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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Elevated Temperature Compressive Strength Properties of Oxide Dispersion Strengthened NiAl After Cryo-milling and Roasting in Nitrogen

In an effort to superimpose two different elevated temperature strengthening mechanisms in NiAl, several lots of oxide dispersion strengthened (ODS) NiAl powder have been cryo-milled in liquid nitrogen to introduce AlN particles at the grain boundaries. As an alternative to cryo-milling, one lot of ODS NiAl was roasted in nitrogen to produce AlN. Both techniques resulted in hot extruded AlN-strengthened, ODS NiAl alloys which were stronger than the base ODS NiAl between 1200 and 1400 K. However, neither the cryo-milled nor the N2-roasted ODS NiAl alloys were as strong as cryo-milled binary NiAl containing like amounts of AlN. The reason(s) for the relative weakness of cryo-milled ODS NiAl is not certain; however the lack of superior strength in N2-roasted ODS NiAl is probably due to its relatively large AlN particles.

Whittenberger, J. Daniel↗
DOE OSTI2024

Non-compact gauge groups, tensor fields and Yang-Mills-Einstein amplitudes

Abstract Scattering amplitudes in Yang-Mills-Einstein theories have been investigated mostly for compact gauge groups. While non-compact gauge groups are not physically viable in Yang-Mills theory, non-compact gaugings feature prominently in the supergravity literature, where any choice of perturbative vacuum spontaneously breaks the gauge group to a compact subgroup. In this paper, we formulate double-copy constructions for several five-dimensional$$ \mathcal{N} $$ N = 2 supergravities with non-compact gauge groups. On one side of the double copy, we employ amplitudes from a super-Yang-Mills theory with a massive hypermultiplet. On the other, we use amplitudes from particular non-supersymmetric Yang-Mills-scalar theories with massive fermions, chosen to obey constraints coming from color/kinematics duality. Supergravities with massive self-dual tensors in five dimensions are also considered, showing that tensors are straightforwardly realized as double copies of gauge-theory fermions with suitable choices of signs in the corresponding solutions of the Dirac equation. We present several examples of these constructions, noting in particular the appearance of Heisenberg groups in the supergravity gauge symmetry and, in some cases, the possibility of exotic tensor-vector matter couplings.

Physics↗
DOE OSTI2025

Biogenic carbon capture at pulp mills via sodium spiking and oxy-fuel calcination

Over 13 million metric tons of biogenic carbon dioxide (CO 2 ) are mineralized yearly in United States (US) pulp mill recovery boilers as molten sodium carbonate. The mineralized CO 2 is released downstream in the rotary lime kiln where it can be captured at a relatively low cost for permanent sequestration. The use of biocarbon and bioenergy at pulp mills enables the possibility for atmospheric carbon removal when biogenic CO2 is captured and sequestered. We demonstrate the feasibility of capturing biogenic CO 2 via sodium spiking coupled with oxy-fuel calcination in the rotary lime kiln at existing kraft pulp mills. Sodium (Na) spiking elevates the Na ion loading in the kraft chemical looping process by replacing chlorine-based bleaching with a highly alkaline bleaching sequence. Chemical pulping processes are modeled and simulated to understand the technical limits of implementing sodium spiking in existing pulp mills. Each 1 % of sodium added to the bleaching operations increases the rate of CO 2 mineralization by 4 %, and the maximum increase in sodium content in the kraft process is 9 %. Without sodium spiking, estimated CO 2 capture costs are $131 and $107/mt CO 2 for air and oxy-fuel combustion, respectively. With the implementation of sodium spiking, the cost of CO 2 captured decreases by 27 % and 31 %, showing costs of $96 and $74/mt CO 2 for air and oxy-fuel combustion, respectively. Oxy-fuel combustion reduces the costs of CO 2 capture compared to air combustion, but merged deployment with sodium spiking seems to be the most cost-effective pathway to integrate carbon capture.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Modeling Analysis of Ball-Milling Process for Battery-Electrode Synthesis

The mechanical alloying process is a promising method for synthesizing electrode materials for batteries owing to its benefits such as the ability to produce nanostructured, high-performing electrode alloys, no adverse effects on the solid electrolyte for solid-state batteries, stable production of thick electrodes, simple processing steps, and low processing costs. It is gaining intensive attention in the battery industry as one of the best methods to replace the conventional wet-slurry-solvent method, and its application is rapidly increasing these days. However, the operation is currently conducted purely based on trial-and-error methods without fully utilizing the features of its functions. Here, this may be attributed to a lack of understanding of the effect of operating parameters on the alloying process and final products. Surprisingly, there is a scarcity of the literature conducting fundamental research to comprehend the underlying physics of the entire mechanical alloying process, resulting in a significant knowledge gap. To address this knowledge gap, extensive research was conducted. The existing literature on mechanical alloying was reviewed to comprehend the current state of understanding and to discuss the direction for future research. Mathematical expressions were developed to create physics-based models capable of capturing the entire mechanical alloying process, including milling kinetics and defect-enhanced phase evolution. These methods were then applied to investigate the impact of operating parameters such as milling frequency, initial mole ratio of the alloyed materials, density of grinding balls, and energy required for the powders to become amorphous (i.e., the amorphization energy threshold). This research aimed not only to comprehend the direct effects of these operating parameters but also to unveil the physics underlying the ball-milling process. The results of our study can serve as crucial information for the battery industry in designing or operating the ball-milling process.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Plasma Focused Ion Beam Milling of High-Aspect-Ratio Holes in Diamond

Plasma focused ion beam (PFIB) technology has a great potential for applications requiring rapid micro-machining of high-aspect-ratio features. Here, we use 30-keV Ar, Xe, and O 2 ion beams to study PFIB milling of high-aspect-ratio circular holes in polycrystalline diamond. Our results show that Xe and O 2 ion beams have the highest milling efficiency for low-aspect-ratio and high-aspect-ratio hole milling, respectively. Each ion beam species produces holes with its characteristic shape and wall surface morphology. In conclusion, based on these results, we demonstrate a “hybrid” hole milled in a two-step process with Xe and O 2 ion beams with the geometry and wall morphology attractive for the attachment of a fuel fill tube to the inertial confinement fusion capsule.

ICF targets↗
DOE OSTI2024

Technoeconomic Analysis of Kraft Pulp Mill Integration with an Advanced Nuclear Reactor

This study focuses on post-combustion capture and oxy-fuel combustion for the boilers at the mill, as well as steam integration with the nuclear power plant. The primary goal of the research outlined in this report is to design, analyze, and document the integration of industrial-scale HTGR with a reference Kraft Pulp Mill. The purpose is to deliver reliable, cost-effective, and sustainable clean energy alternatives while reducing CO2 emissions. Specifically, this study focuses on 6 different scenarios that include carbon capture equipment and some of them use nuclear power to meet the heat and electricity needs of the reference plant. Also, 2 of these scenarios are created while also producing clean hydrogen through integrated High-Temperature Steam Electrolysis (HTSE). This report offers a detailed techno-economic assessment of different scenarios for a Kraft Pulp Mill, including an analysis of tax credits (section 45V, 45Q, and 48E) provided by the Inflation Reduction Act (IRA) of 2022. The evaluation explores the potential economic benefits and challenges of incorporating different configurations, including nuclear energy, into Kraft Pulp Mill operations, with particular attention to energy efficiency, economic implications, and environmental impact. By assessing both the technical feasibility and economic viability, this analysis aims to identify existing gaps and propose solutions for the successful implementation of nuclear integration. The findings are intended to provide valuable insights for stakeholders considering the adoption of advanced nuclear reactors in the pulp and paper industries.

08 HYDROGEN↗
DOE OSTI2025

Exploring the Early Lightning Notification of an Electric Field Mill at the Savannah River Site

At the Savannah River Site (SRS), employees receive automated broadcast notification about lightning only after three strikes have already occurred near the site boundary. To increase employee safety, it is preferential to give employees lead time before lightning strikes occur. We compared measurements from an on-site electric field mill to lightning detection data from the National Lightning Detection Network and the Geostationary Lightning Mapper. Using a difference threshold, we determined that the electric field mill provided a lead time greater than 6 minutes for 95% of lightning events from 2009-2020, with an average lead time of 56 minutes. Detection of events were limited to a 7-mile radius around the field mill. We also identified that the field mill threshold generated many false detections not clearly identified. False detections and detections from only precipitation can be reduced by using a second threshold without creating too many missed detections (Type II errors). The two thresholds used together provide the best information about rapidly changing electric fields and aid in advanced detection necessary to improve the lightning warning system used at SRS.

42 ENGINEERING↗
NASA NTRS1975

Chemical reactions of metal powders with organic and inorganic liquids during ball milling

Chromium and/or nickel powders were milled in metal chlorides and in organic liquids representative of various functional groups. The powders always reacted with the liquid and became contaminated with elements from them. The milled powders had specific surface areas ranging from 0.14 to 37 sq m/g, and the total contamination with elements from the milling liquid ranged from 0.01 to 56 weight percent. Compounds resulting from substitution, addition, or elimination reactions formed in or from the milling liquid.

Arias, A.↗
NASA NTRS1976

Oxide dispersion strengthened nickel produced by nonreactive milling

It is shown that oxide dispersion strengthened alloys can be produced by a postulated nonreactive milling mechanism whereby the dispersoid is trapped at the interface between welding metal powder particles. This interparticle welding is possible because, without a suitable and sufficiently vigorous chemical reaction between the metal powder particles and the milling fluid, no protective, weld-preventing reaction coating is formed on these particles. Using water as the nonreactive milling fluid, Ni - 1.8-vol % thoria and Ni - 1.8-vol % yttria alloys with 1093 C tensile strengths ranging from 122.3 to 141.5 MN/sq m (17,900 to 20,500 psi) were produced by nonreactive milling.

Arias, A.↗
NASA NTRS1979

Bend strengths of reaction bonded silicon nitride prepared from dry attrition milled silicon powder

Dry attrition milled silicon powder was compacted, sintered in helium, and reaction bonded in nitrogen-4 volume percent hydrogen. Bend strengths of bars with as-nitrided surfaces averaged as high as 210 MPa at room temperature and 220 MPa at 1400 C. Bars prepared from the milled powder were stronger than those prepared from as-received powder at both room temperature and at 1400 C. Room temperature strength decreased with increased milling time and 1400 C strength increased with increased milling time.

Herbell, T. P.↗
NASA NTRS1980

Effect of milling and leaching on the structure of sintered silicon

The effects of attrition milling and acid leaching on the sintering behavior and the resultant structures of two commercial silicon powders were investigated. Sintering was performed in He for 16 hours at 1200, 1250, and 1300 C. Compacts of as-received Si did not densify during sintering. Milling reduced the average particle size to below 0.5 microns and enhanced densification (1.75 g/cc). Leaching milled Si further enhanced densification (1.90 g/cc max.) and decreased structural coarsening. After sintering, the structure of the milled and leached powder compacts appears favorable for the production of reaction bonded silicon nitride.

Yeh, H. C.↗
NASA NTRS2004

Ion Milling of Sapphire

The ion milling of sapphire is a complicated operation due to several characteristics of the material itself. It is a relatively hard transparent nonconductive crystalline material that does not transfer heat nearly as well as metals that have been successfully ion milled in the past. This investigation involved designing an experimental arrangement, using existing ion milling equipment, as the precursor to figuring the surface of sapphire and other insulating optical materials. The experimental arrangement employs a laser probe beam to constantly monitor the stresses being induced in the material, as it is being ion milled. The goal is to determine if the technique proposed would indeed indicate the stress being induced in the material so that these stresses can be managed to prevent failure of the optic.

Gregory, Don A.↗
NASA NTRS2008

Rotationally Vibrating Electric-Field Mill

A proposed instrument for measuring a static electric field would be based partly on a conventional rotating-split-cylinder or rotating-split-sphere electric-field mill. However, the design of the proposed instrument would overcome the difficulty, encountered in conventional rotational field mills, of transferring measurement signals and power via either electrical or fiber-optic rotary couplings that must be aligned and installed in conjunction with rotary bearings. Instead of being made to rotate in one direction at a steady speed as in a conventional rotational field mill, a split-cylinder or split-sphere electrode assembly in the proposed instrument would be set into rotational vibration like that of a metronome. The rotational vibration, synchronized with appropriate rapid electronic switching of electrical connections between electric-current-measuring circuitry and the split-cylinder or split-sphere electrodes, would result in an electrical measurement effect equivalent to that of a conventional rotational field mill. A version of the proposed instrument is described.

Kirkham, Harold↗
DOE OSTI2024

A Methodology for determining optimal milling parameters for low-taper microtensile sample production

Femtosecond lasers are beginning to see an increase in interest for industrial and high throughput microsample milling applications. Despite this, much of the literature regarding removal rate studies for ultrashort pulse laser milling continues to focus on single-pulse or similar experiments that have a very small time on target. The material volume removal rates of femtosecond milling can vary wildly depending on parameters like laser scan speed, hatch spacing, z-axis step size, and pulses on the material. Currently, there is no established methodology for determining the optimal values of these parameters for micromilling applications. This methodology was developed in this study. The methodology consists of a pulse study, a repeat study, and a z-step study that will return the milling parameters that resulted in the largest volume removal rate for the laser used for this research. The methodology was created for the laser system used in this study, and was tested on 316 Stainless Steel, but was developed in such a way that it may be adapted to any material, and with some tweaking of variables might be used in other laser systems. The laser system used in this study utilizes a novel positioning stage that introduces 6 degrees of freedom to the translation of laser samples, being able to tilt and move in all three axes. Using both the developed methodology and the unique capabilities of the laser microtensile samples were produced with taper angles of <1° in 316 Stainless Steel.

Barker, Zachary Wayne↗
DOE OSTI2024

Heteronuclear single quantum coherence (HSQC) NMR spectra of lignin isolated from switchgrass residues after fermentation with milling

Here we present a curated dataset of two-dimensional heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectra of lignin isolated from a herbaceous energy crop (Panicum virgatum L.). The lowland variant “Timber” switchgrass from Ernst seeds was used. The switchgrass was knife milled and passed through a 2 mm sieve prior to consolidated bioprocessing (CBP) process. Switchgrass was suspended in Milli-Q water and autoclaved for 90 min on liquid cycles. The residues after autoclaving were then subjected to CBP using coculture of Clostridium thermocellum (C. thermocellum DSM 1313 (LL1004)) and Thermoanaerobacterium thermosaccarolyticum ( T. thermosaccharolyticum HG-8 ATCC 31960 (LL1244)). Once-fermented and twice-fermented (FF) switchgrass were subjected to ball and disc milling in bioreactors at 55 °C and 60, 48 grams/L solids loadings for primary and secondary fermentation respectively. When fermentations were completed, the residual solids were rinsed with milli-Q water. Lignin was isolated from the pretreated residues after ball-milling in a porcelain jar with ceramic balls via Retsch PM 200 at 600 rpm for 2 h followed by enzymatic hydrolysis in acetate buffer (pH 4.8, 50 °C) for 48 h. The dry lignin samples were dissolved in deuterated dimethyl sulfoxide (d6) and characterized using 13C–1H HSQC in a Bruker Avance III HD 500-MHz NMR spectrometer. A standard Bruker pulse sequence (hsqcetgpsisp.2) was used on a Prodigy platform cryoprobe. The spectra were acquired with the following acquisition conditions: 230 ppm spectral width in F1 (13C) dimension with 256 data points and 12 ppm spectral width in F2 (1H) dimension with 2048 data points, a 90° pulse, with a C–H coupling constant of 145 Hz, a 1.0 s pulse delay, and 64 scans. Spectra were processed using the Bruker TopSpin 3.6 software.

Lignin, HSQC, Switchgrass, CBP , Ball mill, Disc m↗
DOE OSTI2026

The properties of the nitrogen-vacancy center in milled chemical vapor deposition nanodiamonds

Fluorescent nanodiamonds (FNDs) containing negatively charged nitrogen-vacancy (NV − ) centers are vital for many emerging quantum sensing applications from magnetometry to intracellular sensing in biology. However, developing a scalable fabrication method for FNDs hosting color centers with consistent bulk-like photoluminescence (PL) and spin coherence properties remains a highly desired but unrealized goal. Here, we investigate optimized ball milling of single-crystal diamonds produced via chemical vapor deposition (CVD) and containing 2 ppm of substitutional nitrogen and 0.3 ppm of NV − to achieve this goal. The NV charge state, PL lifetime, and spin properties of bulk CVD diamond samples are directly compared to milled CVD FNDs and commercial high-pressure high-temperature (HPHT) FNDs. We find that on average, the relative contribution of the NV − charge state to the total NV PL is lower and the NV PL lifetime is longer in CVD FNDs compared to HPHT FNDs, both likely due to the lower N s 0 concentration in CVD FNDs. The CVD bulk and CVD FNDs on average show similar average T 1 spin relaxation times of 3.2 ± 0.7 ms and 4.7 ± 1.6 ms, respectively, compared to 0.17 ± 0.01 ms for commercial HPHT FNDs. Our results demonstrate that ball milling of CVD diamonds enables the large-scale fabrication of NV ensembles in FNDs with bulk-like T 1 spin relaxation properties.

chemical vapor deposition↗
DOE OSTI2026

Quantifying atmospheric carbon removal at pulp and paper mills: a life cycle assessment across system boundaries

The pulp and paper industry is a promising yet underexplored platform for large-scale carbon dioxide removal (CDR) due to its use of biogenic feedstocks and production of concentrated CO 2 emissions from point sources. This study presents the first comprehensive life cycle assessment (LCA) of retrofitting an amine-based carbon capture and storage (CCS) system into a representative virgin kraft pulp and paper mill in the Southeastern U.S. We evaluate carbon removal across five system configurations, applying both static and dynamic LCA methods under multiple functional units: CO 2 captured, biomass input, and paper output. Results show that CCS retrofits can convert a conventional mill from a net emitter into a net carbon sink, with total removal efficiencies from 17% to 92% (metric tonnes of CO 2 removed per metric tonne of CO 2 available for removal under selected boundary conditions). When carbon removal is normalized to the quantity of biogenic CO 2 captured—a narrow, gate-to-gate system boundary that considers only CCS facility emissions—removal efficiencies reached as high as 92%. The use of such narrow boundaries aligns with precedents in traditional LCA methodology, where gate-to-gate assessments are commonly applied to isolate process-level performance and allocate emissions accordingly, providing a consistent basis for comparison across technologies. Under broader cradle-to-grave boundaries—which begin tracking carbon at the point of its physical removal from the atmosphere via photosynthesis in the forest, and extend to include upstream forest operations, mill-wide emissions, and downstream product decomposition—efficiencies declined, ranging from 17% to 46% under static assumptions and dropping to 12% when accounting for dynamic biogenic carbon fluxes over time. These results underscore how system boundary definitions influence reported outcomes, while also illustrating the complementary roles of narrow and broad perspectives for different decision-making contexts.

09 BIOMASS FUELS↗
DOE OSTI2026

From Powder to Power: Tailored Pre-Milling Strategy that Optimizes Microstructure for Efficient Hydrogen Evolution

The hydrogen evolution reaction (HER) plays a critical role in enabling large-scale electrolytic hydrogen production and advancing future technologies and fuel production. Among non-precious metals, NiMo-based catalysts are particularly attractive due to their capability to promote both water dissociation and hydrogen adsorption in alkaline media. However, conventional NiMo catalysts often suffer from incomplete alloying, particle aggregation, weak metal–support interactions, and surface oxidation, which significantly limit active site utilization, electronic conductivity, and long-term stability. Herein, we report a scalable, solid-state, two-step ball milling strategy for constructing an efficient NiMo/C catalyst for the HER. Pre-milling the metal precursors prior to carbon incorporation promotes efficient solid-state activation, leading to the formation of uniformly alloyed, ultrafine, and defect-rich Ni–Mo nanoparticles with robust metal–carbon interfacial anchoring. Benefiting from this integrated structural design, the optimized NiMo/C catalyst exhibits low overpotentials and Tafel slopes, reduced charge-transfer resistance, and excellent durability under alkaline conditions. Comprehensive structural and surface analysis reveal that the enhanced HER performance can be attributed to the synergistic interplay of homogeneous Ni–Mo alloying, uniform nanoparticle dispersion on a defect-rich carbon scaffold, enhanced accessibility of catalytically active sites, and optimized electronic coupling that stabilizes the catalyst surface. This work highlights the two-step solid-state ball milling strategy as a simple, robust, and scalable route for the preparation of effective and durable non-precious metal HER electrocatalysts, offering practical insights toward large-scale and inexpensive hydrogen production.

Yang, Xiaoxuan [Oak Ridge National Laboratory (ORN↗