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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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At least 1,387 records · Page 77
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Percutaneous Neurolysis for Pain Management in Oncological Patients

Cancer pain is most commonly classified as nociceptive (somatic or visceral) or neuropathic. Different types of pain or pain syndromes are present in all phases of cancer (early and metastatic) and are inadequately treated in 56% to 82.3% of patients. Percutaneous neurolysis and neuromodulation are feasible and reproducible, efficient (70–80% success rate) and safe (≈ 0.5% mean complication rate) palliative therapies for pain reduction in oncologic patients with refractory pain. Percutaneous neurolysis can be performed either by injection of a chemical agent (phenol or alcohol) or by application of continuous radiofrequency or cryoablation. During chemical neurolysis nerve damage is achieved by means of Wallerian degeneration. A thorough knowledge of neural anatomy and pain transmission pathways is fundamental to appropriate patient and technique selection. Imaging guidance and strict asepsis are prerequisites. The purpose of this article is to describe the basic concepts of percutaneous neurolysis in oncologic patients. Controversies concerning techniques and products will be addressed. Finally, the necessity for an individually tailored approach for the selection of the different techniques and targets will be emphasized.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Sacroiliac Joint Ablation Using MR-HIFU

The sacroiliac joint is the culprit in 15–30% of patients with chronic lumbar back pain. Ablation of the posterior sensory nerves supplying the joint is an established treatment option before arthrodesis. We report the successful application of MR-HIFU in a patient with therapy–refractory pain using the Sonalleve MR-HIFU system. The outpatient procedure was performed under spinal anaesthesia and analgosedation. The ramus dorsalis of L5 as well as the lateral branches of the ramus dorsalis S1–S3 was targeted, and tissue peak temperature per sonication was controlled using MR-thermometry. There were no post-interventional complications. Clinical improvement began 4 days post-intervention with complete resolution of the pain after 1 month.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Effect of Ladle Usage on Cleanliness of Bearing Steel

To investigate the effects of ladle usage on the inclusions and total oxygen contents of bearing steel, MgO refractory rods with different glazes were used to simulate different ladle usages. The results show that the effects of different ladle usages on the cleanliness of the steel differ from each other. The total oxygen content of steel increases with the decreasing glaze basicity. Ladle glaze having a lower basicity has a more negative impact on the cleanliness of steel in the subsequent production. Inclusions can be generated by the flush-off of ladle glaze, and the initial glaze is important in the evolution of inclusions in the subsequent heats. To avoid the negative effect of ladle usage and to improve the steel cleanliness as much as possible, specialized ladles were suggested for producing high-quality steel grades.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Formation Mechanism of Oxide-Sulfide Complex Inclusions in High-Sulfur-Containing Steel Melts

The [S] content in resulfurized steel is controlled in the range of 200 to 800 ppm to ensure good machinability and workability. It is well known that “MgAl{sub 2}O{sub 4}(spinel)+CaS” complex inclusions are formed in molten steel during the ladle refining process, and these cause nozzle clogging during continuous casting. Thus, in the present study, the “Refractory-Slag-Metal-Inclusions (ReSMI)” multiphase reaction model was employed in conjunction with experiments to investigate the influence of slag composition and [S] content in the steel on the formation of oxide-sulfide complex inclusions. The critical [S] and [Al] contents necessary for the precipitation of CaS in the CaO-Al{sub 2}O{sub 3}-MgO-SiO{sub 2} (CAMS) oxide inclusions were predicted from the composition of the liquid inclusions, as observed by scanning electron microscopy–electron dispersive spectrometry (SEM-EDS) and calculated using the ReSMI multiphase reaction model. The critical [S] content increases with increasing content of SiO{sub 2} in the slag at a given [Al] content. Formation mechanisms for spinel+CaS and spinel+MnS complex inclusions were also proposed.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A New Experimental Design to Study the Kinetics of Solid Dissolution into Liquids at Elevated Temperature

A new method was developed to study the dissolution of a solid cylinder in a liquid under forced convection at elevated temperature. In the new design, a rotating cylinder was placed concentrically in a crucible fabricated by boring four holes into a blank material for creating an internal volume with a quatrefoil profile. A strong flow in the radial direction in the liquid was created, which was evidently shown by computational fluid dynamic (CFD) calculations and experiments at both room temperature and elevated temperature. The new setup was able to freeze the sample as it was at experimental temperature, particularly the interface between the solid and the liquid. This freezing was necessary to obtain reliable information for understanding the reaction mechanism. This was exemplified by the study of dissolution of a refractory in liquid slag. The absence of flow in the radial direction in the traditional setup using a symmetrical cylinder was also discussed. The differences in the findings by past investigators using the symmetrical cylinder are most likely due to the extent of misalignment of the cylinder in the containment vessel.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Formation of β-NiAl Phase During Casting of a Ni-Based Superalloy

A high-refractory Ni-based superalloy prototype was melted on a research scale while simulating industry practices. Ingots were vacuum induction melted and subjected to a computationally optimized homogenization heat treatment prior to fabrication which consisted of forging and hot rolling. Failure of one of the ingots at the early stage of the forging process was attributed to the precipitation of the β-NiAl phase during melting which stabilized the eutectic constituent.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Heat Transfer Coefficient at Cast-Mold Interface During Centrifugal Casting: Calculation of Air Gap

During centrifugal casting, the thermal resistance at the cast-mold interface represents a main blockage mechanism for heat transfer. In addition to the refractory coating, an air gap begins to form due to the shrinkage of the casting and the mold expansion, under the continuous influence of strong centrifugal forces. Here, the heat transfer coefficient at the cast-mold interface h has been determined from calculations of the air gap thickness d{sub a} based on a plane stress model taking into account thermoelastic stresses, centrifugal forces, plastic deformations, and a temperature-dependent Young’s modulus. The numerical approach proposed here is rather novel and tries to offer an alternative to the empirical formulas usually used in numerical simulations for a description of a time-dependent heat transfer coefficient h. Several numerical tests were performed for different coating thicknesses d{sub C}, rotation rates Ω, and temperatures of solidus T{sub sol}. Results demonstrated that the scenario at the interface is unique for each set of parameters, hindering the possibility of employing empirical formulas without a preceding experiment being performed. Initial values of h are simply equivalent to the ratio of the coating thermal conductivity and its thickness (~ 1000 Wm{sup −2} K{sup −1}). Later, when the air gap is formed, h drops exponentially to values at least one order of magnitude smaller (~ 100 Wm{sup −2} K{sup −1}).

36 MATERIALS SCIENCE↗
DOE OSTI2018

A Numerical Simulation of Transport Phenomena During the Horizontal Single Belt Casting Process Using an Inclined Feeding System

Horizontal single belt casting (HSBC) has great potential to replace current conventional continuous casting (CCC) processes for sheet metal production, by directly casting 3 to 1 mm sheet for the automobile industry. In the present paper, two-dimensional mathematical models were developed to study transport phenomena, for the case of an inclined wall feeding system for a liquid aluminum wrought alloy (AA6111). Based on the commercial software ANSYS FLUENT 14.5 and user-defined functions, a two-layer turbulence model was used to examine the fluid flow emanating from a slot nozzle set above a water-cooled, high-speed, steel belt. The Volume of Fluid (VOF) method was used to predict the shape of the melt-air interface. A transformed coordinate system (x′, y′) was established in order to analyze the fluid flow on the inclined wall of the feeding system. The total pressure gauge gradient (∂p{sub total}/∂x) was used to describe the behavior of the melt film inside the slot nozzle of the head box. The modeling results show that during the melt film falling process, the total gauge pressure varies within the slot nozzle, which can decrease the stability of the falling film. The first impingement between the falling film and the inclined refractory wall of the feeding system gives rise to a local oscillation, and this influences the stability of the melt film moving downwards. At the rear meniscus position between the inclined wall and the moving belt, there is a clear vibration of the air-melt interface, together with a recirculation zone. The weak vibration of the air-melt interface could be induced by the periodic variation of the melt-air interface. Moreover, the formation of tiny air pockets is predicted. Finally, on the inclined wall of the feeding system, a suitable length of the transition area is needed to avoid over-acceleration of the melt film due to the force of gravity.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Fluid Force-Induced Detachment Criteria for Nonmetallic Inclusions Adhered to a Refractory/Molten Steel Interface

Since nonmetallic inclusions (NMIs) in steel cannot be completely avoided, a greater understanding of their development and evolution during the steelmaking process is required. In particular, this includes the adhesion of microinclusions to the refractory/steel interface in the flow control system between the tundish and the mold. This phenomenon, commonly referred to as clogging, causes losses in productivity and product quality. Inclusions transported from the bulk melt to the boundary layer may adhere to the refractory/steel interface due to formation of a fluid cavity. A detailed model was derived for the detachment of NMIs adhering to a nozzle wall and is based on the local hydrodynamic conditions combined with the specific interfacial properties in the system consisting of the inclusions, the refractories, and the steel. The model is evaluated for three different application-oriented cases. This study has been focused on providing a better understanding of fluid flow in the near-wall region in order to reduce clogging during steelmaking.

42 ENGINEERING↗
DOE OSTI2018

An Efficient Electrolytic Preparation of MAX-Phased Ti-Al-C

Large-scale deployment of MAX-phased Ti-Al-C with intriguing mechanical and physicochemical properties is significantly retarded by its harsh preparation conditions, in which costly precursors, high temperature and non-atmospheric pressure are generally imperative. We herein report an efficient electrolytic preparation of MAX-phased Ti-Al-C by direct electro-reduction of solid TiO{sub 2}-Al{sub 2}O{sub 3}-C in molten CaCl{sub 2} at 1223 K under normal pressure. Homogeneous layered Ti{sub 3}AlC{sub 2} with an oxygen content of 4300 ppm is prepared under a voltage of 3 V between the solid cathode and graphite anode for only 4 hours. The electro-reduction of TiO{sub 2}-Al{sub 2}O{sub 3}-C exhibits a much faster speed compared with the electrolysis employing TiO{sub 2}, TiO{sub 2}-C and TiO{sub 2}-Al{sub 2}O{sub 3} as the precursors. Time-dependent electrolysis indicates that TiC{sub x}O{sub y} is the main intermediate. The generation of refractory and highly conducting TiC{sub x}O{sub y} intermediate enhances the reduction. Density functional theory simulations show a weak affinity towards oxygen of the resulting Ti{sub 3}AlC{sub 2}, which is beneficial to fast and thorough deoxidation. The formation of a layered structure of Ti{sub 3}AlC{sub 2} is attributed to the template effect of the precursory graphite. By simply varying the precursory stoichiometry, layered Ti{sub 2}AlC is also prepared. The present protocol featuring affordable feedstock, low temperature, ambient pressure, high energy efficiency and controllable stoichiometry is promising for large-scale application.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Characterization of Nonmetallic Inclusions in 18CrNiMo7-6

The detrimental effect of nonmetallic inclusions (NMIs) in steels on, e.g., fatigue lifetime is well known. In order to increase the durability and safety of materials and components, inclusion control and a deep understanding of inclusion formation are essential. The present study examines the formation of inclusions as well as their content, type, morphology, and size distribution for different batches of the steel alloy 18CrNiMo7-6 (AISI 4317), which was processed with various refractory crucible materials. To this end, extensive metallographic investigations were carried out including fracture surface analyses, metallographic sections, and the chemical extraction of inclusions. Scanning electron microscopy supported by energy-dispersive X-ray spectroscopy was used alongside electron backscatter diffraction for the qualitative and quantitative analysis of the NMIs. Oxide contents were found to have a significant effect on sulfide precipitation behavior, and had a strong impact on the resulting sizes and numbers of inclusions. The formation and growth of sulfides and oxide-sulfides featuring different morphologies is discussed on the basis of these experimental results.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Rate of MgO Pickup in Alumina Inclusions in Aluminum-Killed Steel

This work aims to clarify the rate and mechanism of MgO pickup by alumina inclusions and the effect of oxide impurities in MgO crucibles on this transformation. Two MgO crucibles from different batches from the same supplier were used in laboratory experiments with Al-killed steel. A kinetic model was developed, based on mass-transfer control in the liquid steel. Rate constants were fitted using inclusion analysis. The rate of magnesium transfer from the two types of crucibles was found to differ by a factor of 20; faster magnesium transfer was associated with formation of a slag layer on the inner surface of the crucible wall (rather than a solid spinel product layer). The kinetic model was also used to simulate industrial scale ladle refining (1) to illustrate the effects of total oxygen concentration and (2) to evaluate the contribution of steel-refractory reaction (in addition to steel-slag reaction) on the rate of MgO pickup in alumina inclusion. The rate of MgO pickup was higher with a lower inclusion concentration. For ladle desulfurization, the extent of MgO pickup in inclusions is directly linked to the extent of desulfurization; both reactions are controlled by the oxygen potential at the steel-slag interface.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Quantitative Evaluations of Surface Cleanliness in IF Steel Slabs at Unsteady Casting

Macro-inclusions in the surface layer of slabs are mainly responsible for the sliver defects in IF steel sheets. In the present work, macro-inclusions in six kinds of unsteady cast IF steel slabs involving four unsteady states (casting start, ladle change, nozzle change and casting end) in one casting sequence were quantitatively characterized using an automatic inclusion analyzer with a total detection area of 238,048 mm{sup 2}. The cleanliness of corresponding normal slabs was also evaluated as the benchmark study, and the number density (ND) of inclusions > 50 µm was used to describe the surface slab cleanliness. Generally, alumina-based and mold powder inclusions were detected, and the former type was further subdivided into alumina clusters, alumina associated with bubbles, refractory-related alumina, Al-Ti complex oxides and CaO-Al{sub 2}O{sub 3}-MgO. Several large-sized alumina-based inclusions were detected in the normal slabs with an average ND of 0.31 N/cm{sup 2}, although they had very low total oxygen (TO) contents (10~13 ppm). No mold powder inclusions were found in normal slabs. For all the unsteady slabs, alumina-based and mold powder inclusions were both observed, and the percentage of the former kind was ≥ 90 pct. The average density of macro-inclusions for the first slab was 1.621 N/cm{sup 2}, whose cleanliness was much worse than any of the other unsteady slabs. The first slab should be downgraded. For the second slab, the ND of macro-inclusions was 0.385 N/cm{sup 2}, which was still larger than the normal slabs because of the lasting effect of the re-oxidation. For the penultimate, cap-off and SEN changed slabs, the density of macro-inclusions fluctuated from 0.25~0.35 N/cm{sup 2}, which was close to the average level of normal slabs. However, mold flux-originated inclusions were frequently observed in these slabs because of flow pattern variations due to the casting speed change. In terms of the slab during the ladle change process, mold powder inclusions were frequently detected even though the casting speed remained constant. A mold powder entrapment mechanism was proposed, which showed the entrapment occurred owing to the flow pattern change induced by forming/dropping of SEN clogs due to re-oxidation by FeO in the ladle slag and tundish steel temperature variations during the ladle change practice. The severity of powder entrapment and re-oxidation was also given for different kinds of unsteady slabs, which provides a direct guide to treating these slabs in the steel plant.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Interaction Between Liquid Steel and AlN Substrate Containing Al-Y-Oxides

Reactions between molten iron, molten silicon steel, and ceramic materials are of great importance from the perspective of the corrosion of refractory material in the steelmaking and continuous casting processes. Reactions between liquid steel and aluminum nitride (AlN) substrate containing Al-Y-oxides were investigated using the sessile drop method at 1833 K (1560 °C). The liquid–substrate interface was observed with the increasing holding time, and the reaction mechanism was studied. In the case of the liquid iron and the silicon steel on the AlN substrate containing Al-Y-oxides, the reaction products on the steel side of the interface between the steel and the substrate were Al-rich Al-Y-oxides and Al{sub 2}O{sub 3} particles. For silicon steel and pure AlN substrate, Al{sub 2}O{sub 3} particles were the main products. Contact angles were lower for liquid iron than for silicon steel due to the higher oxygen content in iron. In addition, the solid–liquid interfacial tension and the work of adhesion between AlN and steel were measured.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Optimized Gating System for Steel Castings

Computer modeling using a commercially available software package was used to explore the optimization of filling systems based on the relatively new concepts of avoiding entrainment of air bubbles and oxides by avoiding surface turbulence. The test casting was based on a pattern for a traditional top poured test bar, whose cross section was a tri-lobed clover-like shape. The study illustrates clearly that the detailed design of the filling system has a major influence on the conditions for defect generation during filling. Traditional steel casting systems using the widely popular assembly of preformed refractory tubes were found to behave poorly. Systems were demonstrated which were capable of delivering highly controlled filling behavior. The latest systems to be developed employed (1) a naturally pressurized filling system and (2) the use of filters placed flush on the top of the runner to act as bubble diverters, together with (3) terminal spin traps. These novel filling systems demonstrated excellent performance in simulation, in agreement with practical experience of the capability (of the trident gate in particular) to produce, for the first time in the history of casting, defect-free castings on a routine basis.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Design, Processing, and Properties of WTaCrV-Hf Multi-principal Element Alloys

Refractory multi-principal element alloys are candidates for high-temperature structural components due, in part, to their high strength and high melting points. Single-phase materials are initially preferred for isotropic material properties as a function of time and temperature in service conditions. This work outlines a computational rank-ordering and experimental validation methodology for single-phase body-centered-cubic phase stability in WTaCrV-Hf alloys using order–disorder transition temperature. Eight compositions were fabricated by arc-melting and heat-treated at 1400 °C for 24 hrs. X-ray diffraction, energy-dispersive x-ray spectroscopy, and Vickers hardness testing showed alloys with order–disorder transition temperatures below 600 °C formed a single-phase body-centered-cubic structure during solidification and remained single-phase after heat-treatment. The sample possessing the lowest order–disorder transition temperature exhibited slip traces suggestive of room-temperature plastic deformation under Vickers indentation, with both heat-treated single-phase samples exhibiting hardnesses over 800 HV with little cracking compared to tungsten. These results establish order–disorder transition temperature as a viable predictive parameter for multi-principal element alloy phase stability. The methodology outlined in this work provides a framework for future design, fabrication, and characterization of high-temperature structural multi-principal element alloys.

CALPHAD↗
DOE OSTI2025

Multi-modal characterization of the B2 phase in the Ta-Re binary system

The energy and transportation industries demand materials that retain their mechanical property at high temperatures. Refractory complex concentrated alloys (RCCAs) with a BCC + B2 microstructure offer a potential solution, where maintaining the high temperature mechanical properties can be achieved by precipitation strengthening. This depends on the B2 phase in RCCAs being thermodynamically stable with a high solvus temperature. Recently, we predicted the high temperature stability of the B2 structure in the Ta-Re binary system, using density functional theory. Here, in this study, we provide experimental evidence for the existence of this phase for the first time, using a Ta 65 Re 35 alloy. Despite Ta-Re binary phase diagrams predicting a single-phase BCC microstructure for Ta 65 Re 35 , we show that a high Z nanoscale secondary phase appears after heat treatment at 1550 °C and 1100 °C. Scanning transmission electron microscopy (STEM) revealed that this phase has a cubic structure and is equiatomic TaRe though B2 superlattice reflections were absent in fast Fourier transforms (FFT) and diffraction patterns (DPs). DP simulations indicate that the B2 TaRe superlattice reflections are up to two orders of magnitude weaker than their fundamental reflections, making their detection challenging via electron microscopy. Neutron diffraction confirmed the second phase had a B2 structure. This study identified a previously unobserved high temperature stable B2 phase in the Ta-Re system, enabling the development of new high temperature BCC + B2 RCCAs.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Reactive oxygen species regulatory mechanisms associated with rapid response of MC3T3-E1 cells for vibration stress

Although many previous studies have shown that refractory period-dependent memory effect of vibration stress is anabolic for skeletal homeostasis, little is known about the rapid response of osteoblasts simply derived from vibration itself. In view of the potential role of reactive oxygen species (ROS) in mediating differentiated activity of osteoblasts, whether and how ROS regulates the rapid effect of vibration deserve to be demonstrated. Our findings indicated that MC3T3-E1 cells underwent decreased gene expression of Runx2, Col-I and ALP and impaired ALP activity accompanied by increased mitochondrial fission immediately after vibration loading. Moreover, we also revealed the involvement of ERK-Drp1 signal transduction in ROS regulatory mechanisms responsible for the rapid effect of vibration stress. - Highlights: • ROS contributed to the rapid response of MC3T3-E1 cells for vibration stress. • Imbalance of mitochondrial dynamics were linked to the LMHFV-derived rapid response. • The role of ERK-Drp1 signal pathway in the LMHFV-derived osteoblast rapid response.

60 APPLIED LIFE SCIENCES↗