HPE near the electrode surface in a potential has also been studied with in-situ reflectivity experiments. Our results indicate that a change in the chemical structure/hydrophilicity of the electrode surface does not significantly impact the ordering of HPE polymer or NOHM-I-HPE near the surface. Here, this study also indicates that the NOHM-I-HPE particles form a clear layer near the electrode surface immediately above an adsorbed layer of free polymer on the electrode surface. The addition of salt does not impact the layering of NOHM-I-HPE, though it does alter the conformation of the polymer grafted to the nanoparticle surface and free polymer sequestered near the surface. Finally, the application of negative potential results in an increased amount of free polymer near the electrode surface. Correlating the depth profile of free polymer and NOHM-I-HPE particles with the electrochemical performance indicates that this assembly of free polymer near the electrode surface in NOHM-I-HPE solutions contributes to the higher current density of the system. Therefore, this holistic study offers insight into the importance of the assembly of NOHM-I-HPE electrolyte and free polymer near the electrode surface in an electrochemical milieu on its performance.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Pathways of CdS Quantum Dot Degradation during Photocatalysis: Implications for Enhancing Stability and Efficiency for Organic Synthesis
CdS quantum dots (QDs) are widely employed as photocatalysts for reactions such as hydrogen evolution, and their degradation under aerobic aqueous conditions is well understood. However, despite evidence of aggregation and precipitation of CdS QD photocatalysts under anaerobic conditions, catalyst speciation and degradation under such conditions are underexplored. In this work, we demonstrate that during a reductive dehalogenation reaction, CdS QDs undergo surface ligand etching, which leads to a loss of colloidal stability and the formation of microcrystalline cadmium metal deposits. We hypothesize that this results from the accumulation of electrons on the QD surface. In addition, we demonstrate mild surface sulfur oxidation and the formation of an ammonium salt byproduct of a commonly used hole quencher. Furthermore, this work adds to our atomic-level understanding of the reactions occurring at the QD surface during photocatalysis, so that we can design more stable and efficient photocatalysts for organic synthesis.
cadmium sulfide↗
Assessment of Benefits of Solid-State Advanced Manufacturing Processes for Nuclear Energy Products
The Advanced Materials and Manufacturing Technology (AMMT) program develops cross cutting technologies in support of a broad range of nuclear reactor technologies and maintains U.S. leadership in materials and manufacturing technologies for nuclear energy applications. This overall project provides the U.S. Department of Energy a critical feasibility study comparison of three solid-state processes to other AM processes, thereby providing the feasibility of the solid-state processes examined to manufacture 316H SS and ODS steel components: • Fused-filament fabrication (FFF): This work provides an initial evaluation of the impact of powder morphology and sizes on the FFF process, and the feasibility and adaptability for different material systems, to use FFF for ODS steels and 316 SS. • Shear-assisted processing and extrusion (ShAPE): Specifically for this portion of the project on ShAPE tube forming, the objectives will be to determine the feasibility to direct tube forming of high tensile strength steel tubing, specifically for ODS steel to determine the effect of the patented extrusion process on the dispersoids of the ODS material. Additionally, as often ODS powders are mechanically alloyed and therefore more platelike or angular, this feasibility was to explore the impact on the optimization process and initial feasibility of direct tube forming. • Cold spray and friction stir additive manufacturing as a stretch goal: Bulk and near net shape manufacturing processes for high-temperature, high-strength alloys are needed. Additionally, cold spray techniques can be applied in-situ at the operational level for repair and can provide multiple benefits to the nuclear industry. These tasks aim to provide information to show benefits of cold spray during the full life cycle, namely research and development, product manufacturing, and repair to mention a few key points.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
Surface Roughness Calculations of Additively Manufactured Cylinders via X-Ray Computed Tomography
X-ray Computed Tomography (X-ray CT) is an analytical technique used in materials science to non–destructively characterize features in variety of materials like polymers, metals, composites, and explosives. It also has the capability of imaging additively manufactured, machined and assembled parts and processes. The non-destructive imaging allows for the analysis of features (voids and cracks), which give a fundamental understanding of material characteristics. Additionally, X-ray CT can obtain accurate measurements of dimensional and topographic variations as a result of different stimuli, and assess accuracy of material production. This study will focus on parts manufactured via metal additive manufacturing (AM). Although, AM produces parts faster and easier, the printing process can produce defects (pores and surface roughness) that undermine the part’s mechanical properties. The analysis of 3D printed objects has a strength in analysis in that the material has an STL file from which the item was printed, which is not available in many manufactured materials (i.e. foams) due to stochastic structures. For this study, the print accuracy of several 3D printed cylinders will be assessed via X-ray CT to determine optimal printing parameters for parts with less defects and stronger mechanical properties. This will be accomplished by having the original STL file serve as the baseline surface to compute difference in the CT rendering to calculate surface roughness for each cylinders.
36 MATERIALS SCIENCE↗
Why does a phosphonium-phosphinate ionic liquid protect the contact surfaces from wear and micropitting but increase vibration when used as an additive in rolling-sliding lubrication?
A phosphonium-phosphinate ionic liquid (IL) was studied as a lubricant additive for rolling-sliding contacts. The bench-scale test was designed to simulate automotive rear axle operation during cold start, highway towing, and overload conditions. Adding such an IL (2%) into a base oil significantly reduced wear loss and rolling contact fatigue, e.g., microcracking and micropitting, but made the vibrational noise notably higher under a low (-1.5%) sliding roll ratio (SRR). Additionally, worn surface characterization revealed an interesting texture pattern with alternating smoother plateaus and rougher valleys, which is believed to cause the high vibration. No increased vibration was observed at a high (-30%) SRR, possibly because the more aggressive sliding abrasion prevented such a surface texture from forming.
36 MATERIALS SCIENCE↗
Aerosol jet printing of surface acoustic wave microfluidic devices
Abstract The addition of surface acoustic wave (SAW) technologies to microfluidics has greatly advanced lab-on-a-chip applications due to their unique and powerful attributes, including high-precision manipulation, versatility, integrability, biocompatibility, contactless nature, and rapid actuation. However, the development of SAW microfluidic devices is limited by complex and time-consuming micro/nanofabrication techniques and access to cleanroom facilities for multistep photolithography and vacuum-based processing. To simplify the fabrication of SAW microfluidic devices with customizable dimensions and functions, we utilized the additive manufacturing technique of aerosol jet printing. We successfully fabricated customized SAW microfluidic devices of varying materials, including silver nanowires, graphene, and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). To characterize and compare the acoustic actuation performance of these aerosol jet printed SAW microfluidic devices with their cleanroom-fabricated counterparts, the wave displacements and resonant frequencies of the different fabricated devices were directly measured through scanning laser Doppler vibrometry. Finally, to exhibit the capability of the aerosol jet printed devices for lab-on-a-chip applications, we successfully conducted acoustic streaming and particle concentration experiments. Overall, we demonstrated a novel solution-based, direct-write, single-step, cleanroom-free additive manufacturing technique to rapidly develop SAW microfluidic devices that shows viability for applications in the fields of biology, chemistry, engineering, and medicine.
77 NANOSCIENCE AND NANOTECHNOLOGY↗
Processing aluminum alloy with hybrid wire arc additive manufacturing and ultrasonic nanocrystalline surface modification to improve porosity, surface finish, and hardness
Here, in this paper, a novel hybrid wire arc additive manufacturing (WAAM) and ultrasonic nanocrystal surface modification (UNSM) on porosity manipulation and surface properties of aluminum 5356 alloys was studied. The goal is to improve the quality of the WAAM-built part by eliminating bigger pores and reducing its size, reducing surface roughness, and increasing surface hardness. The as-built WAAM and WAAM-UNSM-treated samples were quantitatively studied for porosity using an X-ray micro-computed tomography (μ-CT). The surface roughness was measured on the surface profile of the same samples before and after UNSM treatment. Followed by the Vickers micro-hardness tests to evaluate the hardness modified by the influence of the UNSM treatment. It was found that the bigger pores in the as-built WAAM samples were eliminated and the medium-sized pores were shrunk to almost half the size after the UNSM treatment. Further, the UNSM treatment showed a significant improvement in both surface roughness and hardness on the WAAM Al5356 samples. This experimental work demonstrates the critical advantages of hybrid WAAM-UNSM in improving the qualities of the WAAM processed parts.
Hardness↗
Laser spot welding of additive manufactured 304L stainless steel
Here, the goal of this work is to understand if an additively manufactured 304L stainless steel exhibits similar spot-welding behavior as wrought 304L stainless steel. Due to the many differences between an additively manufactured component and wrought product, it is important to determine how the material interacts with the laser and how it affects the weld bead morphology. In this paper, the laser coupling efficiency, weld size, and solidification of spot welds produced in wrought and additively manufactured 304L stainless steel were investigated. The coupling efficiency of wrought and additively manufactured 304L stainless steel of similar surface condition were approximately the same over a range of applied laser energies. Laser welding of the untreated (rougher) surface of additively manufactured 304L, however, showed improved coupling efficiency ranging between 3.3 and 100%. The rougher surface traps the incoming light and increases the coupling efficiency at lower laser energies, while at higher energy, the absorption efficiency is dominated by intrinsic absorption from the keyhole formation rather than surface roughness. The resulting spot weld microstructures differed from welds made in wrought 304L and additively manufactured 304L. Welds made in wrought 304L were fully austenitic containing what is suspected to be massive austenite, which suggests that these welds solidified as primary ferrite. Welds made in additively manufactured 304L were also fully austenitic and contained both cellular austenite and what is suspected to be massive austenite. These observations mean that welds made in additively manufactured 304L solidified as primary ferrite and primary austenite. The differences in weld microstructures made in wrought and AM 304L can be attributed to differences in the composition and solidification rate.
304L stainless steel↗
First-principles study of the surface properties of LiAl 5 O 8 : Stability and tritiated water formation
LiAl 5 O 8 is an important secondary phase of γ-LiAlO 2 ceramics in tritium ( 3 H, T)-producing burnable absorber rods (TPBARs), present in small quantities in the as-fabricated condition and in larger quantities after irradiation due to Li burnup and mobility in the radiation-damaged lattice. In this work, we performed first-principles calculations to study the stabilities and structures of LiAl 5 O 8 surfaces the possibility of T 2 O formation on the (111) surface. By calculating the surface energies of all possible symmetrical stoichiometric and nonstoichiometric low-index surfaces, we identified the two most stable surfaces, one stoichiometric (001) surface and one nonstoichiometric (111) surface in an O-rich condition. The surface oxygen atoms on the nonstoichiometric (111) surface have remarkable displacements after relaxation, due to the large dangling O bonds. Considering a Li-poor and 3 H-rich condition relevant to TPBARs, we further studied these two stable surfaces with 37.5%, 75%, and 100% surface O atoms covered by 3 H atoms. Our results show that the 3H saturation is favorable for the nonstoichiometric (111) surface but not for the stoichiometric (001) surface. In addition, the structure of nonstoichiometric (111) surface is well stabilized when the surface O atoms are 100% saturated by 3 H atoms. Based on the fully 3H-saturated (111) surface, the 3 H 2 O desorption with an energy barrier of 0.69 eV is preferable in the 3 H-rich condition.
36 MATERIALS SCIENCE↗
Moisture-Driven Formation and Growth of Quasi-2-D Organolead Halide Perovskite Crystallites
Ruddlesden–Popper phase quasi-2-D organolead halide perovskites like n-butylammonium methylammonium lead iodide (nBA-MAPI) exhibit improved moisture stability over typical 3-D perovskite materials, making them exciting for use in a variety of applications such as photovoltaic (PV) devices. This improved stability is the result of a unique disproportionation-based degradation mechanism that protects the bulk of the nBA-MAPI from extensive damage through the formation of a protective, low-n surface layer. In addition to this surface layer, nBA-MAPI films also exhibit the dynamic growth of micrometer-scale crystallites and cracks at the surface of the film, unique and potentially important byproducts of quasi-2-D perovskite disproportionation. Here, we present a detailed study of these crystallites using several analytical techniques including photoluminescence spectroscopy (PL), confocal fluorescence microscopy (CFM), atomic force microscopy (AFM) combined with time-of-flight-secondary ion mass spectrometry (ToF-SIMS), and others in an effort to better understand the relationship between material disproportionation and crystallite growth. Our results show that the crystallites form after exposure to humid air and confirm that they are composed of low-n phases of nBA-MAPI. The crystallites are found to extend into the interior of the film and exhibit continued growth while exposed to moisture over 72 h. This growth is accompanied by both a decrease in the bulk 2-D phase and an increase in a 3-D-like phase in the surface PL spectra, indicating that the crystallites are likely a product of moisture-driven disproportionation. Importantly, similar crystallites are also observed to form within model PV devices, indicating that such processes must be accounted for when designing future devices containing materials like nBA-MAPI.
36 MATERIALS SCIENCE↗
Role of Sea‐Surface Salinity in Simulating Historical Decadal Variations of Atlantic Meridional Overturning Circulation in a Coupled Climate Model
Abstract Extending climate prediction from seasonal to decadal timescales requires realistic initialization of not only upper ocean heat content but also the Atlantic meridional overturning circulation (AMOC). However, it remains a major challenge to realistically initialize AMOC in a coupled system while also maintaining a balanced atmosphere‐ocean initial state. This study demonstrates the feasibility of generating fully coupled historical states with realistic AMOC variability. Employing a forced ocean—sea‐ice (FOSI) model simulation as the “truth,” we show reproducibility of key features of historical AMOC decadal variability in a fully coupled model by restoring sea‐surface salinity, in addition to sea‐surface temperature restoring widely used in seasonal prediction. The atmospheric state of the restored coupled model solution is much closer to that of the free coupled simulation than to the observations used in FOSI, pointing to potential advantages of using this approach for initializing decadal predictions with reduced ocean initialization shock.
54 ENVIRONMENTAL SCIENCES↗
Grinding of additively manufactured silicon carbide surfaces for optical applications
Many of the properties of Silicon carbide (SiC) are advantageous for optical applications, such as telescope mirrors and industrial laser systems. However, the base shapes of complex components are costly and difficult to manufacture. Leveraging additive manufacturing, near net complex components are readily processed. In this work, we investigate the post processing of additively manufactured SiC (AM SiC) compared to chemical vapor deposited (CVD) SiC. The specific grinding energy for the AM SiC was lower than CVD, however the trends were the same. A specular finish was observed on both materials but the AM SiC finish was limited due to residual porosity.
36 MATERIALS SCIENCE↗