Engineering topics

Ryerson, F. J.

Publications and source records attributed to Ryerson, F. J..

At least 19 records

DOE OSTI2022

Mass Transport in Binary TiO 2 :SiO 2 and GeO 2 :SiO 2 Direct Ink Write Glasses

The mass transport mechanisms of Ti in TiO 2 :SiO 2 and Ge in GeO 2 :SiO 2 direct ink write, additively manufactured glasses were studied. Due to the low solubility of Ti in SiO2 and high melting point of TiO 2 relative to SiO 2 , Ti transport was found to occur via solid state interdiffusion between adjoining SiO 2 and TiO 2 precursor particles. The diffusivity of titanium in SiO 2 measured over typical sintering temperatures (1000-1300 °C) using Rutherford backscattering spectrometry was D = 9.1 × 10 -7 [m2/sec] exp ($\frac{378[\frac{kJ}{mol}]}{RT}$. This provides an estimate of ~30 nm for the diffusion length under typical sintering conditions (2 hrs. at 1200 °C). Although Ti and Ge have similar diffusivities in SiO 2 glass at low concentrations, GeO 2 was found to be much more mobile during the sintering of printed GeO 2 :SiO 2 green bodies. This was evident in glasses with phase separated GeO 2 regions over length scales of ~10 μm and in experiments involving binary xerogels in which GeO 2 migrated over ~10 μm through cracked, porous SiO 2 layers. Large phase separated regions and long transport lengths in GeO 2 :SiO 2 suggest that the transport of GeO 2 occurs prior to the densification of the SiO 2 matrix via an alternative mechanism such as capillary flow. These results inform important considerations in the design of index modifying inks for the direct ink write process, namely initial precursor phase, mutual solubility with the base SiO 2 glass, and mass transport throughout the sintering process.

36 MATERIALS SCIENCE↗

DOE OSTI2022

The solubility of titanite in silicate melt determined from growth and dissolution experiments

The solubility of titanite (CaTiSiO 5 ) in Si-rich melts was measured experimentally through growth experiments at 800–1000 °C, 0.5–1.0 GPa, log fO 2 ~ CCO–0.8, t = 72–168 h, and H 2 O = 0 to 4 wt.%, and in dissolution experiments at 925–1300 °C, 0.8 GPa, t = 18–118 h, and H 2 O = 1–10 wt.% in a piston-cylinder apparatus. Run product glasses in growth experiments were homogeneous, and iron loss suppressed ilmenite crystallization. Saturation concentrations in dissolution experiments were estimated by fitting measured diffusion profiles. Titanite solubility increases with increasing temperature and melt composition parameter $M = {\text{ molar }}\left( {{\text{Na }} + {\text{ K }} + {\text{ 2Ca}}} \right)/\left( {{\text{Al }} \times {\text{ Si}}} \right)$ . Multiple linear regression of glass composition data from growth and dissolution experiments ( n = 29) plus 39 experiments from the LEPR database (Hirschmann et al. 2008 ) yielded the titanite solubility equation (adj. r 2 = 0.95): $\left( {TiO_{2} } \right)^{melt} \left( {wt.\% } \right) = 0.978 \times M + 0.0048 \times T\left( K \right){-}5.90$ . This model correctly predicted undersaturation in 95% of 2344 experiments from the LEPR database that did not have titanite or rutile. Application to natural rocks yields saturation temperatures that are similar to independent temperature estimates. Finally, this equation should be useful for constraining the temperatures of titanite-saturated melts, for determining whether titanite saturation in magmatic source regions is likely, and for determining when titanite can crystallize and begin to exert an influence on melt geochemistry.

58 GEOSCIENCES↗

DOE OSTI2021

Block Tectonics across Western Tibet and Multi-Millennial Recurrence of Great Earthquakes on the Karakax Fault

We report that fault slip rates are critical to quantify continental deformation. Those along the Karakax fault (northwestern Altyn Tagh Fault: ATF) have been debated, even though it is one of Tibet's most outstanding active faults. At Taersa, using LiDAR measurements of terrace and fan riser offsets (~6 to ~500 m) and 10 Be/ 26 Al dating of alluvial surfaces (<210 ka), we obtain a late Quaternary slip rate of ~2.5 ± 0.5 mm/yr. This doubles the ~2.6 ± 0.5 mm/yr rate time span found to the east and west. We interpret the ~150 km-long, free-faced rupture along the fault to be that of the M ~ 7.6 event felt in Hotan in 1882. Characteristic slip (~6 m) during four large earthquakes since ~10 ka implies a ~2500 ± 500 years return time. A ~3 mm/yr rate is consistent with the ~80 km offset of the Karakax river since uplift of the West Kunlun range and sediment deposition in the Tarim foreland accelerated, ~24 Ma ago. The faster slip rate (~10.5 mm/yr) on the central ATF matches the sum of those along the reactivated West Tibetan terrane boundaries (Karakax and Longmu-Gozha Co faults) at the Uzatagh triple junction (~36°N, 83°E). The abrupt termination and altitude drop of the Karakorum range where the Longmu Co and Karakorum faults meet (Angmong junction), also reflect triple junction kinematics. Such localized changes account for the rise of the Karakorum and West Kunlun ranges and support lithospheric block tectonics rather than diffusely distributed deformation.

58 GEOSCIENCES↗

DOE OSTI2021

External Review Committee Report on the California Geological Survey

In May and June of 2021, the External Review Committee (ERC) assessed the activities and major programs of the California Geological Survey (CGS). The ERC reviewed materials from the five CGS program areas and upper management, as well as online presentations from program leaders and the California Department of Conservation (DOC), which oversees CGS.

58 GEOSCIENCES↗

DOE OSTI2021

Thermal expansion of liquid Fe-S alloy at high pressure

The local structure and density of liquid Fe-S alloys at high pressure have been determined in situ by combined angle and energy dispersive X-ray diffraction experiments in a multi-anvil apparatus, covering a large temperature and compositional range. Precise density measurements collected for increasing temperature allowed us to directly derive the thermal expansion coefficients for liquid Fe-S alloys as a function of composition. In turn, thermal expansion has been used to refine thermodynamic models and to address the crystallization regime of telluric planetary cores by comparing the adiabatic temperature gradient and the slope of the liquidus in the Fe-FeS system. For Fe-S cores of asteroids and small planetesimals, top-down solidification is the dominant scenario as the compositional domain for which the slope of the liquidus is greater than the adiabatic gradient is limited to a narrow portion on the Fe-rich side. However, bottom-up growth of the inner core is expected for S-poor cases, with this compositional domain expanding to more S-rich compositions with increasing pressure (size of the planetary body). In particular, bottom-up crystallization cannot be excluded for the Moon and Ganymede.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Directed energy deposition additive manufacturing of functionally graded Al-W composites

Directed energy deposition using laser heat sources (DED-L) is a metal additive manufacturing method that can be used to fabricate functionally graded materials by feeding multiple powder streams directly into a laser-generated melt pool. Additionally, the composition can be spatially varied by independent control of the materials feed rates. DED-L additive manufacturing is used in this work to create continuously graded Al/W composites that span 0–55 vol% W in Al over length scales from 0.6 to 1.2 mm with individual layers on the order of 0.1 mm and powder particle sizes on the order of 10 µm. The obtained composition and thickness ranges are comparable to those typically achieved using conventional powder metallurgy approaches and enables fabrication of composites to be used as a high impedance graded density impactor (GDI) in dynamic ramp compression experiments to study matter under extreme conditions. DED-L additive manufacturing of a GDI presents an opportunity to reduce GDI fabrication time to less than a day compared to many weeks by conventional methods. It is also possible to scale the deposition by DED-L to essentially unlimited dimensions in the lateral directions, whereas conventional methods become limited.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Presentation of the Dana Medal of the Mineralogical Society of America for 2019 to Matthew J. Kohn

If there’s one word that describes Matt Kohn’s career, it’s eclectic. What is possibly most astounding is that Matt’s contributions have not been in a single, narrow field, but in two distinct fields that, at least at first glance, are not even that closely related. While Matt is a metamorphic petrologist par excellence making significant contributions to the fields of geo-thermobarometry, metamorphic phase equilibria, metamorphic fluid flow, monazite geochronology, argon geochronology, and metamorphic P-T-t studies and their tectonic implications, he has also pioneered the use of stable isotopes to unravel vertebrate paleodietary patterns and paleoclimate.

58 GEOSCIENCES↗

DOE OSTI2019

Alloying titanium and niobium via electron beam cold hearth melting

Electron beam cold hearth melting of titanium and niobium was performed to assess the feasibility of this technique for uranium processing and to determine system requirements for LLNL applications. The demonstration consisted of (1) alloying titanium and niobium, (2) feeding and melting scrap of various forms and (3) consolidating powder feedstock. Emphasis was placed on the former, with focused efforts to produce and deliver stoichiometric amounts of titanium and niobium to the hearth for alloying. This effort demonstrated the ability to melt via electron beam and cast titanium into a thin-walled (~0.06”) niobium tube. This process was performed repeatably and an optimal set of operational parameters was identified through an iterative approach. Three alloyed ingots were produced using niobium tubes filled with titanium, by casting and slip-fit. The alloyed ingots were characterized using multiple approaches and were shown to be comprised of columnar grains, low inclusion amounts and a small degree of ordered (center to edge, top to bottom) variation in niobium concentration. Based on these findings, it is concluded that alloying can be accomplished in a single step, without the need for an additional melting step after electron beam cold hearth melting. Details of these analyses, along with efforts to adopt cold hearth melting technology for scrap and powder recycle are provided herein.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2018

Additive Manufacturing of a y0-Tetragonal Uranium-Niobium Alloy

The ability to process near-net shape structures is of particular interest in applications using rare or expensive materials. Laser powder bed fusion additive manufacturing can meet this challenge, yet also introduces significant processing and materials challenges toward achieving structural integrity. Broadly addressed aspects affecting powder bed fusion structures include surface roughness, residual stresses, and porosity. Here, we focus on materials-specific challenges—namely, the influence of multiple pass reheating during processing and post-processing homogenization on phase transformations and the role of impurities and oxides on grain morphology and mechanical behavior—with a view of adopting laser powder bed fusion processing for the shape memory alloy, uranium-6 wt.% niobium. Our observations to date on the factors influencing material behavior and post-processing requirements and recommendations for process improvement are discussed herein.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Low Temperature Age Hardening in Cast Uranium-6 wt. pct. Niobium

An investigation to determine whether cast U-6Nb would exhibit low temperature (<250°C) age hardening behavior, which has been well-documented in wrought U-6Nb, was performed using a 6 year old near-cylindrical U-6Nb casting, courtesy of AWE, UK. The casting was sectioned, and metallographic cubes and tensile bars were machined and subjected to a variety of heat treatments. Our results indicate that the cast U-6Nb has a larger grain size than wrought U-6Nb, ranging from ~200-500 μm, and that these grains are equiaxed. A significant quantity of inclusions are present at the <10 μm size range and appear to be carbides, based on their morphology (faceted) and color (dark gray). There does not appear to be significant porosity present and the few pores observed were <40 μm in size and spherical. Tensile bars (TBs) were lathe machined, solutionized, then water quenched prior to testing. A group of TBs were subjected to low temperature artificial aging heat treatments consisting of a hold at 200°C for 1 or 2h, followed by furnace cooling, all under a helium backfill. Mechanical testing confirms that cast U-6Nb TBs exhibit low temperature age hardening, with an increase in initial yield stress (Y1) of >425 MPa—a significant increase over wrought U-6Nb yield stress of 100-200 MPa for the same heat treatment. This increase is accompanied by a reduction in failure strain, which is indicative of a reduction in ductility. Modifying the heat treatment temperature and/or time may allow the properties to be tailored to the requirements. This study is intended as a preliminary investigation. Overall, this high impurity content casting exhibits a reasonable mechanical response which can be tailored in a consistent manner through low temperature heat treatment. As the result, a more comprehensive investigation of low temperature aging in cleaner cast U-6Nb, better representative of the state-of-the-art, shall be performed in FY19.

36 MATERIALS SCIENCE↗

DOE OSTI2017

Mechanical Behavior of Additively Manufactured Uranium-6 wt. pct. Niobium

This report describes an effort to process uranium-6 weight% niobium using laser powder bed fusion. The chemistry, crystallography, microstructure and mechanical response resulting from this process are discussed with particular emphasis on the effect of the laser powder bed fusion process on impurities. In an effort to achieve homogenization and uniform mechanical behavior from different builds, as well as to induce a more conventional loading response, we explore post-processing heat treatments on this complex alloy. Elevated temperature heat treatment for recrystallization is evaluated and the effect of recrystallization on mechanical behavior in laser powder bed fusion processed U-6Nb is discussed. Wrought-like mechanical behavior and grain sizes are achieved through post-processing and are reported herein.

36 MATERIALS SCIENCE↗

DOE OSTI2016

Terrestrial cosmogenic surface exposure dating of glacial and associated landforms in the Ruby Mountains-East Humboldt Range of central Nevada and along the northeastern flank of the Sierra Nevada

Deposits near Lamoille in the Ruby Mountains-East Humboldt Range of central Nevada and at Woodfords on the eastern edge of the Sierra Nevada each record two distinct glacial advances. In this paper, we compare independent assessments of terrestrial cosmogenic nuclide (TCN) surface exposure ages for glacial deposits that we have determined to those obtained by others at the two sites. At each site, TCN ages of boulders on moraines of the younger advance are between 15 and 30 ka and may be associated with marine oxygen isotope stage (MIS) 2. At Woodfords, TCN ages of boulders on the moraine of the older advance are younger than ~ 60 ka and possibly formed during MIS 4, whereas boulders on the correlative outwash surface show ages approaching 140 ka (~ MIS 6). The TCN ages of boulders on older glacial moraine at Woodfords thus appear to severely underestimate the true age of the glacial advance responsible for the deposit. The same is possibly true at Lamoille where clasts sampled from the moraine of the oldest advance have ages ranging between 20 and 40 ka with a single outlier age of ~ 80 ka. The underestimations are attributed to the degradation and denudation of older moraine crests. Noting that boulder ages on the older advances at each site overlap significantly with MIS 2. Finally, we speculate that erosion of the older moraines has been episodic, with a pulse of denudation accompanying the inception of MIS 2 glaciation.

58 GEOSCIENCES↗

DOE OSTI2016

Characterization of low concentration uranium glass working materials

A series of uranium-doped silicate glasses were created at (Lawrence Livermore National Laboratory) LLNL, to be used as working reference material analogs for low uranium concentration research. Specifically, the aim of this effort was the generation of well-characterized glasses spanning a range of concentrations and compositions, and of sufficient homogeneity in uranium concentration and isotopic composition, for instrumentation research and development purposes. While the glasses produced here are not intended to replace or become standard materials for uranium concentration or uranium isotopic composition, it is hoped that they will help fill a current gap, providing low-level uranium glasses sufficient for methods development and method comparisons within the limitations of the produced glass suite. Glasses are available for research use by request.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2015

Spatially-Resolved Analyses of Aerodynamic Fallout from a Uranium-Fueled Nuclear Test

The fiive silicate fallout glass spherules produced in a uranium-fueled, near-surface nuclear test were characterized by secondary ion mass spectrometry, electron probe microanalysis, autoradiography, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Several samples display compositional heterogeneity suggestive of incomplete mixing between major elements and natural U ( 238 U/ 235 U = 0.00725) and enriched U. Samples exhibit extreme spatial heterogeneity in U isotopic composition with 0.02 < 235 U/ 238 U < 11.84 among all five spherules and 0.02 < 235 U/ 238 U < 7.41 within a single spherule. Moreover, in two spherules, the 235 U/ 238 U ratio is correlated with changes in major element composition, suggesting the agglomeration of chemically and isotopically distinct molten precursors. Two samples are nearly homogenous with respect to major element and uranium isotopic composition, suggesting extensive mixing possibly due to experiencing higher temperatures or residing longer in the fireball. Linear correlations between 234 U/ 238 U, 235 U/ 238 U, and 236 U/ 238 U ratios are consistent with a two-component mixing model, which is used to illustrate the extent of mixing between natural and enriched U end members.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2015

Composition of the core from gallium metal–silicate partitioning experiments

We present gallium concentration (normalized to CI chondrites) in the mantle is at the same level as that of lithophile elements with similar volatility, implying that there must be little to no gallium in Earth's core. Metal-silicate partitioning experiments, however, have shown that gallium is a moderately siderophile element and should be therefore depleted in the mantle by core formation. Moreover, gallium concentrations in the mantle (4 ppm) are too high to be only brought by the late veneer; and neither pressure, nor temperature, nor silicate composition has a large enough effect on gallium partitioning to make it lithophile. We therefore systematically investigated the effect of core composition (light element content) on the partitioning of gallium by carrying out metal–silicate partitioning experiments in a piston–cylinder press at 2 GPa between 1673 K and 2073 K. Four light elements (Si, O, S, C) were considered, and their effect was found to be sufficiently strong to make gallium lithophile. The partitioning of gallium was then modeled and parameterized as a function of pressure, temperature, redox and core composition. A continuous core formation model was used to track the evolution of gallium partitioning during core formation, for various magma ocean depths, geotherms, core light element contents, and magma ocean composition (redox) during accretion. The only model for which the final gallium concentration in the silicate Earth matched the observed value is the one involving a light-element rich core equilibrating in a FeO-rich deep magma ocean (>1300 km) with a final pressure of at least 50 GPa. More specifically, the incorporation of S and C in the core provided successful models only for concentrations that lie far beyond their allowable cosmochemical or geophysical limits, whereas realistic O and Si amounts (less than 5 wt.%) in the core provided successful models for magma oceans deeper that 1300 km. In conclusion, these results offer a strong argument for an O- and Si-rich core, formed in a deep terrestrial magma ocean, along with oxidizing conditions.

58 GEOSCIENCES↗

DOE OSTI2014

SIMS Analyses of Aerodynamic Fallout from a Uranium-Fueled Test

Five silicate fallout glass spherules produced in a uranium-fueled, near-surface nuclear test were characterized by secondary ion mass spectrometry, electron probe microanalysis, autoradiography, scanning electron microscopy, and energy-dispersive x ray spectroscopy. Several samples display distinctive compositional heterogeneity suggestive of incomplete mixing, and exhibit heterogeneity in U isotopes with 0.02 < 235 U/ 238 U < 11.8 among all five samples and 0.02 < 235 U/ 238 U < 7.81 within a single sample. In two samples, the 235 U/ 238 U ratio is correlated with major element composition, consistent with the agglomeration of chemically and isotopically distinct molten precursors. Two samples are quasi-homogeneous with respect to composition and uranium isotopic composition, suggesting extensive mixing possibly due longer residence time in the fireball. Correlated variations between 234 U, 235 U, 236 U and 238 U abundances point to mixing of end-members corresponding to uranium derived from the device and natural U ( 238 U/ 235 U = 0.00725) found in soil.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2013

GEOS Code Development Road Map

GEOS is a massively parallel computational framework designed to enable HPC-based simulations of subsurface reservoir stimulation activities with the goal of optimizing current operations and evaluating innovative stimulation methods. GEOS will enable coupling of different solvers associated with the various physical processes occurring during reservoir stimulation in unique and sophisticated ways, adapted to various geologic settings, materials and stimulation methods. The overall architecture of the framework includes consistent data structures and will allow incorporation of additional physical and materials models as demanded by future applications. Along with predicting the initiation, propagation and reactivation of fractures, GEOS will also generate a seismic source term that can be linked with seismic wave propagation codes to generate synthetic microseismicity at surface and downhole arrays. Similarly, the output from GEOS can be linked with existing fluid/thermal transport codes. GEOS can also be linked with existing, non-intrusive uncertainty quantification schemes to constrain uncertainty in its predictions and sensitivity to the various parameters describing the reservoir and stimulation operations. We anticipate that an implicit-explicit 3D version of GEOS, including a preliminary seismic source model, will be available for parametric testing and validation against experimental and field data by Oct. 1, 2013.

02 PETROLEUM↗

NASA NTRS1980

The role of P2O5 in silicate melts

Phase equilibria data in the systems SiO2-P2O5, P2O5-M(x)O(y), and P2O5-M(x)O(y)-SiO2 are employed in conjunction with chromatographic and spectral data to investigate the role of P2O5 in silicate melts. P2O5 depolymerizes pure SiO2 melts by entering the network as a four-fold coordinated cation, but polymerizes melts in which an additional metal cation other than silicon is present. In this complex system P2O5 acts to increase phase separation by further enrichment of the high charge density cations Ti, Fe, Mg, Mn, Ca, in the ferrobasaltic liquid. The dual behavior of P2O5 is explained in a model which requires complexing of phosphate anions and metal cations in the melt. This interaction destroys Si-O-M-O-Si bonds polymerizing the melt. The higher concentration of Si-O-M-O-Si bond complexes in immiscible ferrobasaltic liquids relative to their conjugate immiscible granite liquids explains the partitioning of P2O5 into the ferrobasaltic liquid.

Ryerson, F. J.↗