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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS2021

Investigation of Ionic Liquids Isolated Iron for Ductile Iron Castings

As research continues for missions beyond low-Earth orbit, in-situ resource utilization (ISRU) methods are critical. For Lunar and Martian colonization, the ability to manufacture mechanical and structural components with local resources is essential. Ionic liquids (IL) are being studied at NASA Marshall Space Flight Center (MSFC) to harvest elemental metals from meteorites and regolith oxides. In this investigation, the viability of casting ductile iron using ionic liquids sourced iron and nickel was explored given ductile iron’s range of applications and performance as an as-cast alloy. Ingots were produced using commercial elements to simulate the use of IL iron with carbon sourced from the by-products of a life support system currently tested at MSFC. Samples were cast and compared to commercial ductile iron with phase transformation diagrams,microstructures, and hardness. Results showed ionic liquids sourced elements are a viable source of elemental alloying materials for a range of ductile iron alloys.

Ionic Liquids↗
DOE OSTI2023

Coating composition embodiments for use in investment casting methods

Disclosed herein are embodiments of a coating composition for use in investment casting. The coating composition embodiments provide a solidified coat that can be as a mold for casting castable materials and that is easily removed from the casted material using water. The coating composition embodiments disclosed herein are reusable and are non-toxic and exhibit high thermal stability.

Cluff, Kyle↗
DOE OSTI2024

Accelerating the Scalability of PrintCast structures using High Pressure Die Casting

PrintCast composites are fabricated by infiltrating a metal mesh or preform (e.g., an additively-manufactured 316L lattices) with molten metal of a lower melting temperature (e.g., A380 aluminum). The resulting PrintCast composite has been shown in the literature to produce diverse and unique mechanical properties that are controllable at the local or global level by adjusting volume-fraction and/or topology of the preforms geometry and overall volume fraction. Although promising mechanical and thermal properties have been achieved at the laboratory scale level, the scalability from laboratory to full scale components has been limited using conventional casting infiltration. This work highlights how using high pressure die casting can significantly advance the development and eventual deployment of PrintCast approaches at large scales. We have successfully produced 9-inch by 6-inch by 1-inch thick PrintCast 316L stainless steel/A380 aluminum “bricks” via high pressure die casting. Initial findings show excellent infiltration and production capability. The resulting approach demonstrates the scalability and manufacturability of hybrid cost effective metal-metal matrix composites at larger length scales with high quality infiltration results.

Splitter, Derek↗
DOE OSTI2024

High-modulus, high-strength, low alloy gray cast iron for cylinder liners and automotive applications

A high elastic modulus, high ultimate tensile strength, and low alloy gray cast iron for cylinder liners. The gray cast iron includes from 2.60 wt % to 3.30 wt % Carbon (C); from 1.50 wt % to 2.30 wt % Silicon (Si); from 0.30 wt % to 0.80 wt % Manganese (Mn); from 0.15 wt % to 0.35 wt % Phosphorus (P); from 0.05 wt % to 0.11 wt % Sulphur (S); from 0.60 wt % to 1.20 wt % Copper (Cu); from 0.10 wt % to 0.30 wt % Chromium (Cr); from greater than 0.0 wt % to 0.1 wt % Nickle (Ni); from 0.15 wt % to 0.40 wt % Molybdenum (Mo); and balance wt % Iron (Fe). The total wt % of Si, Mn, P, S, Cu, Cr, Ni, and Mo is less than about 4.10 wt %. The gray cast iron has a Carbon Equivalent (CE) from 3.00 wt % to 3.90 wt % and the product of Mn %*S % is from 0.025 to 0.045.

Yang, Jianghuai↗
DOE OSTI2018

Optimization of Mold Flux for the Continuous Casting of Cr-Contained Steels

To compensate the negative effect caused by the absorption of chromium oxide inclusions during the casting process of Cr-contained steels, a new mold flux system has been designed and investigated. The melting temperature range of the newly designed mold flux system is from [1124 K to 1395 K (851 °C to 1122 °C)]. The viscosity at 1573 K (1300 °C) and the break temperature increase with the addition of MnO and Cr{sub 2}O{sub 3} but decrease with the addition of B{sub 2}O{sub 3}. The crystalline fraction of mold flux decreases from 81 to 42.1 pct with the addition of MnO and Cr{sub 2}O{sub 3}, and then further decreases to 25.3 pct with the addition of B{sub 2}O{sub 3}; however, it improves from 54.4 to 81.5 pct when the basicity increases. Besides, the heat-transfer ability of mold flux is inverse to the crystallization ratio of the slag. The comprehensive study of the properties for the four designed mold fluxes suggests that the mold flux with 1.15 basicity-3.01 pct B{sub 2}O{sub 3}-1.10 pct MnO-2.10 pct Cr{sub 2}O{sub 3} shows the best properties for the continuous casting of Cr-contained steels.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Three-Dimensional Distribution of Hooks in Al-Killed Low-Carbon Continuous Casting Steel Slabs

In the current study, steel samples were etched and hooks on several successive layers of longitudinal and transverse slab sections were obtained to investigate the three-dimensional (3-D) distribution of hooks in low-carbon continuous casting slabs. The data from industrial trials and numerical calculation were used to explain the variation in the distribution and morphology of hooks. Around the slab perimeter, the mean depth of hooks at the center and edge of the wide face and the edge of the narrow face was larger than that of other locations. The 3-D hook demonstrated a varied characteristic on different layers, as the observed surface changed in the longitudinal direction. By several layers of the transverse section being polished off, hooks in the transverse direction below the slab surface were obtained, in which the truncated hook and the joint hook between the wide face and narrow face were observed at the slab corner. The same oscillation mark could show as hook type and depression type, depending on the occurrence of the overflow between the solidified meniscus and the copper plate. Industrial trials and the numerical calculation illustrated that the transient variation of hooks in the 3-D space was related to the level fluctuation of molten steel in the mold and temperature fluctuation with casting time and the fluid flow and temperature near the meniscus. Finally, the influence area and volume of hooks on the capture of inclusions and bubbles were discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Numerical Simulation of the Effects of Horizontal and Vertical EMBr on Jet Flow and Mold Level Fluctuation in Continuous Casting

In this article, a new type of electromagnetic braking (EMBr), named vertical EMBr (V-EMBr) was introduced in the continuous casting process. In order to investigate its capability and applicability, the impacts of horizontal and vertical EMBrs on the flow pattern in a continuous casting mold were simulated by means of an implemented Reynolds-averaged Navier–Stokes (RANS) SST k–ω turbulence model. The characteristics of electromagnetic field and flow field inside a 1450 mm × 230 mm mold with Ruler-EMBr and V-EMBr have been compared. The numerical simulation results indicate that the static magnetic field generated by Ruler-EMBr can cover the main part of the discharging jet flow, which has a better control of the flow pattern in lower part of the mold. The static magnetic field generated by V-EMBr can cover both the vicinity of the mold narrow faces and the impingement region of the jet flow, which can effectively control the liquid steel flow in the upper recirculation zone. The parametric study also shows that the large vortices beneath the jet flow can be almost completely eliminated at an optimized magnetic flux density with Ruler-EMBr. In addition, the surface velocity and steel/slag interface fluctuation can be suppressed with the application of V-EMBr to acceptable values even with a wide variation of SEN port angles. It is estimated that to reach the same level of braking effect on the upper recirculation flow, a magnetic flux density of 0.1 T is sufficient for V-EMBr, while 0.2 T is needed for Ruler-EMBr. Based on the results, a second-generation V-EMBr has been developed, which combines both of the merits of Ruler-EMBr and V-EMBr.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Nozzle Port Angle on Transient Flow and Surface Slag Behavior During Continuous Steel-Slab Casting

Undesirable flow variations can cause severe instabilities at the interface between liquid mold flux and molten steel across the mold top-region during continuous steel casting, resulting in surface defects in the final products. A three-dimensional Large Eddy Simulation (LES) model using the volume of fluid method for the slag and molten steel phases is validated with plant measurements, and applied to gain new insights into the effects of nozzle port angle on transient flow, top slag/steel interface movement, and slag behavior during continuous slab casting under nominally steady conditions. Upward-angled ports produce a single-roll flow pattern with lower surface velocity, due to rapid momentum dissipation of the spreading jet. However, strong jet wobbling from the port leads to greater interface variations. Severe level drops allow easy entrapment of liquid flux by the solidifying steel shell at the meniscus. Sudden level rises may also be detrimental, leading to overflow of the solidified meniscus region. Downward-angled ports produce a classic double-roll pattern with less jet turbulence and a more stable interface everywhere except near the narrow faces. Finally, the flow patterns, surface velocity, and level predicted from the validated LES model are compared with steady-state standard k-ε model predictions.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Experimental Study of the Mold Flow Induced by a Swirling Flow Nozzle and Electromagnetic Stirring for Continuous Casting of Round Blooms

This study focuses on an experimental investigation of the fluid flow in round bloom continuous casting using a 1:3 model of the industrial casting process. A swirling flow nozzle, represented by the specific design of the RHI Magnesita GYRONOZZLE, is used to produce a swirling motion in the cylindrical mold. The test section is integrated into the Mini-LIMMCAST facility at HZDR, which is operated at room temperature using the ternary alloy GaInSn. Systematic measurements of horizontal and vertical velocity profiles are performed by means of the Ultrasound Doppler Velocimetry. The second part of the study focuses on the interaction between the flow driven by the GYRONOZZLE and concurrent electromagnetic stirring in the mold (M-EMS) by applying rotating magnetic fields (RMFs) at different magnetic flux densities. The effect of the GYRONOZZLE on the flow pattern inside the mold is examined with and without superimposed RMFs and compared to those of a standard single-port nozzle. The measurements reveal that the GYRONOZZLE induces a swirling flow in the whole mold. It is further shown that the influence of a simultaneously applied RMF is mainly restricted to the lower part of the mold since the transport of angular momentum to the top is suppressed by the jets pouring out from the GYRONOZZLE.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Characteristics of Slag Infiltration in High-Mn Steel Castings

To determine the composition difference between the solid and liquid films in plant practice for high-Mn steel castings, a reaction experiment was carried out to investigate the composition profile of MnO and SiO{sub 2} in the slag layer. Based on the experimental results, a mathematical model of the mold slag for high-Mn steel was developed to describe the nonuniform infiltration behavior of mold slag during oscillation cycles. Moreover, the effects of uneven slag films on slab lubrication and heat transfer in the mold are discussed. The results show that the concentrations of MnO and SiO{sub 2} over the flux layer have an opposite stair-step distribution, which consists of a reaction layer and nonreaction layer. When the reaction layer thickness is 5 mm, a thicker liquid film is formed between the slab and the mold. The inhomogeneity of the composition in the solid film causes large fluctuations in the heat flux in the mold, resulting in irregular depressions on the shell surface. With a reacting thickness of 10 mm, the reacting slag fills in the gap to generate a thinner solid film, which increases the overall heat flux in the mold. Since mold oscillation combined with slag rim enhances the pressure flow in the vicinity of the meniscus, the liquid slag within 80 mm of the mold wall is mixed and consumed quickly. In contrast, the liquid slag beyond 80 mm from the mold wall with a low velocity stays longer in the liquid pool. The model predictions illuminate the characteristics of slag infiltration during high-Mn steel casting, showing good agreement with plant measurements.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Influence of Electropulsing Treatment on the Initial Solidification of Molten Steel During Continuous Casting

An electropulsing-assisted mold simulator (EPMS) technique was developed to investigate the effect of pulsed electric current on the initial solidification behavior of molten steel during the process of continuous casting. The results indicated that the variation of mold hot surface temperatures in the meniscus area decreased from 375.8 K to 394 K for the case without electropulsing treatment (EPT) to 363.5 K to 377.3 K for the one with EPT. The mold surface heat fluxes fluctuated around the baseline of 0.83 and 2.42 MW/m{sup 2} in the cases with and without EPT, respectively, which indicated that a higher thermal resistance between the initial shell and copper mold was introduced by employing the EPT. The crystal fraction of slag films increased from 69.8 to 77.9 pct, whereas the grain size of mold flux film decreased, when compared the case of EPT treatment with the benchmark one, which suggested that the pulsed electric current promotes the movement of molten clusters and particles, leading to the enhancement of mold flux crystallization and the improvement of thermal resistance. Moreover, the solidification structure of steel along the direction of solidification (from the mold to melt) includes a fine chilled grain layer close to the mold, a columnar dendrite layer in the middle, and equiaxed grains next to the melt core, in which a compacted microstructure with smaller secondary dendrite arm spacing was observed in the case of the EPT. The results demonstrate that the EPT could refine the as-cast solidification microstructure.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Influence of flowability, casting time and formwork geometry on fiber orientation and mechanical properties of UHPFRC

In this study, fiber orientation in ultra-high-performance fiber-reinforced-concrete (UHPFRC) with different formwork geometry was evaluated using visualization model concrete and via analysis involving 3D visualization based on X-ray computed tomography (CT). Differences in fiber orientation in the height direction were first reviewed. Furthermore, the influence of flowability and casting time on the fiber orientation and mechanical properties of UHPFRC were examined. The results indicated that flowability dictates eventual fiber orientation in parts close to the surfaces of formwork. The use of UHPFRC with superior flowability results in more fibers being oriented parallel to the longitudinal direction of slabs in comparison to UHPFRC with inferior flowability. It was also found that flowability and casting time can have strong influences on the mechanical properties of UHPFRC. Residual flexural strength after initial cracking exhibited perfect linear dependence on the effective number of fibers at fracture planes.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Study of grain structure evolution during annealing of a twin-roll-cast Mg alloy

The evolution of microstructure under static annealing was studied for mid-thickness section of a twin-roll-cast (TRC) magnesium alloy. Annealing was performed at 300 °C and 500 °C for different times. Microstructural evolution was quantitatively analyzed, from optical micrographs, using grain path envelope analysis. Additional information from electron backscatter diffraction (EBSD) was used for addressing the possible mechanism(s). It was found that the TRC structure had a bimodal grain size, which was preserved even after annealing at 300 °C. However, the annealing at 500 °C led to a unimodal grain size. This difference in the grain size distribution created a contrasting behavior in the normalized standard deviations. This was primarily attributed to a competition between recovery and recrystallization, and their respective dominance at 300° and 500 °C. A deformation induced recrystallization recovery (DIRR) model was proposed. The proposed model could successfully address the experimental microstructural evolution. - Highlights: • Annealing of twin roll cast (TRC) magnesium alloy was done at temperatures of 300 °C and 500 °C. • TRC had bimodal structure. Bimodality preserved for annealing at 300 °C. Annealing at 500 °C led to unimodal structure. • Grain evolution was described based on the competition between recovery and recrystallization. • Deformation induced recrystallization recovery (DIRR) mechanistic model was developed.

36 MATERIALS SCIENCE↗
DOE OSTI2016

3D analysis of macrosegregation in twin-roll cast AA3003 alloy

Twin-roll cast aluminium alloys have a high potential for industrial applications. However, one of the drawbacks of such materials is an inhomogeneous structure generated by macrosegregation, which appears under certain conditions in the center of sheets during solidification. Segregations in AA3003 alloy form as manganese, iron and silicon rich channels spread in the rolling direction. Their spatial distribution was successfully detected by X-ray computed tomography. Scanning electron microscopy was used for a detailed observation of microstructure, morphology and chemical analysis of the segregation. - Highlights: •Macrosegregations in twin-roll cast sheets stretch along the rolling direction. •X-ray computed tomography is an effective tool for visualization of the segregation. •The segregations copy the shape of grain boundaries.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Development of three-wavelength CCD image pyrometer used for the temperature field measurements of continuous casting billets

This paper develops an imaging based three-color pyrometer for the monitoring of temperature distribution in a continuous casting billet. A novel optical device, together with an embedded electronic system, is designed to sequentially collect a dark image and three thermal images with specified wavelengths on a same monochromatic charge-coupled-device (CCD). The three thermal images provide the basis for the determination of target temperature, while the dark image is used to online eliminate the dark noise of CCD with a differential method. This image pyrometer is not only independent of target emissivity but also overcomes the dissimilarity of measuring accuracy between the micro-sensors of CCD resulted from the non-uniformity of pixels’ intensity response and the vignetting of optical system. Furthermore, a precise two-color temperature field measuring model on the CCD pyrometer is established, based on which a self-adaptive light-integration mechanism is presented. Compared with the traditional fixed light-integration method, the measuring range of the pyrometer is greatly extended and its sensitivity in low temperature segment is improved. The test results in a steel factory demonstrate that the pyrometer is capable of meeting the requirement of surface temperature measurements about casting billets. Reliability and accuracy of measurement results are also discussed herein.

42 ENGINEERING↗
DOE OSTI2018

Casting Aluminum Alloys: Their Physical and Mechanical Metallurgy

The follow up to the fall 2007 work on the structure, properties, thermal resistance, corrosion and fatigue of aluminum alloys in industrial manufacturing, discusses findings from the past decade, including sections on new casting alloys, novel casting technologies, and new methods of alloys design. The book also includes other hot topics, such as the implementation of computational technologies for the calculation of phase equilibria and thermodynamic properties of alloys, the development of software for calculation of diffusion processes in aluminum alloys, computational modeling of solidification microstructure and texture evolution of multi-component aluminum materials.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Versatile Sequential Casting Processing for Highly Efficient and Stable Binary Organic Photovoltaics

Forming an ideal bulk heterojunction (BHJ) morphology is a critical issue governing the photon to electron process in organic solar cells (OSCs). Complementary to the widely-used blend casting (BC) method for BHJ construction, sequential casting (SC) can also enable similar or even better morphology and device performance for OSCs. Here, BC and SC methods on three representative donor:acceptor (D:A) blends are utilized, that is, PM6:PC 71 BM, PM6:IT-4F and PM6:L8-BO. Higher power conversion efficiencies (PCEs) in all cases by taking advantage of beneficial morphology from SC processing are achieved, and a champion PCE of 18.86% (certified as 18.44%) based on the PM6:L8-BO blend is reached, representing the record value among binary OSCs. The observations on phase separation and vertical distribution inspire the proposal of the swelling–intercalation phase-separation model to interpret the morphology evolution during SC processing. Further, the vertical phase segregation is found to deliver an improvement of device performance via affecting the charge transport and collection processes, as evidenced by the D:A-ratio-dependent photovoltaic properties. Besides, OSCs based on SC processing show advantages on device photostability and upscale fabrication. Finally, this work demonstrates the versatility and efficacy of the SC method for BHJ-based OSCs.

14 SOLAR ENERGY↗