Secondary Waste Form Down Selection Data Package – Ceramicrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cantrell, Kirk J.; Westsik, Joseph H.

2011-08-31

As part of high-level waste pretreatment and immobilized low activity waste processing, liquid secondary wastes will be generated that will be transferred to the Effluent Treatment Facility on the Hanford Site for further treatment. These liquid secondary wastes will be converted to stable solid waste forms that will be disposed in the Integrated Disposal Facility. Currently, four waste forms are being considered for stabilization and solidification of the liquid secondary wastes. These waste forms are Cast Stone, Ceramicrete, DuraLith, and Fluidized Bed Steam Reformer. The preferred alternative will be down selected from these four waste forms. Pacific Northwest National Laboratorymore » is developing data packages to support the down selection process. The objective of the data packages is to identify, evaluate, and summarize the existing information on the four waste forms being considered for stabilization and solidification of the liquid secondary wastes. The information included will be based on information available in the open literature and from data obtained from testing currently underway. This data package is for the Ceramicrete waste form. Ceramicrete is a relatively new engineering material developed at Argonne National Laboratory to treat radioactive and hazardous waste streams (e.g., Wagh 2004; Wagh et al. 1999a, 2003; Singh et al. 2000). This cement-like waste form can be used to treat solids, liquids, and sludges by chemical immobilization, microencapsulation, and/or macroencapsulation. The Ceramicrete technology is based on chemical reaction between phosphate anions and metal cations to form a strong, dense, durable, low porosity matrix that immobilizes hazardous and radioactive contaminants as insoluble phosphates and microencapsulates insoluble radioactive components and other constituents that do not form phosphates. Ceramicrete is a type of phosphate-bonded ceramic, which are also known as chemically bonded phosphate ceramics. The Ceramicrete binder is formed through an acid-base reaction between calcined magnesium oxide (MgO; a base) and potassium hydrogen phosphate (KH{sub 2}PO{sub 4}; an acid) in aqueous solution. The reaction product sets at room temperature to form a highly crystalline material. During the reaction, the hazardous and radioactive contaminants also react with KH{sub 2}PO{sub 4} to form highly insoluble phosphates. In this data package, physical property and waste acceptance data for Ceramicrete waste forms fabricated with wastes having compositions that were similar to those expected for secondary waste effluents, as well as secondary waste effluent simulants from the Hanford Tank Waste Treatment and Immobilization Plant were reviewed. With the exception of one secondary waste form formulation (25FA+25 W+1B.A. fabricated with the mixed simulant did not meet the compressive strength requirement), all the Ceramicrete waste forms that were reviewed met or exceeded Integrated Disposal Facility waste acceptance criteria.« less

Cryolite process for the solidification of radioactive wastes

DOEpatents

Wielang, Joseph A.; Taylor, Larry L.

1976-01-01

An improved method is provided for solidifying liquid wastes containing significant quantities of sodium or sodium compounds by calcining in a fluidized-bed calciner. The formation of sodium nitrate which will cause agglomeration of the fluidized-bed particles is retarded by adding aluminum and a fluoride to the waste in order to produce cryolite during calcination. The off-gas of the calciner is scrubbed with a solution containing aluminum in order to complex any fluoride which may be liberated by subsequent dissolution of cryolite and prevent corrosion in the off-gas cleanup system.

Updated Liquid Secondary Waste Grout Formulation and Preliminary Waste Form Qualification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saslow, Sarah A.; Um, Wooyong; Russell, Renee L.

This report describes the results from liquid secondary waste grout (LSWG) formulation and cementitious waste form qualification tests performed by Pacific Northwest National Laboratory (PNNL) for Washington River Protection Solutions, LLC (WRPS). New formulations for preparing a cementitious waste form from a high-sulfate liquid secondary waste stream simulant, developed for Effluent Management Facility (EMF) process condensates merged with low activity waste (LAW) caustic scrubber, and the release of key constituents (e.g. 99Tc and 129I) from these monoliths were evaluated. This work supports a technology development program to address the technology needs for Hanford Site Effluent Treatment Facility (ETF) liquid secondarymore » waste (LSW) solidification and supports future Direct Feed Low-Activity Waste (DFLAW) operations. High-priority activities included simulant development, LSWG formulation, and waste form qualification. The work contained within this report relates to waste form development and testing and does not directly support the 2017 integrated disposal facility (IDF) performance assessment (PA). However, this work contains valuable information for use in PA maintenance past FY17, and for future waste form development efforts. The provided data should be used by (i) cementitious waste form scientists to further understanding of cementitious dissolution behavior, (ii) IDF PA modelers who use quantified constituent leachability, effective diffusivity, and partitioning coefficients to advance PA modeling efforts, and (iii) the U.S. Department of Energy (DOE) contractors and decision makers as they assess the IDF PA program. The results obtained help fill existing data gaps, support final selection of a LSWG waste form, and improve the technical defensibility of long-term waste form performance estimates.« less

Preliminary study on immobilization of buffing dust by solidification method in ceramic brick

NASA Astrophysics Data System (ADS)

Yuliansyah, Ahmad Tawfiequrrahman; Prasetya, Agus; Putra, Arif Eka; Satriawan, Humam Budi

2017-11-01

Leather-based industries generate a substantial amount of hazardous solid and liquid wastes in their process. One of the solid wastes is buffing dust, which is fine particulates containing fat, tanning, dyes and chromium. From 1 ton of leather processed, approximately 2-6 kg of buffing dust is generated. Chromium in the buffing dust is carcinogenic, so a proper handling is highly required. Solidification is a method commonly used to immobilize toxic material. Hence, the material is trapped in a matrix made of binding agents to minimize its mobility. However, a very small amount of the materials is sometimes released to the environment during storage. This study investigates leaching process of chromium from immobilized buffing dust in ceramic brick. Buffing dust, which contains chromium, is solidified by mixing it with clay at certain compositions and fired in a muffle furnace to produce a ceramic brick. Performance of the solidification process is evaluated by measuring the leaching of chromium in the leaching test. The results show that the solidification has significantly reduced the potential release of chromium to the environment. Higher of the firing temperature, less chromium is leached from ceramic brick. The chromium concentration of leachate water from 800°C brick is 0.376 ppm, while those from 850 and 900°C brick are 0.212 and 0.179 ppm respectively.

ENGINEERING BULLETIN: SOLIDIFICATION/STABILIZATION OF ORGANICS AND INORGANICS

EPA Science Inventory

Solidification refers to techniques that encapsulate hazardous waste into a solid material of high structural integrity. Encapsulation involves either fine waste particles (microencapsulation) or a large block or container of wastes (macroencapsulation). Stabilization refe...

Solidification as low cost technology prior to land filling of industrial hazardous waste sludge.

PubMed

El-Sebaie, O; Ahmed, M; Ramadan, M

2000-01-01

The aim of this study is to stabilize and solidify two different treated industrial hazardous waste sludges, which were selected from factories situated close to Alexandria. They were selected to ensure their safe transportation and landfill disposal by reducing their potential leaching of hazardous elements, which represent significant threat to the environment, especially the quality of underground water. The selected waste sludges have been characterized. Ordinary Portland Cement (OPC), Cement Kiln Dust (CKD) from Alexandria Portland Cement Company, and Calcium Sulphate as a by-product from the dye industry were used as potential solidification additives to treat the selected treated waste sludges from tanning and dyes industry. Waste sludges as well as the solidified wastes have been leach-tested, using the General Acid Neutralization Capacity (GANC) procedure. Concentration of concerning metals in the leachates was determined to assess changes in the mobility of major contaminants. The treated tannery waste sludge has an acid neutralization capacity much higher than that of the treated dyes waste sludge. Experiment results demonstrated the industrial waste sludge solidification mix designs, and presented the reduction of contaminant leaching from two types of waste sludges. The main advantages of solidification are that it is simple and low cost processing which includes readily available low cost solidification additives that will convert industrial hazardous waste sludges into inert materials.

AN EVALUATION OF FACTORS AFFECTING THE SOLIDIFICATION/STABILIZATION OF HEAVY METAL SLUDGE

EPA Science Inventory

Solidification/stabilization (SIS) of hazardous waste involves mixing the waste with a binder material to enhance the physical properties of the waste and to immobilize contaminants that may be detrimental to the environment. Many hazardous wastes contain materials that are know...

OVERVIEW OF THE HISTORY, PRESENT STATUS, AND FUTURE DIRECTION OF SOLIDIFICATION/STABILIZATION TECHNOLOGIES FOR HAZARDOUS WASTE TREATMENT

EPA Science Inventory

Solidification/stabilization (S/S) technology processes are currently being utilized in the United States to treat inorganic and organic hazardous waste and radioactive waste. These wastes are generated from operating industry or have resulted from the uncontrolled management of ...

Secondary Waste Form Down-Selection Data Package—Fluidized Bed Steam Reforming Waste Form

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qafoku, Nikolla; Westsik, Joseph H.; Strachan, Denis M.

2011-09-12

The Hanford Site in southeast Washington State has 56 million gallons of radioactive and chemically hazardous wastes stored in 177 underground tanks (ORP 2010). The U.S. Department of Energy (DOE), Office of River Protection (ORP), through its contractors, is constructing the Hanford Tank Waste Treatment and Immobilization Plant (WTP) to convert the radioactive and hazardous wastes into stable glass waste forms for disposal. Within the WTP, the pretreatment facility will receive the retrieved waste from the tank farms and separate it into two treated process streams. These waste streams will be vitrified, and the resulting waste canisters will be sentmore » to offsite (high-level waste [HLW]) and onsite (immobilized low-activity waste [ILAW]) repositories. As part of the pretreatment and ILAW processing, liquid secondary wastes will be generated that will be transferred to the Effluent Treatment Facility (ETF) on the Hanford Site for further treatment. These liquid secondary wastes will be converted to stable solid waste forms that will be disposed of in the Integrated Disposal Facility (IDF). To support the selection of a waste form for the liquid secondary wastes from WTP, Washington River Protection Solutions (WRPS) has initiated secondary waste form testing work at Pacific Northwest National Laboratory (PNNL). In anticipation of a down-selection process for a waste form for the Solidification Treatment Unit to be added to the ETF, PNNL is developing data packages to support that down-selection. The objective of the data packages is to identify, evaluate, and summarize the existing information on the four waste forms being considered for stabilizing and solidifying the liquid secondary wastes. At the Hanford Site, the FBSR process is being evaluated as a supplemental technology for treating and immobilizing Hanford LAW radioactive tank waste and for treating secondary wastes from the WTP pretreatment and LAW vitrification processes.« less

Nature of solidification of nanoconfined organic liquid layers.

PubMed

Lang, X Y; Zhu, Y F; Jiang, Q

2007-01-30

A simple model is established for solidification of a nanoconfined liquid under nonequilibrium conditions. In terms of this model, the nature of solidification is the conjunct finite size and interface effects, which is directly related to the cooling rate or the relaxation time of the undercooled liquid. The model predictions are consistent with available experimental results.

Technology Demonstration Summary: International Waste Technologies In Situ Stabilization/Solidification, Hialeah, Florida

EPA Science Inventory

An evaluation was performed of the International Waste Technologies (IWT) HWT-20 additive and the Geo-Con, Inc. deep-soil-mixing equipment for an in situ stabilization/solidification process and its applicability as an on-site treatment method for waste site cleanup. The analysis...

Functional Nanoclay Suspension for Printing-Then-Solidification of Liquid Materials.

PubMed

Jin, Yifei; Compaan, Ashley; Chai, Wenxuan; Huang, Yong

2017-06-14

Additive manufacturing (AM) enables the freeform fabrication of complex structures from various build materials. The objective of this study is to develop a novel Laponite nanoclay-enabled "printing-then-solidification" additive manufacturing approach to extrude complex three-dimensional (3D) structures made of various liquid build materials. Laponite, a member of the smectite mineral family, is investigated to serve as a yield-stress support bath material for the extrusion printing of liquid build materials. Using the printing-then-solidification approach, the printed structure remains liquid and retains its shape with the help of the Laponite support bath. Then the completed liquid structures are solidified in situ by applying suitable cross-linking mechanisms. Finally, the solidified structures are harvested from the Laponite nanoclay support bath for any further processing as needed. Due to its chemical and physical stability, liquid build materials with different solidification/curing/gelation mechanisms can be fabricated in the Laponite bath using the printing-then-solidification approach. The feasibility of the proposed Laponite-enabled printing-then-solidification approach is demonstrated by fabricating several complicated structures made of various liquid build materials, including alginate with ionic cross-linking, gelatin with thermal cross-linking, and SU-8 with photo-cross-linking. During gelatin structure printing, living cells are included and the postfabrication cell viability is above 90%.

Liquid-liquid phase separation and solidification behavior of Al55Bi36Cu9 monotectic alloy with different cooling rates

NASA Astrophysics Data System (ADS)

Bo, Lin; Li, Shanshan; Wang, Lin; Wu, Di; Zuo, Min; Zhao, Degang

2018-03-01

The cooling rate has a significant effect on the solidification behavior and microstructure of monotectic alloy. In this study, different cooling rate was designed through casting in the copper mold with different bore diameters. The effects of different cooling rate on the solidification behavior of Al55Bi36Cu9 (at.%) immiscible alloy have been investigated. The liquid-liquid phase separation of Al55Bi36Cu9 immiscible alloy melt was investigated by resistivity test. The solidification microstructure and phase analysis of Al55Bi36Cu9 immiscible alloy were performed by the SEM and XRD, respectively. The results showed that the liquid-liquid phase separation occurred in the solidification of Al55Bi36Cu9 monotectic melt from 917 °C to 653 °C. The monotectic temperature, liquid phase separation temperature and immiscibility zone of Al55Bi36Cu9 monotectic alloy was lower than those of Al-Bi binary monotectic alloy. The solidification morphology of Al55Bi36Cu9 monotectic alloy was very sensitive to the cooling rate. The Al/Bi core-shell structure formed when Al55Bi36Cu9 melt was cast in the copper mold with a 8 mm bore diameter.

Displacement-dispersive liquid-liquid microextraction based on solidification of floating organic drop of trace amounts of palladium in water and road dust samples prior to graphite furnace atomic absorption spectrometry determination.

PubMed

Ghanbarian, Maryam; Afzali, Daryoush; Mostafavi, Ali; Fathirad, Fariba

2013-01-01

A new displacement-dispersive liquid-liquid microextraction method based on the solidification of floating organic drop was developed for separation and preconcentration of Pd(ll) in road dust and aqueous samples. This method involves two steps of dispersive liquid-liquid microextraction based on solidification. In Step 1, Cu ions react with diethyldithiocarbamate (DDTC) to form Cu-DDTC complex, which is extracted by dispersive liquid-liquid microextraction based on a solidification procedure using 1-undecanol (extraction solvent) and ethanol (dispersive solvent). In Step 2, the extracted complex is first dispersed using ethanol in a sample solution containing Pd ions, then a dispersive liquid-liquid microextraction based on a solidification procedure is performed creating an organic drop. In this step, Pd(ll) replaces Cu(ll) from the pre-extracted Cu-DDTC complex and goes into the extraction solvent phase. Finally, the Pd(ll)-containing drop is introduced into a graphite furnace using a microsyringe, and Pd(ll) is determined using atomic absorption spectrometry. Several factors that influence the extraction efficiency of Pd and its subsequent determination, such as extraction and dispersive solvent type and volume, pH of sample solution, centrifugation time, and concentration of DDTC, are optimized.

Investigating gas-phase defect formation in late-stage solidification using a novel phase-field crystal alloy model

NASA Astrophysics Data System (ADS)

Wang, Nan; Smith, Nathan; Provatas, Nikolas

2017-09-01

We study late-stage solidification and the associated formation of defects in alloy materials using a novel model based on the phase-field-crystal technique. It is shown that our model successfully captures several important physical phenomena that occur in the late stages of solidification, including solidification shrinkage, liquid cavitation and microsegregation, all in a single framework. By examining the interplay of solidification shrinkage and solute segregation, this model reveals that the formation of gas pore defects at the late stage of solidification can lead to nucleation of second phase solid particles due to solute enrichment in the eutectic liquid driven by gas-phase nucleation and growth. We also predict a modification of the Gulliver-Scheil equation in the presence of gas pockets in confined liquid pools.

Recovery and safer disposal of phosphate coating sludge by solidification/stabilization.

PubMed

Ucaroglu, Selnur; Talinli, Ilhan

2012-08-30

Solidification/stabilization (S/S) of automotive phosphate coating sludge (PS) containing potentially toxic heavy metals was studied. The hazardous characteristics of this waste were assessed according to both Turkish and U.S. Environmental Protection Agency (EPA) regulations for hazardous solid waste. Unconfined compressive strength (UCS) and leaching behavior tests of the solidified/stabilized product were performed. Solidification studies were conducted using Portland cement (PC) as the binder. UCS was found to decrease with increasing waste content. It was found that recovery of the waste for construction applications was possible when the waste content of the mortar was 20% and below, but solidification for safe disposal was achieved only when higher waste concentrations were added. Cu, Cr, Ni, Pb and Zn were found to be significantly immobilized by the solidification/stabilization process. Ni and Zn, which were present at particularly high concentrations (2.281 and 135.318 g/kg respectively) in the PS, had highest the retention levels (94.87% and 98.74%, respectively) in the PC mortars. The organic contaminants and heavy metals present in PS were determined to be immobilized by the S/S process in accordance with the BS 6920 standard. Thus, the potential for hazardous PS waste to adversely impact human health and the environment was effectively eliminated by the S/S procedure. We conclude that S/S-treated PS is safe for disposal in landfills, while recovery of S/S-treated PS constituents remains possible. Copyright © 2012 Elsevier Ltd. All rights reserved.

APPLICATIONS ANALYSIS REPORT: SITE PROGRAM DEMONSTRATION TEST SOLIDITECH, INC. SOLIDIFICATION/ STABILIZATION PROCESS

EPA Science Inventory

This Applications Analysis Report evaluates the Soliditech, Inc., solidification/ stabilization process for the on-site treatment of waste materials. The Soliditech process mixes and chemically treats waste material with Urrichem (a proprietary reagent), additives, pozzolanic mat...

SURVEY OF SOLIDIFICATION/STABILIZATION TECHNOLOGY FOR HAZARDOUS INDUSTRIAL WASTES

EPA Science Inventory

Stabilization/solidification or fixation is a process for treating industrial solid wastes (primarily sludges) that contain hazardous constituents to prevent dissolution and loss of toxic materials into the environment. Most of these treatment processes are designed to produce a ...

DEMONSTRATION BULLETIN: SOLIDIFICATION/STABILIZATION PROCESS, Hazcon, Inc.

EPA Science Inventory

The solidification/stabilization technology mixes hazardous wastes, cement, water and an additive called Chloranan. Chloranan, a nontoxic chemical, encapsulates organic molecules, rendering them ineffective in retarding or inhibiting solidification. This treatment technol...

Stabilization and Solidification of Nitric Acid Effluent Waste at Y-12

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Dileep; Lorenzo-Martin, Cinta

Consolidated Nuclear Security, LLC (CNS) at the Y-12 plant is investigating approaches for the treatment (stabilization and solidification) of a nitric acid waste effluent that contains uranium. Because the pH of the waste stream is 1-2, it is a difficult waste stream to treat and stabilize by a standard cement-based process. Alternative waste forms are being considered. In this regard, Ceramicrete technology, developed at Argonne National Laboratory, is being explored as an option to solidify and stabilize the nitric acid effluent wastes.

Study of Solidification Cracking in a Transformation-Induced Plasticity-Aided Steel

NASA Astrophysics Data System (ADS)

Agarwal, G.; Kumar, A.; Gao, H.; Amirthalingam, M.; Moon, S. C.; Dippenaar, R. J.; Richardson, I. M.; Hermans, M. J. M.

2018-04-01

In situ high-temperature laser scanning confocal microscopy is applied to study solidification cracking in a TRIP steel. Solidification cracking was observed in the interdendritic region during the last stage of solidification. Atom probe tomography revealed notable enrichment of phosphorus in the last remaining liquid. Phase field simulations also confirm phosphorus enrichment leading to severe undercooling of more than 160 K in the interdendritic region. In the presence of tensile stress, an opening at the interdendritic region is difficult to fill with the remaining liquid due to low permeability and high viscosity, resulting in solidification cracking.

TECHNOLOGY EVALUATION REPORT: CHEMFIX TECHNOLOGIES, INC. - SOLIDIFICATION/STABILIZATION PROCESS - CLACKAMAS, OREGON - VOLUME I

EPA Science Inventory

The CHEMFIX solidification/stabilization process was evaluated in the U.S. Environment Protection Agency's SITE program. Waste from an uncontrolled hazardous waste site was treated by the CHEMFIX process and subjected to a variety of physical and chemical test methods. Physical t...

TECHNOLOGY EVALUATION REPORT: CHEMFIX TECHNOLOGIES, INC. - SOLIDIFICATION/STABILIZATION PROCESS - CLACKAMAS, OREGON - VOLUME II

EPA Science Inventory

The CHEMFIX solidification/stabilization process was evaluated in the U.S. Environmental Protection Agency's SITE program. Waste from an uncontrolled hazardous waste site was treated by the CHEMFIX process and subjected to a variety of physical and chemical test methods. Physical...

Rapid solidification of levitation melted Ni-Sn alloy droplets with high undercooling

NASA Technical Reports Server (NTRS)

Shiohara, Yuh; Flemings, Merton C.; Wu, Yanzhong; Piccone, Thomas J.

1985-01-01

Experimental results obtained by high-speed optical temperature sensing for the rapid solidification of highly undercooled, levitation-melted Ni-Sn alloy droplets are presented. These data suggest a solidification model proceeding according to overlapping steps: (1) dendritic growth within the bulk undercooled melt, (2) continued recalescence as supersaturation of the interdendritic liquid dissipates, (3) fine-scale remelting within the dendrites, (4) ripening of the fine structure, and (5) solidification of remaining liquid at the end of recalescence.

Method for treating materials for solidification

DOEpatents

Jantzen, Carol M.; Pickett, John B.; Martin, Hollis L.

1995-01-01

A method for treating materials such as wastes for solidification to form a solid, substantially nonleachable product. Addition of reactive silica rather than ordinary silica to the material when bringing the initial molar ratio of its silica constituent to a desired ratio within a preselected range increases the solubility and retention of the materials in the solidified matrix. Materials include hazardous, radioactive, mixed, and heavy metal species. Amounts of other constituents of the material, in addition to its silica content are also added so that the molar ratio of each of these constituents is within the preselected ranges for the final solidified product. The mixture is then solidified by cement solidification or vitrification. The method can be used to treat a variety of wastes, including but not limited to spent filter aids from waste water treatment, waste sludges, combinations of spent filter aids and waste sludges, combinations of supernate and waste sludges, incinerator ash, incinerator offgas blowdown, combinations of incinerator ash and offgas blowdown, cementitious wastes and contaminated soils.

Solidification Sequence of Spray-Formed Steels

NASA Astrophysics Data System (ADS)

Zepon, Guilherme; Ellendt, Nils; Uhlenwinkel, Volker; Bolfarini, Claudemiro

2016-02-01

Solidification in spray-forming is still an open discussion in the atomization and deposition area. This paper proposes a solidification model based on the equilibrium solidification path of alloys. The main assumptions of the model are that the deposition zone temperature must be above the alloy's solidus temperature and that the equilibrium liquid fraction at this temperature is reached, which involves partial remelting and/or redissolution of completely solidified droplets. When the deposition zone is cooled, solidification of the remaining liquid takes place under near equilibrium conditions. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to analyze the microstructures of two different spray-formed steel grades: (1) boron modified supermartensitic stainless steel (SMSS) and (2) D2 tool steel. The microstructures were analyzed to determine the sequence of phase formation during solidification. In both cases, the solidification model proposed was validated.

CASE STUDY: IN-SITU SOLIDIFICATION/STABILIZATION OF HAZARDOUS ACID WASTE OIL SLUDGE AND LESSONS LEARNED

EPA Science Inventory

The South 8th Street site contained a 2.5 acre oily sludge pit with very low pH waste produced by oil recycling activities. This sludge was treated using in-situ solidification/stabilization technology applied by deep soil mixing augers. The problems encountered, solutions develo...

Numerical Simulation of Polysilicon Solid-liquid Interface Transmogrification in Heat Transfer Process

NASA Astrophysics Data System (ADS)

Yang, Xi; Ma, Wenhui; Lv, Guoqiang; Zhang, Mingyu

2018-01-01

The shape of solid-liquid interface during the directional solidification process, which is difficult to be observed and measured in actual processes, controls the grain orientation and grain size of polysilicon ingot. We carried out numerical calculations of the directional solidification progress of polycrystalline silicon and invested the means to deal with the latent heat of solidification in numerical simulation. The distributions of the temperature field of the melt for the crystallization progress as well as the transformation of the solid-liquid interface were obtained. The simulation results are consistent with the experimental outcomes. The results show that the curvature of solid-liquid interface is small and stability, larger grain sized columnar crystal can be grown in the laboratory-scale furnace at a solidification rate of 10 μm•s-1. It shall provide important theoretical basis for metallurgical process and polysilicon production technology.

Heat of Hydration of Low Activity Cementitious Waste Forms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nasol, D.

2015-07-23

During the curing of secondary waste grout, the hydraulic materials in the dry mix react exothermally with the water in the secondary low-activity waste (LAW). The heat released, called the heat of hydration, can be measured using a TAM Air Isothermal Calorimeter. By holding temperature constant in the instrument, the heat of hydration during the curing process can be determined. This will provide information that can be used in the design of a waste solidification facility. At the Savannah River National Laboratory (SRNL), the heat of hydration and other physical properties are being collected on grout prepared using three simulantsmore » of liquid secondary waste generated at the Hanford Site. From this study it was found that both the simulant and dry mix each had an effect on the heat of hydration. It was also concluded that the higher the cement content in the dry materials mix, the greater the heat of hydration during the curing of grout.« less

Review of Literature on Waste Solidification/Stabilization with Emphasis on Metal-Bearing Wastes

DTIC Science & Technology

1989-08-01

applicability to treating a wide variety of waste types, and the ease with 4 which they are implemented in the field (Wiles and Apel , undated). Asphaltic...Wiles, C.C., 1987. A Review of Solidification/Stabilization Technology. Journal of Hazardous Materials, 14:5-21. Wiles, C.C., and Apel , M.L., undated...Personal correspondence and attachments from William McLaughlin, 1-714-693-1818, 1988. Trident Engineering Associates, 48 Maryland Ave., Annapolis, Maryland

Radionuclide Retention Mechanisms in Secondary Waste-Form Testing: Phase II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Um, Wooyong; Valenta, Michelle M.; Chung, Chul-Woo

2011-09-26

This report describes the results from laboratory tests performed at Pacific Northwest National Laboratory (PNNL) for Washington River Protection Solutions (WRPS) to evaluate candidate stabilization technologies that have the potential to successfully treat liquid secondary waste stream effluents produced by the Hanford Tank Waste Treatment and Immobilization Plant (WTP). WRPS is considering the design and construction of a Solidification Treatment Unit (STU) for the Effluent Treatment Facility (ETF) at Hanford. The ETF, a multi-waste, treatment-and-storage unit that has been permitted under the Resource Conservation and Recovery Act (RCRA), can accept dangerous, low-level, and mixed wastewaters for treatment. The STU needsmore » to be operational by 2018 to receive secondary liquid waste generated during operation of the WTP. The STU will provide the additional capacity needed for ETF to process the increased volume of secondary waste expected to be produced by WTP. This report on radionuclide retention mechanisms describes the testing and characterization results that improve understanding of radionuclide retention mechanisms, especially for pertechnetate, {sup 99}TcO{sub 4}{sup -} in four different waste forms: Cast Stone, DuraLith alkali aluminosilicate geopolymer, encapsulated fluidized bed steam reforming (FBSR) product, and Ceramicrete phosphate bonded ceramic. These data and results will be used to fill existing data gaps on the candidate technologies to support a decision-making process that will identify a subset of the candidate waste forms that are most promising and should undergo further performance testing.« less

Materials for the Study of Interesting Phenomena of Solidification on Earth and in Orbit (MEPHISTO)

NASA Technical Reports Server (NTRS)

1987-01-01

The MEPHISTO experiment is a cooperative American and French investigation of the fundamentals of crystal growth. MEPHISTO is a French-designed and built materials processing furnace. MEPHISTO experiments study solidation (also called freezing) during the growth cycle of liquid materials used for semiconductor crystals. Solidification is the process where materials change from liquid (melt) to solid. An example of the solidification process is water changing into ice.

Reduction of 68Ge activity containing liquid waste from 68Ga PET chemistry in nuclear medicine and radiopharmacy by solidification.

PubMed

de Blois, Erik; Chan, Ho Sze; Roy, Kamalika; Krenning, Eric P; Breeman, Wouter A P

PET with 68 Ga from the TiO 2 - or SnO 2 - based 68 Ge/ 68 Ga generators is of increasing interest for PET imaging in nuclear medicine. In general, radionuclidic purity ( 68 Ge vs. 68 Ga activity) of the eluate of these generators varies between 0.01 and 0.001%. Liquid waste containing low amounts of 68 Ge activity is produced by eluting the 68 Ge/ 68 Ga generators and residues from PET chemistry. Since clearance level of 68 Ge activity in waste may not exceed 10 Bq/g, as stated by European Directive 96/29/EURATOM, our purpose was to reduce 68 Ge activity in solution from >10 kBq/g to <10 Bq/g; which implies the solution can be discarded as regular waste. Most efficient method to reduce the 68 Ge activity is by sorption of TiO 2 or Fe 2 O 3 and subsequent centrifugation. The required 10 Bq per mL level of 68 Ge activity in waste was reached by Fe 2 O 3 logarithmically, whereas with TiO 2 asymptotically. The procedure with Fe 2 O 3 eliminates ≥90% of the 68 Ge activity per treatment. Eventually, to simplify the processing a recirculation system was used to investigate 68 Ge activity sorption on TiO 2 , Fe 2 O 3 or Zeolite. Zeolite was introduced for its high sorption at low pH, therefore 68 Ge activity containing waste could directly be used without further interventions. 68 Ge activity containing liquid waste at different HCl concentrations (0.05-1.0 M HCl), was recirculated at 1 mL/min. With Zeolite in the recirculation system, 68 Ge activity showed highest sorption.

Solidification of radioactive waste resins using cement mixed with organic material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laili, Zalina, E-mail: liena@nm.gov.my; Waste and Environmental Technology Division, Malaysian Nuclear Agency; Yasir, Muhamad Samudi

2015-04-29

Solidification of radioactive waste resins using cement mixed with organic material i.e. biochar is described in this paper. Different percentage of biochar (0%, 5%, 8%, 11%, 14% and 18%) was investigated in this study. The characteristics such as compressive strength and leaching behavior were examined in order to evaluate the performance of solidified radioactive waste resins. The results showed that the amount of biochar affect the compressive strength of the solidified resins. Based on the data obtained for the leaching experiments performed, only one formulation showed the leached of Cs-134 from the solidified radioactive waste resins.

Positive segregation as a function of buoyancy force during steel ingot solidification.

PubMed

Radovic, Zarko; Jaukovic, Nada; Lalovic, Milisav; Tadic, Nebojsa

2008-12-01

We analyze theoretically and experimentally solute redistribution in the dendritic solidification process and positive segregation during solidification of steel ingots. Positive segregation is mainly caused by liquid flow in the mushy zone. Changes in the liquid steel velocity are caused by the temperature gradient and by the increase in the solid fraction during solidification. The effects of buoyancy and of the change in the solid fraction on segregation intensity are analyzed. The relationships between the density change, liquid fraction and the steel composition are considered. Such elements as W, Ni, Mo and Cr decrease the effect of the density variations, i.e. they show smaller tendency to segregate. Based on the modeling and experimental results, coefficients are provided controlling the effects of chemical composition, secondary dendrite arm spacing and the solid fraction.

Enthalpies of a binary alloy during solidification

NASA Technical Reports Server (NTRS)

Poirier, D. R.; Nandapurkar, P.

1988-01-01

The purpose of the paper is to present a method of calculating the enthalpy of a dendritic alloy during solidification. The enthalpies of the dendritic solid and interdendritic liquid of alloys of the Pb-Sn system are evaluated, but the method could be applied to other binaries, as well. The enthalpies are consistent with a recent evaluation of the thermodynamics of Pb-Sn alloys and with the redistribution of solute in the same during dendritic solidification. Because of the heat of mixing in Pb-Sn alloys, the interdendritic liquid of hypoeutectic alloys (Pb-rich) of less than 50 wt pct Sn has enthalpies that increase as temperature decreases during solidification.

MPS solidification model. Analysis and calculation of macrosegregation in a casting ingot

NASA Technical Reports Server (NTRS)

Poirier, D. R.; Maples, A. L.

1985-01-01

Work performed on several existing solidification models for which computer codes and documentation were developed is presented. The models describe the solidification of alloys in which there is a time varying zone of coexisting solid and liquid phases; i.e., the S/L zone. The primary purpose of the models is to calculate macrosegregation in a casting or ingot which results from flow of interdendritic liquid in this S/L zone during solidification. The flow, driven by solidification contractions and by gravity acting on density gradients in the interdendritic liquid, is modeled as flow through a porous medium. In Model 1, the steady state model, the heat flow characteristics are those of steady state solidification; i.e., the S/L zone is of constant width and it moves at a constant velocity relative to the mold. In Model 2, the unsteady state model, the width and rate of movement of the S/L zone are allowed to vary with time as it moves through the ingot. Each of these models exists in two versions. Models 1 and 2 are applicable to binary alloys; models 1M and 2M are applicable to multicomponent alloys.

Analysis and calculation of macrosegregation in a casting ingot. MPS solidification model. Volume 1: Formulation and analysis

NASA Technical Reports Server (NTRS)

Maples, A. L.; Poirier, D. R.

1980-01-01

The physical and numerical formulation of a model for the horizontal solidification of a binary alloy is described. It can be applied in an ingot. The major purpose of the model is to calculate macrosegregation in a casting ingot which results from flow of interdendritic liquid during solidification. The flow, driven by solidification contractions and by gravity acting on density gradients in the interdendritic liquid, was modeled as flow through a porous medium. The symbols used are defined. The physical formulation of the problem leading to a set of equations which can be used to obtain: (1) the pressure field; (2) the velocity field: (3) mass flow and (4) solute flow in the solid plus liquid zone during solidification is presented. With these established, the model calculates macrosegregation after solidification is complete. The numerical techniques used to obtain solution on a computational grid are presented. Results, evaluation of the results, and recommendations for future development of the model are given. The macrosegregation and flow field predictions for tin-lead, aluminum-copper, and tin-bismuth alloys are included as well as comparisons of some of the predictions with published predictions or with empirical data.

SECONDARY WASTE/ETF (EFFLUENT TREATMENT FACILITY) PRELIMINARY PRE-CONCEPTUAL ENGINEERING STUDY

DOE Office of Scientific and Technical Information (OSTI.GOV)

MAY TH; GEHNER PD; STEGEN GARY

2009-12-28

This pre-conceptual engineering study is intended to assist in supporting the critical decision (CD) 0 milestone by providing a basis for the justification of mission need (JMN) for the handling and disposal of liquid effluents. The ETF baseline strategy, to accommodate (WTP) requirements, calls for a solidification treatment unit (STU) to be added to the ETF to provide the needed additional processing capability. This STU is to process the ETF evaporator concentrate into a cement-based waste form. The cementitious waste will be cast into blocks for curing, storage, and disposal. Tis pre-conceptual engineering study explores this baseline strategy, in additionmore » to other potential alternatives, for meeting the ETF future mission needs. Within each reviewed case study, a technical and facility description is outlined, along with a preliminary cost analysis and the associated risks and benefits.« less

Efficient estimation of diffusion during dendritic solidification

NASA Technical Reports Server (NTRS)

Yeum, K. S.; Poirier, D. R.; Laxmanan, V.

1989-01-01

A very efficient finite difference method has been developed to estimate the solute redistribution during solidification with diffusion in the solid. This method is validated by comparing the computed results with the results of an analytical solution derived by Kobayashi (1988) for the assumptions of a constant diffusion coefficient, a constant equilibrium partition ratio, and a parabolic rate of the advancement of the solid/liquid interface. The flexibility of the method is demonstrated by applying it to the dendritic solidification of a Pb-15 wt pct Sn alloy, for which the equilibrium partition ratio and diffusion coefficient vary substantially during solidification. The fraction eutectic at the end of solidification is also obtained by estimating the fraction solid, in greater resolution, where the concentration of solute in the interdendritic liquid reaches the eutectic composition of the alloy.

Convection and Solidification with Applications to Crystal Growth

NASA Technical Reports Server (NTRS)

DeVahl Davis, Graham

1994-01-01

An outline is given of research on the directional solidification of a liquid, and of the effects of natural convection thereon. Three problems which have been studied are described. Finally, current work on solidification in microgravity conditions is discussed.

Some Pecularities of Solidification of the Almandine Impact Melt

NASA Astrophysics Data System (ADS)

Feldman, V. I.; Kozlov, E. A.; Zhugin, Yu. N.

1996-03-01

SOME PECULIARITIES OF SOLIDIFICATION OF THE ALMANDINE IMPACT MELT. Feldman V.I. Moscow State University, Geological Faculty, Department of Petrology, 119899, Moscow, Russia. Kozlov E.A., Zhugin Yu.N. Russian Federal nuclear Center - Research Institute of Technical Physics, P.O.Box 245, 456770, Snezhinsk, Russia. The aim of these investigations is a description of the experiments and the first results of a loading of the garnet sand by spherical converging shock waves. These experiments show that impact liquid have by solidification three stage of liquid immiscibility.

A Citizen's Guide to Solidification and Stabilization

EPA Pesticide Factsheets

This guide describes how solidification and stabilization refer to a group of cleanup methods that prevent or slow the release of harmful chemicals from wastes, such as contaminated soil, sediment, and sludge.

Small hazardous waste generators in developing countries: use of stabilization/solidification process as an economic tool for metal wastewater treatment and appropriate sludge disposal.

PubMed

Silva, Marcos A R; Mater, Luciana; Souza-Sierra, Maria M; Corrêa, Albertina X R; Sperb, Rafael; Radetski, Claudemir M

2007-08-25

The aim of this study was to propose a profitable destination for an industrial sludge that can cover the wastewater treatment costs of small waste generators. Optimized stabilization/solidification technology was used to treat hazardous waste from an electroplating industry that is currently released untreated to the environment. The stabilized/solidified (S/S) waste product was used as a raw material to build concrete blocks, to be sold as pavement blocks or used in roadbeds and/or parking lots. The quality of the blocks containing a mixture of cement, lime, clay and waste was evaluated by means of leaching and solubility tests according to the current Brazilian waste regulations. Results showed very low metal leachability and solubility of the block constituents, indicating a low environmental impact. Concerning economic benefits from the S/S process and reuse of the resultant product, the cost of untreated heavy metal-containing sludge disposal to landfill is usually on the order of US$ 150-200 per tonne of waste, while 1tonne of concrete roadbed blocks (with 25% of S/S waste constitution) has a value of around US$ 100. The results of this work showed that the cement, clay and lime-based process of stabilization/solidification of hazardous waste sludge is sufficiently effective and economically viable to stimulate the treatment of wastewater from small industrial waste generators.

Factors affecting hazardous waste solidification/stabilization: a review.

PubMed

Malviya, Rachana; Chaudhary, Rubina

2006-09-01

Solidification/stabilization is accepted as a well-established disposal technique for hazardous waste. As a result many different types of hazardous wastes are treated with different binders. The S/S products have different property from waste and binders individually. The effectiveness of S/S process is studied by physical, chemical and microstructural methods. This paper summarizes the effect of different waste stream such as heavy metals bearing sludge, filter cake, fly ash, and slag on the properties of cement and other binders. The factors affecting strength development is studied using mix designs, including metal bearing waste alters the hydration and setting time of binders. Pore structure depends on relative quantity of the constituents, cement hydration products and their reaction products with admixtures. Carbonation and additives can lead to strength improvement in waste-binder matrix.

Thermo-Electric-Magnetic Hydrodynamics in Solidification: In Situ Observations and Theory

NASA Astrophysics Data System (ADS)

Fautrelle, Y.; Wang, J.; Salloum-Abou-Jaoude, G.; Abou-Khalil, L.; Reinhart, G.; Li, X.; Ren, Z. M.; Nguyen-Thi, H.

2018-02-01

Solidification of liquid metals contains all the ingredients for the development of the thermo-electric (TE) effect, namely liquid-solid interface and temperature gradients. The combination of TE currents with a superimposed magnetic field gives rise to thermo-electromagnetic (TEM) volume forces acting on both liquid and solid. This results in the generation of fluid flows, which considerably modifies the morphology of the solidification front as well as that of the mushy zone. TEM forces also act on the solid and cause both fragmentation of dendrite branches and a movement of equiaxed grains in suspension. These phenomena have already been unveiled by post-mortem analysis of samples, but they can be analyzed in more detail by using x-ray in situ and real-time observations. Here, we present conclusive evidence of all the aforementioned effects thanks to in situ observations of Al-Cu alloy solidification under static magnetic field.

Effects of Space Environment on Flow and Concentration During Directional Solidification

NASA Technical Reports Server (NTRS)

Benjapiyaporn, C.; Timchenko, V.; Leonardi, E.; deVahlDavis, G.; deGroh, H. C., III

2000-01-01

A study of directional solidification of a weak binary alloy (specifically, Bi - 1 at% Sn) based on the fixed grid single domain approach is being undertaken. The enthalpy method is used to solve for the temperature field over the computational domain including both the solid and liquid phases; latent heat evolution is treated with the aid of an effective specific heat coefficient. A source term accounting for the release of solute into the liquid during solidification has been incorporated into the solute transport equation. The vorticity-stream function formulation is used to describe thermosolutal convection in the liquid region. In this paper we numerically investigate the effects of g-jitter on directional solidification. A background gravity of 1 micro-g has been assumed, and new results for the effects of periodic disturbances over a range of amplitudes and frequencies on solute field and segregation have been presented.

WASTE TREATMENT BUILDING SYSTEM DESCRIPTION DOCUMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

F. Habashi

2000-06-22

The Waste Treatment Building System provides the space, layout, structures, and embedded subsystems that support the processing of low-level liquid and solid radioactive waste generated within the Monitored Geologic Repository (MGR). The activities conducted in the Waste Treatment Building include sorting, volume reduction, and packaging of dry waste, and collecting, processing, solidification, and packaging of liquid waste. The Waste Treatment Building System is located on the surface within the protected area of the MGR. The Waste Treatment Building System helps maintain a suitable environment for the waste processing and protects the systems within the Waste Treatment Building (WTB) from mostmore » of the natural and induced environments. The WTB also confines contaminants and provides radiological protection to personnel. In addition to the waste processing operations, the Waste Treatment Building System provides space and layout for staging of packaged waste for shipment, industrial and radiological safety systems, control and monitoring of operations, safeguards and security systems, and fire protection, ventilation and utilities systems. The Waste Treatment Building System also provides the required space and layout for maintenance activities, tool storage, and administrative facilities. The Waste Treatment Building System integrates waste processing systems within its protective structure to support the throughput rates established for the MGR. The Waste Treatment Building System also provides shielding, layout, and other design features to help limit personnel radiation exposures to levels which are as low as is reasonably achievable (ALARA). The Waste Treatment Building System interfaces with the Site Generated Radiological Waste Handling System, and with other MGR systems that support the waste processing operations. The Waste Treatment Building System interfaces with the General Site Transportation System, Site Communications System, Site Water System, MGR Site Layout, Safeguards and Security System, Site Radiological Monitoring System, Site Electrical Power System, Site Compressed Air System, and Waste Treatment Building Ventilation System.« less

Cooling and solidification of liquid-metal drops in a gaseous atmosphere

NASA Technical Reports Server (NTRS)

Mccoy, J. K.; Markworth, A. J.; Collings, E. W.; Brodkey, R. S.

1992-01-01

The free fall of a liquid-metal drop, heat transfer from the drop to its environment, and solidification of the drop are described for both gaseous and vacuum atmospheres. A simple model, in which the drop is assumed to fall rectilinearly, with behavior like that of a rigid particle, is developed to describe cooling behavior. Recalescence of supercooled drops is assumed to occur instantaneously when a specified temperature is passed. The effects of solidification and experimental parameters on drop cooling are calculated and discussed. Major results include temperature as a function of time, and of drag, time to complete solidification, and drag as a function of the fraction of the drop solidified.

Effect of mineral viscosity-enhancing admixtures on the solidification of evaporator concentrates.

PubMed

Lin, Chung-Yung; Huang, Wan-Ting

2015-11-15

It is known that partial replacement of cement by viscosity-enhancing admixtures, also known as anti-washout admixtures, affects the quality of the waste form or concrete. To reduce the bleeding rate of the paste, the characteristics of various mineral viscosity-enhancing admixtures dispersed in saline solutions were investigated, including sedimentation and viscosity. The admixture candidates included fly ash, silica fume, bentonite, and palygorskite. The effect of these admixtures blended with a cement-based matrix on the bleeding rate of the solidification of evaporator concentrates was also examined in this paper. The experimental results show the palygorskite Type 400 is the best choice to improve the quality of waste form, due to its excellent suspension property in the saline solution. The bleeding rate of paste decreased as the dispersion volume of the admixture suspension increased. For consideration of the quality of waste forms and the concentrate loading, the optimization of the palygorskite/concentrate ratio of 15-17 wt% and solidification agent/concentrate ratio of 1.0-1.2 were adopted. With this recipe, the quality of waste forms resulting from the solidification of simulated and actual evaporator concentrates mainly containing chloride met the regulations' requirements. Copyright © 2015 Elsevier B.V. All rights reserved.

Densities of Pb-Sn alloys during solidification

NASA Technical Reports Server (NTRS)

Poirier, D. R.

1988-01-01

Data for the densities and expansion coefficients of solid and liquid alloys of the Pb-Sn system are consolidated in this paper. More importantly, the data are analyzed with the purpose of expressing either the density of the solid or of the liquid as a function of its composition and temperature. In particular, the densities of the solid and of the liquid during dendritic solidification are derived. Finally, the solutal and thermal coefficients of volume expansion for the liquid are given as functions of temperature and composition.

Matching time and spatial scales of rapid solidification: dynamic TEM experiments coupled to CALPHAD-informed phase-field simulations

NASA Astrophysics Data System (ADS)

Perron, Aurelien; Roehling, John D.; Turchi, Patrice E. A.; Fattebert, Jean-Luc; McKeown, Joseph T.

2018-01-01

A combination of dynamic transmission electron microscopy (DTEM) experiments and CALPHAD-informed phase-field simulations was used to study rapid solidification in Cu-Ni thin-film alloys. Experiments—conducted in the DTEM—consisted of in situ laser melting and determination of the solidification kinetics by monitoring the solid-liquid interface and the overall microstructure evolution (time-resolved measurements) during the solidification process. Modelling of the Cu-Ni alloy microstructure evolution was based on a phase-field model that included realistic Gibbs energies and diffusion coefficients from the CALPHAD framework (thermodynamic and mobility databases). DTEM and post mortem experiments highlighted the formation of microsegregation-free columnar grains with interface velocities varying from ˜0.1 to ˜0.6 m s-1. After an ‘incubation’ time, the velocity of the planar solid-liquid interface accelerated until solidification was complete. In addition, a decrease of the temperature gradient induced a decrease in the interface velocity. The modelling strategy permitted the simulation (in 1D and 2D) of the solidification process from the initially diffusion-controlled to the nearly partitionless regimes. Finally, results of DTEM experiments and phase-field simulations (grain morphology, solute distribution, and solid-liquid interface velocity) were consistent at similar time (μs) and spatial scales (μm).

Matching time and spatial scales of rapid solidification: Dynamic TEM experiments coupled to CALPHAD-informed phase-field simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perron, Aurelien; Roehling, John D.; Turchi, Patrice E. A.

A combination of dynamic transmission electron microscopy (DTEM) experiments and CALPHAD-informed phase-field simulations was used to study rapid solidification in Cu–Ni thin-film alloys. Experiments—conducted in the DTEM—consisted of in situ laser melting and determination of the solidification kinetics by monitoring the solid–liquid interface and the overall microstructure evolution (time-resolved measurements) during the solidification process. Modelling of the Cu–Ni alloy microstructure evolution was based on a phase-field model that included realistic Gibbs energies and diffusion coefficients from the CALPHAD framework (thermodynamic and mobility databases). DTEM and post mortem experiments highlighted the formation of microsegregation-free columnar grains with interface velocities varying frommore » ~0.1 to ~0.6 m s –1. After an 'incubation' time, the velocity of the planar solid–liquid interface accelerated until solidification was complete. In addition, a decrease of the temperature gradient induced a decrease in the interface velocity. The modelling strategy permitted the simulation (in 1D and 2D) of the solidification process from the initially diffusion-controlled to the nearly partitionless regimes. Lastly, results of DTEM experiments and phase-field simulations (grain morphology, solute distribution, and solid–liquid interface velocity) were consistent at similar time (μs) and spatial scales (μm).« less

Matching time and spatial scales of rapid solidification: Dynamic TEM experiments coupled to CALPHAD-informed phase-field simulations

DOE PAGES

Perron, Aurelien; Roehling, John D.; Turchi, Patrice E. A.; ...

2017-12-05

A combination of dynamic transmission electron microscopy (DTEM) experiments and CALPHAD-informed phase-field simulations was used to study rapid solidification in Cu–Ni thin-film alloys. Experiments—conducted in the DTEM—consisted of in situ laser melting and determination of the solidification kinetics by monitoring the solid–liquid interface and the overall microstructure evolution (time-resolved measurements) during the solidification process. Modelling of the Cu–Ni alloy microstructure evolution was based on a phase-field model that included realistic Gibbs energies and diffusion coefficients from the CALPHAD framework (thermodynamic and mobility databases). DTEM and post mortem experiments highlighted the formation of microsegregation-free columnar grains with interface velocities varying frommore » ~0.1 to ~0.6 m s –1. After an 'incubation' time, the velocity of the planar solid–liquid interface accelerated until solidification was complete. In addition, a decrease of the temperature gradient induced a decrease in the interface velocity. The modelling strategy permitted the simulation (in 1D and 2D) of the solidification process from the initially diffusion-controlled to the nearly partitionless regimes. Lastly, results of DTEM experiments and phase-field simulations (grain morphology, solute distribution, and solid–liquid interface velocity) were consistent at similar time (μs) and spatial scales (μm).« less

Novel Directional Solidification Processing of Hypermonotectic Alloys

NASA Technical Reports Server (NTRS)

Grugel, Richard N.

1999-01-01

Gravity driven separation precludes uniform microstructural development during controlled directional solidification (DS) processing of hypermonotectic alloys. It is well established that liquid/liquid suspensions, in which the respective components are immiscible and have significant density differences, can be established and maintained by utilizing ultrasound. A historical introduction to this work is presented with the intent of establishing the basis for applying the phenomena to promote microstructural uniformity during controlled directional solidification processing of immiscible mixtures. Experimental work based on transparent organics, as well as salt systems, will be presented in view of the processing parameters.

Ordinary portland cement based solidification of toxic wastes: The role of OPC reviewed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hills, C.D.; Sollars, C.J.; Perry, R.

1993-01-01

A mixed waste stream, which is commercially solidified, has been solidified in the laboratory using OPC and PFA (pulverized fly ash) in a variety of mix proportions. The solidified products have been subjected to calorimetric, physical and microstructural analysis. The heat of hydration for OPC/waste mixes showed that a progressive poisoning of normal hydration reactions occurred with increasing waste addition. Once poisoned OPC failed to act as a cement and was substituted by PFA and other products in this role. Strength development was found to be related to the heat of hydration; this suggests that conduction calorimetry could be usedmore » to determine the suitability of a particular waste for OPC based solidification.« less

APPLICATIONS ANALYSIS REPORT: CHEMFIX TECHNOLOGIES, INC. - SOLIDIFICATION/STABILIZATION PROCESS

EPA Science Inventory

In support of the U.S. Environmental Protection Agency's (EPA) Superfund Innovative Technology Evaluation (SITE) Program, this report evaluates the Chemfix Technologies, Inc. (Chemfix), solidification/stabilization technology for on-site treatment of hazardous waste. The Chemfix ...

DEMONSTRATION BULLETIN - SOLIDIFICATION/ STABILIZATION PROCESS, SOLIDTECH, INC.

EPA Science Inventory

The Soliditech solidification/stabilization technology mixes hazardous waste materials in soils or sludges with pozzolanic material (cement, fly ash, or kiln dust), a proprietary additive called Urrichem, other proprietary additives, and water. The process is designed to aid ...

An alternative method for the treatment of waste produced at a dye and a metal-plating industry using natural and/or waste materials.

PubMed

Fatta, Despo; Papadopoulos, Achilleas; Stefanakis, Nikos; Loizidou, Maria; Savvides, Chrysanthos

2004-08-01

The aim of this study was to develop cost-effective, appropriate solidification technologies for treating hazardous industrial wastes that are currently disposed of in ways that may threaten the quality of local groundwater. One major objective was to use materials other than cement, and preferably materials that are themselves wastes, as the solidification additives, namely using wastes to treat wastes or locally available natural material. This research examines the cement-based and lime-based stabilization/solidification (S/S) techniques applied for waste generated at a metal-plating industry and a dye industry. For the lime-based S/S process the following binder mixtures were used: cement kiln dust/ lime, bentonite/lime and gypsum/lime. For the cement-based S/S process three binder mixtures were used: cement kiln dust/cement, bentonite/cement and gypsum/cement. The leachability of the wastes was evaluated using the toxicity characteristic leaching procedure. The applicability and optimum weight ratio of the binder mixtures were estimated using the unconfined compressive strength test. The optimum ratio mixtures were mixed with waste samples in different ratios and cured for 28 days in order to find the S/S products with the highest strength and lowest leachability at the same time. The results of this work showed that the cement-and lime-based S/S process, using cement kiln dust and bentonite as additives can be effectively used in order to treat industrial waste.

Analysis and calculation of macrosegregation in a casting ingot, exhibits C and E

NASA Technical Reports Server (NTRS)

Poirier, D. R.; Maples, A. L.

1984-01-01

A computer model which describes the solidification of a binary metal alloy in an insulated rectangular mold with a temperature gradient is presented. A numerical technique, applicable to a broad class of moving boundary problems, was implemented therein. The solidification model described is used to calculate the macrosegregation within the solidified casting by coupling the equations for liquid flow in the solid/liquid or mushy zone with the energy equation for heat flow throughout the ingot and thermal convection in the bulk liquid portion. The rate of development of the solid can be automatically calculated by the model. Numerical analysis of such solidification parameters as enthalpy and boundary layer flow is displayed. On-line user interface and software documentation are presented.

The influence of buoyant forces and volume fraction of particles on the particle pushing/entrapment transition during directional solidification of Al/SiC and Al/graphite composites

NASA Technical Reports Server (NTRS)

Stefanescu, Doru M.; Moitra, Avijit; Kacar, A. Sedat; Dhindaw, Brij K.

1990-01-01

Directional solidification experiments in a Bridgman-type furnace were used to study particle behavior at the liquid/solid interface in aluminum metal matrix composites. Graphite or silicon-carbide particles were first dispersed in aluminum-base alloys via a mechanically stirred vortex. Then, 100-mm-diameter and 120-mm-long samples were cast in steel dies and used for directional solidification. The processing variables controlled were the direction and velocity of solidification and the temperature gradient at the interface. The material variables monitored were the interface energy, the liquid/particle density difference, the particle/liquid thermal conductivity ratio, and the volume fraction of particles. These properties were changed by selecting combinations of particles (graphite or silicon carbide) and alloys (Al-Cu, Al-Mg, Al-Ni). A model which consideres process thermodynamics, process kinetics (including the role of buoyant forces), and thermophysical properties was developed. Based on solidification direction and velocity, and on materials properties, four types of behavior were predicted. Sessile drop experiments were also used to determine some of the interface energies required in calculation with the proposed model. Experimental results compared favorably with model predictions.

The influence of buoyant forces and volume fraction of particles on the particle pushing/entrapment transition during directional solidification of Al/SiC and Al/graphite composites

NASA Astrophysics Data System (ADS)

Stefanescu, Doru M.; Moitra, Avijit; Kacar, A. Sedat; Dhindaw, Brij K.

1990-01-01

Directional solidification experiments in a Bridgman-type furnace were used to study particle behavior at the liquid/solid interface in aluminum metal matrix composites. Graphite or siliconcarbide particles were first dispersed in aluminum-base alloys via a mechanically stirred vortex. Then, 100-mm-diameter and 120-mm-long samples were cast in steel dies and used for directional solidification. The processing variables controlled were the direction and velocity of solidification and the temperature gradient at the interface. The material variables monitored were the interface energy, the liquid/particle density difference, the particle/liquid thermal conductivity ratio, and the volume fraction of particles. These properties were changed by selecting combinations of particles (graphite or silicon carbide) and alloys (Al-Cu, Al-Mg, Al-Ni). A model which considers process thermodynamics, process kinetics (including the role of buoyant forces), and thermophysical properties was developed. Based on solidification direction and velocity, and on materials properties, four types of behavior were predicted. Sessile drop experiments were also used to determine some of the interface energies required in calculation with the proposed model. Experimental results compared favorably with model predictions.

Coupled Growth in Hypermonotectics

NASA Technical Reports Server (NTRS)

Andrews, J. Barry; Coriell, Sam R.

2001-01-01

The overall objective of this project is to obtain a fundamental understanding of the physics controlling solidification processes in immiscible alloy systems. The investigation involves both experimentation and the development of a model describing solidification in monotectic systems. The experimental segment was designed to first demonstrate that it is possible to obtain interface stability and steady state coupled growth in hypermonotectic alloys through microgravity processing. Microgravity results obtained to date have verified this possibility. Future flights will permit experimental determination of the limits of interface stability and the influence of alloy composition and growth rate on microstructure. The objectives of the modeling segment of the investigation include prediction of the limits of interface stability, modeling of convective flow due to residual acceleration, and the influence of surface tension driven flows at the solidification interface. The study of solidification processes in immiscible alloy systems is hindered by the inherent convective flow that occurs on Earth and by the possibility of sedimentation of the higher density immiscible liquid phase. It has been shown that processing using a high thermal gradient and a low growth rate can lead to a stable macroscopically planar growth front even in hypermonotectic alloys. Processing under these growth conditions can avoid constitutional supercooling and prevent the formation of the minor immiscible liquid phase in advance of the solidification front. However, the solute depleted boundary layer that forms in advance of the solidification front is almost always less dense than the liquid away from the solidification front. As a result, convective instability is expected. Ground based testing has indicated that convection is a major problem in these alloy systems and leads to gross compositional variations along the sample and difficulties maintaining interface stability. Sustained low gravity processing conditions are necessary in order to minimize these problems and obtain solidification conditions which approach steady state.

Technology Demonstration Summary Site Program Demonstration Test Soliditech Inc Solidification-stabilization Process

EPA Science Inventory

The major objective of the Soliditech, Inc., SITE demonstration was to develop reliable performance and cost information about the Soliditech solidification, stabilization technology. The Soliditech process mixes hazardous waste materials with Portland cement or pozzolanic m...

STABILIZATION/SOLIDIFICATION OF CERCLA AND RCRA WASTES

EPA Science Inventory

This Handbook provides U.S. EPA regional staff responsible for reviewing CERCLA remedial action plans and RCRA permit applications with a tool for interpreting information on stabilization/solidification treatment. As a practical day-to-day reference guide, it will also provide t...

SOLIDIFICATION/STABILIZATION: IS IT ALWAYS APPROPRIATE?

EPA Science Inventory

The findings of recent research and evaluation efforts are assessed to determine whether solidification/stabilization (S/S) has been properly and appropriately applied for different types of hazardous wastes. Results from these studies are mixed and, as a result, the need for pro...

SUMMARY OF SOLIDIFICATION/STABILIZATION SITE DEMONSTRATIONS AT UNCONTROLLED HAZARDOUS WASTE SITES

EPA Science Inventory

Four large-scale solidification/stabilization demonstrations have occurred under EPA's SITE program. In general, physical testing results have been acceptable. Reduction in metal leachability, as determined by the TCLP test, has been observed. Reduction in organic leachability ha...

Effective solidification/stabilisation of mercury-contaminated wastes using zeolites and chemically bonded phosphate ceramics.

PubMed

Zhang, Shaoqing; Zhang, Xinyan; Xiong, Ya; Wang, Guoping; Zheng, Na

2015-02-01

In this study, two kinds of zeolites materials (natural zeolite and thiol-functionalised zeolite) were added to the chemically bonded phosphate ceramic processes to treat mercury-contaminated wastes. Strong promotion effects of zeolites (natural zeolite and thiol-functionalised zeolite) on the stability of mercury in the wastes were obtained and these technologies showed promising advantages toward the traditional Portland cement process, i.e. using Portland cement as a solidification agent and natural or thiol-functionalised zeolite as a stabilisation agent. Not only is a high stabilisation efficiency (lowered the Toxicity Characteristic Leaching Procedure Hg by above 10%) obtained, but also a lower dosage of solidification (for thiol-functionalised zeolite as stabilisation agent, 0.5 g g(-1) and 0.7 g g(-1) for chemically bonded phosphate ceramic and Portland cement, respectively) and stabilisation agents (for natural zeolite as stabilisation agent, 0.35 g g(-1) and 0.4 g g(-1) for chemically bonded phosphate ceramic and Portland cement, respectively) were used compared with the Portland cement process. Treated by thiol-functionalised zeolite and chemically bonded phosphate ceramic under optimum parameters, the waste containing 1500 mg Hg kg(-1) passed the Toxicity Characteristic Leaching Procedure test. Moreover, stabilisation/solidification technology using natural zeolite and chemically bonded phosphate ceramic also passed the Toxicity Characteristic Leaching Procedure test (the mercury waste containing 625 mg Hg kg(-1)). Moreover, the presence of chloride and phosphate did not have a negative effect on the chemically bonded phosphate ceramic/thiol-functionalised zeolite treatment process; thus, showing potential for future application in treatment of 'difficult-to-manage' mercury-contaminated wastes or landfill disposal with high phosphate and chloride content. © The Author(s) 2015.

Microgravity

NASA Image and Video Library

1987-12-17

The MEPHISTO experiment is a cooperative American and French investigation of the fundamentals of crystal growth. MEPHISTO is a French-designed and built materials processing furnace. MEPHISTO experiments study solidation (also called freezing) during the growth cycle of liquid materials used for semiconductor crystals. Solidification is the process where materials change from liquid (melt) to solid. An example of the solidification process is water changing into ice.

Numerical Simulation of Transient Liquid Phase Bonding under Temperature Gradient

NASA Astrophysics Data System (ADS)

Ghobadi Bigvand, Arian

Transient Liquid Phase bonding under Temperature Gradient (TG-TLP bonding) is a relatively new process of TLP diffusion bonding family for joining difficult-to-weld aerospace materials. Earlier studies have suggested that in contrast to the conventional TLP bonding process, liquid state diffusion drives joint solidification in TG-TLP bonding process. In the present work, a mass conservative numerical model that considers asymmetry in joint solidification is developed using finite element method to properly study the TG-TLP bonding process. The numerical results, which are experimentally verified, show that unlike what has been previously reported, solid state diffusion plays a major role in controlling the solidification behavior during TG-TLP bonding process. The newly developed model provides a vital tool for further elucidation of the TG-TLP bonding process.

Time-Resolved In Situ Measurements During Rapid Alloy Solidification: Experimental Insight for Additive Manufacturing

NASA Astrophysics Data System (ADS)

McKeown, Joseph T.; Zweiacker, Kai; Liu, Can; Coughlin, Daniel R.; Clarke, Amy J.; Baldwin, J. Kevin; Gibbs, John W.; Roehling, John D.; Imhoff, Seth D.; Gibbs, Paul J.; Tourret, Damien; Wiezorek, Jörg M. K.; Campbell, Geoffrey H.

2016-03-01

Additive manufacturing (AM) of metals and alloys is becoming a pervasive technology in both research and industrial environments, though significant challenges remain before widespread implementation of AM can be realized. In situ investigations of rapid alloy solidification with high spatial and temporal resolutions can provide unique experimental insight into microstructure evolution and kinetics that are relevant for AM processing. Hypoeutectic thin-film Al-Cu and Al-Si alloys were investigated using dynamic transmission electron microscopy to monitor pulsed-laser-induced rapid solidification across microsecond timescales. Solid-liquid interface velocities measured from time-resolved images revealed accelerating solidification fronts in both alloys. The observed microstructure evolution, solidification product, and presence of a morphological instability at the solid-liquid interface in the Al-4 at.%Cu alloy are related to the measured interface velocities and small differences in composition that affect the thermophysical properties of the alloys. These time-resolved in situ measurements can inform and validate predictive modeling efforts for AM.

Time-Resolved In Situ Measurements During Rapid Alloy Solidification: Experimental Insight for Additive Manufacturing

DOE PAGES

McKeown, Joseph T.; Zweiacker, Kai; Liu, Can; ...

2016-01-27

In research and industrial environments, additive manufacturing (AM) of metals and alloys is becoming a pervasive technology, though significant challenges remain before widespread implementation of AM can be realized. In situ investigations of rapid alloy solidification with high spatial and temporal resolutions can provide unique experimental insight into microstructure evolution and kinetics that are relevant for AM processing. Hypoeutectic thin-film Al–Cu and Al–Si alloys were investigated using dynamic transmission electron microscopy to monitor pulsed-laser-induced rapid solidification across microsecond timescales. Solid–liquid interface velocities measured from time-resolved images revealed accelerating solidification fronts in both alloys. We observed microstructure evolution, solidification product, andmore » presence of a morphological instability at the solid–liquid interface in the Al–4 at.%Cu alloy are related to the measured interface velocities and small differences in composition that affect the thermophysical properties of the alloys. These time-resolved in situ measurements can inform and validate predictive modeling efforts for AM.« less

Solid-liquid and liquid-solid transitions in metal nanoparticles.

PubMed

Hou, M

2017-02-22

The melting and solidification temperatures of nanosystems may differ by several hundred Kelvin. To understand the origin of this difference, transitions in small metallic nanoparticles on the atomic scale were analyzed using molecular dynamics (MD). Palladium was used as a case study, which was then extended to a range of other elemental metals. It was argued that in realistic environments, such as gases at low pressure (of the order of 1 mbar), heat transfers allow the microcanonical thermal equilibrium evolution of the nanoparticles between successive collisions with gas atoms. This is shown to have no significant influence on the mechanism of melting, whereas in an isolated nanoparticle, solidification triggers a huge and rapid increase in temperature. A simple relationship between the melting and solidification temperatures was found, indicating that the magnitude of the latent heat of melting governs undercooling. Whereas melting occurs via heterogeneous nucleation, solidification displays characteristics of spinodal decomposition. Consistently, the melting temperature scales with the surface-to-volume ratio, whereas the solidification temperature displays no significant dependence on the particle size.

SILICATE TECHNOLOGY CORPORATION'S SOLIDIFICATION/ STABILIZATION TECHNOLOGY FOR ORGANIC AND INORGANIC CONTAMINANTS IN SOILS - APPLICATIONS ANALYSIS REPORT

EPA Science Inventory

This Applications Analysis Report evaluates the solidification/stabilization treatment process of Silicate Technology Corporation (STC) for the on-site treatment of hazardous waste. The STC immobilization technology utilizes a proprietary product (FMS Silicate) to chemically stab...

Hazcon Solidification Process, Douglassville, Pa.: Applications Analysis Report

EPA Science Inventory

This document is an evaluation of the HAZCON solidification technology and its applicability as an on-site treatment method for waste site cleanup. A Demonstration was held at the Douglassville, Pennsylvania Superfund site in the fall of 1987. Operational data and sampling and an...

Solidification characteristics and segregation behavior of a P-containing Ni-Fe-Cr-based alloy

NASA Astrophysics Data System (ADS)

Wang, Changshuai; Su, Haijun; Guo, YongAn; Guo, Jianting; Zhou, Lanzhang

2017-09-01

Solidification characteristics and segregation behavior of a P-containing Ni-Fe-Cr-based alloy, considered as boiler and turbine materials in 700 °C advanced ultra-supercritical coal-fired power plants, have been investigated by differential thermal analysis and directional solidification quenching technique. Results reveal that P decreases the solidus temperature, but only has negligible influence on liquidus temperature. After P was added, the solidification sequence has no apparent change, but the width of the mushy zone increases and dendritic structures become coarser. Moreover, P increases the amount and changes the morphology of MC carbide. Energy-dispersive spectroscopy analysis reveals that P has obvious influence on the segregation behavior of the constitute elements with equilibrium partition coefficients (ki) far away from unity, whereas has negligible effect on the constituent elements with ki close to unity and has more influence on the final stage of solidification than at early stage. The distribution profiles reveal that P atoms pile up ahead of the solid/liquid (S/L) interface and strongly segregate to the interdendritic liquid region. The influence of P on solidification characteristics and segregation behavior of Ni-Fe-Cr-based alloy could be attributed to the accumulation of P ahead of the S/L interface during solidification.

Westinghouse Cementation Facility of Solid Waste Treatment System - 13503

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobs, Torsten; Aign, Joerg

2013-07-01

During NPP operation, several waste streams are generated, caused by different technical and physical processes. Besides others, liquid waste represents one of the major types of waste. Depending on national regulation for storage and disposal of radioactive waste, solidification can be one specific requirement. To accommodate the global request for waste treatment systems Westinghouse developed several specific treatment processes for the different types of waste. In the period of 2006 to 2008 Westinghouse awarded several contracts for the design and delivery of waste treatment systems related to the latest CPR-1000 nuclear power plants. One of these contracts contains the deliverymore » of four Cementation Facilities for waste treatment, s.c. 'Follow on Cementations' dedicated to three locations, HongYanHe, NingDe and YangJiang, of new CPR-1000 nuclear power stations in the People's Republic of China. Previously, Westinghouse delivered a similar cementation facility to the CPR-1000 plant LingAo II, in Daya Bay, PR China. This plant already passed the hot functioning tests successfully in June 2012 and is now ready and released for regular operation. The 'Follow on plants' are designed to package three 'typical' kind of radioactive waste: evaporator concentrates, spent resins and filter cartridges. The purpose of this paper is to provide an overview on the Westinghouse experience to design and execution of cementation facilities. (authors)« less

Segregation and convection in dendritic alloys

NASA Technical Reports Server (NTRS)

Poirier, D. R.

1990-01-01

Microsegregation in dentritic alloys is discussed, including solidification with and without thermal gradient, the convection of interdendritic liquid. The conservation of momentum, energy, and solute is considered. Directional solidification and thermosolutal convection are discussed.

Solidification Microstructure, Segregation, and Shrinkage of Fe-Mn-C Twinning-Induced Plasticity Steel by Simulation and Experiment

NASA Astrophysics Data System (ADS)

Lan, Peng; Tang, Haiyan; Zhang, Jiaquan

2016-06-01

A 3D cellular automaton finite element model with full coupling of heat, flow, and solute transfer incorporating solidification grain nucleation and growth was developed for a multicomponent system. The predicted solidification process, shrinkage porosity, macrosegregation, grain orientation, and microstructure evolution of Fe-22Mn-0.7C twinning-induced plasticity (TWIP) steel match well with the experimental observation and measurement. Based on a new solute microsegregation model using the finite difference method, the thermophysical parameters including solid fraction, thermal conductivity, density, and enthalpy were predicted and compared with the results from thermodynamics and experiment. The effects of flow and solute transfer in the liquid phase on the solidification microstructure of Fe-22Mn-0.7C TWIP steel were compared numerically. Thermal convection decreases the temperature gradient in the liquid steel, leading to the enlargement of the equiaxed zone. Solute enrichment in front of the solid/liquid interface weakens the thermal convection, resulting in a little postponement of columnar-to-equiaxed transition (CET). The CET behavior of Fe-Mn-C TWIP steel during solidification was fully described and mathematically quantized by grain morphology statistics for the first time. A new methodology to figure out the CET location by linear regression of grain mean size with least-squares arithmetic was established, by which a composition design strategy for Fe-Mn-C TWIP steel according to solidification microstructure, matrix compactness, and homogeneity was developed.

A Three-Stage Mechanistic Model for Solidification Cracking During Welding of Steel

NASA Astrophysics Data System (ADS)

Aucott, L.; Huang, D.; Dong, H. B.; Wen, S. W.; Marsden, J.; Rack, A.; Cocks, A. C. F.

2018-03-01

A three-stage mechanistic model for solidification cracking during TIG welding of steel is proposed from in situ synchrotron X-ray imaging of solidification cracking and subsequent analysis of fracture surfaces. Stage 1—Nucleation of inter-granular hot cracks: cracks nucleate inter-granularly in sub-surface where maximum volumetric strain is localized and volume fraction of liquid is less than 0.1; the crack nuclei occur at solute-enriched liquid pockets which remain trapped in increasingly impermeable semi-solid skeleton. Stage 2—Coalescence of cracks via inter-granular fracture: as the applied strain increases, cracks coalesce through inter-granular fracture; the coalescence path is preferential to the direction of the heat source and propagates through the grain boundaries to solidifying dendrites. Stage 3—Propagation through inter-dendritic hot tearing: inter-dendritic hot tearing occurs along the boundaries between solidifying columnar dendrites with higher liquid fraction. It is recommended that future solidification cracking criterion shall be based on the application of multiphase mechanics and fracture mechanics to the failure of semi-solid materials.

Numerical study of coupled turbulent flow and solidification for steel slab casters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aboutalebi, M.R.; Hasan, M.; Guthrie, R.I.L.

1995-09-01

A two-dimensional numerical modeling study was undertaken to account for coupled turbulent flow and heat transfer with solidification in the mold and submold regions of a steel slab coaster. Liquid steel is introduced into a water-cooled mold through a bifurcated submerged entry nozzle. Turbulence phenomena in the melt pool of the caster were accounted for, using a modified version of the low-Reynolds-number {kappa}-{epsilon} turbulence model of Launder and Sharma. The mushy region solidification, in the presence of turbulence, was taken into account by modifying the standard enthalpy-porosity technique, which is presently popular for modeling solidification problems. Thermocapillary and buoyancy effectsmore » have been considered in this model to evaluate the influences of the liquid surface tension gradient at the meniscus surface, and natural convection on flow patterns in the liquid pool. Parametric studies were carried out to evaluate the effects of typical variables, such as inlet superheat and casting speed, on the fluid flow and heat transfer results. The numerical predictions were compared with available experimental data.« less

Behavior of ceramic particles at the solid-liquid metal interface in metal matrix composites

NASA Technical Reports Server (NTRS)

Stefanescu, D. M.; Dhindaw, B. K.; Kacar, S. A.; Moitra, A.

1988-01-01

Directional solidification results were obtained in order to investigate particle behavior at the solid-liquid interface in Al-2 pct Mg (cellular interface) and Al-6.1 pct Ni (eutectic interface) alloys. It is found that particles can be entrapped in the solid if adequate solidification rates and temperature gradients are used. Model results showed critical velocity values slightly higher than those obtained experimentally.

Method for formation of subsurface barriers using viscous colloids

DOEpatents

Apps, J.A.; Persoff, P.; Moridis, G.; Pruess, K.

1998-11-17

A method is described for formation of subsurface barriers using viscous liquids where a viscous liquid solidifies at a controlled rate after injection into soil and forms impermeable isolation of the material enclosed within the subsurface barriers. The viscous liquid is selected from the group consisting of polybutenes, polysiloxanes, colloidal silica and modified colloidal silica of which solidification is controlled by gelling, cooling or cross-linking. Solidification timing is controlled by dilution, addition of brines, coating with alumina, stabilization with various agents and by temperature. 17 figs.

EPA SITE DEMONSTRATION OF THE INTERNATIONAL WASTE TECHNOLOGIES/GEO-CON IN SITU STABILIZATION/ SOLIDIFICATION PROCESS

EPA Science Inventory

This paper presents an EPA evaluation of the first field demonstration of an in situ stabilization/solidification process for contaminated soil under the EPA Superfund Innovative Technology Evaluation (SITE) program. Demonstration of this process was a joint effort of two vendors...

Treatment of waste printed wire boards in electronic waste for safe disposal.

PubMed

Niu, Xiaojun; Li, Yadong

2007-07-16

The printed wire boards (PWBs) in electronic waste (E-waste) have been found to contain large amounts of toxic substances. Studies have concluded that the waste PWBs are hazardous wastes because they fails the toxicity characteristic leaching procedure (TCLP) test with high level of lead (Pb) leaching out. In this study, two treatment methods - high-pressure compaction and cement solidification - were explored for rendering the PWBs into non-hazardous forms so that they may be safely disposed or used. The high-pressure compaction method could turn the PWBs into high-density compacts with significant volume reduction, but the impact resistance of the compacts was too low to keep them intact in the environment for a long run. In contrast, the cement solidification could turn the PWBs into strong monoliths with high impact resistance and relatively high compressive strength. The leaching of the toxic heavy metal Pb from the solidified samples was evaluated by both a dynamic leaching test and the TCLP test. The dynamic leaching results revealed that Pb could be effectively confined in the solidified products under very harsh environmental conditions. The TCLP test results showed that the leaching level of Pb was far below the regulatory level of 5mg/L, suggesting that the solidified PWBs are no longer hazardous. It was concluded that the cement solidification is an effective way to render the waste PWBs into environmentally benign forms so that they can be disposed of as ordinary solid wastes or beneficially used in the place of concrete in some applications.

Overview of waste stabilization with cement.

PubMed

Batchelor, B

2006-01-01

Cement can treat a variety of wastes by improving physical characteristics (solidification) and reducing the toxicity and mobility of contaminants (stabilization). Potentially adverse waste-binder interactions are an important consideration because they can limit solidification. Stabilization occurs when a contaminant is converted from the dissolved (mobile) phase to a solid (immobile) phase by reactions, such as precipitation, sorption, or substitution. These reactions are often strongly affected by pH, so the presence of components of the waste that control pH are critical to stabilization reactions. Evaluating environmental impacts can be accomplished in a tiered strategy in which simplest approach would be to measure the maximum amount of contaminant that could be released. Alternatively, the sequence of release can be determined, either by microcosm tests that attempt to simulate conditions in the disposal zone or by mechanistic models that attempt to predict behavior using fundamental characteristics of the treated waste.

A comparison of acoustic levitation with microgravity processing for containerless solidification of ternary Al-Cu-Sn alloy

NASA Astrophysics Data System (ADS)

Yan, N.; Hong, Z. Y.; Geng, D. L.; Wei, B.

2015-07-01

The containerless rapid solidification of liquid ternary Al-5 %Cu-65 %Sn immiscible alloy was accomplished at both ultrasonic levitation and free fall conditions. A maximum undercooling of 185 K (0.22 T L) was obtained for the ultrasonically levitated alloy melt at a cooling rate of about 122 K s-1. Meanwhile, the cooling rate of alloy droplets in drop tube varied from 102 to 104 K s-1. The macrosegregation was effectively suppressed through the complex melt flow under ultrasonic levitation condition. In contrast, macrosegregation became conspicuous and core-shell structures with different layers were formed during free fall. The microstructure formation mechanisms during rapid solidification at containerless states were investigated in comparison with the conventional static solidification process. It was found that the liquid phase separation and structural growth kinetics may be modulated by controlling both alloy undercooling and cooling rate.

Microstructure and property of directionally solidified Ni-Si hypereutectic alloy

NASA Astrophysics Data System (ADS)

Cui, Chunjuan; Tian, Lulu; Zhang, Jun; Yu, Shengnan; Liu, Lin; Fu, Hengzhi

2016-03-01

This paper investigates the influence of the solidification rate on the microstructure, solid/liquid interface, and micro-hardness of the directionally solidified Ni-Si hypereutectic alloy. Microstructure of the Ni-Si hypereutectic alloy is refined with the increase of the solidification rate. The Ni-Si hypereutectic composite is mainly composed of α-Ni matrix, Ni-Ni3Si eutectic phase, and metastable Ni31Si12 phase. The solid/liquid interface always keeps planar interface no matter how high the solidification rate is increased. This is proved by the calculation in terms of M-S interface stability criterion. Moreover, the Ni-Si hypereutectic composites present higher micro-hardness as compared with that of the pure Ni3Si compound. This is caused by the formation of the metastable Ni31Si12 phase and NiSi phase during the directional solidification process.

Chernobyl NPP: Completion of LRW Treatment Plant and LRW Management on Site - 12568

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fedorov, Denis; Adamovich, Dmitry; Klimenko, I.

2012-07-01

Since a beginning of ChNPP operation, and after a tragedy in 1986, a few thousands m3 of LRW have been collected in a storage tanks. In 2004 ChNPP started the new project on creation of LRW treatment plant (LRWTP) financed from EBRD fund. But it was stopped in 2008 because of financial and contract problems. In 2010 SIA RADON jointly with Ukrainian partners has won a tender on completion of LRWTP, in particular I and C system. The purpose of LRTP is to process liquid rad-wastes from SSE 'Chernobyl NPP' site and those liquids stored in the LRWS and SLRWSmore » tanks as well as the would-be wastes after ChNPP Power Units 1, 2 and 3 decommissioning. The LRTP design lifetime - 20 years. Currently, the LRTP is getting ready to perform the following activities: 1. retrieval of waste from tanks stored at ChNPP LWS using waste retrieval system with existing equipment involved; 2. transfer of retrieved waste into LRTP reception tanks with partial use of existing transfer pipelines; 3. laboratory chemical and radiochemical analysis of reception tanks contest to define the full spectrum of characteristics before processing, to acknowledge the necessity of preliminary processing and to select end product recipe; 4. preliminary processing of the waste to meet the requirements for further stages of the process; 5. shrinkage (concentrating) of preliminary processed waste; 6. solidification of preliminary processed waste with concrete to make a solid-state (end product) and load of concrete compound into 200-l drums; 7. curing of end product drums in LRTP curing hall; 8. radiologic monitoring of end product drums and their loading into special overpacks; 9. overpack radiological monitoring; 10. send for disposal (ICSRM Lot 3); The current technical decisions allow to control and return to ChNPP of process media and supporting systems outputs until they satisfy the following quality norms: salt content: < 100 g/l; pH: 1 - 11; anionic surface-active agent: < 25 mg/l; oil dissipated in the liquid: < 2 mg/l; overall gamma-activity: < 3,7 x10{sup 5} Bq/l. (authors)« less

Real-Time X-Ray Microscopy of Al-Cu Eutectic Solidification

NASA Technical Reports Server (NTRS)

Kaukler, William F.; Curreri, Peter A.; Sen, Subhayu

1998-01-01

Recent improvements in the resolution of the X-ray Transmission Microscope (XTM) for Solidification Studies provide microstructure feature detectability down to 5 micrometers during solidification. This presentation will show the recent results from observations made in real-time of the solid-liquid interfacial morphologies of the Al-CuAI2 eutectic alloy. Lamellar dimensions and spacings, transitions of morphology caused by growth rate changes, and eutectic grain structures are open to measurements. A unique vantage point viewing the face of the interface isotherm is possible for the first time with the XTM due to its infinite depth of field. A video of the solid-liquid interfaces seen in-situ and in real-time will be shown.

Bubble Induced Disruption of a Planar Solid-Liquid Interface During Controlled Directional Solidification in a Microgravity Environment

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Brush, Lucien N.; Anilkumar, Amrutur V.

2013-01-01

Pore Formation and Mobility Investigation (PFMI) experiments were conducted in the microgravity environment aboard the International Space Station with the intent of better understanding the role entrained porosity/bubbles play during controlled directional solidification. The planar interface in a slowing growing succinonitrile - 0.24 wt% water alloy was being observed when a nitrogen bubble traversed the mushy zone and remained at the solid-liquid interface. Breakdown of the interface to shallow cells subsequently occurred, and was later evaluated using down-linked data from a nearby thermocouple. These results and other detrimental effects due to the presence of bubbles during solidification processing in a microgravity environment are presented and discussed.

The Solidification Velocity of Undercooled Nickel and Titanium Alloys with Dilute Solute

NASA Technical Reports Server (NTRS)

Algoso, Paul R.; Altgilbers, A. S.; Hofmeister, William H.; Bayuzick, Robert J.

2003-01-01

The study of solidification velocity is important for two reasons. First, understanding the manner in which the degree of undercooling of the liquid and solidification velocity affect the microstructure of the solid is fundamental. Second, there is disagreement between theoretical predictions of the relationship between undercooling and solidification velocity and experimental results. Thus, the objective of this research is to accurately and systematically quantify the solidification velocity as a function of undercooling for dilute nickel-and titanium-based alloys. The alloys chosen for study cover a wide range of equilibrium partition coefficients, and the results are compared to current theory.

Overview of the Tusas Code for Simulation of Dendritic Solidification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trainer, Amelia J.; Newman, Christopher Kyle; Francois, Marianne M.

2016-01-07

The aim of this project is to conduct a parametric investigation into the modeling of two dimensional dendrite solidification, using the phase field model. Specifically, we use the Tusas code, which is for coupled heat and phase-field simulation of dendritic solidification. Dendritic solidification, which may occur in the presence of an unstable solidification interface, results in treelike microstructures that often grow perpendicular to the rest of the growth front. The interface may become unstable if the enthalpy of the solid material is less than that of the liquid material, or if the solute is less soluble in solid than itmore » is in liquid, potentially causing a partition [1]. A key motivation behind this research is that a broadened understanding of phase-field formulation and microstructural developments can be utilized for macroscopic simulations of phase change. This may be directly implemented as a part of the Telluride project at Los Alamos National Laboratory (LANL), through which a computational additive manufacturing simulation tool is being developed, ultimately to become part of the Advanced Simulation and Computing Program within the U.S. Department of Energy [2].« less

The solidification of Al–Pd–Mn studied by high-energy X-ray diffraction from electrostatically levitated samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quirinale, Dante G.

Here, we report on the results of a high-energy x-ray diffraction study of Al–Pd–Mn to investigate the solidification products obtained during free-cooling using an electrostatic levitation furnace. The primary solidification product from the melt is i-Al–Pd–Mn which coexists with a significant remaining liquid component. As the sample cools further, we find that the solidification pathway is consistent with the liquidus projection and pseudo-binary cut through the ternary phase diagram reported previously. At ambient temperature we have identified the major phase to be the ξ'-phase orthorhombic approximant, along with minor phases identified as Al and, most likely, the R-phase orthorhombic approximant.more » We have also observed a distinct prepeak in the liquid at high temperature, signifying the presence of extended atomic order. Interestingly, this prepeak was not observed in previous neutron diffraction measurements on the Al–Pd–Mn system. No undercooling was observed preceding the solidification of the i-Al–Pd–Mn phase from the melt which may signal the close similarity of the short-range order in the solid and liquid. However, this can not be clearly determined because of the potential for heterogenous nucleation associated with the presence of an Al2O3 impurity at the surface of the sample.« less

Low gravity containerless processing of immiscible gold rhodium alloys

NASA Technical Reports Server (NTRS)

Andrews, J. Barry

1986-01-01

Under normal one-g conditions immiscible alloys segregate extensively during solidification due to sedementation of the more dense of the immiscible liquid phases. However, under low-g conditions it should be possible to form a dispersion of the two immiscible liquids and maintain this dispersed structure during solidification. Immiscible (hypermonotectic) gold-rhodium alloys were processed in the Marshall Space Flight Center 105 meter drop tube in order to investigate the influence of low gravity, containerless solidification on their microstructure. Hypermonotectic alloys composed of 65 atomic % rhodium exhibited a tendency for the gold rich liquid to wet the outer surface of the containerless processed samples. This tendency led to extensive segregation in several cases. However, well dispersed microstructures consisting of 2 to 3 micron diameter rhodium-rich spheres in a gold-rich matrix were produced in 23.4 atomic % rhodium alloys. This is one of the best dispersions obtained in research on immiscible alloy-systems to data.

Project Description and Publications List for UAH CMMR

NASA Technical Reports Server (NTRS)

Kaukler, William F.

1999-01-01

This research combines a state of the art X-ray Transmission Microscope, XTM, with a specially designed x-ray transparent horizontal Bridgman furnace to image (with resolutions up to 3 micrometers) the solidification of metal alloys in real-time. The objective is to obtain real-time dynamic data to provide direct measure of the solute profile in the liquid, phase coalescence and growth in the liquid, and the detailed interface morphology (e,g., dendrites and cells) during solidification. We are also enhancing the XTM data with precise solid-liquid interfacial temperature and the thermal gradient measurement techniques, and working on the application of this technology to the study of the fundamentals of solidification in microgravity. Over the last several years we have successfully imaged in real-time: interfacial-morphologies, phase growth, coalescence, incorporation of phases into the growing interface, and the solute boundary layer in the liquid at the solid-liquid interface. We have also measured true local growth rates and can evaluate segregation structures in the solid. Interfacial undercoolings are being measured either with a special Seebeck furnace or with micro-thermocouple arrays we are developing. These later techniques are presently being incorporated with the XTM furnace. This last year emphasized the investigation of the solute layer in the melt during solidification. Methods were developed to quantify the solute concentrations using x-ray absorption and to compare to predictions from simulations. In addition, work is being completed on a brass-board portable XTM that incorporates a vertical Bridgman furnace.

Leaching behaviour and mechanical properties of copper flotation waste in stabilized/solidified products.

PubMed

Mesci, Başak; Coruh, Semra; Ergun, Osman Nuri

2009-02-01

This research describes the investigation of a cement-based solidification/stabilization process for the safe disposal of copper flotation waste and the effect on cement properties of the addition of copper flotation waste (CW) and clinoptilolite (C). In addition to the reference mixture, 17 different mixtures were prepared using different proportions of CW and C. Physical properties such as setting time, specific surface area and compressive strength were determined and compared to a reference mixture and Turkish standards (TS). Different mixtures with the copper flotation waste portion ranging from 2.5 to 12.5% by weight of the mixture were tested for copper leachability. The results show that as cement replacement materials especially clinoptilolite had clear effects on the mechanical properties. Substitution of 5% copper flotation waste for Portland cement gave a similar strength performance to the reference mixture. Higher copper flotation waste addition such as 12.5% replacement yielded lower strength values. As a result, copper flotation waste and clinoptilolite can be used as cementitious materials, and copper flotation waste also can be safely stabilized/solidified in a cement-based solidification/stabilization system.

Solidification phenomena of binary organic mixtures

NASA Technical Reports Server (NTRS)

Chang, K.

1982-01-01

The coalescence rates and motion of liquid bubbles in binary organic mixtures were studied. Several factors such as temperature gradient, composition gradient, interfacial tension, and densities of the two phases play important roles in separation of phases of immiscible liquids. An attempt was made to study the effect of initial compositions on separation rates of well-dispersed organic mixtures at different temperatures and, ultimately, on the homogeneity of solidification of the immiscible binary organic liquids. These organic mixtures serve as models for metallic pseudo binary systems under study. Two specific systems were investigated: ethyl salicylate - diethyl glycol and succinonitrile - water.

On the hot cracking susceptibility of a semisolid aluminium 6061 weld: Application of a coupled solidification- thermomechanical model

NASA Astrophysics Data System (ADS)

Zareie Rajani, H. R.; Phillion, A. B.

2015-06-01

A coupled solidification-thermomechanical model is presented that investigates the hot tearing susceptibility of an aluminium 6061 semisolid weld. Two key phenomena are considered: excessive deformation of the semisolid weld, initiating a hot tear, and the ability of the semisolid weld to heal the hot tear by circulation of the molten metal. The model consists of two major modules: weld solidification and thermomechanical analysis. 1) By means of a multi-scale model of solidification, the microstructural evolution of the semisolid weld is simulated in 3D. The semisolid structure, which varies as a function of welding parameters, is composed of solidifying grains and a network of micro liquid channels. The weld solidification module is utilized to obtain the solidification shrinkage. The size of the micro liquid channels is used as an indicator to assess the healing ability of the semisolid weld. 2) Using the finite element method, the mechanical interaction between the weld pool and the base metal is simulated to capture the transient force field deforming the semisolid weld. Thermomechanical stresses and shrinkage stresses are both considered in the analysis; the solidification contractions are extracted from the weld solidification module and applied to the deformation simulation as boundary conditions. Such an analysis enables characterization of the potential for excessive deformation of the weld. The outputs of the model are used to study the effect of welding parameters including welding current and speed, and also welding constraint on the hot cracking susceptibility of an aluminium alloy 6061 semisolid weld.

Property measurements and solidification studies by electrostatic levitation.

PubMed

Paradis, Paul-François; Yu, Jianding; Ishikawa, Takehiko; Yoda, Shinichi

2004-11-01

The National Space Development Agency of Japan has recently developed several electrostatic levitation furnaces and implemented new techniques and procedures for property measurement, solidification studies, and atomic structure research. In addition to the contamination-free environment for undercooled and liquid metals and semiconductors, the newly developed facilities possess the unique capabilities of handling ceramics and high vapor pressure materials, reducing processing time, and imaging high luminosity samples. These are exemplified in this paper with the successful processing of BaTiO(3). This allowed measurement of the density of high temperature solid, liquid, and undercooled phases. Furthermore, the material resulting from containerless solidification consisted of micrometer-size particles and a glass-like phase exhibiting a giant dielectric constant exceeding 100,000.

When a water drop freezes before it solidifies

NASA Astrophysics Data System (ADS)

Kavehpour, Pirouz; Davis, Stephen; Tavakoli, Faryar

2012-11-01

When a drop of liquid is placed on a substrate which temperature is below the melting point of the liquid, one would expect the drop to solidify instantaneously. However, many liquids, such as water, must be subcooled to solidify below its melting temperature due to homogeneous nucleation's high activation energy. Most of the drop solidification research, particularly for water, phase change is assumed to occur at equilibrium freezing temperature; however, this is not the case. We found that after a certain degree of supercooling, a kinetic based nucleation begins and latent heat of fusion is suddenly liberated, causing an increase in liquid temperature. At the end of this stage, approximately 20% of the drop is crystallized. This phenomenon is known among metallurgists as recalescence. This is followed by a slow solidification process at the melting point. As a water droplet spreads on a cold substrate, its contact line stops just prior to freezing inception from the liquid-solid interface. In this study, we assert that recalescence prior to solidification may be the cause of water's sudden immobility, which results in a fixed contact angle and droplet diameter. In our experiments, the nucleation front initiates from the trijunction point and propagates to the drop volume.

[Recent advance in solidification/stabilization technology for the remediation of heavy metals-contaminated soil].

PubMed

Hao, Han-zhou; Chen, Tong-bin; Jin, Meng-gui; Lei, Mei; Liu, Cheng-wu; Zu, Wen-pu; Huang, Li-mi

2011-03-01

Remediation of heavy metals-contaminated soil is still a difficulty and a hotspot of international research projects. At present, the technologies commonly adopted for the remediation of contaminated sites mainly include excavation, solidification/stabilization (S/S), soil washing, soil vapor extraction (SVE), thermal treatment, and bioremediation. Based on the S/S technical guidelines of Unite State Environmental Protection Agency (EPA) and United Kingdom Environment Agency (EA) and the domestic and foreign patents, this paper introduced the concepts of S/S and its development status at home and abroad, and discussed its future development directions. Solidification refers to a process that binds contaminated media with a reagent, changing the media's physical properties via increasing its compressive strength, decreasing its permeability, and encapsulating the contaminants to form a solid material. Stabilization refers to the process that involves a chemical reaction which reduces the leachability of a waste, chemically immobilizes the waste and reduces its solubility, making the waste become less harmful or less mobile. S/S technology includes cement solidification, lime pozzolanic solidification, plastic materials stabilization, vitrification, and regent-based stabilization. Stabilization (or immobilization) treatment processes convert contaminants to less mobile forms through chemical or thermal interactions. In stabilization technology, the aim of adding agents is to change the soil physical and chemical properties through pH control technology, redox potential technology, precipitation techniques, adsorption technology, and ion-exchange technology that change the existing forms of heavy metals in soil, and thus, reduce the heavy metals bioavailability and mobility. This review also discussed the S/S evaluation methods, highlighted the need to enhance S/S technology in the molecular bonding, soil polymers, and formulation of China's S/S technical guidelines.

Flight Planning for the International Space Station - Levitation Observation of Dendrite Evolution in Steel Ternary Alloy Rapid Solidification (LODESTARS)

NASA Technical Reports Server (NTRS)

Flemings, Merton C.; Matson, Douglas M.; Hyers, Robert W.; Rogers, Jan R.

2003-01-01

During rapid solidification, a molten sample is cooled below its equilibrium solidification temperature to form a metastable liquid. Once nucleation is initiated, growth of the solid phase proceeds and can be seen as a sudden rise in temperature. The heat of fusion is rejected ahead of the growing dendrites into the undercooled liquid in a process known as recalescence. Fe-Cr-Ni alloys may form several equilibrium phases and the hypoeutectic alloys, with compositions near the commercially important 316 stainless steel alloy, are observed to solidify by way of a two-step process known as double recalescence. During double recalescence, the first temperature rise is associated with formation of the metastable ferritic solid phase with subsequent conversion to the stable austenitic phase during the second temperature rise. Selection of which phase grows into the undercooled melt during primary solidification may be accomplished by choice of the appropriate nucleation trigger material or by control of the processing parameters during rapid solidification. Due to the highly reactive nature of the molten sample material and in order to avoid contamination of the undercooled melt, a containerless electromagnetic levitation (EML) processing technique is used. In ground-based EML, the same forces that support the weight of the sample against gravity also drive convection in the liquid sample. However, in microgravity, the force required to position the sample is greatly reduced, so convection may be controlled over a wide range of internal flows. Space Shuttle experiments have shown that the double recalescence behavior of Fe-Cr-Ni alloys changes between ground and space EML experiments. This program is aimed at understanding how melt convection influences phase selection and the evolution of rapid solidification microstructures.

On the Coupling Mechanism of Equiaxed Crystal Generation with the Liquid Flow Driven by Natural Convection During Solidification

NASA Astrophysics Data System (ADS)

Stefan-Kharicha, Mihaela; Kharicha, Abdellah; Wu, Menghuai; Ludwig, Andreas

2018-02-01

The influence of the melt flow on the solidification structure is bilateral. The flow plays an important role in the solidification pattern, via the heat transfer, grain distribution, and segregations. On the other hand, the crystal structure, columnar or equiaxed, impacts the flow, via the thermosolutal convection, the drag force applied by the crystals on the melt flow, etc. As the aim of this research was to further explore the solidification-flow interaction, experiments were conducted in a cast cell (95 * 95 * 30 mm3), in which an ammonium chloride-water solution (between 27 and 31 wt pct NH4Cl) was observed as it solidified. The kinetic energy (KE) of the flow and the average flow velocity were calculated throughout the process. Measurements of the volume extension of the mush in the cell and the velocity of the solid front were also taken during the solidification experiment. During the mainly columnar experiments (8 cm liquid height) the flow KE continuously decreased over time. However, during the later series of experiments at higher liquid height (9.5 cm), the flow KE evolution presented a strong peak shortly after the start of solidification. This increase in the total flow KE correlated with the presence of falling equiaxed crystals. Generally, a clear correlation between the strength of the flow and the occurrence of equiaxed crystals was evident. The analysis of the results strongly suggests a fragmentation origin of equiaxed crystals appearing in the melt. The transition from purely columnar growth to a strongly equiaxed rain (CET) was found to be triggered by (a) the magnitude of the coupling between the flow intensity driven by the equiaxed crystals, and (b) the release and transport of the fragments by the same flow recirculating within the mushy zone.

Probes and monitors for the study of solidification of molten semiconductors

NASA Technical Reports Server (NTRS)

Sadoway, D. R.

1986-01-01

The purpose is to examine solidification in the LiCl-KCl system to determine if phenomena such as solute rejection can be obseved by laser schlieren imaging. Molten salts have attributes that make them attractive as physical models in solidification studies. With optical techniques of investigation such as schlieren imaging, it is possible to study fluid flow phenomena in molten salts and to watch the trajectory of the solid-liquid interface.

Sensitive determination of methadone in human serum and urine by dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet followed by HPLC-UV.

PubMed

Taheri, Salman; Jalali, Fahimeh; Fattahi, Nazir; Jalili, Ronak; Bahrami, Gholamreza

2015-10-01

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet was developed for the extraction of methadone and determination by high-performance liquid chromatography with UV detection. In this method, no microsyringe or fiber is required to support the organic microdrop due to the usage of an organic solvent with a low density and appropriate melting point. Furthermore, the extractant droplet can be collected easily by solidifying it at low temperature. 1-Undecanol and methanol were chosen as extraction and disperser solvents, respectively. Parameters that influence extraction efficiency, i.e. volumes of extracting and dispersing solvents, pH, and salt effect, were optimized by using response surface methodology. Under optimal conditions, enrichment factor for methadone was 134 and 160 in serum and urine samples, respectively. The limit of detection was 3.34 ng/mmL in serum and 1.67 ng/mL in urine samples. Compared with the traditional dispersive liquid-liquid microextraction, the proposed method obtained lower limit of detection. Moreover, the solidification of floating organic solvent facilitated the phase transfer. And most importantly, it avoided using high-density and toxic solvents of traditional dispersive liquid-liquid microextraction method. The proposed method was successfully applied to the determination of methadone in serum and urine samples of an addicted individual under methadone therapy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

LEACHING BOUNDARY IN CEMENT-BASED WASTE FORMS

EPA Science Inventory

Cement-based fixation systems are among the most commonly employed stabilization/solidification techniques. These cement haste mixtures, however, are vulnerable to ardic leaching solutions. Leaching of cement-based waste forms in acetic acid solutions with different acidic streng...

Microgravity

NASA Image and Video Library

1991-09-01

The Advanced Automated Directional Solidification Furnace (AADSF) flew during the USMP-2 mission. During USMP-2, the AADSF was used to study the growth of mercury cadmium telluride crystals in microgravity by directional solidification, a process commonly used on earth to process metals and grow crystals. The furnace is tubular and has three independently controlled temperature zones. The sample travels from the hot zone of the furnace (1600 degrees F) where the material solidifies as it cools. The solidification region, known as the solid/liquid interface, moves from one end of the sample to the other at a controlled rate, thus the term directional solidification.

Dynamic evolution of liquid–liquid phase separation during continuous cooling

DOE PAGES

Imhoff, Seth D.; Gibbs, Paul J.; Katz, Martha R.; ...

2015-01-06

Solidification from a multiphase fluid involves many unknown quantities due to the difficulty of predicting the impact of fluid flow on chemical partitioning. Real-time x-ray radiography was used to observe liquid-liquid phase separation in Al 90In 10 prior to solidification. Quantitative image analysis was used to measure the motion and population characteristics of the dispersed indium-rich liquid phase during cooling. Here we determine that the droplet growth characteristics resemble well known steady-state coarsening laws with likely enhancement by concurrent growth due to supersaturation. Simplistic views of droplet motion are found to be insufficient until late in the reaction due tomore » a hydrodynamic instability caused by the large density difference between the dispersed and matrix liquid phases.« less

An exact solution for the solidification of a liquid slab of binary mixture

NASA Technical Reports Server (NTRS)

Antar, B. N.; Collins, F. G.; Aumalia, A. E.

1986-01-01

The time dependent temperature and concentration profiles of a one dimensional finite slab of a binary liquid alloy is investigated during solidification. The governing equations are reduced to a set of coupled, nonlinear initial value problems using the method outlined by Meyer. Two methods will be used to solve these equations. The first method uses a Runge-Kutta-Fehlberg integrator to solve the equations numerically. The second method comprises of finding closed form solutions of the equations.

Metal Solidification Imaging Process by Magnetic Induction Tomography.

PubMed

Ma, Lu; Spagnul, Stefano; Soleimani, Manuchehr

2017-11-06

There are growing number of important applications that require a contactless method for monitoring an object surrounded inside a metallic enclosure. Imaging metal solidification is a great example for which there is no real time monitoring technique at present. This paper introduces a technique - magnetic induction tomography - for the real time in-situ imaging of the metal solidification process. Rigorous experimental verifications are presented. Firstly, a single inductive coil is placed on the top of a melting wood alloy to examine the changes of its inductance during solidification process. Secondly, an array of magnetic induction coils are designed to investigate the feasibility of a tomographic approach, i.e., when one coil is driven by an alternating current as a transmitter and a vector of phase changes are measured from the remaining of the coils as receivers. Phase changes are observed when the wood alloy state changes from liquid to solid. Thirdly, a series of static cold phantoms are created to represent various liquid/solid interfaces to verify the system performance. Finally, a powerful temporal reconstruction method is applied to realise real time in-situ visualisation of the solidification and the measurement of solidified shell thickness, a first report of its kind.

Air pollution control residues from waste incineration: current UK situation and assessment of alternative technologies.

PubMed

Rani, D Amutha; Boccaccini, A R; Deegan, D; Cheeseman, C R

2008-11-01

Current disposal options for APC residues in the UK and alternative treatment technologies developed world-wide have been reviewed. APC residues are currently landfilled in the UK where they undergo in situ solidification, although the future acceptability of this option is uncertain because the EU waste acceptance criteria (WAC) introduce strict limits on leaching that are difficult to achieve. Other APC residue treatment processes have been developed which are reported to reduce leaching to below relevant regulatory limits. The Ferrox process, the VKI process, the WES-PHix process, stabilisation/solidification using cementitious binders and a range of thermal treatment processes are reviewed. Thermal treatment technologies convert APC residues combined with other wastes into inert glass or glass-ceramics that encapsulate heavy metals. The waste management industry will inevitably use the cheapest available option for treating APC residues and strict interpretation and enforcement of waste legislation is required if new, potentially more sustainable technologies are to become commercially viable.

Solute redistribution in dendritic solidification with diffusion in the solid

NASA Technical Reports Server (NTRS)

Ganesan, S.; Poirier, D. R.

1989-01-01

An investigation of solute redistribution during dendritic solidification with diffusion in the solid has been performed using numerical techniques. The extent of diffusion is characterized by the instantaneous and average diffusion parameters. These parameters are functions of the diffusion Fourier number, the partition ratio and the fraction solid. Numerical results are presented as an approximate model, which is used to predict the average diffusion parameter and calculate the composition of the interdendritic liquid during solidification.

Gravitational Acceleration Effects on Macrosegregation: Experiment and Computational Modeling

NASA Technical Reports Server (NTRS)

Leon-Torres, J.; Curreri, P. A.; Stefanescu, D. M.; Sen, S.

1999-01-01

Experiments were performed under terrestrial gravity (1g) and during parabolic flights (10-2 g) to study the solidification and macrosegregation patterns of Al-Cu alloys. Alloys having 2% and 5% Cu were solidified against a chill at two different cooling rates. Microscopic and Electron Microprobe characterization was used to produce microstructural and macrosegregation maps. In all cases positive segregation occurred next to the chill because shrinkage flow, as expected. This positive segregation was higher in the low-g samples, apparently because of the higher heat transfer coefficient. A 2-D computational model was used to explain the experimental results. The continuum formulation was employed to describe the macroscopic transports of mass, energy, and momentum, associated with the solidification phenomena, for a two-phase system. The model considers that liquid flow is driven by thermal and solutal buoyancy, and by solidification shrinkage. The solidification event was divided into two stages. In the first one, the liquid containing freely moving equiaxed grains was described through the relative viscosity concept. In the second stage, when a fixed dendritic network was formed after dendritic coherency, the mushy zone was treated as a porous medium. The macrosegregation maps and the cooling curves obtained during experiments were used for validation of the solidification and segregation model. The model can explain the solidification and macrosegregation patterns and the differences between low- and high-gravity results.

Localized melt-scan strategy for site specific control of grain size and primary dendrite arm spacing in electron beam additive manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raghavan, Narendran; Simunovic, Srdjan; Dehoff, Ryan

In addition to design geometry, surface roughness, and solid-state phase transformation, solidification microstructure plays a crucial role in controlling the performance of additively manufactured components. Crystallographic texture, primary dendrite arm spacing (PDAS), and grain size are directly correlated to local solidification conditions. We have developed a new melt-scan strategy for inducing site specific, on-demand control of solidification microstructure. We were able to induce variations in grain size (30 μm–150 μm) and PDAS (4 μm - 10 μm) in Inconel 718 parts produced by the electron beam additive manufacturing system (Arcam®). A conventional raster melt-scan resulted in a grain size ofmore » about 600 μm. The observed variations in grain size with different melt-scan strategies are rationalized using a numerical thermal and solidification model which accounts for the transient curvature of the melt pool and associated thermal gradients and liquid-solid interface velocities. The refinement in grain size at high cooling rates (>104 K/s) is also attributed to the potential heterogeneous nucleation of grains ahead of the epitaxially growing solidification front. The variation in PDAS is rationalized using a coupled numerical-theoretical model as a function of local solidification conditions (thermal gradient and liquid-solid interface velocity) of the melt pool.« less

Two-dimensional time-resolved X-ray diffraction study of liquid/solid fraction and solid particle size in Fe-C binary system with an electrostatic levitator furnace

NASA Astrophysics Data System (ADS)

Yonemura, M.; Okada, J.; Watanabe, Y.; Ishikawa, T.; Nanao, S.; Shobu, T.; Toyokawa, H.

2013-03-01

Liquid state provides functions such as matter transport or a reaction field and plays an important role in manufacturing processes such as refining, forging or welding. However, experimental procedures are significantly difficult for an observation of solidification process of iron and iron-based alloys in order to identify rapid transformations subjected to fast temperature evolution. Therefore, in order to study the solidification in iron and iron-based alloys, we considered a combination of high energy X-ray diffraction measurements and an electrostatic levitation method (ESL). In order to analyze the liquid/solid fraction, the solidification of melted spherical specimens was measured at a time resolution of 0.1 seconds during rapid cooling using the two-dimensional time-resolved X-ray diffraction. Furthermore, the observation of particle sizes and phase identification was performed on a trial basis using X-ray small angle scattering with X-ray diffraction.

Modern Aspects of Liquid Metal Engineering

NASA Astrophysics Data System (ADS)

Czerwinski, Frank

2017-02-01

Liquid metal engineering (LME) refers to a variety of physical and/or chemical treatments of molten metals aimed at influencing their solidification characteristics. Although the fundamentals have been known for decades, only recent progress in understanding solidification mechanisms has renewed an interest in opportunities this technique creates for an improvement of castings. This review covers conventional and novel concepts of LME with their application to modern manufacturing techniques based not only on liquid but also on semisolid routes. The role of external forces applied to the melt combined with grain nucleation control is explained along with laboratory- and commercial-scale equipment designed for implementation of various concepts exploring mechanical, electromagnetic, and ultrasound principles. An influence of melt treatments on quality of the final product is considered through distinguishing between internal integrity of net shape components and the alloy microstructure. Recent global developments indicate that exploring the synergy of melt chemistry and physical treatments achieved through LME allows creating the optimum conditions for nucleation and growth during solidification, positively affecting quality of castings.

From Solidification Processing to Microstructure to Mechanical Properties: A Multi-scale X-ray Study of an Al-Cu Alloy Sample

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tourret, D.; Mertens, J. C. E.; Lieberman, E.

We follow an Al-12 at. pct Cu alloy sample from the liquid state to mechanical failure, using in situ X-ray radiography during directional solidification and tensile testing, as well as three-dimensional computed tomography of the microstructure before and after mechanical testing. The solidification processing stage is simulated with a multi-scale dendritic needle network model, and the micromechanical behavior of the solidified microstructure is simulated using voxelized tomography data and an elasto-viscoplastic fast Fourier transform model. This study demonstrates the feasibility of direct in situ monitoring of a metal alloy microstructure from the liquid processing stage up to its mechanical failure,more » supported by quantitative simulations of microstructure formation and its mechanical behavior.« less

Modelling of the Thermo-Physical and Physical Properties for Solidification of Al-Alloys

NASA Astrophysics Data System (ADS)

Saunders, N.; Li, X.; Miodownik, A. P.; Schillé, J.-P.

The thermo-physical and physical properties of the liquid and solid phases are critical components in casting simulations. Such properties include the fraction solid transformed, enthalpy release, thermal conductivity, volume and density, all as a function of temperature. Due to the difficulty in experimentally determining such properties at solidification temperatures, little information exists for multi-component alloys. As part of the development of a new computer program for modelling of materials properties (JMatPro) extensive work has been carried out on the development of sound, physically based models for these properties. Wide ranging results will presented for Al-based alloys, which will include more detailed information concerning the density change of the liquid that intrinsically occurs during solidification due to its change in composition.

From Solidification Processing to Microstructure to Mechanical Properties: A Multi-scale X-ray Study of an Al-Cu Alloy Sample

DOE PAGES

Tourret, D.; Mertens, J. C. E.; Lieberman, E.; ...

2017-09-13

We follow an Al-12 at. pct Cu alloy sample from the liquid state to mechanical failure, using in situ X-ray radiography during directional solidification and tensile testing, as well as three-dimensional computed tomography of the microstructure before and after mechanical testing. The solidification processing stage is simulated with a multi-scale dendritic needle network model, and the micromechanical behavior of the solidified microstructure is simulated using voxelized tomography data and an elasto-viscoplastic fast Fourier transform model. This study demonstrates the feasibility of direct in situ monitoring of a metal alloy microstructure from the liquid processing stage up to its mechanical failure,more » supported by quantitative simulations of microstructure formation and its mechanical behavior.« less

From Solidification Processing to Microstructure to Mechanical Properties: A Multi-scale X-ray Study of an Al-Cu Alloy Sample

NASA Astrophysics Data System (ADS)

Tourret, D.; Mertens, J. C. E.; Lieberman, E.; Imhoff, S. D.; Gibbs, J. W.; Henderson, K.; Fezzaa, K.; Deriy, A. L.; Sun, T.; Lebensohn, R. A.; Patterson, B. M.; Clarke, A. J.

2017-11-01

We follow an Al-12 at. pct Cu alloy sample from the liquid state to mechanical failure, using in situ X-ray radiography during directional solidification and tensile testing, as well as three-dimensional computed tomography of the microstructure before and after mechanical testing. The solidification processing stage is simulated with a multi-scale dendritic needle network model, and the micromechanical behavior of the solidified microstructure is simulated using voxelized tomography data and an elasto-viscoplastic fast Fourier transform model. This study demonstrates the feasibility of direct in situ monitoring of a metal alloy microstructure from the liquid processing stage up to its mechanical failure, supported by quantitative simulations of microstructure formation and its mechanical behavior.

75 FR 15423 - U.S. Nuclear Regulatory Commission Technical Evaluation Report for the Phase 1 Decommissioning...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-29

... DOE to carry out a high-level radioactive waste management demonstration project at the Western New... solidification of high-level radioactive waste for disposal in a Federal repository for permanent disposal. The... and other facilities where the solidified high-level radioactive waste was stored, the facilities used...

Investigation into the artificial ageing effects on the microstructure of an industrial solid waste treated with cement.

PubMed

Choura, M; Keskes, M; Tayibi, H; Rouis, J

2011-04-01

Metal hydroxide sludges are classified as hazardous wastes in the European Hazardous Waste Catalogue (EHWC) because of their high heavy metal contents (Zn, Cr, Fe, Cu, etc.) and the release of these pollutants to the environment. Thereby, the disposal of this waste without any treatment is a substantial environmental problem. Stabilization/solidification technologies are widely used for the treatment of wastes and residues in order to obtain inert materials. This work aims to assess the effectiveness of the chemical fixation and solidification of a metal hydroxide sludge generated by the electrotyping surface treatment industry, using Portland Artificial Cement. In order to predict the medium- and long-term behaviour of the solidified waste, an artificial ageing by means of thermal shocks and humidity variation cycles was applied. Scanning Electron Microscopy (SEM) and X-ray Diffraction studies revealed a considerable increase in calcite within the solid matrix after the artificial ageing, which can be attributed to the phenomenon of carbonation. It was also found that the mechanical properties of the solidified material, after ageing, were improved by up to 30%.

Effects of high pressure on microstructure evolution and crystallization mechanisms during solidification of nickel

NASA Astrophysics Data System (ADS)

Zhang, Hai-Tao; Mo, Yun-Fei; Liu, Rang-Su; Tian, Ze-An; Liu, Hai-Rong; Hou, Zhao-Yang; Zhou, Li-Li; Liang, Yong-Chao; Peng, Ping

2018-03-01

To deeply understand the effects of high pressure on microstructural evolutions and crystallization mechanisms of liquid metal Ni during solidification process, MD simulation studies have been performed under 7 pressures of 0 ˜ 30 GPa, at cooling rate of 1.0 × 1011 K s-1. Adopting several microstructural analyzing methods, especially the cluster-type index method (CTIM-2) to analyze the local microstructures in the system. It is found that the pressure has important influence on the formation and evolution of microstructures, especially of the main basic clusters in the system. All the simulation systems are directly solidified into crystal structures, and the 1421, 1422, 1441 and 1661 bond-types, as well the FCC (12 0 0 0 12 0), HCP (12 0 0 0 6 6) and BCC (14 6 0 8 0 0) clusters play a key role in the microstructure transitions from liquid to crystal structures. The crystallization temperature T c is enhanced almost linearly with the increase of pressure. Highly interesting, it is found for the first time that there is an important phase transformation point from FCC to BCC structures between 20 ˜ 22.5 GPa during the solidification processes from the same initial liquid system at the same cooling rate. And the effect of increasing pressure is similar to that of decreasing cooling rate for the phase transformation of microstructures during solidification process of liquid metal Ni system, though they have different concrete effecting mechanisms.

Stabilization/solidification of hot dip galvanizing ash using different binders.

PubMed

Vinter, S; Montanes, M T; Bednarik, V; Hrivnova, P

2016-12-15

This study focuses on solidification of hot dip-galvanizing ash with a high content of zinc and soluble substances. The main purpose of this paper is to immobilize these pollutants into a matrix and allow a safer way for landfill disposal of that waste. Three different binders (Portland cement, fly ash and coal fluidized-bed combustion ash) were used for the waste solidification. Effectiveness of the process was evaluated using leaching test according to EN 12457-4 and by using the variance analysis and the categorical multifactorial test. In the leaching test, four parameters were observed: pH, zinc concentration in leachate, and concentration of chlorides and dissolved substances in leachate. The acquired data was then processed using statistical software to find an optimal solidifying ratio of the addition of binder, water, and waste to the mixture, with the aim to fulfil the requirement for landfill disposal set by the Council Decision 2003/33/EC. The influence on the main observed parameters (relative amount of water and a binder) on the effectiveness of the used method and their influence of measured parameters was also studied. Copyright © 2016 Elsevier B.V. All rights reserved.

Experimental and Computational Studies of the Control of Convection of Non-Conducting Liquids During solidification by Means of a Magnetic Field Gradient

NASA Technical Reports Server (NTRS)

Seybert, C. D.; Evans, J. W.; Leslie, F.; Jones, W. K., Jr.

2001-01-01

The elimination of convection is essential in experimental investigations of diffusive transport (of heat and matter) during solidification. One classical approach to damping convection in a conducting liquid is the application of a magnetic field. The damping phenomenon is the induction, by the motion of a conductor in a magnetic field, of currents which interact with the field to produce Lorentz forces that oppose the flow. However, there are many liquids which are not sufficiently conducting to exploit this phenomenon; examples include the transparent liquids (such as succinonitrile-acetone) that are used as "model alloys" in fundamental solidification studies. There have been several investigations of the solidification of these liquids that have been carried out in orbiting laboratories to eliminate natural convection. The paper describes an investigation of an alternative approach whereby a magnetic field gradient is applied to the liquid. A magnetic body force then arises which is dependent on the susceptibility of the liquid and thereby on the temperature and or concentration. With the field gradient aligned vertically and of correct magnitude, the variation of gravitational body force due to temperature/concentration dependent density can be counterbalanced by a variation in magnetic body force. Experiments have been carried out in a super-conducting magnet at Marshall Space Flight Center to measure velocities in an aqueous manganese chloride solution. The solution was contained in a chamber with temperature controlled end walls and glass side walls. Velocities were measured by particle image velocimetry. Starting from zero current in the magnet (zero field gradient) flow driven by the temperature difference between the end walls was measured. At a critical current the flow was halted. At higher currents the normal convection was reversed. The experiments included ones where the solution was solidified and were accompanied by solution of the flow/transport equations using the software package FLUENT.

DEMONSTRATION BULLETIN: SOLIDIFICATION/STABILIZATION OF ORGANIC/INORGANIC CONTAMINANTS - SILICATE TECHNOLOGY CORPORATION

EPA Science Inventory

Silicate Technology Corporation's (STC's) technology for treating hazardous waste utilizes silicate compounds to stabilize organic and inorganic constituents in contaminated soils and sludges. STC has developed two groups of reagents: SOILSORB HM for treating wastes with inorgan...

Fundamental Studies of Solidification in Microgravity Using Real-Time X-Ray Microscopy

NASA Technical Reports Server (NTRS)

Curreri, Peter A.; Kaukler, William; Sen, Subhayu; Bhat, Biliyar N.

1999-01-01

This research applies a state of the art X-ray Transmission Microscope, XTM, to image (with resolutions up to 3 micrometers) the solidification of metallic or semiconductor alloys in real-time. We have successfully imaged in real-time: interfacial morphologies, phase growth, coalescence, incorporation of phases into the growing interface, and the solute boundary layer in the liquid at the solid-liquid interface. We have also measured true local growth rates and can evaluate segregation structures in the solid; a form of in-situ metallography. During this study, the growth of secondary phase fibers and lamellae from eutectic and monotectic alloys have been imaged during solidification, in real-time, for the first time in bulk metal alloys. Current high resolution X-ray sources and high contrast X-ray detectors have advanced to allow systematic study of solidification dynamics and the resulting microstructure. We have employed a state-of-the-art sub-micron source with acceleration voltages of 10-100 kV to image solidification of metals. One useful strength of the XTM stems from the manner an image is formed. The radiographic image is a shadow formed by x-ray photons that are not absorbed as they pass through the specimen. Composition gradients within the specimen cause variations in absorption of the flux such that the final image represents a spatial integral of composition (or thickness). The ability to image these features in real-time enables more fundamental and detailed understanding of solidification dynamics than has previously been possible. Hence, application of this technique towards microgravity experiments will allow rigorous testing of critical solidification models.

Ageless Aluminum-Cerium-Based Alloys in High-Volume Die Casting for Improved Energy Efficiency

DOE PAGES

Stromme, Eric T.; Henderson, Hunter B.; Sims, Zachary C.; ...

2018-04-25

Strong chemical reactions between Al and Ce lead to the formation of intermetallics with exceptional thermal stability. The rapid formation of intermetallics directly from the liquid phase during solidification of Al-Ce alloys leads to an ultrafine microconstituent structure that effectively strengthens as-cast alloys without further microstructural optimization via thermal processing. Die casting is a high-volume manufacturing technology that accounts for greater than 40% of all cast Al products, whereas Ce is highly overproduced as a waste product of other rare earth element (REE) mining. Reducing heat treatments would stimulate significant improvements in manufacturing energy efficiency, exceeding (megatonnes/year) per large-scale heat-treatmentmore » line. In this study, multiple compositions were evaluated with wedge mold castings to test the sensitivity of alloys to the variable solidification rate inherent in high-pressure die casting. Once a suitable composition was determined, it was successfully demonstrated at 800 lbs/h in a 600-ton die caster, after which the as-die cast parts performed similarly to ubiquitous A380 in the same geometry without requiring heat treatment. Furthermore, this work demonstrates the compatibility of Al REE alloys with high-volume die-casting applications with minimal heat treatments.« less

Ageless Aluminum-Cerium-Based Alloys in High-Volume Die Casting for Improved Energy Efficiency

NASA Astrophysics Data System (ADS)

Stromme, Eric T.; Henderson, Hunter B.; Sims, Zachary C.; Kesler, Michael S.; Weiss, David; Ott, Ryan T.; Meng, Fanqiang; Kassoumeh, Sam; Evangelista, James; Begley, Gerald; Rios, Orlando

2018-06-01

Strong chemical reactions between Al and Ce lead to the formation of intermetallics with exceptional thermal stability. The rapid formation of intermetallics directly from the liquid phase during solidification of Al-Ce alloys leads to an ultrafine microconstituent structure that effectively strengthens as-cast alloys without further microstructural optimization via thermal processing. Die casting is a high-volume manufacturing technology that accounts for greater than 40% of all cast Al products, whereas Ce is highly overproduced as a waste product of other rare earth element (REE) mining. Reducing heat treatments would stimulate significant improvements in manufacturing energy efficiency, exceeding (megatonnes/year) per large-scale heat-treatment line. In this study, multiple compositions were evaluated with wedge mold castings to test the sensitivity of alloys to the variable solidification rate inherent in high-pressure die casting. Once a suitable composition was determined, it was successfully demonstrated at 800 lbs/h in a 600-ton die caster, after which the as-die cast parts performed similarly to ubiquitous A380 in the same geometry without requiring heat treatment. This work demonstrates the compatibility of Al REE alloys with high-volume die-casting applications with minimal heat treatments.

Ageless Aluminum-Cerium-Based Alloys in High-Volume Die Casting for Improved Energy Efficiency

NASA Astrophysics Data System (ADS)

Stromme, Eric T.; Henderson, Hunter B.; Sims, Zachary C.; Kesler, Michael S.; Weiss, David; Ott, Ryan T.; Meng, Fanqiang; Kassoumeh, Sam; Evangelista, James; Begley, Gerald; Rios, Orlando

2018-04-01

Strong chemical reactions between Al and Ce lead to the formation of intermetallics with exceptional thermal stability. The rapid formation of intermetallics directly from the liquid phase during solidification of Al-Ce alloys leads to an ultrafine microconstituent structure that effectively strengthens as-cast alloys without further microstructural optimization via thermal processing. Die casting is a high-volume manufacturing technology that accounts for greater than 40% of all cast Al products, whereas Ce is highly overproduced as a waste product of other rare earth element (REE) mining. Reducing heat treatments would stimulate significant improvements in manufacturing energy efficiency, exceeding (megatonnes/year) per large-scale heat-treatment line. In this study, multiple compositions were evaluated with wedge mold castings to test the sensitivity of alloys to the variable solidification rate inherent in high-pressure die casting. Once a suitable composition was determined, it was successfully demonstrated at 800 lbs/h in a 600-ton die caster, after which the as-die cast parts performed similarly to ubiquitous A380 in the same geometry without requiring heat treatment. This work demonstrates the compatibility of Al REE alloys with high-volume die-casting applications with minimal heat treatments.

Ageless Aluminum-Cerium-Based Alloys in High-Volume Die Casting for Improved Energy Efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stromme, Eric T.; Henderson, Hunter B.; Sims, Zachary C.

Strong chemical reactions between Al and Ce lead to the formation of intermetallics with exceptional thermal stability. The rapid formation of intermetallics directly from the liquid phase during solidification of Al-Ce alloys leads to an ultrafine microconstituent structure that effectively strengthens as-cast alloys without further microstructural optimization via thermal processing. Die casting is a high-volume manufacturing technology that accounts for greater than 40% of all cast Al products, whereas Ce is highly overproduced as a waste product of other rare earth element (REE) mining. Reducing heat treatments would stimulate significant improvements in manufacturing energy efficiency, exceeding (megatonnes/year) per large-scale heat-treatmentmore » line. In this study, multiple compositions were evaluated with wedge mold castings to test the sensitivity of alloys to the variable solidification rate inherent in high-pressure die casting. Once a suitable composition was determined, it was successfully demonstrated at 800 lbs/h in a 600-ton die caster, after which the as-die cast parts performed similarly to ubiquitous A380 in the same geometry without requiring heat treatment. Furthermore, this work demonstrates the compatibility of Al REE alloys with high-volume die-casting applications with minimal heat treatments.« less

Microgravity

NASA Image and Video Library

1992-03-12

The Advanced Automated Directional Solidification Furnace (AADSF) with the Experimental Apparatus Container (EAC) removed flew during the USMP-2 mission. During USMP-2, the AADSF was used to study the growth of mercury cadmium telluride crystals in microgravity by directional solidification, a process commonly used on earth to process metals and grow crystals. The furnace is tubular and has three independently controlled temperature zones . The sample travels from the hot zone of the furnace (1600 degrees F) where the material solidifies as it cools. The solidification region, known as the solid/liquid interface, moves from one end of the sample to the other at a controlled rate, thus the term directional solidification.

Thermophysical and heat transfer properties of phase change material candidate for waste heat transportation system

NASA Astrophysics Data System (ADS)

Kaizawa, Akihide; Maruoka, Nobuhiro; Kawai, Atsushi; Kamano, Hiroomi; Jozuka, Tetsuji; Senda, Takeshi; Akiyama, Tomohiro

2008-05-01

A waste heat transportation system trans-heat (TH) system is quite attractive that uses the latent heat of a phase change material (PCM). The purpose of this paper is to study the thermophysical properties of various sugars and sodium acetate trihydrate (SAT) as PCMs for a practical TH system and the heat transfer property between PCM selected and heat transfer oil, by using differential scanning calorimetry (DSC), thermogravimetry-differential thermal analysis (TG-DTA) and a heat storage tube. As a result, erythritol, with a large latent heat of 344 kJ/kg at melting point of 117°C, high decomposition point of 160°C and excellent chemical stability under repeated phase change cycles was found to be the best PCM among them for the practical TH system. In the heat release experiments between liquid erythritol and flowing cold oil, we observed foaming phenomena of encapsulated oil, in which oil droplet was coated by solidification of PCM.

Formation of Nitrogen Bubbles During Solidification of Duplex Stainless Steels

NASA Astrophysics Data System (ADS)

Dai, Kaiju; Wang, Bo; Xue, Fei; Liu, Shanshan; Huang, Junkai; Zhang, Jieyu

2018-04-01

The nucleation and growth of nitrogen bubbles for duplex stainless steels are of great significance for the formation mechanism of bubbles during solidification. In the current study, numerical method and theoretical analysis of formula derivation were used to study the formation of nitrogen bubbles during solidification. The critical sizes of the bubble for homogeneous nucleation and heterogeneous nucleation at the solid-liquid interface during solidification were derived theoretically by the classical nucleation theory. The results show that the calculated values for the solubility of nitrogen in duplex stainless steel are in good agreement with the experimental values which are quoted by references: for example, when the temperature T = 1823 K and the nitrogen partial pressure P_{{N2 }} = 40P^{Θ} , the calculated value (0.8042 wt pct) for the solubility of Fe-12Cr alloy nitrogen in molten steel is close to the experimental value (0.780 wt pct). Moreover, the critical radii for homogeneous nucleation and heterogeneous nucleation are identical during solidification. On the one hand, with the increasing temperature or the melt depth, the critical nucleation radius of bubbles at the solid-liquid interface increases, but the bubble growth rate decreases. On the other hand, with the decreasing initial content of nitrogen or the cooling rate, the critical nucleation radius of bubbles at the solid-liquid interface increases, but the bubble growth rate decreases. Furthermore, when the melt depth is greater than the critical depth, which is determined by the technological conditions, the change in the Gibbs free energy for the nucleation is not conducive enough to form new bubbles.

Advanced Microscopic Integrated Thermocouple Arrays

NASA Technical Reports Server (NTRS)

Pettigrew, Penny J.

1999-01-01

The purpose of this research is to develop and refine a technique for making microscopic thermocouple arrays for use in measuring the temperature gradient across a solid-liquid interface during the solidification process. Current thermocouple technology does not allow for real-time measurements across the interface due to the prohibitive size of available thermocouples. Microscopic thermocouple arrays will offer a much greater accuracy and resolution of temperature measurements across the solid-liquid interface which will lead to a better characterization of the solidification process and interface reaction which affect the properties of the resulting material.

Solidification in direct metal deposition by LENS processing

NASA Astrophysics Data System (ADS)

Hofmeister, William; Griffith, Michelle

2001-09-01

Thermal imaging and metallographic analysis were used to study Laser Engineered Net Shaping (LENS™) processing of 316 stainless steel and H13 tool steel. The cooling rates at the solid-liquid interface were measured over a range of conduction conditions. The length scale of the molten zone controls cooling rates during solidification in direct metal deposition. In LENS processing, the molten zone ranges from 0.5 mm in length to 1.5 mm, resulting in cooling rates at the solid-liquid interface ranging from 200 6,000 Ks-1.

Multiscale X-ray and Proton Imaging of Bismuth-Tin Solidification

NASA Astrophysics Data System (ADS)

Gibbs, P. J.; Imhoff, S. D.; Morris, C. L.; Merrill, F. E.; Wilde, C. H.; Nedrow, P.; Mariam, F. G.; Fezzaa, K.; Lee, W.-K.; Clarke, A. J.

2014-08-01

The formation of structural patterns during metallic solidification is complex and multiscale in nature, ranging from the nanometer scale, where solid-liquid interface properties are important, to the macroscale, where casting mold filling and intended heat transfer are crucial. X-ray and proton imaging can directly interrogate structure, solute, and fluid flow development in metals from the microscale to the macroscale. X-rays permit high spatio-temporal resolution imaging of microscopic solidification dynamics in thin metal sections. Similarly, high-energy protons permit imaging of mesoscopic and macroscopic solidification dynamics in large sample volumes. In this article, we highlight multiscale x-ray and proton imaging of bismuth-tin alloy solidification to illustrate dynamic measurement of crystal growth rates and solute segregation profiles that can be that can be acquired using these techniques.

EFFECTS OF LEACHING ON PORE SIZE DISTRIBUTION OF SOLIDIFIED/STABILIZED WASTES

EPA Science Inventory

Chemical solidification/stabilization processes are commonly used to immobilize metals in fly ash and flue gas desulfurization (FGD) sludges and to convert these wastes into monolithic or granular materials with better handling properties and reduced permeabilities. his study eva...

Dispersive solid-phase extraction followed by vortex-assisted dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet for the determination of benzoylurea insecticides in soil and sewage sludge.

PubMed

Peng, Guilong; He, Qiang; Mmereki, Daniel; Lu, Ying; Zhong, Zhihui; Liu, Hanyang; Pan, Weiliang; Zhou, Guangming; Chen, Junhua

2016-04-01

A novel dispersive solid-phase extraction combined with vortex-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet was developed for the determination of eight benzoylurea insecticides in soil and sewage sludge samples before high-performance liquid chromatography with ultraviolet detection. The analytes were first extracted from the soil and sludge samples into acetone under optimized pretreatment conditions. Clean-up of the extract was conducted by dispersive solid-phase extraction using activated carbon as the sorbent. The vortex-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet procedure was performed by using 1-undecanol with lower density than water as the extraction solvent, and the acetone contained in the solution also acted as dispersive solvent. Under the optimum conditions, the linearity of the method was in the range 2-500 ng/g with correlation coefficients (r) of 0.9993-0.9999. The limits of detection were in the range of 0.08-0.56 ng/g. The relative standard deviations varied from 2.16 to 6.26% (n = 5). The enrichment factors ranged from 104 to 118. The extraction recoveries ranged from 81.05 to 97.82% for all of the analytes. The good performance has demonstrated that the proposed methodology has a strong potential for application in the multiresidue analysis of complex matrices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Formation mechanism of atomic cluster structures in Al-Mg alloy during rapid solidification processes

NASA Astrophysics Data System (ADS)

Liu, Feng-xiang; Liu, Rang-su; Hou, Zhao-yang; Liu, Hai-Rong; Tian, Ze-an; Zhou, Li-li

2009-02-01

The rapid solidification processes of Al 50Mg 50 liquid alloy consisting of 50,000 atoms have been simulated by using molecular dynamics method based on the effective pair potential derived from the pseudopotential theory. The formation mechanisms of atomic clusters during the rapid solidification processes have been investigated adopting a new cluster description method—cluster-type index method (CTIM). The simulated partial structure factors are in good agreement with the experimental results. And Al-Mg amorphous structure characterized with Al-centered icosahedral topological short-range order (SRO) is found to form during the rapid solidification processes. The icosahedral cluster plays a key role in the microstructure transition. Besides, it is also found that the size distribution of various clusters in the system presents a magic number sequence of 13, 19, 23, 25, 29, 31, 33, 37, …. The magic clusters are more stable and mainly correspond to the incompact arrangements of linked icosahedra in the form of rings, chains or dendrites. And each magic number point stands correspondingly for one certain combining form of icosahedra. This magic number sequence is different from that generated in the solidification structure of liquid Al and those obtained by methods of gaseous deposition and ionic spray, etc.

Solidification of Dredged Sludge by Hydraulic Ash-Slag Cementitious Materials

NASA Astrophysics Data System (ADS)

Zhu, Shu-Jing; Qin, Ying; Hwang, Jiann-Yang

Solidification treatment is used to treat hazardous wastes for disposal and to remediate the contaminated land. It is an increasingly popular technology for redevelopment of brown fields since treated wastes can often be left on-site, which can improve the site's soil for subsequent construction. In order to find home for the dredged sludge from the Pearl River Estuary Channel in China, the potential uses of treated dredged sludge by solidification treatment as valuable structural fill was investigated. Structure fills were prepared under various formula and curing conditions. Modulus of elasticity was detemined at 7 days, 14 days and 28 days with different types of load application. Atterberg limit, compactibility and CBR values are reported. The relationship between the microstructure and engineering properties of treated sludge are examined. The results clearly show the technical benefits by stabilizing soft soils with Hydraulic ash-slag cementitious materials. XRD and DTA-TG tests were carried out on certain samples to characterize the hydraulic compounds formed.

Tranpsort phenomena in solidification processing of functionally graded materials

NASA Astrophysics Data System (ADS)

Gao, Juwen

A combined numerical and experimental study of the transport phenomena during solidification processing of metal matrix composite functionally graded materials (FGMs) is conducted in this work. A multiphase transport model for the solidification of metal-matrix composite FGMs has been developed that accounts for macroscopic particle segregation due to liquid-particle flow and particle-solid interactions. An experimental study has also been conducted to gain physical insight as well as to validate the model. A novel method to in-situ measure the particle volume fraction using fiber optic probes is developed for transparent analogue solidification systems. The model is first applied to one-dimensional pure matrix FGM solidification under gravity or centrifugal field and is extensively validated against the experimental results. The mechanisms for the formation of particle concentration gradient are identified. Two-dimensional solidification of pure matrix FGM with convection is then studied using the model as well as experiments. The interaction among convection flow, solidification process and the particle transport is demonstrated. The results show the importance of convection in the particle concentration gradient formation. Then, simulations for alloy FGM solidification are carried out for unidirectional solidification as well as two-dimensional solidification with convection. The interplay among heat and species transport, convection and particle motion is investigated. Finally, future theoretical and experimental work is outlined.

Impact of Metal Droplets: A Numerical Approach to Solidification

NASA Astrophysics Data System (ADS)

Koldeweij, Robin; Mandamparambil, Rajesh; Lohse, Detlef

2016-11-01

Layer-wise deposition of material to produce complex products is a subject of increasing technological relevance. Subsequent deposition of droplets is one of the possible 3d printing technologies to accomplish this. The shape of the solidified droplet is crucial for product quality. We employ the volume-of-fluid method (in the form of the open-source code Gerris) to study liquid metal (in particular tin) droplet impact. Heat transfer has been implemented based on the enthalpy approach for the liquid-solid phase. Solidification is modeled by adding a sink term to the momentum equations, reducing Navier-Stokes to Darcy's law for high solid fraction. Good agreement is found when validating the results against experimental data. We then map out a phase diagram in which we distinguish between solidification behavior based on Weber and Stefan number. In an intermediate impact regime impact, solidification due to a retracting phase occurs. In this regime the maximum spreading diameter almost exclusively depends on Weber number. Droplet shape oscillations lead to a broad variation of the morphology of the solidified droplet and determine the final droplet height. TNO.

Ice Layer Spreading along a Solid Substrate during Solidification of Supercooled Water: Experiments and Modeling.

PubMed

Schremb, Markus; Campbell, James M; Christenson, Hugo K; Tropea, Cameron

2017-05-16

The thermal influence of a solid wall on the solidification of a sessile supercooled water drop is experimentally investigated. The velocity of the initial ice layer propagating along the solid substrate prior to dendritic solidification is determined from videos captured using a high-speed video system. Experiments are performed for varying substrate materials and liquid supercooling. In contrast to recent studies at moderate supercooling, in the case of metallic substrates only a weak influence of the substrate's thermal properties on the ice layer velocity is observed. Using the analytical solution of the two-phase Stefan problem, a semiempirical model for the ice layer velocity is developed. The experimental data are well described for all supercooling levels in the entire diffusion limited solidification regime. For higher supercooling, the model overestimates the freezing velocity due to kinetic effects during molecular attachment at the solid-liquid interface, which are not accounted for in the model. The experimental findings of the present work offer a new perspective on the design of anti-icing systems.

The effect of surface tension, superheat and surface films on the rate of heat transfer from an iron droplet to a water cooled copper mold

NASA Astrophysics Data System (ADS)

Phinichka, Natthapong

In strip casting the cast surface forms during the initial stage of solidification and the phenomenon that occurs during the first 50 milliseconds of contact time between the liquid steel and the mold define the cast surface and its quality. However the exact mechanism of the initial solidification and the process variables that affect initial solidification phenomena during that time are not well understood. The primary goal of this work is to develop a fundamental understanding of factors controlling strip casting. The purpose of the experimental study is to better understand the role of processing parameters on initial solidification phenomena, heat transfer rate and the formation of the cast steel surface. An investigation was made to evaluate the heat transfer rate of different kinds of steels. The experimental apparatus was designed for millisecond resolution of heat transfer behavior. A novel approach of simultaneous in-situ observation and measurement of rapid heat transfer was developed and enabled a coupling between the interfacial heat transfer rate and droplet solidification rate. The solidification rate was estimated from the varying position of the solidification front as captured by a CCD camera. The effects of experimental parameters such as melt superheat, sulfur content and oxide accumulation at the interface on measured heat flux were studied. It was found that the heat flux increased slightly when the percent of sulfur and increased significantly when superheat increased. The oxide accumulation at the interface was found to be manganese and silicon based oxide. When the liquid steel droplets were ejected onto the copper substrate repeatedly, without cleaning the substrate surface between the ejections, a large increase in the interfacial heat flux was observed. The results of the film study indicated that a liquid oxide film existed at the interface. The surface roughness measurement of the solidified specimen decreased with repeated experimentation and better contact between the droplet and the mold was found to be the cause of the improved heat transfer rate.

Treatment of Petroleum Sludge By Using Solidification/Stabilization (S/S) Method : Effect of Hydration Days to Heavy Metals Leaching and Strength

NASA Astrophysics Data System (ADS)

Murshid, N.; Kamil, N. A. F. M.; Kadir, A. A.

2018-04-01

Petroleum sludge is one of the major solid wastes generated in the petroleum industry. Generally, there are numbers of heavy metals in petroleum sludge and one treatment that is gaining prominence to treat a variety of mixed organic and inorganic waste is solidification/stabilization (S/S) method. The treatment protects human health and the environment by immobilizing contaminants within the treated material and prevents migration of the contaminants. In this study, solidification/stabilization (S/S) method has been used to treat the petroleum sludge. The comparison of hydration days, namely, 7th and 28th days in these cement-based waste materials were studied by using Synthetic Precipitate Leaching Procedure (SPLP). The results were compared to the United States Environmental Protection Agency (USEPA) standards. The results for leaching test concluded that less percentage OPC gave maximum concentration of heavy metals leaching due to deficient in Calcium Oxide (CaO), which is can caused weak solidification in the mixture. Physical and mechanical properties conducted such as compressive strength and density test. From the results, it shows addition up to of 30percentage PS give results which comply with minimum landfill dispose limit. The results shows correlation between strength and density are strong regression coefficient of 82.7%. In conclusion, S/S method can be alternative disposal method for PS in the same time complies with standard for minimum landfill disposal limit. The results for leaching test concluded the less OPC percentage gave maximum concentration of heavy metals leaching.

Solidification/stabilization of fly ash from city refuse incinerator facility and heavy metal sludge with cement additives.

PubMed

Cerbo, Atlas Adonis V; Ballesteros, Florencio; Chen, Teng Chien; Lu, Ming-Chun

2017-01-01

Solidification and stabilization are well-known technologies used for treating hazardous waste. These technologies that use cementitious binder have been applied for decades as a final treatment procedure prior to the hazardous waste disposal. In the present work, hazardous waste like fly ash containing high concentrations of heavy metals such Zn (4715.56 mg/kg), Pb (1300.56 mg/kg), and Cu (534.72 mg/kg) and amounts of Ag, Cd, Co, Cr, Mn, and Ni was sampled from a city refuse incinerator facility. This fly ash was utilized in the solidification/stabilization of heavy metal sludge since fly ash has cement-like characteristics. Cement additives such as sodium sulfate, sodium carbonate, and ethylenediaminetetraacetic acid (EDTA) was incorporated to the solidified matrix in order to determine its effect on the solidification/stabilization performance. The solidified matrix was cured for 7, 14, 21, and 28 days prior for its physical and chemical characterizations. The results show that the solidified matrix containing 40% fly ash and 60% cement with heavy metal sludge was the formulation that has the highest fly ash content with a satisfactory strength. The solidified matrix was also able to immobilize the heavy metals both found in the fly ash and sludge based on the toxicity characteristic leaching procedure (TCLP) test. It also shows that the incorporation of sodium carbonate into the solidified matrix not only further improved the compressive strength from 0.36 MPa (without Na 2 CO 3 ) to 0.54 MPa (with Na 2 CO 3 ) but also increased its leaching resistance.

A comparative study of quantitative microsegregation analyses performed during the solidification of the Ni-base superalloy CMSX-10

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seo, Seong-Moon, E-mail: castme@kims.re.kr; Jeong, Hi-Won; Ahn, Young-Keun

Quantitative microsegregation analyses were systematically carried out during the solidification of the Ni-base superalloy CMSX-10 to clarify the methodological effect on the quantification of microsegregation and to fully understand the solidification microstructure. Three experimental techniques, namely, mushy zone quenching (MZQ), planar directional solidification followed by quenching (PDSQ), and random sampling (RS), were implemented for the analysis of microsegregation tendency and the magnitude of solute elements by electron probe microanalysis. The microprobe data and the calculation results of the diffusion field ahead of the solid/liquid (S/L) interface of PDSQ samples revealed that the liquid composition at the S/L interface is significantlymore » influenced by quenching. By applying the PDSQ technique, it was also found that the partition coefficients of all solute elements do not change appreciably during the solidification of primary γ. All three techniques could reasonably predict the segregation behavior of most solute elements. Nevertheless, the RS approach has a tendency to overestimate the magnitude of segregation for most solute elements when compared to the MZQ and PDSQ techniques. Moreover, the segregation direction of Cr and Mo predicted by the RS approach was found to be opposite from the results obtained by the MZQ and PDSQ techniques. This conflicting segregation behavior of Cr and Mo was discussed intensively. It was shown that the formation of Cr-rich areas near the γ/γ′ eutectic in various Ni-base superalloys, including the CMSX-10 alloy, could be successfully explained by the results of microprobe analysis performed on a sample quenched during the planar directional solidification of γ/γ′ eutectic. - Highlights: • Methodological effect on the quantification of microsegregation was clarified. • The liquid composition at the S/L interface was influenced by quenching. • The segregation direction of Cr varied depending on the experimental techniques. • Cr and Mo segregation in Ni-base superalloys was fully understood.« less

Design and characterization of microporous zeolitic hydroceramic waste forms for the solidification and stabilization of sodium bearing wastes

NASA Astrophysics Data System (ADS)

Bao, Yun

During the production of nuclear weapon by the DOE, large amounts of liquid waste were generated and stored in millions of gallons of tanks at Savannah River, Hanford and INEEL sites. Typically, the waste contains large amounts of soluble NaOH, NaNO2 and NaNO3 and small amounts of soluble fission products, cladding materials and cleaning solution. Due to its high sodium content it has been called sodium bearing waste (SBW). We have formulated, tested and evaluated a new type of hydroceramic waste form specifically designed to solidify SBW. Hydroceramics can be made from an alumosilicate source such as metakaolin and NaOH solutions or the SBW itself. Under mild hydrothermal conditions, the mixture is transformed into a solid consisting of zeolites. This process leads to the incorporation of radionuclides into lattice sites and the cage structures of the zeolites. Hydroceramics have high strength and inherent stability in realistic geologic settings. The process of making hydroceramics from a series of SBWs was optimized. The results are reported in this thesis. Some SBWs containing relatively small amounts of NaNO3 and NaNO2 (SigmaNOx/Sigma Na<25 mol%) can be directly solidified with metakaolin. The remaining SBW having high concentrations of nitrate and nitrite (SigmaNOx/Sigma Na>25 mol%) require pretreatment since a zeolitic matrix such as cancrinite is unable to host more than 25 mol% nitrate/nitrite. Two procedures to denitrate/denitrite followed by solidification were developed. One is based on calcination in which a reducing agent such as sucrose and metakaolin have been chosen as a way of reducing nitrate and nitrite to an acceptable level. The resulting calcine can be solidified using additional metakaolin and NaOH to form a hydroceramic. As an alternate, a chemical denitration/denitrition process using Si and Al powders as the reducing agents, followed by adding metakaolin to the solution prepare a hydroceramic was also investigated. Si and Al not only are the reducing agents, but they also provide Si and Al species to make zeolites during the reducing process. Performance of the hydroceramics was documented using SEM microstructure and X-ray diffraction phase analysis, mechanical property and leaching tests (Product Consistency Test and ANSI/ANS-16.1 leaching test).

Computational modelling for the embolization of brain arteriovenous malformations.

PubMed

Orlowski, Piotr; Summers, Paul; Noble, J Alison; Byrne, James; Ventikos, Yiannis

2012-09-01

Treatment of arteriovenous malformations (AVMs) of the brain often requires the injection of a liquid embolic material to reduce blood flow through the malformation. The type of the liquid and the location of injection have to be carefully planned in a pre-operative manner. We introduce a new model of the interaction of liquid embolic materials with blood for the simulation of their propagation and solidification in the AVM. Solidification is mimicked by an increase of the material's viscosity. Propagation is modelled by using the concept of two-fluids modelling and that of scalar transport. The method is tested on digital phantoms and on one anatomically derived patient AVM case. Simulations showed that intuitive behaviour of the two-fluid system can be confirmed and that two types of glue propagation through the malformation can be reproduced. Distinction between the two types of propagation could be used to identify fistulous and plexiform compartments composing the AVM and to characterize the solidification of the embolic material in them. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

Implementation of the Leaching Environmental Assessment Framework (LEAF) in the United States

EPA Science Inventory

LEAF provides a uniform and integrated approach for evaluating leaching from solid materials (e.g., waste, treated wastes such as by solidification/stabilization, secondary materials such as blast furnace slags, energy residuals such as coal fly ash, soil, sediments, mining and m...

Multilayer hexagonal silicon forming in slit nanopore

PubMed Central

He, Yezeng; Li, Hui; Sui, Yanwei; Qi, Jiqiu; Wang, Yanqing; Chen, Zheng; Dong, Jichen; Li, Xiongying

2015-01-01

The solidification of two-dimensional liquid silicon confined to a slit nanopore has been studied using molecular dynamics simulations. The results clearly show that the system undergoes an obvious transition from liquid to multilayer hexagonal film with the decrease of temperature, accompanied by dramatic change in potential energy, atomic volume, coordination number and lateral radial distribution function. During the cooling process, some hexagonal islands randomly appear in the liquid first, then grow up to grain nuclei, and finally connect together to form a complete polycrystalline film. Moreover, it is found that the quenching rate and slit size are of vital importance to the freezing structure of silicon film. The results also indicate that the slit nanopore induces the layering of liquid silicon, which further induces the slit size dependent solidification behavior of silicon film with different electrical properties. PMID:26435518

Investigation of compositional segregation during unidirectional solidification of solid solution semiconducting alloys

NASA Technical Reports Server (NTRS)

Wang, J. C.

1982-01-01

Compositional segregation of solid solution semiconducting alloys in the radial direction during unidirectional solidification was investigated by calculating the effect of a curved solid liquid interface on solute concentration at the interface on the solid. The formulation is similar to that given by Coriell, Boisvert, Rehm, and Sekerka except that a more realistic cylindrical coordinate system which is moving with the interface is used. Analytical results were obtained for very small and very large values of beta with beta = VR/D, where V is the velocity of solidification, R the radius of the specimen, and D the diffusivity of solute in the liquid. For both very small and very large beta, the solute concentration at the interface in the solid C(si) approaches C(o) (original solute concentration) i.e., the deviation is minimal. The maximum deviation of C(si) from C(o) occurs for some intermediate value of beta.

Secondary Waste Form Screening Test Results—Cast Stone and Alkali Alumino-Silicate Geopolymer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pierce, Eric M.; Cantrell, Kirk J.; Westsik, Joseph H.

2010-06-28

PNNL is conducting screening tests on the candidate waste forms to provide a basis for comparison and to resolve the formulation and data needs identified in the literature review. This report documents the screening test results on the Cast Stone cementitious waste form and the Geopolymer waste form. Test results suggest that both the Cast Stone and Geopolymer appear to be viable waste forms for the solidification of the secondary liquid wastes to be treated in the ETF. The diffusivity for technetium from the Cast Stone monoliths was in the range of 1.2 × 10-11 to 2.3 × 10-13 cm2/smore » during the 63 days of testing. The diffusivity for technetium from the Geopolymer was in the range of 1.7 × 10-10 to 3.8 × 10-12 cm2/s through the 63 days of the test. These values compare with a target of 1 × 10-9 cm2/s or less. The Geopolymer continues to show some fabrication issues with the diffusivities ranging from 1.7 × 10-10 to 3.8 × 10-12 cm2/s for the better-performing batch to from 1.2 × 10-9 to 1.8 × 10-11 cm2/s for the poorer-performing batch. In the future more comprehensive and longer term performance testing will be conducted, to further evaluate whether or not these waste forms will meet the regulation and performance criteria needed to cost-effectively dispose of secondary wastes.« less

Phase-Field Simulation of Concentration and Temperature Distribution During Dendritic Growth in a Forced Liquid Metal Flow

NASA Astrophysics Data System (ADS)

Du, Lifei; Zhang, Rong

2014-12-01

A phase-field model with convection is employed to investigate the effect of liquid flow on the dendritic structure formation of a Ni-Cu alloy during rapid solidification. Temperature and solute diffusion are significantly changed with induced liquid metal flow, and distribution changes of concentration and temperature are also analyzed and discussed. The solute segregation is affected due to the concentration diffusion layer thickness change caused by the liquid flow. The flow reduces the solute segregation in the upstream and leads to a fast dendrite growing, while solidifying in the downstream gets constrained with the large solute diffusion layer. Increasing flow velocity increases the asymmetry of dendrite morphology with much more suppressed growth in the downstream. The temperature distribution is also asymmetrical due to the non-uniform latent heat released during solidification coupling with heat diffusion changed by the liquid flow. Therefore, the forced liquid flow significantly affects the dendrite morphology, concentration, and temperature distributions in the solidifying microstructure.

Undercooling, Liquid Separation and Solidification of Cu-Co Alloys

NASA Technical Reports Server (NTRS)

Robinson, M. B.; Li, D.; Rathz, J.; Williams, G.

1998-01-01

Large undercooling can induce not only various solidification pathways, but also a precursor reaction, or liquid separation. This paper deals with the latter effect of undercooling using examples of the Cu-Co system which has a flattened liquidus. Bulk Cu-Co alloys (about 7mm diameter) at compositions ranging from 10 to 90 wt pct Co were highly undercooled using a fluxing technique. Except for Cu-90 wt pct Co, liquid separation was directly observed as undercooling exceeded a critical value depending on the composition. It was also confirmed by a microstructural transition from dendrites to droplets above the critical undercooling. Finally, theoretical calculations regarding the metastable miscibility boundary and maximum droplet radius were made to analyze the experimental results.

A novel dispersive liquid-liquid microextraction based on solidification of floating organic droplet method for determination of polycyclic aromatic hydrocarbons in aqueous samples.

PubMed

Xu, Hui; Ding, Zongqing; Lv, Lili; Song, Dandan; Feng, Yu-Qi

2009-03-16

A new dispersive liquid-liquid microextraction based on solidification of floating organic droplet method (DLLME-SFO) was developed for the determination of five kinds of polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. In this method, no specific holder, such as the needle tip of microsyringe and the hollow fiber, is required for supporting the organic microdrop due to the using of organic solvent with low density and proper melting point. Furthermore, the extractant droplet can be collected easily by solidifying it in the lower temperature. 1-Dodecanol was chosen as extraction solvent in this work. A series of parameters that influence extraction were investigated systematically. Under optimal conditions, enrichment factors (EFs) for PAHs were in the range of 88-118. The limit of detections (LODs) for naphthalene, diphenyl, acenaphthene, anthracene and fluoranthene were 0.045, 0.86, 0.071, 1.1 and 0.66ngmL(-1), respectively. Good reproducibility and recovery of the method were also obtained. Compared with the traditional liquid-phase microextraction (LPME) and dispersive liquid-liquid microextraction (DLLME) methods, the proposed method obtained about 2 times higher enrichment factor than those in LPME. Moreover, the solidification of floating organic solvent facilitated the phase transfer. And most importantly, it avoided using high-density and toxic solvent in the traditional DLLME method. The proposed method was successfully applied to determinate PAHs in the environmental water samples. The simple and low-cost method provides an alternative method for the analysis of non-polar compounds in complex environmental water.

Solidification of II-VI Compounds in a Rotating Magnetic Field

NASA Technical Reports Server (NTRS)

Gillies, D. C.; Volz, M. P.; Mazuruk, K.; Motakef, S.; Dudley, M.; Matyi, R.

1999-01-01

This project is aimed at using a rotating magnetic field (RMF) to control fluid flow and transport during directional solidification of elemental and compound melts. Microgravity experiments have demonstrated that small amounts of residual acceleration of less than a micro-g can initiate and prolong fluid flow, particularly when there is a static component of the field perpendicular to the liquid solid interface. Thus a true diffusion boundary layer is not formed, and it becomes difficult to verify theories of solidification or to achieve diffusion controlled solidification. The RMF superimposes a stirring effect on an electrically conducting liquid, and with appropriate field strengths and frequencies, controlled transport of material through a liquid column can be obtained. As diffusion conditions are precluded and complete mixing conditions prevail, the technique is appropriate for traveling solvent zone or float zone growth methods in which the overall composition of the liquid can be maintained throughout the growth experiment. Crystals grown by RMF techniques in microgravity in previous, unrelated missions have shown exceptional properties. The objective of the project is two-fold, namely (1) using numerical modeling to simulate the behavior of a solvent zone with applied thermal boundary conditions and demonstrate the effects of decreasing gravity levels, or an increasing applied RMF, or both, and (2) to grow elements and II-VI compounds from traveling solvent zones both with and without applied RMFs, and to determine objectively how well the modeling predicts solidification parameters. Numerical modeling has demonstrated that, in the growth of CdTe from a tellurium solution, a rotating magnetic field can advantageously modify the shape of the liquid solid interface such that the interface is convex as seen from the liquid. Under such circumstances, the defect structure is reduced as any defects which are formed tend to grow out and not propagate. The flow of liquid, however, is complex due to the competing flow induced by the rotating magnetic field and the buoyancy driven convection. When the acceleration forces are reduced to one thousandth of gravity, the flow pattern is much simplified and well controlled material transport through the solvent zone can be readily achieved. Triple axis diffractometry and x-ray synchrotron topography have demonstrated that there is no significant improvement in crystal quality for HgCdTe grown on earth from a tellurium solution when a rotating magnetic field is applied. However, modeling shows that the flow in microgravity with a rotating magnetic field would produce a superior product.

Alkali activated solidification/stabilisation of air pollution control residues and co-fired pulverised fuel ash.

PubMed

Shirley, Robin; Black, Leon

2011-10-30

This paper examines the potential treatment by solidification/stabilisation (S/S) of air pollution control (APC) residues using only waste materials otherwise bound for disposal, namely a pulverised fuel ash (PFA) from a co-fired power station and a waste caustic solution. The use of waste materials to stabilise hazardous wastes in order to meet waste acceptance criteria (WAC) would offer an economical and efficient method for reducing the environmental impact of the hazardous waste. The potential is examined against leach limits for chlorides, sulphates and total dissolved solids, and compressive strength performance described in the WAC for stable non-reactive (SNR) hazardous waste landfill cells in England and Wales. The work demonstrates some potential for the treatment, including suitable compressive strengths to meet regulatory limits. Monolithic leach results showed good encapsulation compared to previous work using a more traditional cement binder. However, consistent with previous work, SNR WAC for chlorides was not met, suggesting the need for a washing stage. The potential problems of using a non-EN450 PFA for S/S applications were also highlighted, as well as experimental results which demonstrate the effect of ionic interactions on the mobility of phases during regulatory leach testing. Copyright © 2011 Elsevier B.V. All rights reserved.

MANAGING ARSENIC CONTAMINATED SOIL, SEDIMENT, AND INDUSTRIAL WASTE WITH SOLIDIFICATION/STABILIZATION TREATMENT

EPA Science Inventory

Arsenic contamination of soil, sediment and groundwater is a widespread problem in certain areas and has caused great public concern due to increased awareness of the health risks. Often the contamination is naturally occurring, but it can also be a result of waste generated from...

Mitigating Impacts Of Arsenic Contaminated Materials Via Two (2) Stabilization Methods Based On Polymeric And Cement Binders

EPA Science Inventory

The primary objective of this study was to evaluate the performance of two selected chemical stabilization and solidification (S/S) techniques to treat three types of arsenic-contaminated wastes 1) chromated copper arsenate (CCA) wood treater waste, 2) La Trinidad Mine tailings, ...

Ultrafast synchrotron X-ray imaging studies of microstructure fragmentation in solidification under ultrasound

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Bing; Tan, Dongyue; Lee, Tung Lik

Ultrasound processing of metal alloys is an environmental friendly and promising green technology for liquid metal degassing and microstructural refinement. However many fundamental issues in this field are still not fully understood, because of the difficulties in direct observation of the dynamic behaviours caused by ultrasound inside liquid metal and semisolid metals during the solidification processes. In this paper, we report a systematic study using the ultrafast synchrotron X-ray imaging (up to 271,554 frame per second) technique available at the Advanced Photon Source, USA and Diamond Light Source, UK to investigate the dynamic interactions between the ultrasonic bubbles/acoustic flow andmore » the solidifying phases in a Bi-8%Zn alloy. The experimental results were complimented by numerical modelling. The chaotic bubble implosion and dynamic bubble oscillations were revealed in-situ for the first time in liquid metal and semisolid metal. The fragmentation of the solidifying Zn phases and breaking up of the liquid-solid interface by ultrasonic bubbles and enhanced acoustic flow were clearly demonstrated and agreed very well with the theoretical calculations. The research provides unambiguous experimental evidence and robust theoretical interpretation in elucidating the dominant mechanisms of microstructure fragmentation and refinement in solidification under ultrasound.« less

Ultrafast synchrotron X-ray imaging studies of microstructure fragmentation in solidification under ultrasound

DOE PAGES

Wang, Bing; Tan, Dongyue; Lee, Tung Lik; ...

2017-11-03

Ultrasound processing of metal alloys is an environmental friendly and promising green technology for liquid metal degassing and microstructural refinement. However many fundamental issues in this field are still not fully understood, because of the difficulties in direct observation of the dynamic behaviours caused by ultrasound inside liquid metal and semisolid metals during the solidification processes. In this paper, we report a systematic study using the ultrafast synchrotron X-ray imaging (up to 271,554 frame per second) technique available at the Advanced Photon Source, USA and Diamond Light Source, UK to investigate the dynamic interactions between the ultrasonic bubbles/acoustic flow andmore » the solidifying phases in a Bi-8%Zn alloy. The experimental results were complimented by numerical modelling. The chaotic bubble implosion and dynamic bubble oscillations were revealed in-situ for the first time in liquid metal and semisolid metal. The fragmentation of the solidifying Zn phases and breaking up of the liquid-solid interface by ultrasonic bubbles and enhanced acoustic flow were clearly demonstrated and agreed very well with the theoretical calculations. The research provides unambiguous experimental evidence and robust theoretical interpretation in elucidating the dominant mechanisms of microstructure fragmentation and refinement in solidification under ultrasound.« less

Mechanism of Macrosegregation Formation in Continuous Casting Slab: A Numerical Simulation Study

NASA Astrophysics Data System (ADS)

Jiang, Dongbin; Wang, Weiling; Luo, Sen; Ji, Cheng; Zhu, Miaoyong

2017-12-01

Solidified shell bulging is supposed to be the main reason for slab center segregation, while the influence of thermal shrinkage rarely has been considered. In this article, a thermal shrinkage model coupled with the multiphase solidification model is developed to investigate the effect of the thermal shrinkage, solidification shrinkage, grain sedimentation, and thermal flow on solute transport in the continuous casting slab. In this model, the initial equiaxed grains contract freely with the temperature decrease, while the coherent equiaxed grains and columnar phase move directionally toward the slab surface. The results demonstrate that the center positive segregation accompanied by negative segregation in the periphery zone is mainly caused by thermal shrinkage. During the solidification process, liquid phase first transports toward the slab surface to compensate for thermal shrinkage, which is similar to the case considering solidification shrinkage, and then it moves opposite to the slab center near the solidification end. It is attributed to the sharp decrease of center temperature and the intensive contract of solid phase, which cause the enriched liquid to be squeezed out. With the effect of grain sedimentation and thermal flow, the negative segregation at the external arc side (zone A1) and the positive segregation near the columnar-to-equiaxed transition at the inner arc side (position B1) come into being. Besides, it is found that the grain sedimentation and thermal flow only influence solute transport before equiaxed grains impinge with each other, while the solidification and thermal shrinkage still affect solute redistribution in the later stage.

Comparison of two microextraction methods based on solidification of floating organic droplet for the determination of multiclass analytes in river water samples by liquid chromatography tandem mass spectrometry using Central Composite Design.

PubMed

Asati, Ankita; Satyanarayana, G N V; Patel, Devendra K

2017-09-01

Two low density organic solvents based liquid-liquid microextraction methods, namely Vortex assisted liquid-liquid microextraction based on solidification of floating organic droplet (VALLME-SFO) and Dispersive liquid-liquid microextraction based on solidification of floating organic droplet(DLLME-SFO) have been compared for the determination of multiclass analytes (pesticides, plasticizers, pharmaceuticals and personal care products) in river water samples by using liquid chromatography tandem mass spectrometry (LC-MS/MS). The effect of various experimental parameters on the efficiency of the two methods and their optimum values were studied with the aid of Central Composite Design (CCD) and Response Surface Methodology(RSM). Under optimal conditions, VALLME-SFO was validated in terms of limit of detection, limit of quantification, dynamic linearity range, determination of coefficient, enrichment factor and extraction recovery for which the respective values were (0.011-0.219ngmL -1 ), (0.035-0.723ngmL -1 ), (0.050-0.500ngmL -1 ), (R 2 =0.992-0.999), (40-56), (80-106%). However, when the DLLME-SFO method was validated under optimal conditions, the range of values of limit of detection, limit of quantification, dynamic linearity range, determination of coefficient, enrichment factor and extraction recovery were (0.025-0.377ngmL -1 ), (0.083-1.256ngmL -1 ), (0.100-1.000ngmL -1 ), (R 2 =0.990-0.999), (35-49), (69-98%) respectively. Interday and intraday precisions were calculated as percent relative standard deviation (%RSD) and the values were ≤15% for VALLME-SFO and DLLME-SFO methods. Both methods were successfully applied for determining multiclass analytes in river water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Rapid solidification of metallic particulates

NASA Technical Reports Server (NTRS)

Grant, N. J.

1982-01-01

In order to maximize the heat transfer coefficient the most important variable in rapid solidification is the powder particle size. The finer the particle size, the higher the solidification rate. Efforts to decrease the particle size diameter offer the greatest payoff in attained quench rate. The velocity of the liquid droplet in the atmosphere is the second most important variable. Unfortunately the choices of gas atmospheres are sharply limited both because of conductivity and cost. Nitrogen and argon stand out as the preferred gases, nitrogen where reactions are unimportant and argon where reaction with nitrogen may be important. In gas atomization, helium offers up to an order of magnitude increase in solidification rate over argon and nitrogen. By contrast, atomization in vacuum drops the quench rate several orders of magnitude.

Multi-discipline Waste Acceptance Process at the Nevada National Security Site - 13573

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carilli, Jhon T.; Krenzien, Susan K.

2013-07-01

The Nevada National Security Site low-level radioactive waste disposal facility acceptance process requires multiple disciplines to ensure the protection of workers, the public, and the environment. These disciplines, which include waste acceptance, nuclear criticality, safety, permitting, operations, and performance assessment, combine into the overall waste acceptance process to assess low-level radioactive waste streams for disposal at the Area 5 Radioactive Waste Management Site. Four waste streams recently highlighted the integration of these disciplines: the Oak Ridge Radioisotope Thermoelectric Generators and Consolidated Edison Uranium Solidification Project material, West Valley Melter, and classified waste. (authors)

Molecular dynamics modelling of solidification in metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boercker, D.B.; Belak, J.; Glosli, J.

1997-12-31

Molecular dynamics modeling is used to study the solidification of metals at high pressure and temperature. Constant pressure MD is applied to a simulation cell initially filled with both solid and molten metal. The solid/liquid interface is tracked as a function of time, and the data are used to estimate growth rates of crystallites at high pressure and temperature in Ta and Mg.

Analytical description of the ternary melt and solution crystallization with a non-linear phase diagram

NASA Astrophysics Data System (ADS)

Toropova, L. V.; Alexandrov, D. V.

2018-05-01

The directional solidification of a ternary system with an extended phase transition region is theoretically studied. A mathematical model is developed to describe quasi-stationary solidification, and its analytical solution is constructed with allowance for a nonlinear liquids line equation. We demonstrate that the phase diagram nonlinearity leads to substantial changes of analytical solutions.

Study on solidification of immisible alloys (M-10)

NASA Technical Reports Server (NTRS)

Kamio, Akihiko

1993-01-01

Alloying of immiscible alloys under microgravity is of interest in metallurgical processes. Several experiments investigating the alloying of immiscible alloys, such as Al-In, Al-Bi, Zn-Bi, and Zn-Pb, were done in space. Homogeneous distribution of small L2 particles in the matrix, such as an emulsion structure, was expected in the space-solidifed alloys. However, the alloys demonstrated an extremely segregated structure. To date insufficient information was obtained to explain these unexpected results. Our experiment was proposed to clarify the solidification manner of immiscible alloys and to obtain fundamental information concerning structural control of the alloys. In space, density differences between the two liquids separated in immiscible regions can be neglected, so that no sedimentation of L(sub 2) phase will take place. When the growth of the alloys is interrupted and this status is frozen by an adequate rapid cooling procedure, it will provide much information concerning decomposing homogeneous liquid and the interaction between the monotectic growth front morphology and the distribution of L(sub 2) phase. It is anticipated that the results will be useful for elucidating the monotectic solidification manner and it will be instructive to explain the segregated structures obtained in the past space experiments.

Grain Floatation During Equiaxed Solidification of an Al-Cu Alloy in a Side-Cooled Cavity: Part II—Numerical Studies

NASA Astrophysics Data System (ADS)

Kumar, Arvind; Walker, Mike J.; Sundarraj, Suresh; Dutta, Pradip

2011-08-01

In this article, a single-phase, one-domain macroscopic model is developed for studying binary alloy solidification with moving equiaxed solid phase, along with the associated transport phenomena. In this model, issues such as thermosolutal convection, motion of solid phase relative to liquid and viscosity variations of the solid-liquid mixture with solid fraction in the mobile zone are taken into account. Using the model, the associated transport phenomena during solidification of Al-Cu alloys in a rectangular cavity are predicted. The results for temperature variation, segregation patterns, and eutectic fraction distribution are compared with data from in-house experiments. The model predictions compare well with the experimental results. To highlight the influence of solid phase movement on convection and final macrosegregation, the results of the current model are also compared with those obtained from the conventional solidification model with stationary solid phase. By including the independent movement of the solid phase into the fluid transport model, better predictions of macrosegregation, microstructure, and even shrinkage locations were obtained. Mechanical property prediction models based on microstructure will benefit from the improved accuracy of this model.

Indirect measurement of the solid/liquid interface using the minimization technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, H.; Chun, M.

1985-11-01

The phenomenon of solidification of a flowing fluid in a vertical tube is closely related to the relocation dynamics of molten nuclear fuels in hypothetical core-disruptive accidents of a liquid-metal fast breeder reactor. The knowledge of the transient shape and the position of the liquid/solid interface is of practical importance in analysis of phase change processes. Sparrow and Broadbent directly measured the solid liquid interface via experiments, whereas Viskanta observed the solid/liquid interface motion via a photographic method. In this paper, a new method to predict the transient position of the solid/liquid interface is developed. This method is based onmore » the minimization technique. To use this method one needs the temperature of the wall on which the phase change is to take place. The new technique is useful, in particular, for the case of inward solidification of a flowing fluid in a tube where direct measurement of the solid/liquid interface is not possible, whereas the tube wall temperature measurement is relatively easy.« less

A Solid Case for Microgravity Processing

NASA Technical Reports Server (NTRS)

Grugel, Richard N.

2000-01-01

Solidification of metals, particularly alloys, is a complicated process. At some sufficiently high temperature, the components comprising an alloy fully mix, producing a single homogeneous liquid. Unfortunately, after this liquid is cast into a mold and allowed to freeze, the resulting solid is usually very inhomogeneous. In most cases the first solid to "freeze out" of the liquid has a composition very close to one of the pure metals. This initially solidifying metal usually comprises microscopic, pine-tree shaped components, collectively referred to as a dendritic array, whose distribution, alignment, and scale directly influence a materials strength and docility. During dendrite growth the adjacent liquid becomes enriched, and consequently, solidifies a much lower temperature and considerably later time. Thus, in the course of solidification, both the solid and the enriched liquid can have compositions (and local temperatures) significantly different from those of the bulk liquid. Different compositions and temperatures imply different densities that, in Earth's gravity, induce motion in the liquid. Such motion promotes formation of a casting that is denser at the bottom and lighter at the top. This condition known as macrosegregation, precludes optimized, uniform material properties.

Dispersive liquid-liquid microextraction based on the solidification of floating organic drop followed by ICP-MS for the simultaneous determination of heavy metals in wastewaters

NASA Astrophysics Data System (ADS)

Li, Yong; Peng, Guilong; He, Qiang; Zhu, Hui; Al-Hamadani, Sulala M. Z. F.

2015-04-01

In the present work, a dispersive liquid-liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of Pb, Co, Cu, Ni, Zn. The influences of analytical parameters, including pH, extraction solvent volume, disperser solvent volume, concentration of chelating agent on the quantitative recoveries of Pb, Co, Cu, Ni, Zn were investigated. The effect of the interfering ions on the analytes recovery was also investigated. Under the optimized conditions, the limits of detection were 0.97-2.18 ng L-1. The relative standard deviations (RSDs) were 2.62-4.51% (n = 7, C = 20 ng L-1). The proposed method was successfully applied for the analysis of ultra trace metals in wastewater samples.

Coupled Heat Transfer and Fluid Dynamics Modeling of InSb Solidification

NASA Astrophysics Data System (ADS)

Barvinschi, Paul; Barvinschi, Floricica

2011-10-01

A method for the directional solidification of melted InSb in a silica ampoule is presented and solved with COMSOL Multiphysics. The configuration and initial boundary settings of the model resemble those used in a de-wetting vertical Bridgman configuration [1]. A slightly modified version of the method presented by Voller and Prakash [2] is used to account for solidification of the liquid phase, including convection and conduction heat transfer with mushy region phase change. Axial-symmetric numerical simulations of temperature and velocity fields, under normal gravity, are carried out using different thermal conditions.

Simulating the Dynamics of Particles Interacting with Solidification Fronts (Preprint - Briefing Charts)

DTIC Science & Technology

2007-07-01

A π =Π )( lslpsp γγγγ +−=Δ A = Hamaker constant ~ Δγ Δγ > 0 repulsive Δγ < 0 attractive VSparticle solid liquid d Previous work on thermal effects of...Solidification velocity = 500 microns/sec, Rp = 1 micron, Hamaker = -8E-19 J, kp/kl = 1.0 (planar), no premelting Vs Vt Vp Velocity vs. t and d vs. t plots...premelting Solidification velocity = 500 microns/sec, Rp = 1 micron, Hamaker = -8E-19 J, kp/kl = 1.0 (planar), premelting kp/kl ≥ 1.0 ALWAYS ENGULFS

Comparison of solidification/stabilization effects of calcite between Australian and South Korean cements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Dongjin; Waite, T. David; Swarbrick, Gareth

2005-11-15

The differences in the effect of calcite on the strength and stability of Pb-rich wastes solidified and stabilized using Australian and South Korean ordinary Portland cements are examined in this study. Pb-rich waste stabilized using Australian OPC has been shown to possess both substantially higher unconfined compressive strength and lead immobilization ability than South Korean OPC as a result of its higher C{sub 3}S content and the associated enhanced degree of precipitation of lead on the surfaces of silicate phases present. Calcite addition is observed to have an accelerating effect on the OPC-induced solidification/stabilization of Pb-rich wastes as gauged bymore » the unconfined compressive strength and leachability of the solids formed. This effect is observed to be far more dramatic for South Korean OPC than for Australian OPC. Using scanning electron microscopy, waste stabilized with cement and calcite was observed to develop significantly greater proportions of hydrated crystals than wastes stabilized with cement alone. The results of X-ray diffraction studies have shown that the presence of calcite in South Korean OPC results in greater acceleration in the formation of portlandite than is the case for Australian OPC.« less

Microscopic calculations of liquid and solid neutron star matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakravarty, Sudip; Miller, Michael D.; Chia-Wei, Woo

1974-02-01

As the first step to a microscopic determination of the solidification density of neutron star matter, variational calculations are performed for both liquid and solid phases using a very simple model potential. The potential, containing only the repulsive part of the Reid /sup 1/S/sub o/ interaction, together with Boltzmann statistics defines a homework problem'' which several groups involved in solidification calculations have agreed to solve. The results were to be compared for the purpose of checking calculational techniques. For the solid energy good agreement with Canuto and Chitre was found. Both the liquid and solid energies are much lower thanmore » those of Pandharipande. It is shown that for this oversimplified model, neutron star matter will remain solid down to ordinary nuclear matter density.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reeve, Kathlene N.; Holaday, John R.; Choquette, Stephanie M.

New electronics applications demanding enhanced performance and higher operating temperatures have led to continued research in the field of Pb-free solder designs and interconnect solutions. In this paper, recent advances in the microstructural design of Pb-free solders and interconnect systems were discussed by highlighting two topics: increasing β-Sn nucleation in Sn-based solders, and isothermally solidified interconnects using transient liquid phases. Issues in β-Sn nucleation in Sn-based solders were summarized in the context of Swenson’s 2007 review of the topic. Recent advancements in the areas of alloy composition manipulation, nucleating heterogeneities, and rapid solidification were discussed, and a proposal based onmore » a multi-faceted solidification approach involving the promotion of constitutional undercooling and nucleating heterogeneities was outlined for future research. The second half of the paper analyzed two different approaches to liquid phase diffusion bonding as a replacement for high-Pb solders, one based on the application of the pseudo-binary Cu-Ni-Sn ternary system, and the other on a proposed thermodynamic framework for identifying potential ternary alloys for liquid phase diffusion bonding. Furthermore, all of the concepts reviewed relied upon the fundamentals of thermodynamics, kinetics, and solidification, to which Jack Smith substantially contributed during his scientific career.« less

In situ metathesis reaction combined with liquid-phase microextraction based on the solidification of sedimentary ionic liquids for the determination of pyrethroid insecticides in water samples.

PubMed

Hu, Lu; Zhang, Panjie; Shan, Wanyu; Wang, Xuan; Li, Songqing; Zhou, Wenfeng; Gao, Haixiang

2015-11-01

A novel dispersion liquid-liquid microextraction method based on the solidification of sedimentary ionic liquids (SSIL-DLLME), in which an in situ metathesis reaction forms an ionic liquid (IL) extraction phase, was developed to determine four pyrethroid insecticides (i.e., permethrin, cyhalothrin, fenpropathrin, and transfluthrin) in water followed by separation using high-performance liquid chromatography. In the developed method, in situ DLLME was used to enhance the extraction efficiency and yield. After centrifugation, the extraction solvent, tributyldodecylphosphonium hexafluorophosphate ([P44412][PF6]), was easily collected by solidification in the bottom of the tube. The effects of various experimental parameters, the quantity of tributyldodecylphosphonium bromide ([P44412]Br), the molar ratio of [P44412]Br to potassium hexafluorophosphate (KPF6), the ionic strength, the temperature of the sample solution, and the centrifugation time, were optimized using a Plackett-Burman design to identify the significant factors that affected the extraction efficiency. These significant factors were then optimized using a central composite design. Under the optimized conditions, the recoveries of the four pyrethroid insecticides at four spiked levels ranged from 87.1% to 101.7%, with relative standard deviations (RSDs) ranging from 0.1% to 5.5%. At concentration levels between 1 and 500 µg/L, good linearity was obtained, with coefficients of determination greater than 0.9995. The limits of detection (LODs) for the four pyrethroid insecticides were in the range of 0.71-1.54 µg/L. The developed method was then successfully used for the determination of pyrethroid insecticides in environmental samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Laser ultrasonic investigations of vertical Bridgman crystal growth

NASA Astrophysics Data System (ADS)

Queheillalt, Douglas Ted

The many difficulties associated with the growth of premium quality CdTe and (Cd,Zn)Te alloys has stimulated an interest in the development of a non-invasive ultrasonic approach to monitor critical growth parameters such as the solid-liquid interface position and shape during vertical Bridgman growth. This sensor methodology is based upon the recognition that in most materials, the ultrasonic velocity (and the elastic stiffness constants that control it) of the solid and liquid phases are temperature dependent and an abrupt increase of the longitudinal wave velocity occurs upon solidification. The laser ultrasonic approach has also been used to measure the ultrasonic velocity of solid and liquid Cd0.96Zn0.04Te as a function of temperature up to 1140°C. Using longitudinal and shear wave velocity values together with data for the temperature dependent density allowed a complete evaluation of the temperature dependent single crystal elastic stiffness constants for solid and the adiabatic bulk modulus for liquid Cd0.96Zn0.04 Te. It was found that the ultrasonic velocities exhibited a strong monotonically decreasing function of temperature in the solid and liquid phases and the longitudinal wave indicated an abrupt almost 50% decrease upon melting. Because ray propagation in partially solidified bodies is complex and defines the sensing methodology, a ray tracing algorithm has been developed to analyze two-dimensional wave propagation in the diametral plane of cylindrical solid-liquid interfaces. Ray path, wavefront and time-of-flight (TOF) projections for rays that travel from a source to an arbitrarily positioned receiver on the diametral plane have been calculated and compared to experimentally measured data on a model liquid-solid interface. The simulations and the experimental results reveal that the interfacial region can be identified from transmission TOF data and when used in conjunction with a nonlinear least squares reconstruction algorithm, the interface geometry (i.e. axial location and shape) can be precisely recovered and the ultrasonic velocities of both solid and liquid phases obtained. To gain insight into the melting and solidification process, a single zone VB growth furnace was integrated with the laser ultrasonic sensor system and used to monitor the melting-solidification and directional solidification characteristics of Cd0.96Zn 0.04Te.

The growth of metastable peritectic compounds

NASA Technical Reports Server (NTRS)

Larson, D. J., Jr.; Pirich, R. G.

1981-01-01

The influence of gravitationally driven thermosolutal convection on the directional solidification of peritectic alloys is considered as well as the relationships between the solidification processing conditions, and the microstructure, chemistry, and magnetic properties of such alloys. Analysis of directionally solidified Pb-Bi peritectic samples indicates that appreciable macrosegregation occurs due to thermosolutal convection and/or Soret diffusion. A peritectic solidification model which accounts for partial mixing in the liquid ahead of the planar solidification interface and describes macrosegregation has been developed. Two-phase dendritic and banded microstructures were grown in the Pb-Bi peritectic system, refined two-phase microstructures have were observed, and candidate formation mechanisms proposed. Material handling, containment, casting, microstructural and magnetic characterization techniques were developed for the Sm-Co system. Alloys produced with these procedures are homogeneous.

Novel method of realizing metal freezing points by induced solidification

NASA Astrophysics Data System (ADS)

Ma, C. K.

1997-07-01

The freezing point of a pure metal, tf, is the temperature at which the solid and liquid phases are in equilibrium. The purest metal available is actually a dilute alloy. Normally, the liquidus point of a sample, tl, at which the amount of the solid phase in equilibrium with the liquid phase is minute, provides the closest approximation to tf. Thus the experimental realization of tf is a matter of realizing tl. The common method is to cool a molten sample continuously so that it supercools and recalesces. The highest temperature after recalescence is normally the best experimental value of tl. In the realization, supercooling of the sample at the sample container and the thermometer well is desirable for the formation of dual solid-liquid interfaces to thermally isolate the sample and the thermometer. However, the subsequent recalescence of the supercooled sample requires the formation of a certain amount of solid, which is not minute. Obviously, the plateau temperature is not the liquidus point. In this article we describe a method that minimizes supercooling. The condition that provides tl is closely approached so that the latter may be measured. As the temperature of the molten sample approaches the anticipated value of tl, a small solid of the same alloy is introduced into the sample to induce solidification. In general, solidification does not occur as long as the temperature is above or at tl, and occurs as soon as the sample supercools minutely. Thus tl can be obtained, in principle, by observing the temperature at which induced solidification begins. In case the solid is introduced after the sample has supercooled slightly, a slight recalescence results and the subsequent maximum temperature is a close approximation to tl. We demonstrate that the principle of induced solidification is indeed applicable to freezing point measurements by applying it to the design of a copper-freezing-point cell for industrial applications, in which a supercooled sample is reheated and then induced to solidify by the solidification of an auxiliary sample. Further experimental studies are necessary to assess the practical advantages and disadvantages of the induction method.

Characterization of weld metal microstructure in a Ni-30Cr alloy with additions of niobium and molybdenum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wheeling, Rebecca A., E-mail: wheeling.8@osu.edu; Lippold, John C., E-mail: lippold.1@osu.edu

2016-05-15

Additions of niobium (Nb) and molybdenum (Mo) were made to an Alloy 690 base alloy in order to investigate the formation of a eutectic constituent at the end of solidification and to evaluate the effect of the eutectic liquid on backfilling (or healing) of solidification cracks. Solidification cracking was induced using the cast pin tear test (CPTT) and regions of backfilling were located and characterized via optical and electron microscopy. Computational predictions of fraction eutectic and composition of the eutectic constituent were compared to experimental findings and were found to correlate well in both cases. The extent of crack backfillingmore » increased significantly with increasing Nb content, but the addition of Mo did not seem to influence the amount of eutectic constituent or the degree of backfilling. SEM/EDS analysis confirmed that the eutectic composition is constant and that increasing Nb above 4 wt% has little effect on expanding the solidification temperature range, but has a beneficial effect on mitigating solidification cracking by a crack healing effect. - Highlights: • Increasing fraction eutectic as a function of Nb, as predicted by ThermoCalc™, is consistent with image analysis results. • Nb, unlike Mo, had a significant effect on the fraction eutectic formed. • Both influence the composition of the eutectic. • Thermocalc™ predictions regarding Nb content in eutectic are consistent with EDS results, but are high for the Mo content. • Increased levels of niobium resulted in a higher degree of crack backfilling and leads to a lower cracking susceptibility. • Mo may influence the eutectic liquid along solidification grain boundaries, improving backfill and thus cracking resistance.« less

Microstructural Development during Directional Solidification of Peritectic Alloys

NASA Technical Reports Server (NTRS)

Lograsso, Thomas A.

1996-01-01

A thorough understanding of the microstructures produced through solidification in peritectic systems has yet to be achieved, even though a large number of industrially and scientifically significant materials are in this class. One type of microstructure frequently observed during directional solidification consists of alternating layers of primary solid and peritectic solid oriented perpendicular to the growth direction. This layer formation is usually reported for alloy compositions within the two-phase region of the peritectic isotherm and for temperature gradient and growth rate conditions that result in a planar solid-liquid interface. Layered growth in peritectic alloys has not previously been characterized on a quantitative basis, nor has a mechanism for its formation been verified. The mechanisms that have been proposed for layer formation can be categorized as either extrinsic or intrinsic to the alloy system. The extrinsic mechanisms rely on externally induced perturbations to the system for layer formation, such as temperature oscillations, growth velocity variations, or vibrations. The intrinsic mechanisms approach layer formation as an alternative type of two phase growth that is inherent for certain peritectic systems and solidification conditions. Convective mixing of the liquid is an additional variable which can strongly influence the development and appearance of layers due to the requisite slow growth rate. The first quantitative description of layer formation is a model recently developed by Trivedi based on the intrinsic mechanism of cyclic accumulation and depiction of solute in the liquid ahead of the interface, linked to repeated nucleation events in the absence of convection. The objective of this research is to characterize the layered microstructures developed during ground-based experiments in which external influences have been minimized as much as possible and to compare these results to the current the model. Also, the differences between intrinsic and externally influenced layer formation were explored. The choice of alloy system is critical to a study of the formation of layered microstructures. The ideal system would have a well-characterized phase diagram, equal densities of both elements in the liquid state to minimize compositionally-driven convective flows, a low peritectic temperature to simplify directional solidification and the achievement of a high temperature gradient in the liquid, a broad composition range for the peritectic reaction, and a reasonable hardness at room temperature to facilitate handling and metallographic preparation. The In-Sn system was selected initially due to a very low peritectic temperature and the nearly equal densities of In and Sn in the liquid state. Since the In-rich peritectic reaction had apparently not been utilized previously for solidification research, experiments were conducted to check the phase diagram in the region of interest. The alloys in this system proved to be difficult to handle and prepare in bulk form with the equipment available, so experiments were initiated with the Sn-Cd system. Layered microstructures had been observed previously in Sn-Cd.

Undercooling, Rapid Solidification, and Relations to Processing in Low Earth Orbit (A Review of the Works of Bingbo Wei)

NASA Technical Reports Server (NTRS)

deGroh, Henry C., III

1999-01-01

This is a survey of the published works of Prof. Bingbo Wei of the Department of Applied Physics at Northwestern Polytechnical University, Xian P.R. China. Transformations among solid - liquid - and vapor are fundamental to the foundations of life and culture on Earth. The development and understanding of materials has lead the evolution and advancement of the human race since antiquity. Materials and fluids research is continuing today, with us standing on the shoulders of those that have gone before us. Technological and scientific breakthroughs continue due to studies of greater and greater complexity, that include for example, research done at high pressures, in high magnetic fields, at temperatures near absolute zero, and in the low gravity environment of low Earth orbit. Of particular technological importance is the liquid to solid transformation of metals and alloys. Solidification processing is generally the most important factor in the final properties of objects made of metal; and undercooling is the fundamental driving force for all solidification. The interest and resources dedicated to the study of solidification and undercooling are great and World wide. For many years B. Wei and his coworkers have been studying undercooling and rapid solidification and have amassed a significant body of published research in this important field, contributing to the leading edge of the state-of-the-art. It is the goal of this memorandum to provide a review of the research of B. Wei et al.; publications in Chinese are included in the reference list but are not discussed. The bulk of Wei's work has been in the area of undercooling and rapid solidification [1-11, 13-16, 24-36] with papers dating back to 1989, the same year he earned his Ph.D. Below, discussions of Wei's undercooling and rapid solidification research have been grouped together mostly on the basis of alloy type, such as eutectic, intermetallic, or monotectic.

Finite Element Multi-scale Modeling of Chemical Segregation in Steel Solidification Taking into Account the Transport of Equiaxed Grains

NASA Astrophysics Data System (ADS)

Nguyen, Thi-Thuy-My; Gandin, Charles-André; Combeau, Hervé; Založnik, Miha; Bellet, Michel

2018-02-01

The transport of solid crystals in the liquid pool during solidification of large ingots is known to have a significant effect on their final grain structure and macrosegregation. Numerical modeling of the associated physics is challenging since complex and strong interactions between heat and mass transfer at the microscopic and macroscopic scales must be taken into account. The paper presents a finite element multi-scale solidification model coupling nucleation, growth, and solute diffusion at the microscopic scale, represented by a single unique grain, while also including transport of the liquid and solid phases at the macroscopic scale of the ingots. The numerical resolution is based on a splitting method which sequentially describes the evolution and interaction of quantities into a transport and a growth stage. This splitting method reduces the non-linear complexity of the set of equations and is, for the first time, implemented using the finite element method. This is possible due to the introduction of an artificial diffusion in all conservation equations solved by the finite element method. Simulations with and without grain transport are compared to demonstrate the impact of solid phase transport on the solidification process as well as the formation of macrosegregation in a binary alloy (Sn-5 wt pct Pb). The model is also applied to the solidification of the binary alloy Fe-0.36 wt pct C in a domain representative of a 3.3-ton steel ingot.

Real Time Characterization of Solid/Liquid Interfaces During Directional Solidification

NASA Technical Reports Server (NTRS)

Sen, S.; Kaukler, W. K.; Curreri, P. A.; Peters, P.

1997-01-01

A X-Ray Transmission Microscope (XTM) has been developed to observe in real time and in-situ solidification phenomenon at the solid/liquid interface. Recent improvements in the horizontal Bridgman furnace design provides real-time magnification (during solidification) up to 12OX. The increased magnification has enabled for the first time the XTM imaging of real-time growth of fibers and particles with diameters of 3-6 micrometers. Further, morphological transitions from planar to cellular interfaces have also been imaged. Results from recent XTM studies on Al-Bi monotectic system, Al-Au eutectic system and interaction of insoluble particles with s/I interfaces in composite materials will be presented. An important parameter during directional solidification of molten metal is the interfacial undercooling. This parameter controls the morphology and composition at the s/I interface. Conventional probes such as thermocouples, due to their large bead size, do not have sufficient resolution for measuring undercooling at the s/I interface. Further, the intrusive nature of the thermocouples also distorts the thermal field at the s/I interface. To overcome these inherent problems we have recently developed a compact furnace which utilizes a non-intrusive technique (Seebeck) to measure undercooling at the S/I interface. Recent interfacial undercooling measurements obtained for the Pb-Sn system will be presented. The Seebeck measurement furnace in the future will be integrated with the XTM to provide the most comprehensive tool for real time characterization of s/I interfaces during solidification.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Felicelli, S.D.; Poirier, D.R.; Heinrich, J.C.

The formation of macrosegregation defects known as freckles was simulated using a three-dimensional finite element model that calculates the thermosolutal convection and macrosegregation during the dendritic solidification of multicomponent alloys. A recently introduced algorithm was used to calculate the complicated solidification path of alloys of many components, which can accommodate liquidus temperatures that are general functions of liquid concentrations. The calculations are started from an all-liquid state, and the growth of the mushy zone is followed in time. Simulations are started from an all-liquid state, and the growth of the mushy zone is followed in time. Simulations of a Ni-Al-Ta-Wmore » alloy were performed on a rectangular cylinder until complete solidification. The results reveal details of the formation of freckles not previously observed in two-dimensional simulations. Liquid plumes in the form of chimney convection emanate from channels within the mushy zone, with similar qualitative features previously observed in transparent systems. Associated with the formation of channels, there is a complex three-dimensional flow produced by the interaction of the different solutal buoyancies of the alloy solutes. Regions of enhanced solid growth develop around the channel mouths, which are visualized as volcanoes on top of the mushy zone. The prediction of volcanoes differs from previous calculations with multicomponent alloys in two dimensions, in which the volcanoes were not nearly as apparent. These and other features of freckle formation phenomena are illustrated.« less

Thermal control of low-pressure fractionation processes. [in basaltic magma solidification

NASA Technical Reports Server (NTRS)

Usselman, T. M.; Hodge, D. S.

1978-01-01

Thermal models detailing the solidification paths for shallow basaltic magma chambers (both open and closed systems) were calculated using finite-difference techniques. The total solidification time for closed chambers are comparable to previously published calculations; however, the temperature-time paths are not. These paths are dependent on the phase relations and the crystallinity of the system, because both affect the manner in which the latent heat of crystallization is distributed. In open systems, where a chamber would be periodically replenished with additional parental liquid, calculations indicate that the possibility is strong that a steady-state temperature interval is achieved near a major phase boundary. In these cases it is straightforward to analyze fractionation models of the basaltic liquid evolution and their corresponding cumulate sequences. This steady thermal fractionating state can be invoked to explain large amounts of erupted basalts of similar composition over long time periods from the same volcanic center and some rhythmically layered basic cumulate sequences.

Modeling of Dendritic Structure and Microsegregation in Solidification of Al-Rich Quaternary Alloys

NASA Astrophysics Data System (ADS)

Dai, Ting; Zhu, Mingfang; Chen, Shuanglin; Cao, Weisheng

A two-dimensional cellular automaton (CA) model is coupled with a CALPHAD tool for the simulation of dendritic growth and microsegregation in solidification of quaternary alloys. The dynamics of dendritic growth is calculated according to the difference between the local equilibrium liquidus temperature and the actual temperature, incorporating with the Gibbs—Thomson effect and preferential dendritic growth orientations. Based on the local liquid compositions determined by solving the solutal transport equation in the domain, the local equilibrium liquidus temperature and the solid concentrations at the solid/liquid (SL) interface are calculated by the CALPHAD tool. The model was validated through the comparisons of the simulated results with the Scheil predictions for the solid composition profiles as a function of solid fraction in an Al-6wt%Cu-0.6wt%Mg-1wt%Si alloy. It is demonstrated that the model is capable of not only reproducing realistic dendrite morphologies, but also reasonably predicting microsegregation patterns in solidification of Al-rich quaternary alloys.

The Power of Materials Science Tools for Gaining Insights into Organic Semiconductors

NASA Astrophysics Data System (ADS)

Treat, Neil D.; Westacott, Paul; Stingelin, Natalie

2015-07-01

The structure of organic semiconductors can be complex because features from the molecular level (such as molecular conformation) to the micrometer scale (such as the volume fraction and composition of phases, phase distribution, and domain size) contribute to the definition of the optoelectronic landscape of the final architectures and, hence, to device performance. As a consequence, a detailed understanding of how to manipulate molecular ordering, e.g., through knowledge of relevant phase transitions, of the solidification process, of relevant solidification mechanisms, and of kinetic factors, is required to induce the desired optoelectronic response. In this review, we discuss relevant structural features of single-component and multicomponent systems; provide a case study of the multifaceted structure that polymer:fullerene systems can adopt; and highlight relevant solidification mechanisms such as nucleation and growth, liquid-liquid phase separation, and spinodal decomposition. In addition, cocrystal formation, solid solutions, and eutectic systems are treated and their relevance within the optoelectronic area emphasized.

Space Processing Applications Rocket project, SPAR 1

NASA Technical Reports Server (NTRS)

Reeves, F. (Compiler); Chassay, R. (Compiler)

1976-01-01

The experiment objectives, design/operational concepts, and final results of each of nine scientific experiments conducted during the first Space Processing Applications Rocket (SPAR) flight are summarized. The nine individual SPAR experiments, covering a wide and varied range of scientific materials processing objectives, were entitled: solidification of Pb-Sb eutectic, feasibility of producing closed-cell metal foams, characterization of rocket vibration environment by measurement of mixing of two liquids, uniform dispersions of crystallization processing, direct observation of solidification as a function of gravity levels, casting thoria dispersion-strengthened interfaces, contained polycrystalline solidification, and preparation of a special alloy for manufacturing of magnetic hard superconductor under zero-g environment.

A molecular dynamics study of cooling rate during solidification of metal nanoparticles

NASA Astrophysics Data System (ADS)

Shibuta, Yasushi; Suzuki, Toshio

2011-01-01

The effect of the cooling rate on the solidification behavior of metal nanoparticles is investigated by molecular dynamics simulation. The structure of molybdenum nanoparticles varies with the cooling rate. That is, single-crystalline, polycrystalline then glassy nanoparticles are obtained as the cooling rate is increased from 2.0 × 10 10 to 1.0 × 10 13 K/s. The solidification point decreases with increasing cooling rate then drops rapidly at a cooling rate on the order of 10 12 K/s. These results are summarized in a continuous cooling transformation (CCT) diagram, in which regions corresponding the liquid, single-crystalline, polycrystalline and glassy structures appear.

Numerical model for dendritic solidification of binary alloys

NASA Technical Reports Server (NTRS)

Felicelli, S. D.; Heinrich, J. C.; Poirier, D. R.

1993-01-01

A finite element model capable of simulating solidification of binary alloys and the formation of freckles is presented. It uses a single system of equations to deal with the all-liquid region, the dendritic region, and the all-solid region. The dendritic region is treated as an anisotropic porous medium. The algorithm uses the bilinear isoparametric element, with a penalty function approximation and a Petrov-Galerkin formulation. Numerical simulations are shown in which an NH4Cl-H2O mixture and a Pb-Sn alloy melt are cooled. The solidification process is followed in time. Instabilities in the process can be clearly observed and the final compositions obtained.

The study of flow pattern and phase-change problem in die casting process

NASA Technical Reports Server (NTRS)

Wang, T. S.; Wei, H.; Chen, Y. S.; Shang, H. M.

1996-01-01

The flow pattern and solidification phenomena in die casting process have been investigated in the first phase study. The flow pattern in filling process is predicted by using a VOF (volume of fluid) method. A good agreement with experimental observation is obtained for filling the water into a die cavity with different gate geometry and with an obstacle in the cavity. An enthalpy method has been applied to solve the solidification problem. By treating the latent heat implicitly into the enthalpy instead of explicitly into the source term, the CPU time can be reduced at least 20 times. The effect of material properties on solidification fronts is tested. It concludes that the dependence of properties on temperature is significant. The influence of the natural convection over the diffusion has also been studied. The result shows that the liquid metal solidification phenomena is diffusion dominant, and the natural convection can affect the shape of the interface. In the second phase study, the filling and solidification processes will be considered simultaneously.

Macrosegregation and Grain Formation Caused by Convection Associated with Directional Solidification Through Cross-Section Increase

NASA Technical Reports Server (NTRS)

Ghods, Masoud; Lauer, Mark; Tewari, Surendra; Poirier, David; Grugel, Richard

2016-01-01

Cylindrical Al-7 wt% Silicon, Al-19 wt% Copper and Lead-6 wt% Antimony alloy samples were directionally solidified (DS) with liquid above, solid below, and gravity pointing down, in graphite crucibles having an abrupt cross-sectional increase. These alloys have similar solidification shrinkage but are expected to have different degrees of thermosolutal convection during solidification. Microstructures in the DS samples in the vicinity of the section change have been studied in order to examine the effect of convection associated with the combined influence of thermosolutal effects and solidification shrinkage. Extensive radial and axial macrosegregation associated with cross-section change is observed. It also appears that steepling and local primary alpha-phase remelting resulting from convection are responsible for stray grain formation at the reentrant corners. Preliminary results from a numerical model, which includes solidification shrinkage and thermosolutal convection in the mushy zone, indicate that these regions are prone to solutal remelting of dendrites.

Preliminary in situ and real-time study of directional solidification of metallic alloys by x-ray imaging techniques

NASA Astrophysics Data System (ADS)

Nguyen Thi, H.; Jamgotchian, H.; Gastaldi, J.; Härtwig, J.; Schenk, T.; Klein, H.; Billia, B.; Baruchel, J.; Dabo, Y.

2003-05-01

During directional solidification of a binary alloy, the solid-liquid interface exhibits a variety of patterns that are due to the Mullins-Sekerka instability and governed by the growth conditions. It is well known that properties of the grown material are largely controlled by the microstructures left in the solid during processing. Thus, a precise mastering of the solidification is essential to tailor products in a reproducible fashion to a specified quality. One major difficulty for this study is the real-time and in situ observation of the interface, especially for metallic alloys. A possibility is to use an intense and coherent third generation x-ray beam. By combining different x-ray imaging techniques (absorption/phase contrast radiography and diffraction topography), we have studied the directional melting and solidification of aluminium-based alloys. The preliminary results show the great potential of these techniques for the study of the coupling between stress effects and microstructure formation in solidification processing.

Effect of Slag-Steel Reaction on the Initial Solidification of Molten Steel during Continuous Casting

NASA Astrophysics Data System (ADS)

Wang, Wanlin; Lou, Zhican; Zhang, Haihui

2018-03-01

With the mold simulator technique, the effect of slag-steel reaction on the initial shell solidification as well as the heat transfer and lubrication behavior of the infiltrated mold/shell slag film was studied in this article. The results showed that the Al2O3 content, the CaO/SiO2 ratio, and the viscosity of mold flux were increased with the progress of the slag-steel reaction during casting. The slag-steel reaction has two major effects on the initial shell solidification: one is increasing the mold heat flux and shell thickness by the decrease of slag film thickness. The other is the reduction of mold heat flux by the increase of crystal fraction in slag film. Mold flux with a lower basicity, viscosity, and crystallization temperature would result in a larger liquid slag consumption and the uneven infiltration of slag into the mold and shell gap that eventually leads to the irregular solidification of initial shell with a poor surface quality, such as slag entrapment and depressions as well as glaciation marks. Conversely, mold flux with a higher viscosity, basicity, and crystallization temperature would result in a smaller liquid slag consumption, which would cause the poor mold lubrication, the longitudinal shell surface defects, and drag marks.

Experimental investigation of CO2 condensation process using cryogen

NASA Astrophysics Data System (ADS)

Lee, Cheonkyu; Yoo, Junghyun; Lee, Jisung; Park, Hana; Jeong, Sangkwon

2014-01-01

Carbon dioxide (CO2) is one of the dominant gas molecules that causes greenhouse effect, i.e. global warming. Numerous studies have been carried out to regulate the emission of CO2 to reduce greenhouse gas. The liquid CO2 is a convenient form of transportation compared to high-pressurized gaseous CO2. Therefore, the direct liquefaction mechanism of CO2 at low temperature draws technical attention recently. In particular, cold thermal energy of Liquefied Natural Gas (LNG) could be a candidate to condense gaseous CO2, especially in the LNG powered ship. In this paper, the detailed direct condensation process of CO2 using LN2 with intermittent solidification is investigated. Pressurized CO2 at 600 kPa is directly liquefied in a vessel by liquid nitrogen which is supplied into the coiled tube heat exchanger inside the CO2 vessel. The heat exchanger temperature is controlled from 130 K to 205 K to regulate the solidification and sublimation of CO2 by duty control with cryogenic solenoid valve. The characteristics of CO2 condensation process with cryogen are analyzed from the measurement results. The results show that the solidification causes the significant degradation of CO2 condensation heat transfer. Finally, the condensation rate with and without solidification is compared.

Ultrasound Flow Mapping for the Investigation of Crystal Growth.

PubMed

Thieme, Norman; Bonisch, Paul; Meier, Dagmar; Nauber, Richard; Buttner, Lars; Dadzis, Kaspars; Patzold, Olf; Sylla, Lamine; Czarske, Jurgen

2017-04-01

A high energy conversion and cost efficiency are keys for the transition to renewable energy sources, e.g., solar cells. The efficiency of multicrystalline solar cells can be improved by enhancing the understanding of its crystallization process, especially the directional solidification. In this paper, a novel measurement system for the characterization of flow phenomena and solidification processes in low-temperature model experiments on the basis of ultrasound (US) Doppler velocimetry is described. It captures turbulent flow phenomena in two planes with a frame rate of 3.5 Hz and tracks the shape of the solid-liquid interface during multihour experiments. Time-resolved flow mapping is performed using four linear US arrays with a total of 168 transducer elements. Long duration measurements are enabled through an online, field-programmable gate array (FPGA)-based signal processing. Nine single US transducers allow for in situ tracking of a solid-liquid interface. Results of flow and solidification experiments in the model experiment are presented and compared with numerical simulation. The potential of the developed US system for measuring turbulent flows and for tracking the solidification front during a directional crystallization process is demonstrated. The results of the model experiments are in good agreement with numerical calculations and can be used for the validation of numerical models, especially the selection of the turbulence model.

Effect of Slag-Steel Reaction on the Initial Solidification of Molten Steel during Continuous Casting

NASA Astrophysics Data System (ADS)

Wang, Wanlin; Lou, Zhican; Zhang, Haihui

2018-06-01

With the mold simulator technique, the effect of slag-steel reaction on the initial shell solidification as well as the heat transfer and lubrication behavior of the infiltrated mold/shell slag film was studied in this article. The results showed that the Al2O3 content, the CaO/SiO2 ratio, and the viscosity of mold flux were increased with the progress of the slag-steel reaction during casting. The slag-steel reaction has two major effects on the initial shell solidification: one is increasing the mold heat flux and shell thickness by the decrease of slag film thickness. The other is the reduction of mold heat flux by the increase of crystal fraction in slag film. Mold flux with a lower basicity, viscosity, and crystallization temperature would result in a larger liquid slag consumption and the uneven infiltration of slag into the mold and shell gap that eventually leads to the irregular solidification of initial shell with a poor surface quality, such as slag entrapment and depressions as well as glaciation marks. Conversely, mold flux with a higher viscosity, basicity, and crystallization temperature would result in a smaller liquid slag consumption, which would cause the poor mold lubrication, the longitudinal shell surface defects, and drag marks.

Onset of solid state mantle convection and mixing during magma ocean solidification

NASA Astrophysics Data System (ADS)

Maurice, Maxime; Tosi, Nicola; Samuel, Henri; Plesa, Ana-Catalina; Hüttig, Christian; Breuer, Doris

2017-04-01

The fractional crystallization of a magma ocean can cause the formation of a compositional layering that can play a fundamental role for the subsequent long-term dynamics of the interior, for the evolution of geochemical reservoirs, and for surface tectonics. In order to assess to what extent primordial compositional heterogeneities generated by magma ocean solidification can be preserved, we investigate the solidification of a whole-mantle Martian magma ocean, and in particular the conditions that allow solid state convection to start mixing the mantle before solidification is completed. To this end, we performed 2-D numerical simulations in a cylindrical geometry. We treat the liquid magma ocean in a parametrized way while we self-consistently solve the conservation equations of thermochemical convection in the growing solid cumulates accounting for pressure-, temperature- and, where it applies, melt-dependent viscosity as well as parametrized yield stress to account for plastic yielding. By testing the effects of different cooling rates and convective vigor, we show that for a lifetime of the liquid magma ocean of 1 Myr or longer, the onset of solid state convection prior to complete mantle crystallization is likely and that a significant part of the compositional heterogeneities generated by fractionation can be erased by efficient mantle mixing.

Finite element analysis of the effect of a non-planar solid-liquid interface on the lateral solute segregation during unidirectional solidification

NASA Technical Reports Server (NTRS)

Carlson, F. M.; Chin, L.-Y.; Fripp, A. L.; Crouch, R. K.

1982-01-01

The effect of solid-liquid interface shape on lateral solute segregation during steady-state unidirectional solidification of a binary mixture is calculated under the assumption of no convection in the liquid. A finite element technique is employed to compute the concentration field in the liquid and the lateral segregation in the solid with a curved boundary between the liquid and solid phases. The computational model is constructed assuming knowledge of the solid-liquid interface shape; no attempt is made to relate this shape to the thermal field. The influence of interface curvature on the lateral compositional variation is investigated over a range of system parameters including diffusivity, growth speed, distribution coefficient, and geometric factors of the system. In the limiting case of a slightly nonplanar interface, numerical results from the finite element technique are in good agreement with the analytical solutions of Coriell and Sekerka obtained by using linear theory. For the general case of highly non-planar interface shapes, the linear theory fails and the concentration field in the liquid as well as the lateral solute segregation in the solid can be calculated by using the finite element method.

Solidification Dynamics of Spherical Drops in a Free Fall Environment

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Brush, Lucien N.

2006-01-01

Silver drops (99.9%, 4, 5, 7, and 9 mm diameter) were levitated, melted, and released to fall through Marshall Space Flight Center's 105 meter drop tube in helium - 6% hydrogen and pure argon atmospheres. By varying a drop s initial superheat the extent of solidification prior to impact ranged from complete to none during the approx. 4.6s of free fall time. Comparison of the experimental observations is made with numerical solutions to a model of the heat transfer and solidification kinetics associated with cooling of the drop during free fall, particularly with regard to the fraction of liquid transformed. Analysis reveals the relative importance ,of the initial parameters affecting the cooling and solidification rates within the drop. A discussion of the conditions under which the actual observations deviate from the assumptions used in the model is presented.

Solidification Dynamics of Metal Drops in a Free Fall Environment

NASA Technical Reports Server (NTRS)

Grugel, R. N.; Brush, L. N.; Curreri, Peter A. (Technical Monitor)

2001-01-01

Comparison of experimental observations were made with numerical solutions to a model of the heat transfer and solidification kinetics associated with the cooling of a molten drop during free fall, particularly with regard to the fraction of liquid transformed. Experimentally, silver drops (99.9%, 4-9 mm diameter) were levitated, melted, and released to fall through Marshall Space Flight Center's 105m drop tube in helium - 6% hydrogen and argon atmospheres. By systematically varying the drops initial superheat the extent of solidification prior to impact ranged from complete to none during the approximately 4.6s of free fall time. Analysis reveals the relative importance of the initial parameters affecting the cooling and solidification rates within the drop. A discussion of the conditions under which the actual observations deviate from the assumptions used in the model is presented.

Microstructure Formations in the Two-Phase Region of the Binary Peritectic Organic System TRIS-NPG

NASA Technical Reports Server (NTRS)

Mogeritsch, Johann; Ludwig, Andreas

2012-01-01

In order to prepare for an onboard experiment on the International Space Station (ISS), systematic directional solidification experiments with transparent hypoperitectic alloys were carried out at different solidification rates around the critical velocity for morphological stability of both solid phases. The investigations were done in the peritectic region of the binary transparent organic TRIS-NPG system where the formation of layered structures is expected to occur. The transparent appearance of the liquid and solid phase enables real time observations of the dynamic of pattern formation during solidification. The investigations show that frequently occurring nucleation events govern the peritectic solidification morphology which occurs at the limit of morphological stability. As a consequence, banded structures lead to coupled growth even if the lateral growth is much faster compared to the growth in pulling direction.

Effect of boundary heat flux on columnar formation in binary alloys: A phase-field study

NASA Astrophysics Data System (ADS)

Du, Lifei; Zhang, Peng; Yang, Shaomei; Chen, Jie; Du, Huiling

2018-02-01

A non-isothermal phase-field model was employed to simulate the columnar formation during rapid solidification in binary Ni-Cu alloy. Heat flux at different boundaries was applied to investigate the temperature gradient effect on the morphology, concentration and temperature distributions during directional solidifications. With the heat flux input/extraction from boundaries, coupling with latent heat release and initial temperature gradient, temperature distributions are significantly changed, leading to solute diffusion changes during the phase-transition. Thus, irregular columnar structures are formed during the directional solidification, and the concentration distribution in solid columnar arms could also be changed due to the different growing speeds and temperature distributions at the solid-liquid interfaces. Therefore, applying specific heat conditions at the solidifying boundaries could be an efficient way to control the microstructure during solidifications.

A model for the influence of pressure on the bulk modulus and the influence of temperature on the solidification pressure for liquid lubricants

NASA Technical Reports Server (NTRS)

Jacobson, B. O.; Vinet, P.

1986-01-01

Two pressure chambers, for compression experiments with liquids from zero to 2.2 GPa pressure, are described. The experimentally measured compressions are then compared to theoretical values given by an isothermal model of equation of state recently introduced for solids. The model describes the pressure and bulk modulus as a function of compression for different types of lubricants with a very high accuracy up to the pressure limit of the high pressure chamber used (2.2 GPa). In addition the influence of temperature on static solidification pressure was found to be a simple function of the thermal expansion of the fluid.

Undercooling-Induced macrosegregation in directional solidification

NASA Astrophysics Data System (ADS)

de Groh, Henry C.

1994-11-01

The accepted primary mechanism for causing macrosegregation in directional solidification (DS) is thermal and solutal convection in the liquid. This article demonstrates the effects of under-cooling and nucleation on macrosegregation and shows that undercooling, in some cases, can be the cause of end-to-end macrosegregation. Alloy ingots of Pb-Sn were directionally solidified upward and downward, with and without undercooling. A thermal gradient of about 5.1 K/cm and a cooling rate of 7.7 K/h were used. Crucibles of borosilicate glass, stainless steel with Cu bottoms, and fused silica were used. High undercoolings were achieved in the glass crucibles, and very low undercoolings were achieved in the steel/Cu crucible. During under-cooling, large, coarse Pb dendrites were found to be present. Large amounts of macrosegregation developed in the undercooled eutectic and hypoeutectic alloys. This segre-gation was found to be due to the nucleation and growth of primary Pb-rich dendrites, continued coarsening of Pb dendrites during undercooling of the interdendritic liquid, Sn enrichment of the liquid, and dendritic fragmentation and settling during and after recalescence. Eutectic ingots that solidified with no undercooling had no macrosegregation, because both Pb and Sn phases were effectively nucleated at the start of solidification, thus initiating the growth of solid of eutectic composition. It is thus shown that undercooling and single-phase nucleation can cause significant macrosegregation by increasing the amount of solute rejected into the liquid and by the movement of unattached dendrites and dendrite fragments, and that macrosegregation in excess of what would be expected due to diffusion transport is not necessarily caused by convection in the liquid.

Timing of mantle overturn during magma ocean solidification

NASA Astrophysics Data System (ADS)

Boukaré, C.-E.; Parmentier, E. M.; Parman, S. W.

2018-06-01

Solidification of magma oceans (MOs) formed early in the evolution of planetary bodies sets the initial condition for their evolution on much longer time scales. Ideal fractional crystallization would generate an unstable chemical stratification that subsequently overturns to form a stably stratified mantle. The simplest model of overturn assumes that cumulates remain immobile until the end of MO solidification. However, overturning of cumulates and thermal convection during solidification may act to reduce this stratification and introduce chemical heterogeneity on scales smaller than the MO thickness. We explore overturning of cumulates before the end of MO crystallization and the possible consequences for mantle structure and composition. In this model, increasingly dense iron-rich layers, crystallized from the overlying residual liquid MO, are deposited on a thickening cumulate layer. Overturn during solidification occurs if the dimensionless parameter, Rc, measuring the ratio of the MO time of crystallization τMO to the timescale associated with compositional overturn τov = μ / ΔρgH exceeds a threshold value. If overturn did not occur until after solidification, this implies that the viscosity of the solidified mantle must have been sufficiently high (possibly requiring efficient melt extraction from the cumulate) for a given rate of solidification. For the lunar MO, possible implications for the generation of the Mg-suites and mare basalt are suggested.

Stable solidification of silica-based ammonium molybdophosphate by allophane: Application to treatment of radioactive cesium in secondary solid wastes generated from fukushima.

PubMed

Wu, Yan; Lee, Chuan-Pin; Mimura, Hitoshi; Zhang, Xiaoxia; Wei, Yuezhou

2018-01-05

Silica-based ammonium molybdophosphate (AMP/SiO 2 ) is an absorbent material that can effectively remove Cs from radioactive-contaminated wastewater (RCW) generated by Fukushima nuclide accident. Pressing/sintering method was used for final disposal of secondary waste (spent absorbent) to achieve the volume reduction of AMP-Cs/SiO 2 (AMP/SiO 2 saturation adsorption of Cs) and stable solidification of Cs by adding natural allophane. The structure of AMP-Cs completely collapsed at approximately 700°C, and most Mo and P species in AMP sublimed. The optimal sintering temperature was estimated as 900°C. The stable crystalline phase of Cs 4 Al 4 Si 20 O 48 was recrystallized by the reaction of Cs 2 O, Al 2 O 3 , and SiO 2 , and the immobilization ratio of Cs was approximately 100%. The leachability of Cs from the sintered product in distilled water was approximately 0.41%. The high immobilization and low leachability of Cs were attributed to the excellent solidification properties of the sintered products of AMP-Cs/SiO 2 -allophane. Copyright © 2017 Elsevier B.V. All rights reserved.

Isentropic compression of liquid metals near the melt line

NASA Astrophysics Data System (ADS)

Seagle, Christopher; Porwitzky, Andrew

2017-06-01

A series of experiments designed to study the liquid metal response to isentropic compression have been conducted at Sandia's Z Pulsed Power Facility. Cerium and Tin have been shock melted by driving a quasi-ballistic flyer into the samples followed by a ramp compression wave generated by an increased driving magnetic field. The sound speed of the liquid metals has been investigated with the purpose of exploring possible solidification on ramp compression. Additional surface sensitive diagnostics have been employed to search for signatures of solidification at the window interface. Results of these experiments will be discussed in relation to the existing equation of state models and phase diagrams for these materials as well as future plans for exploring the response of liquid metals near the melt line. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

A 3D coupled hydro-mechanical granular model for the prediction of hot tearing formation

NASA Astrophysics Data System (ADS)

Sistaninia, M.; Phillion, A. B.; Drezet, J.-M.; Rappaz, M.

2012-07-01

A new 3D coupled hydro-mechanical granular model that simulates hot tearing formation in metallic alloys is presented. The hydro-mechanical model consists of four separate 3D modules. (I) The Solidification Module (SM) is used for generating the initial solid-liquid geometry. Based on a Voronoi tessellation of randomly distributed nucleation centers, this module computes solidification within each polyhedron using a finite element based solute diffusion calculation for each element within the tessellation. (II) The Fluid Flow Module (FFM) calculates the solidification shrinkage and deformation-induced pressure drop within the intergranular liquid. (III) The Semi-solid Deformation Module (SDM) is used to simulate deformation of the granular structure via a combined finite element / discrete element method. In this module, deformation of the solid grains is modeled using an elasto-viscoplastic constitutive law. (IV) The Failure Module (FM) is used to simulate crack initiation and propagation with the fracture criterion estimated from the overpressure required to overcome the capillary forces at the liquid-gas interface. The FFM, SDM, and FM are coupled processes since solid deformation, intergranular flow, and crack initiation are deeply linked together. The granular model predictions have been validated against bulk data measured experimentally and calculated with averaging techniques.

Advances in Pb-free solder microstructure control and interconnect design

DOE PAGES

Reeve, Kathlene N.; Holaday, John R.; Choquette, Stephanie M.; ...

2016-06-09

New electronics applications demanding enhanced performance and higher operating temperatures have led to continued research in the field of Pb-free solder designs and interconnect solutions. In this paper, recent advances in the microstructural design of Pb-free solders and interconnect systems were discussed by highlighting two topics: increasing β-Sn nucleation in Sn-based solders, and isothermally solidified interconnects using transient liquid phases. Issues in β-Sn nucleation in Sn-based solders were summarized in the context of Swenson’s 2007 review of the topic. Recent advancements in the areas of alloy composition manipulation, nucleating heterogeneities, and rapid solidification were discussed, and a proposal based onmore » a multi-faceted solidification approach involving the promotion of constitutional undercooling and nucleating heterogeneities was outlined for future research. The second half of the paper analyzed two different approaches to liquid phase diffusion bonding as a replacement for high-Pb solders, one based on the application of the pseudo-binary Cu-Ni-Sn ternary system, and the other on a proposed thermodynamic framework for identifying potential ternary alloys for liquid phase diffusion bonding. Furthermore, all of the concepts reviewed relied upon the fundamentals of thermodynamics, kinetics, and solidification, to which Jack Smith substantially contributed during his scientific career.« less

Preconcentration of valsartan by dispersive liquid-liquid microextraction based on solidification of floating organic drop and its determination in urine sample: Central composite design.

PubMed

Pebdani, Arezou Amiri; Shabani, Ali Mohammad Haji; Dadfarnia, Shayesteh; Talebianpoor, Mohammad Sharif; Khodadoust, Saeid

2016-05-01

In this work, a fast, easy, and efficient dispersive liquid-liquid microextraction method based on solidification of floating organic drop followed by high-performance liquid chromatography with UV detection was developed for the separation/preconcentration and determination of the drug valsartan. Experimental design was applied for the optimization of the effective variables (such as volume of extracting and dispersing solvents, ionic strength, and pH) on the extraction efficiency of valsartan from urine samples. The optimized values were 250.0 μL ethanol, 65.0 μL 1-dodecanol, 4.0% w/v NaCl, pH 3.8, 1.0 min extraction time, and 4.0 min centrifugation at 4000 rpm min(-1) . The linear response (r(2) = 0.997) was obtained in the range of 0.013-10.0 μg mL(-1) with a limit of detection of 4.0 ng mL(-1) and relative standard deviations of less than 5.0 % (n = 6). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Decide, design, and dewater de waste: A blueprint from Fitzpatrick

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robert, D.E.

1994-04-01

Using a different process to clean concentrated waste tanks at the James A. FitzPatrick nuclear power plant in New York saved nearly half million dollars. The plan essentially allowed processing concentrator bottoms as waste sludge (solidification versus dewatering) that could still meet burial ground requirements. The process reduced the volume from 802.2 to 55 cubic feet. This resin throwaway system eliminated chemicals in the radwaste systems and was designed to ease pressure on the pradwaste processing system, reduce waste and improve plant chemistry. This article discusses general aspects of the process.

The materials processing research base of the Materials Processing Center

NASA Technical Reports Server (NTRS)

Latanision, R. M.

1986-01-01

An annual report of the research activities of the Materials Processing Center of the Massachusetts Institute of Technology is given. Research on dielectrophoresis in the microgravity environment, phase separation kinetics in immiscible liquids, transport properties of droplet clusters in gravity-free fields, probes and monitors for the study of solidification of molten semiconductors, fluid mechanics and mass transfer in melt crystal growth, and heat flow control and segregation in directional solidification are discussed.

Immiscible phase incorporation during directional solidification of hypermonotectics

NASA Technical Reports Server (NTRS)

Andrews, J. Barry; Merrick, Roger A.

1993-01-01

Solidification processes in immiscible samples were investigated by directly observing the events taking place at the solid-liquid interface during directional solidification. Visualization of these events was made possible through the use of a transparent metal analog system and a temperature gradient stage assembly fitted to an optical microscope. The immiscible transparent analog system utilized was the succinonitrile-glycerol system. This system has been shown to exhibit the same morphological transitions as observed in metallic alloys of monotectic composition. Both monotectic and hypermonotectic composition samples were directionally solidified in order to gain an improved understanding of the manner in which the excess hypermonotectic liquid is incorporated into the solidifying structure. The processing conditions utilized prevented sedimentation of the excess hypermonotectic liquid by directionally solidifying the samples in very thin (13 microns), horizontally oriented cells. High thermal gradient to growth rate ratios (G/R) were used in an effort to prevent constitutional supercooling and the subsequent formation of L(sub 2) droplets in advance of the solidification front during the growth of fibrous composite structures. Results demonstrated that hypermonotectic composites could be produced in samples up to two weight percent off of the monotectic composition by using a G/R ratio greater than or equal to 4.6 x 10(exp 4) C(s)/mm(sup 2) to avoid constitutional supercooling. For hypermonotectic samples processed with G/R ratios below 4.6 x 10(exp 4) C(s)/mm(sup 2), constitutional supercooling occurred and resulted in slight interfacial instability. For these samples, two methods of incorporation of the hypermonotectic liquid were observed and are reported. The correlation between the phase spacing, lambda, and the growth rate, R, was examined and was found to obey a relationship generally associated with a diffusion controlled coupled growth process. For samples with compositions ranging from the monotectic composition up to 2 percent off of the monotectic composition, data indicated that the square of the phase spacing (lambda) varied linearly with the inverse of the growth rate (R).

Melting and solidification characteristics of a mixture of two types of latent heat storage material in a vessel

NASA Astrophysics Data System (ADS)

Yu, JikSu; Horibe, Akihiko; Haruki, Naoto; Machida, Akito; Kato, Masashi

2016-11-01

In this study, we investigated the fundamental melting and solidification characteristics of mannitol, erythritol, and their mixture (70 % by mass mannitol: 30 % by mass erythritol) as potential phase-change materials (PCMs) for latent heat thermal energy storage systems, specifically those pertaining to industrial waste heat, having temperatures in the range of 100-250 °C. The melting point of erythritol and mannitol, the melting peak temperature of their mixture, and latent heat were measured using differential scanning calorimetry. The thermal performance of the mannitol mixture was determined during melting and solidification processes, using a heat storage vessel with a pipe heat exchanger. Our results indicated phase-change (fusion) temperatures of 160 °C for mannitol and 113 and 150 °C for the mannitol mixture. Nondimensional correlation equations of the average heat transfer during the solidification process, as well as the temperature and velocity efficiencies of flowing silicon oil in the pipe and the phase-change material (PCM), were derived using several nondimensional parameters.

Use of rotation to suppress thermosolutal convection in directionally solidified binary alloys

NASA Technical Reports Server (NTRS)

Pearlstein, Arne J.

1994-01-01

Effects of rotation on onset of convection during plane-front directional solidification of Pb-Sn and the pseudobinary system mercury cadmium telluride (Hg(1-x)Cd(x)Te), and on dendritic solidification of Pb-Sn have been studied by means of linear stability analysis. Incorporating Coriolis and centrifugal accelerations into the momentum equation of Coriell et al., we find that under realistic processing conditions, a large degree of stabilization can be achieved using modest rotation rates for both Pb-Sn and mercury cadmium telluride. At a growth velocity of 5 micron/sec and nominal liquid-side temperature gradient of 200 K/cm in Pb-Sn, rotation at 500 rpm results in a hundredfold increase in the critical Sn concentration. Large increases in the maximum allowable growth velocity at fixed melt composition are also attainable with modest rotation rates. The effect is amplified under conditions of reduced gravitational acceleration. For Hg(1-x)Cd(x)Te, we have also studied the nonrotating case. The key differences are due to the existence of a composition range for Hg(1-x)Cd(x)Te in which the melt density has a local maximum as a function of temperature. When the melt solidifies by cooling from below, the liquid density may initially increase with distance above the interface, before ultimately decreasing as the melt temperature increases above the value at which the local density maximum occurs. In contrast to the Pb-Sn case where density depends monotonically on temperature and composition, for Hg(1-x)Cd(x)Te there exists a critical value of the growth velocity above which plane-front solidification is unstable for all bulk CdTe mole fractions. Again, rotation leads to significant inhibition of onset. We identify the predicted stabilization with the Taylor-Proudman mechanism by which rotation inhibits thermal convection in a single-component fluid heated from below. In a binary liquid undergoing solidification, rotation inhibits the onset of buoyancy-driven convection, and has no effect on the short-wavelength morphological instability. At large growth velocities, the plane-front interface between liquid and solid becomes unstable with respect to a morphological instability and solidification occurs dendritically, with a mushy zone of dendrites and interdendritic fluid separating the solid from the melt. For the Pb-Sn system, rotation substantially suppresses the onset of convection in the mushy zone and in the overlying liquid, holding open the promise that rotation can suppress freckling and other macrosegregation defects.

Simulating the Effect of Space Vehicle Environments on Directional Solidification of a Binary Alloy

NASA Technical Reports Server (NTRS)

Westra, D. G.; Heinrich, J. C.; Poirier, D. R.

2003-01-01

Space microgravity missions are designed to provide a microgravity environment for scientific experiments, but these missions cannot provide a perfect environment, due to vibrations caused by crew activity, on-board experiments, support systems (pumps, fans, etc.), periodic orbital maneuvers, and water dumps. Therefore, it is necessary to predict the impact of these vibrations on space experiments, prior to performing them. Simulations were conducted to study the effect of the vibrations on the directional solidification of a dendritic alloy. Finite element ca!cu!attie?ls were dme with a simd2titcr based on a continuum model of dendritic solidification, using the Fractional Step Method (FSM). The FSM splits the solution of the momentum equation into two steps: the viscous intermediate step, which does not enforce continuity; and the inviscid projection step, which calculates the pressure and enforces continuity. The FSM provides significant computational benefits for predicting flows in a directionally solidified alloy, compared to other methods presently employed, because of the efficiency gains in the uncoupled solution of velocity and pressure. finite differences, arises when the interdendritic liquid reaches the eutectic temperature and concentration. When a node reaches eutectic temperature, it is assumed that the solidification of the eutectic liquid continues at constant temperature until all the eutectic is solidified. With this approach, solidification is not achieved continuously across an element; rather, the element is not considered solidified until the eutectic isotherm overtakes the top nodes. For microgravity simulations, where the convection is driven by shrinkage, it introduces large variations in the fluid velocity. When the eutectic isotherm reaches a node, all the eutectic must be solidified in a short period, causing an abrupt increase in velocity. To overcome this difficulty, we employed a scheme to numerically predict a more accurate value for the rate of change of fraction of liquid as the liquid in an element solidifies. The new method enables us to contrast results of simulations in which the alloy is subjected to no gravity or a steady-state acceleration versus simulations when the alloy is subjected to vibration disturbances; therefore, the effect of vibration disturbances can be assessed more accurately. To assess the impact of these vibration-perturbations, transient accelerometer data from a space shuttle mission are used as inputs for the simulation model. These on-orbit acceleration data were obtained from the Microgravity Science Division at Glenn Research Center (GRC- MSD) and are applied to the buoyancy term of the momentum equation in a simulation of a Pb-5.8 wt. % Sb alloy that solidifies in a thermal gradient of 4000 K/m and a translation velocity of 3 p d s . Figure 2 shows the vertical velocity of a node that begins in the all-liquid region and subsequently solidifies; the vibrations are applied at 5000 seconds in this simulation. An important difficulty, common to all solidification models based on finite elements or 2 The magnitudes of the velocity oscillations that are vibration-induced are very small and acceptable. The biggest concern is whether the concentration of the liquid near the dendrite tips is distorted because of the vibration-induced perturbations. Results for this case show no concentration oscillations present in the all-liquid region.

Phase selection during crystallization of undercooled liquid eutectic lead-tin alloys

NASA Technical Reports Server (NTRS)

Fecht, H. J.

1991-01-01

During rapid solidification substantial amounts of undercooling are in general required for formation of metastable phases. Crystallization at varying levels of undercooling and melting of metastable phases were studied during slow cooling and heating of emulsified PB-Sn alloys. Besides the experimental demonstration of the reversibility of metastable phase equilibra, two different principal solidification paths have been identified and compared with the established metastable phase diagram and predictions from classical nucleation theory. The results suggest that the most probable solidification path is described by the 'step rule' resulting in the formation of metastable phases at low undercooling, whereas the stable eutectic phase mixture crystallizes without metastable phase formation at high undercooling.

Optimisation of industrial wastes reuse as construction materials.

PubMed

Collivignarelli, C; Sorlini, S

2001-12-01

This study concerns the reuse of two inorganic wastes, foundry residues and fly ashes from municipal solid waste incineration, as "recycled aggregate" in concrete production. This kind of reuse was optimised by waste treatment with the following steps: waste washing with water; waste stabilisation-solidification treatment with inorganic reagents; final grinding of the stabilised waste after curing for about 10-20 days. Both the treated wastes were reused in concrete production with different mix-designs. Concrete specimens were characterised by means of conventional physical-mechanical tests (compression, elasticity modulus, shrinkage) and different leaching tests. Experimental results showed that a good structural and environmental quality of "recycled concrete" is due both to a correct waste treatment and to a correct mix-design for concrete mixture.

Microwave-assisted liquid-liquid microextraction based on solidification of ionic liquid for the determination of sulfonamides in environmental water samples.

PubMed

Song, Ying; Wu, Lijie; Lu, Chunmei; Li, Na; Hu, Mingzhu; Wang, Ziming

2014-12-01

An easy, quick, and green method, microwave-assisted liquid-liquid microextraction based on solidification of ionic liquid, was first developed and applied to the extraction of sulfonamides in environmental water samples. 1-Ethy-3-methylimidazolium hexafluorophosphate, which is a solid-state ionic liquid at room temperature, was used as extraction solvent in the present method. After microwave irradiation for 90 s, the solid-state ionic liquid was melted into liquid phase and used to finish the extraction of the analytes. The ionic liquid and sample matrix can be separated by freezing and centrifuging. Several experimental parameters, including amount of extraction solvent, microwave power and irradiation time, pH of sample solution, and ionic strength, were investigated and optimized. Under the optimum experimental conditions, good linearity was observed in the range of 2.00-400.00 μg/L with the correlation coefficients ranging from 0.9995 to 0.9999. The limits of detection for sulfathiazole, sulfachlorpyridazine, sulfamethoxazole, and sulfaphenazole were 0.39, 0.33, 0.62, and 0.85 μg/L, respectively. When the present method was applied to the analysis of environmental water samples, the recoveries of the analytes ranged from 75.09 to 115.78% and relative standard deviations were lower than 11.89%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solidification Dynamics of Silver Drops in a Free Fall Environment

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Brush, Lucien N.

1999-01-01

Silver drops (99.9%, 4, 5, 7, and 9 mm diameter) were levitated, melted, and released to fall through Marshall Space Flight Center's 105m drop tube in helium - 6% hydrogen and pure argon atmospheres. By systematically varying the initial superheat condition of the drop the extent of solidification prior to impact ranged from complete to none during the approximately 4.6s of free fall time. Comparison of the experimental observations is made with numerical solutions to a model of the heat transfer and solidification kinetics associated with cooling of the drop during free fall, particularly with regard to the fraction of liquid transformed. Analysis reveals the relative importance of the initial parameters affecting the cooling and solidification rates within the drop. A discussion of the conditions under which the actual observations deviate from the assumptions used in the model is presented.

Atomic concentration effect on thermal properties during solidification of Pt-Rh alloy: A molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Yildiz, A. K.; Celik, F. A.

2017-04-01

The solidification process of Platinum-Rhodium alloy from liquid phase to solid state is investigated at the nano-scale by using Molecular Dynamics Simulation (MDS) for different atomic concentration ratios of Pt. The critical nucleus radius, the bond order parameter, interfacial free energies and total energy based on nucleation theory of the alloy are examined with respect to the temperature changes. The heat of fusion from high temperatures to low temperatures during solidification of the alloy system is determined from molecular dynamics simulation. The structural development is determined from the radial distribution function. It is observed from the results that the melting point of the alloy system decreases with increasing concentration of Pt and that variation of Pt ratio in the alloy shows a remarkable effect on solidification to understand the cooling process of thermal effects.

Cauchy integral method for two-dimensional solidification interface shapes

NASA Astrophysics Data System (ADS)

Siegel, R.; Sosoka, D. J.

1982-07-01

A method is developed to determine the shape of steady state solidification interfaces formed when liquid above its freezing point circulates over a cold surface. The solidification interface, which is at uniform temperature, will form in a shape such that the non-uniform energy convected to it is locally balanced by conduction into the solid. The interface shape is of interest relative to the crystal structure formed during solidification; regulating the crystal structure has application in casting naturally strengthened metallic composites. The results also pertain to phase-change energy storage devices, where the solidified configuration and overall heat transfer are needed. The analysis uses a conformal mapping technique to relate the desired interface coordinates to the components of the temperature gradient at the interface. These components are unknown because the interface shape is unknown. A Cauchy integral formulation provides a second relation involving the components, and a simultaneous solution yields the interface shape.

Injectable barriers for waste isolation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Persoff, P.; Finsterle, S.; Moridis, G.J.

In this paper the authors report laboratory work and numerical simulation done in support of development and demonstration of injectable barriers formed from either of two fluids: colloidal silica or polysiloxane. Two principal problems addressed here are control of gel time and control of plume emplacement in the vadose zone. Gel time must be controlled so that the viscosity of the barrier fluid remains low long enough to inject the barrier, but increases soon enough to gel the barrier in place. During injection, the viscosity must be low enough to avoid high injection pressures which could uplift or fracture themore » formation. To test the grout gel time in the soil, the injection pressure was monitored as grouts were injected into sandpacks. When grout is injected into the vadose zone, it slumps under the influence of gravity, and redistributes due to capillary forces as it gels. The authors have developed a new module for the reservoir simulator TOUGH2 to model grout injection into the vadose zone, taking into account the increase of liquid viscosity as a function of gel concentration and time. They have also developed a model to calculate soil properties after complete solidification of the grout. The numerical model has been used to design and analyze laboratory experiments and field pilot tests. The authors present the results of computer simulations of grout injection, redistribution, and solidification.« less

Convective and interfacial instabilities during solidification of succinonitrile containing ethanol

NASA Technical Reports Server (NTRS)

Schaefer, R. J.; Coriell, S. R.

1982-01-01

Even though slow convective flow is difficult to detect in solidifying metals, it can readily be observed in transparent materials by observing the motion of small neutrally buoyant particles. Succinonitrile, which solidifies with an unfaceted solid/liquid interface and has well characterized physical properties, is considered an excellent material for such studies. For studies of solute-induced convection, ethanol is a useful addition to succinonitrile since it has a lower density and a somewhat similar molecular structure. Samples of high purity and ethanol-doped succinonitrile are unidirectionally solidified in a vertical temperature gradient. Latex mimcrospheres 2 microns in diameter are suspended in the liquid to reveal the convective flow. Convective and morphological stability is observed as a function of solute concentration and growth velocity. These measurements are compared with theoretical calculations that predict the transition from stability to instability as a function of solidification conditions. The predicted transitions occur at low concentrations and solidification velocities; for this reason, extreme care must be taken in order to eliminate the effects of impurities or thermally induced convection.

Fluid mechanics and solidification investigations in low-gravity environments

NASA Technical Reports Server (NTRS)

Fichtl, G. H.; Lundquist, C. A.; Naumann, R. J.

1980-01-01

Fluid mechanics of gases and liquids and solidification processes were investigated under microgravity conditions during Skylab and Apollo-Soyuz missions. Electromagnetic, acoustic, and aerodynamic levitation devices, drop tubes, aircraft parabolic flight trajectories, and vertical sounding rockets were developed for low-g simulation. The Spacelab 3 mission will be carried out in a gravity gradient flight attitude; analyses of sources of vehicle dynamic accelerations with associated g-levels and angular rates will produce results for future specific experiments.

IJEMS: Iowa Joint Experiment in Microgravity Solidification

NASA Technical Reports Server (NTRS)

Bendle, John R.; Mashl, Steven J.; Hardin, Richard A.

1995-01-01

The Iowa Joint Experiment in Microgravity Solidification (IJEMS) is a cooperative effort between Iowa State University and the University of Iowa to study the formation of metal-matrix composites in a microgravity environment. Of particular interest is the interaction between the solid/liquid interface and the particles in suspension. The experiment is scheduled to fly on STS-69, Space Shuttle Endeavor on August 3, 1995. This project is unique in its heavy student participation and cooperation between the universities involved.

Fundamentals of Mold Free Casting: Experimental and Computational Studies

NASA Technical Reports Server (NTRS)

Tryggvason, Gretar; Ceccio, Steven

1997-01-01

Researchers are developing the technology of 'Ballistic Particle Manufacturing' (BPM) in which individual drops are precisely layered onto a substrate, and the drops are deposited so as to prevent splatting. These individual drops will ultimately be combined to form a net-shape, three-dimensional object. Our understanding of controlled drop deposition as applied to BPM is far from complete. Process parameters include the size and temperature of the liquid metal drop, its impact velocity and trajectory, and the condition and temperature of the substrate. Quantitative knowledge of the fluid mechanics and heat transfer of drop deposition and solidification are necessary to fully optimize the manufacturing process and to control the material microstructure of the final part. The object of this study is to examine the dynamics of liquid metal drops as they impinge upon a solid surface and solidify under conditions consistent with BPM (i.e. conditions which produce non-splatting drops). A program of both numerical simulations and experiments will be conducted. Questions this study will address include the following: How do the deformation and solidification of the drop depend on the properties of the fluid drop and the solid substrate? How does the presence of previously deposited drops affect the impingement and solidification process? How does the impingement of the new drop affect already deposited material? How does the cooling rate and solidification of the drops influence the material microstructure?

Experimental investigation of CO{sub 2} condensation process using cryogen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Cheonkyu; Yoo, Junghyun; Lee, Jisung

2014-01-29

Carbon dioxide (CO{sub 2}) is one of the dominant gas molecules that causes greenhouse effect, i.e. global warming. Numerous studies have been carried out to regulate the emission of CO{sub 2} to reduce greenhouse gas. The liquid CO{sub 2} is a convenient form of transportation compared to high-pressurized gaseous CO{sub 2}. Therefore, the direct liquefaction mechanism of CO{sub 2} at low temperature draws technical attention recently. In particular, cold thermal energy of Liquefied Natural Gas (LNG) could be a candidate to condense gaseous CO{sub 2}, especially in the LNG powered ship. In this paper, the detailed direct condensation process ofmore » CO{sub 2} using LN{sub 2} with intermittent solidification is investigated. Pressurized CO{sub 2} at 600 kPa is directly liquefied in a vessel by liquid nitrogen which is supplied into the coiled tube heat exchanger inside the CO{sub 2} vessel. The heat exchanger temperature is controlled from 130 K to 205 K to regulate the solidification and sublimation of CO{sub 2} by duty control with cryogenic solenoid valve. The characteristics of CO{sub 2} condensation process with cryogen are analyzed from the measurement results. The results show that the solidification causes the significant degradation of CO{sub 2} condensation heat transfer. Finally, the condensation rate with and without solidification is compared.« less

Innovative Solidification Techniques for Hazardous Wastes at Army Installations.

DTIC Science & Technology

1985-11-01

Fixed Hazardous Industrial Wastes and Flue Gas Desulfurization Sludges," Interim Report, EPA-600/2-76-182, US Environmental Protection Agency... flue gas . Flyash from coal-fired power plants is an almost entirely inorganic product having a glassy nature. Consequently, flyash by itself has little...effective- ness of alternative control strategies for reducing environmental impacts. 4. % 46 -"- °° ~~~~~...-.-..o

Green remediation and recycling of contaminated sediment by waste-incorporated stabilization/solidification.

PubMed

Wang, Lei; Tsang, Daniel C W; Poon, Chi-Sun

2015-03-01

Navigational/environmental dredging of contaminated sediment conventionally requires contained marine disposal and continuous monitoring. This study proposed a green remediation approach to treat and recycle the contaminated sediment by means of stabilization/solidification enhanced by the addition of selected solid wastes. With an increasing amount of contaminated sediment (20-70%), the 28-d compressive strength of sediment blocks decreased from greater than 10MPa to slightly above 1MPa. For augmenting the cement hydration, coal fly ash was more effective than lime and ground seashells, especially at low sediment content. The microscopic and spectroscopic analyses showed varying amounts of hydration products (primarily calcium hydroxide and calcium silicate hydrate) in the presence of coal fly ash, signifying the influence of pozzolanic reaction. To facilitate the waste utilization, cullet from beverage glass bottles and bottom ashes from coal combustion and waste incineration were found suitable to substitute coarse aggregate at 33% replacement ratio, beyond which the compressive strength decreased accordingly. The mercury intrusion porosimetry analysis indicated that the increase in the total pore area and average pore diameter were linearly correlated with the decrease of compressive strength due to waste replacement. All the sediment blocks complied with the acceptance criteria for reuse in terms of metal leachability. These results suggest that, with an appropriate mixture design, contaminated sediment and waste materials are useful resources for producing non-load-bearing masonry units or fill materials for construction uses. Copyright © 2014 Elsevier Ltd. All rights reserved.

Large Eddy Simulation of Transient Flow, Solidification, and Particle Transport Processes in Continuous-Casting Mold

NASA Astrophysics Data System (ADS)

Liu, Zhongqiu; Li, Linmin; Li, Baokuan; Jiang, Maofa

2014-07-01

The current study developed a coupled computational model to simulate the transient fluid flow, solidification, and particle transport processes in a slab continuous-casting mold. Transient flow of molten steel in the mold is calculated using the large eddy simulation. An enthalpy-porosity approach is used for the analysis of solidification processes. The transport of bubble and non-metallic inclusion inside the liquid pool is calculated using the Lagrangian approach based on the transient flow field. A criterion of particle entrapment in the solidified shell is developed using the user-defined functions of FLUENT software (ANSYS, Inc., Canonsburg, PA). The predicted results of this model are compared with the measurements of the ultrasonic testing of the rolled steel plates and the water model experiments. The transient asymmetrical flow pattern inside the liquid pool exhibits quite satisfactory agreement with the corresponding measurements. The predicted complex instantaneous velocity field is composed of various small recirculation zones and multiple vortices. The transport of particles inside the liquid pool and the entrapment of particles in the solidified shell are not symmetric. The Magnus force can reduce the entrapment ratio of particles in the solidified shell, especially for smaller particles, but the effect is not obvious. The Marangoni force can play an important role in controlling the motion of particles, which increases the entrapment ratio of particles in the solidified shell obviously.

Containerless solidification of BiFeO3 oxide under microgravity

NASA Astrophysics Data System (ADS)

Yu, Jianding; Arai, Yasutomo; Koshikawa, Naokiyo; Ishikawa, Takehito; Yoda, Shinichi

1999-07-01

Containerless solidification of BiFeO3 oxide has been carried out under microgravity with Electrostatic Levitation Furnace (ELF) aboard on the sounding rocket (TR-IA). It is a first containerless experiment using ELF under microgravity for studying the solidification of oxide insulator material. Spherical BiFeO3 sample with diameter of 5mm was heated by two lasers in oxygen and nitrogen mixing atmosphere, and the sample position by electrostatic force under pinpoint model and free drift model. In order to compare the solidification behavior in microgravity with on ground, solidification experiments of BiFeO3 in crucible and drop tube were carried out. In crucible experiment, it was very difficult to get single BiFeO3 phase, because segregation of Fe2O3 occured very fast and easily. In drop tube experiment, fine homogeneous BiFeO3 microstructure was obtained in a droplet about 300 μm. It implies that containerless processing can promote the phase selection in solidification. In microgravity experiment, because the heating temperature was lower than that of estimated, the sample was heated into Fe2O3+liquid phase region. Fe2O3 single crystal grew on the surface of the spherical sample, whose sample was clearly different from that observed in ground experiments.

Eutectic Formation During Solidification of Ni-Based Single-Crystal Superalloys with Additional Carbon

NASA Astrophysics Data System (ADS)

Wang, Fu; Ma, Dexin; Bührig-Polaczek, Andreas

2017-11-01

γ/ γ' eutectics' nucleation behavior during the solidification of a single-crystal superalloy with additional carbon was investigated by using directional solidification quenching method. The results show that the nucleation of the γ/ γ' eutectics can directly occur on the existing γ dendrites, directly in the remaining liquid, or on the primary MC-type carbides. The γ/γ' eutectics formed through the latter two mechanisms have different crystal orientations than that of the γ matrix. This suggests that the conventional Ni-based single-crystal superalloy castings with additional carbon only guarantee the monocrystallinity of the γ matrix and some γ/ γ' eutectics and, in addition to the carbides, there are other misoriented polycrystalline microstructures existing in macroscopically considered "single-crystal" superalloy castings.

A study of the effects of macrosegregation and buoyancy-driven flow in binary mixture solidification

NASA Technical Reports Server (NTRS)

Sinha, S. K.; Sundararajan, T.; Garg, V. K.

1993-01-01

A generalized anisotropic porous medium approach is developed for modelling the flow, heat and mass transport processes during binary mixture solidification. Transient predictions are obtained using FEM, coupled with an implicit time-marching scheme, for solidification inside a two-dimensional rectangular enclosure. A parametric study focusing attention on the effects of solutal buoyancy and thermal buoyancy is presented. It is observed that three parameters, namely the thermal Rayleigh number, the solutal Rayleigh number, and the relative density change parameter, significantly alter the flow fields in the liquid and the mushy regions. Depending upon the nature of these flow fields, the solute enrichment caused by macrosegregation may occur in the top or the bottom region of the enclosure.

Solidification under zero gravity: A Long Duration Exposure Facility (LDEF) experiment for an early space shuttle mission. [project planning

NASA Technical Reports Server (NTRS)

Bailey, J. A.

1976-01-01

Project planning for two series of simple experiments on the effect of zero gravity on the melting and freezing of metals and nonmetals is described. The experiments will be performed in the Long Duration Exposure Facility, and their purpose will be to study: (1) the general morphology of metals and nonmetals during solidification, (2) the location of ullage space (liquid-vapor interfaces), and (3) the magnitude of surface tension driven convection during solidification of metals and nonmetals. The preliminary design of the experiments is presented. Details of the investigative approach, experimental procedure, experimental hardware, data reduction and analysis, and anticipated results are given. In addition a work plan and cost analysis are provided.

Advancement of X-Ray Microscopy Technology and its Application to Metal Solidification Studies

NASA Technical Reports Server (NTRS)

Kaukler, William F.; Curreri, Peter A.

1996-01-01

The technique of x-ray projection microscopy is being used to view, in real time, the structures and dynamics of the solid-liquid interface during solidification. By employing a hard x-ray source with sub-micron dimensions, resolutions of 2 micrometers can be obtained with magnifications of over 800 X. Specimen growth conditions need to be optimized and the best imaging technologies applied to maintain x-ray image resolution, contrast and sensitivity. It turns out that no single imaging technology offers the best solution and traditional methods like radiographic film cannot be used due to specimen motion (solidification). In addition, a special furnace design is required to permit controlled growth conditions and still offer maximum resolution and image contrast.

Positive Ion Induced Solidification of He4

NASA Astrophysics Data System (ADS)

Moroshkin, P.; Lebedev, V.; Weis, A.

2009-03-01

We have observed bulk solidification of He4 induced by nucleation on positive alkali ions in pressurized superfluid helium. The ions are extracted into the liquid from alkali-doped solid He by a static electric field. The experiments prove the existence of charged particles in a solid structure composed of doped He that was recently shown to coexist with superfluid helium below the He solidification pressure. This supports our earlier suggestion that the Coulomb interaction of positive ions surrounded by a solid He shell (snowballs) and electrons trapped in spherical cavities (electron bubbles), together with surface tension, is responsible for the stability of that structure against melting. We have determined the density of charges in the sample by two independent methods.

Solidification of a liquid crystal: Morphologies and transitions. Ph.D. thesis, Simon Fraser University (Canada)

NASA Astrophysics Data System (ADS)

Hutter, Jeffrey Lee

When a material freezes, the form it takes depends on the solidification conditions. For instance, as the undercooling is increased, one typically sees solidification into less-ordered forms. The resulting growth modes appear to be generic, with qualitative similarities between systems whose microscopic details are quite dissimilar. I have used both optical and atomic-force microscopy to study the transitions between different growth morphologies during the solidification of a particular liquid crystal, 10 OCB. We have observed six different solidification modes, each with a distinct micro and meso structure. The front-velocity-vs.-undercooling curve has a discontinuity in its slope and, in some cases, in the curve itself at mode transitions, suggesting that these transitions are analogous to phase transitions. Such transitions have been seen in other systems, but no general rule has been found that can predict which morphology will be selected. We show that, contrary to intuition and widespread speculation, the fastest-growing mode is not always the one selected. One of the growth modes exhibited by 10 OCB is known as banded spherulitic growth. Spherulites have been seen in a wide variety of materials including minerals, pure elements, polymers, biomolecules, and metal alloys. However, despite a century of study, there is no generally accepted theory of spherulitic growth. In particular, the cause of the concentric banding seen in many spherulites remains a mystery. Our studies of banded spherulites in 10 OCB using both optical and atomic-force microscopy show that the bands are associated with a density modulation and thus are not merely the result of a birefringent effect, as is commonly believed. As the atomic-force microscope (AFM) is a relatively new tool, some time was spent studying its capabilities. We found that because the AFM resolution is largely determined by attractive forces between the tip of the probe and the sample, resolution can be improved by imaging in a suitable liquid medium. We also developed a simple method for calibrating AFM cantilevers--a crucial step in using the AFM to obtain quantitative force data. This work is presented in an appendix.

Space Processing Applications Rocket project, SPAR 2

NASA Technical Reports Server (NTRS)

1977-01-01

Experiment objectives, design/operational concepts, and final results are summarized for six materials science experiments conducted during the second space processing applications rocket mission flown by NASA. The individual experiments discussed are: (1) solidification of Pb-Sb eutectic; (2) feasibility of producing closed-cell metal foams; (3) direct observation of dendrite remelting and macrosegregation in castings; (4) agglomeration in immiscible liquids; (5) casting dispersion - strengthened composites at zero gravity; and (6) solidification behavior of Al-In alloys under zero gravity conditions.

Ultrasound-assisted dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet followed by gas chromatography for the determination of eight pyrethroid pesticides in tea samples.

PubMed

Hou, Xiaohong; Zheng, Xin; Zhang, Conglu; Ma, Xiaowei; Ling, Qiyuan; Zhao, Longshan

2014-10-15

A novel ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet method (UA-DLLME-SFO) combined with gas chromatography (GC) was developed for the determination of eight pyrethroid pesticides in tea for the first time. After ultrasound and centrifugation, 1-dodecanol and ethanol was used as the extraction and dispersive solvent, respectively. A series of parameters, including extraction solvent and volume, dispersive solvent and volume, extraction time, pH, and ultrasonic time influencing the microextraction efficiency were systematically investigated. Under the optimal conditions, the enrichment factors (EFs) were from 292 to 883 for the eight analytes. The linear ranges for the analytes were from 5 to 100μg/kg. The method recoveries ranged from 92.1% to 99.6%, with the corresponding RSDs less than 6.0%. The developed method was considered to be simple, fast, and precise to satisfy the requirements of the residual analysis of pyrethroid pesticides. Copyright © 2014 Elsevier B.V. All rights reserved.

Interaction of Multiple Particles with a Solidification Front: From Compacted Particle Layer to Particle Trapping.

PubMed

Saint-Michel, Brice; Georgelin, Marc; Deville, Sylvain; Pocheau, Alain

2017-06-13

The interaction of solidification fronts with objects such as particles, droplets, cells, or bubbles is a phenomenon with many natural and technological occurrences. For an object facing the front, it may yield various fates, from trapping to rejection, with large implications regarding the solidification pattern. However, whereas most situations involve multiple particles interacting with each other and the front, attention has focused almost exclusively on the interaction of a single, isolated object with the front. Here we address experimentally the interaction of multiple particles with a solidification front by performing solidification experiments of a monodisperse particle suspension in a Hele-Shaw cell with precise control of growth conditions and real-time visualization. We evidence the growth of a particle layer ahead of the front at a close-packing volume fraction, and we document its steady-state value at various solidification velocities. We then extend single-particle models to the situation of multiple particles by taking into account the additional force induced on an entering particle by viscous friction in the compacted particle layer. By a force balance model this provides an indirect measure of the repelling mean thermomolecular pressure over a particle entering the front. The presence of multiple particles is found to increase it following a reduction of the thickness of the thin liquid film that separates particles and front. We anticipate the findings reported here to provide a relevant basis to understand many complex solidification situations in geophysics, engineering, biology, or food engineering, where multiple objects interact with the front and control the resulting solidification patterns.

Fluid flow in solidifying monotectic alloys

NASA Technical Reports Server (NTRS)

Ecker, A.; Frazier, D. O.; Alexander, J. Iwan D.

1989-01-01

Use of a two-wavelength holographic technique results in a simultaneous determination of temperature and composition profiles during directional solidification in a system with a miscibility gap. The relationships among fluid flow, phase separation, and mass transport during the solidification of the monotectic alloy are discussed. The primary sources of fluid motion in this system are buoyancy and thermocapillary forces. These forces act together when phase separation results in the formation of droplets (this occurs at the solid-liquid interface and in the bulk melt). In the absence of phase separation, buoyancy results from density gradients related to temperature and compositional gradients in the single-phase bulk melt. The effects of buoyancy are especially evident in association with water- or ethanol-rich volumes created at the solid-liquid growth interface.

Minimizing Segregation during the Controlled Directional Solidification of Dendric Alloys

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Fedoseyev, Alex; Kim, Shin-Woo

2003-01-01

Gravity-driven convection induced in the liquid by density gradients of temperature or composition disrupts uniform dendritic growth during controlled directional solidification and promotes severe macrosegregation. The solute-rich region about the dendrite tip appears to play a pivotal role in channel initiation. Allen and Hunt referred to this region as an "initial transient" or dynamic region constituting steep concentration gradients. Experimental investigation also point to the role the tip region plays in developing microstructure. Hellawell and co-workers showed that flow-through dendritic channels could be effectively disrupted, and segregation minimized, during the gradient freezing of bulk castings by rotating the melt through a slight angle with respect to Earth's gravity vector. Adapting this principle to controlled directional solidification, it has been shown" that segregation in dendritic alloys can be minimized, and properties improved, by processing the sample near horizontal in conjunction with a slow axial rotation of the crucible. It is postulated that the observed microstructural uniformity arises by maintaining the developing solute field about the dendrite tip. Solute rejected during vertical directional solidification will rise or sink parallel to the primary dendrite arms during axial rotation setting the stage for accumulation, instabilities, and segregation. In contrast, during horizontal growth, the rejected solute will sink or rise perpendicular to the primary dendrite. Now, in the presence of a slight axial rotation, solute that was initially sinking (or rising) will find itself above (or below) its parent dendrite, i.e., still about the tip region. The following is intended to experimentally demonstrate the viability of this concept in coordination with a model that gives predictive insight regarding solute distribution about growing dendrites. Alloys based on the lead-tin eutectic system were used in this study. The system is well characterized, the constituent metals are available in a very pure form, and the thermophysical properties are well known. During solidification of hypoeutectic alloys, e.g., 55 wt pct Pb, the primary dendrites reject the less dense tin, and for the hypereutectic alloys, e.g., 75 wt pct Sn, the primary dendrites reject denser lead. Alloys were prepared by melting appropriate amounts of lead and tin in a glass crucible after which the homogeneous liquid was sucked directly into 5-mm i.d. glass tubes. The sample tube, containing approximately 30 cm of alloy, was then mechanically driven into the directional solidification furnace assembly and positioned such that approx. 20 cm of the sample was remelted. Subsequently, directional solidification was initiated by withdrawing the sample through a water-cooled jacket at a constant growth velocity of 2 ,microns/s. After 5 to 6 cm of growth, the sample was quickly removed from the furnace and quenched in a water bath to preserve the solid-liquid interface. Samples were directionally solidified vertically upward, nearly horizontally, and some in conjunction with an applied axial rotation of the crucible. Temperature gradients at the solid-liquid interface were measured with an in-siru K-type thermocouple. Solidified samples were cut perpendicular and parallel to the growth direction and conventionally prepared for microscopic examination.

Air-assisted liquid-liquid microextraction using floating organic droplet solidification for simultaneous extraction and spectrophotometric determination of some drugs in biological samples through chemometrics methods

NASA Astrophysics Data System (ADS)

Farahmand, Farnaz; Ghasemzadeh, Bahar; Naseri, Abdolhossein

2018-01-01

An air assisted liquid-liquid microextraction by applying the solidification of a floating organic droplet method (AALLME-SFOD) coupled with a multivariate calibration method, namely partial least squares (PLS), was introduced for the fast and easy determination of Atenolol (ATE), Propanolol (PRO) and Carvedilol (CAR) in biological samples via a spectrophotometric approach. The analytes would be extracted from neutral aqueous solution into 1-dodecanol as an organic solvent, using AALLME. In this approach a low-density solvent with a melting point close to room temperature was applied as the extraction solvent. The emulsion was immediately formed by repeatedly pulling in and pushing out the aqueous sample solution and extraction solvent mixture via a 10-mL glass syringe for ten times. After centrifugation, the extractant droplet could be simply collected from the aqueous samples by solidifying the emulsion at a lower than the melting point temperature. In the next step, analytes were back extracted simultaneously into the acidic aqueous solution. Derringer and Suich multi-response optimization were utilized for simultaneous optimizing the parameters of three analytes. This method incorporates the benefits of AALLME and dispersive liquid-liquid microextraction considering the solidification of floating organic droplets (DLLME-SFOD). Calibration graphs under optimized conditions were linear in the range of 0.30-6.00, 0.32-2.00 and 0.30-1.40 μg mL- 1 for ATE, CAR and PRO, respectively. Other analytical parameters were obtained as follows: enrichment factors (EFs) were found to be 11.24, 16.55 and 14.90, and limits of detection (LODs) were determined to be 0.09, 0.10 and 0.08 μg mL- 1 for ATE, CAR and PRO, respectively. The proposed method will require neither a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly.

Air-assisted liquid-liquid microextraction using floating organic droplet solidification for simultaneous extraction and spectrophotometric determination of some drugs in biological samples through chemometrics methods.

PubMed

Farahmand, Farnaz; Ghasemzadeh, Bahar; Naseri, Abdolhossein

2018-01-05

An air assisted liquid-liquid microextraction by applying the solidification of a floating organic droplet method (AALLME-SFOD) coupled with a multivariate calibration method, namely partial least squares (PLS), was introduced for the fast and easy determination of Atenolol (ATE), Propanolol (PRO) and Carvedilol (CAR) in biological samples via a spectrophotometric approach. The analytes would be extracted from neutral aqueous solution into 1-dodecanol as an organic solvent, using AALLME. In this approach a low-density solvent with a melting point close to room temperature was applied as the extraction solvent. The emulsion was immediately formed by repeatedly pulling in and pushing out the aqueous sample solution and extraction solvent mixture via a 10-mL glass syringe for ten times. After centrifugation, the extractant droplet could be simply collected from the aqueous samples by solidifying the emulsion at a lower than the melting point temperature. In the next step, analytes were back extracted simultaneously into the acidic aqueous solution. Derringer and Suich multi-response optimization were utilized for simultaneous optimizing the parameters of three analytes. This method incorporates the benefits of AALLME and dispersive liquid-liquid microextraction considering the solidification of floating organic droplets (DLLME-SFOD). Calibration graphs under optimized conditions were linear in the range of 0.30-6.00, 0.32-2.00 and 0.30-1.40μg mL -1 for ATE, CAR and PRO, respectively. Other analytical parameters were obtained as follows: enrichment factors (EFs) were found to be 11.24, 16.55 and 14.90, and limits of detection (LODs) were determined to be 0.09, 0.10 and 0.08μg mL -1 for ATE, CAR and PRO, respectively. The proposed method will require neither a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly. Copyright © 2017 Elsevier B.V. All rights reserved.

Containerless Liquid-Phase Processing of Ceramic Materials

NASA Technical Reports Server (NTRS)

Weber, J. K. Richard (Principal Investigator); Nordine, Paul C.

1996-01-01

The present project builds on the results of research supported under a previous NASA grant to investigate containerless liquid-phase processing of molten ceramic materials. The research used an aero-acoustic levitator in combination with cw CO2 laser beam heating to achieve containerless melting, superheating, undercooling, and solidification of poorly-conducting solids and liquids. Experiments were performed on aluminum oxide, binary aluminum oxide-silicon dioxide materials, and oxide superconductors.

Cytogenotoxicity of sewage sludge leachate before and after calcium oxide-based solidification in human lymphocytes.

PubMed

Gajski, Goran; Oreščanin, Višnja; Garaj-Vrhovac, Vera

2011-07-01

Present study aimed to establish the chemical composition of sewage sludge leachate before/after calcium oxide-based solidification using energy dispersive X-ray fluorescence (EDXRF). The other aim was to determine leachate effects on human lymphocyte and DNA integrity in vitro using a battery of bioassays (DNA diffusion assay, micronucleus test and comet assay) to determine effects of those complex mixtures of elements on cell and DNA integrity. EDXRF showed that nickel concentration in the leachate of untreated sludge was 18.5 times higher than the upper permissible limit for inert waste landfills. Other elements were kept below the permissible values. After sludge solidification, leachate concentrations of Cr, Mn, Fe, Ni, Cu, Zn, and Pb dropped 1.6, 2.7, 37, 5.9, 3.2, 7.8, and 2.6 times, respectively. Untreated sludge leachate was cytogenotoxic to lymphocytes, and may lead to adverse effects on the exposed human populations, but calcium oxide-based solidification reduced these effects in significant manner. Copyright © 2011 Elsevier Inc. All rights reserved.

Application of dispersion-solidification liquid-liquid microextraction for the determination of triazole fungicides in environmental water samples by high-performance liquid chromatography.

PubMed

Wang, Chun; Wu, Qiuhua; Wu, Chunxia; Wang, Zhi

2011-01-15

A simple, rapid and environmentally friendly method has been developed for the determination of four triazole fungicides (myclobutanil, tebuconazole, triadimenol, hexaconazole) in water samples by dispersion-solidification liquid-liquid microextraction coupled with high performance liquid chromatography-diode array detection. Several variables that affect the extraction efficiencies, including the type and volume of the extraction solvent and dispersive solvent, extraction time, effect of pH and salt addition, were investigated and optimized. Under the optimum conditions, the proposed method is sensitive and shows a good linearity within a range of 0.5-200 ng mL(-1), with the correlation coefficients (r) varying from 0.9992 to 0.9998. High enrichment factors were achieved ranging from 190 to 450. The recoveries of the target analytes from water samples at spiking levels of 1.0, 5.0 and 50.0 ng mL(-1) were between 84.8% and 110.2%. The limits of detection (LODs) for the analytes were ranged in 0.06-0.1 ng mL(-1), and the relative standard deviations (RSD) varied from 3.9% to 5.7%. The proposed method has been successfully applied for the determination of the triazole fungicides in real water samples. Copyright © 2010 Elsevier B.V. All rights reserved.

Effect of Temperature and Sheet Temper on Isothermal Solidification Kinetics in Clad Aluminum Brazing Sheet

NASA Astrophysics Data System (ADS)

Benoit, Michael J.; Whitney, Mark A.; Wells, Mary A.; Winkler, Sooky

2016-09-01

Isothermal solidification (IS) is a phenomenon observed in clad aluminum brazing sheets, wherein the amount of liquid clad metal is reduced by penetration of the liquid clad into the core. The objective of the current investigation is to quantify the rate of IS through the use of a previously derived parameter, the Interface Rate Constant (IRC). The effect of peak temperature and initial sheet temper on IS kinetics were investigated. The results demonstrated that IS is due to the diffusion of silicon (Si) from the liquid clad layer into the solid core. Reduced amounts of liquid clad at long liquid duration times, a roughened sheet surface, and differences in resolidified clad layer morphology between sheet tempers were observed. Increased IS kinetics were predicted at higher temperatures by an IRC model as well as by experimentally determined IRC values; however, the magnitudes of these values are not in good agreement due to deficiencies in the model when applied to alloys. IS kinetics were found to be higher for sheets in the fully annealed condition when compared with work-hardened sheets, due to the influence of core grain boundaries providing high diffusivity pathways for Si diffusion, resulting in more rapid liquid clad penetration.

High-Speed Synchrotron X-ray Imaging Studies of the Ultrasound Shockwave and Enhanced Flow during Metal Solidification Processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Dongyue; Lee, Tung Lik; Khong, Jia Chuan

2015-03-31

The highly dynamic behavior of ultrasonic bubble implosion in liquid metal, the multiphase liquid metal flow containing bubbles and particles, and the interaction between ultrasonic waves and semisolid phases during solidification of metal were studied in situ using the complementary ultrafast and high-speed synchrotron X-ray imaging facilities housed, respectively, at the Advanced Photon Source, Argonne National Laboratory, US, and Diamond Light Source, UK. Real-time ultrafast X-ray imaging of 135,780 frames per second revealed that ultrasonic bubble implosion in a liquid Bi-8 wt pctZn alloy can occur in a single wave period (30 kHz), and the effective region affected by themore » shockwave at implosion was 3.5 times the original bubble diameter. Furthermore, ultrasound bubbles in liquid metal move faster than the primary particles, and the velocity of bubbles is 70 similar to 100 pct higher than that of the primary particles present in the same locations close to the sonotrode. Ultrasound waves can very effectively create a strong swirling flow in a semisolid melt in less than one second. The energetic flow can detach solid particles from the liquid-solid interface and redistribute them back into the bulk liquid very effectively.« less

Solidification Technologies for Restoration of Sites Contaminated with Hazardous Wastes

DTIC Science & Technology

1998-01-01

OR1 -5- 10-0 1 to DOE, Office of Technology Development. Kalb, P., J. Heiser, and P. Colombo, 1991. “ Modified Sulfur Cement Encapsulation of Mixed...Incinerator Ash Waste Encapsulated in Modified Sulfur Cement,” Brookhaven National Laboratory for US DOE Contract No DE-AC02-76CD000 16. Lin, S...wastes, 2 modified sulfur cement, 22,72 47,49,5 I , 53,55,57,59,61,63,65 obsidian, 35,36,38,39,40,32,43 organic binders, 7,25 organic polymer binders

Importance of microscopy in durability studies of solidified and stabilized contaminated soils

USGS Publications Warehouse

Klich, I.; Wilding, L.P.; Drees, L.R.; Landa, E.R.

1999-01-01

Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or achieved in a laboratory warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or archived in a laboratory, warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.

The grape cluster, metal particle 63344,1. [in lunar coarse fines

NASA Technical Reports Server (NTRS)

Goldstein, J. I.; Axon, H. J.; Agrell, S. O.

1975-01-01

The grape cluster metal particle 63344,1 found in lunar coarse fines is examined using the scanning electron microscope (SEM), electron microprobe, and an optical microscope. This metal particle is approximately 0.5 cm in its largest dimension and consists of hundreds of metallic globules welded together to form a structure somewhat like a bunch of grapes. Electron microprobe analysis for Fe, Ni, Co, P, and S in the metal was carried out using wavelength dispersive detectors. No primary solidification structure is observed in the globules, and the particle is slow cooled from the solidification temperature (nearly 1300 C) taking days to probably months to reach 600 C. Two mechanisms for the formation of globules are proposed. One mechanism involves the primary impact of an iron meteorite which produces a metallic liquid and vapor phase. The second mechanism involves the formation of a liquid pool of metal after impact of an iron meteorite projectile followed by a secondary impact in the liquid metal pool.

The volume change during solidification

NASA Technical Reports Server (NTRS)

Rittich, M.

1985-01-01

The liquid-solid phase transformation of solidifying metallic melts is accompanied by a volume change Delta-Vm. This volume change produces a gravity-independent microscopic flow near the solidification front. In a ground-based laboratory, solidification processes are also affected by convection due to temperature and concentration gradients. A quantitative evaluation of the effects of these flows on the formation of structure requires reproducible values of Delta-Vm. Alloys with Delta-Vm = 0 would be best suited for such an evaluation, while alloys with a constant value for Delta-Vm are still usable. Another requirement is related to a solidus-liquidus interval which is as small as possible. One-phase alloys, which would be particularly well suited, could not be found. For these reasons, alloys which solidify in two phases, as for example eutectics, have been considered, taking into account the Al-Ge system. Attention is given to the volume change at the melting point, the measurement of this change, the volume change at solidification, and applications to terrestrial technology.

Thermosolutal convection and macrosegregation in dendritic alloys

NASA Technical Reports Server (NTRS)

Poirier, David R.; Heinrich, J. C.

1993-01-01

A mathematical model of solidification, that simulates the formation of channel segregates or freckles, is presented. The model simulates the entire solidification process, starting with the initial melt to the solidified cast, and the resulting segregation is predicted. Emphasis is given to the initial transient, when the dendritic zone begins to develop and the conditions for the possible nucleation of channels are established. The mechanisms that lead to the creation and eventual growth or termination of channels are explained in detail and illustrated by several numerical examples. A finite element model is used for the simulations. It uses a single system of equations to deal with the all-liquid region, the dendritic region, and the all-solid region. The dendritic region is treated as an anisotropic porous medium. The algorithm uses the bilinear isoparametric element, with a penalty function approximation and a Petrov-Galerkin formulation. The major task was to develop the solidification model. In addition, other tasks that were performed in conjunction with the modeling of dendritic solidification are briefly described.

Resistivity Distribution of Multicrystalline Silicon Ingot Grown by Directional Solidification

NASA Astrophysics Data System (ADS)

Sun, S. H.; Tan, Y.; Dong, W.; Zhang, H. X.; Zhang, J. S.

2012-06-01

The effects of impurities on the resistivity distribution and polarity of multicrystalline silicon ingot prepared by directional solidification were investigated in this article. The shape of the equivalence line of the resistivity in the vertical and cross sections was determined by the solid-liquid interface. Along the solidification height of silicon ingot, the conductive type changed from p-type in the lower part of the silicon ingot to n-type in the upper part of the silicon ingot. The resistivity in the vertical section of the silicon ingot initially increased along the height of the solidified part, and reached its maximum at the polarity transition position, then decreased rapidly along the height of solidified part and approached zero on the top of the ingot because of the accumulation of impurities. The variation of resistivity in the vertical section of the ingot has been proven to be deeply relevant to the distribution of Al, B, and P in the growth direction of solidification.

Direct Observation of Pore Formation and Bubble Mobility during Controlled Melting and Resolidification in Microgravity

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Anilkumar, A. V.; Lee, C. P.

2004-01-01

Detailed studies on the controlled melting and subsequent re-solidification of succinonitrile were conducted in the microgravity environment aboard the International Space Station (ISS) using the PFMI apparatus (Pore Formation and Mobility Investigation) located in the ISS glovebox facility (GBX). Samples were initially prepared on ground by filling glass tubes, 1 cm ID and approximately 30 cm in length, with pure succinonitrile (SCN) under 450 millibar of nitrogen. During Space processing, experimental parameters like temperature gradient and translation speed, for melting and solidification, were remotely monitored and controlled from the ground Telescience Center (TSC) at the Marshall Space Flight Center. Real time visualization during controlled melting revealed bubbles of different sizes initiating at the solid/liquid interface, and traveling up the temperature gradient ahead of them. Subsequent controlled re-solidification of the SCN revealed the details of porosity formation and evolution. A preliminary analysis of the melt back and re- solidification and its implications to future microgravity materials processing is presented and discussed.

Numerical solution of problems concerning the thermal convection of a variable-viscosity liquid

NASA Astrophysics Data System (ADS)

Zherebiatev, I. F.; Lukianov, A. T.; Podkopaev, Iu. L.

A stabilizing-correction scheme is constructed for integrating the fourth-order equation describing the dynamics of a viscous incompressible liquid. As an example, a solution is obtained to the problem of the solidification of a liquid in a rectangular region with allowance for convective energy transfer in the liquid phase as well as temperature-dependent changes of viscosity. It is noted that the proposed method can be used to study steady-state problems of thermal convection in ingots obtained through continuous casting.

A rapid and simple pretreatment method for benzoylurea insecticides in honey samples using in-syringe dispersive liquid-liquid microextraction based on the direct solidification of ionic liquids.

PubMed

Wang, Huazi; Hu, Lu; Li, Wanzhen; Lu, Runhua; Zhang, Sanbing; Zhou, Wenfeng; Gao, Haixiang

2016-11-04

A pretreatment method using in-syringe dispersive liquid-liquid microextraction based on the direct solidification of ionic liquids before high performance liquid chromatography analysis was developed for the determination of benzoylurea insecticides (BUs) in honey samples. The hydrophobic ionic liquid [N 4444 ][PF 6 ], formed in situ by the hydrophilic ionic liquid [N 4444 ]Cl and the ion exchange reagent KPF 6 , was used to extract the target analytes. The entire extraction procedure was performed in a syringe. The extractant was solidified at room temperature and collected using a nylon membrane filter. This technique did not require a dispersive solvent, vortex mixer, ultrasound bath, or centrifugation. The parameters affecting the extraction efficiency were investigated through an experimental design. Under the optimal conditions, the limits of detection for the four BUs varied from 0.21 to 0.42μgL -1 in solution (2.1-4.2μgkg -1 in honey). Good linearities were obtained in the range of 2-300μgL -1 , with coefficients of determination greater than 0.999. The recoveries of the four BUs ranged from 80.94% to 84.59%. The intra-day (n=3) and inter-day (n=3) relative standard deviations were less than 5.08%. Finally, the proposed method was applied to the determination of BUs in commercial honey samples with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

Chromatographic separation of the platinum-group elements, gold, base metals and sulfur during degassing of a compacting and solidifying igneous crystal pile

NASA Astrophysics Data System (ADS)

Boudreau, A. E.; Meurer, W. P.

The major platinum-group elements (PGE) concentrations in layered intrusions are typically associated with zones in which the sulfide abundance begins to increase. In a number of layered intrusions, there is also a distinct stratigraphic separation in the peak concentrations of the PGE from those of the base metals, gold and sulfur through these zones. These stratigraphic ``offsets'' are characterized by a lower, typically S-poor, Pt- and Pd-enriched zone overlain by a zone enriched in the base metals, S and Au. The separations amount to a few decimeters to several tens of meters. In some instances, the high Pt and Pd concentrations are associated with trivial amounts of sulfide. Theoretical considerations suggest that these offsets can be modeled as chromatographic peaks that develop during an infiltration/reaction process. Using Pd as a typical PGE and Cu as a typical base metal, a numeric model is developed that illustrates how metal separations can develop in a vapor-refining zone as fluid evolved during solidification of a cumulus pile leaches sulfide and redeposits it higher in the crystal pile. The solidification/degassing ore-element transport is coupled with a compaction model for the crystal pile. Solidification resulting from conductive cooling through the base of the compacting column leads to an increasing volatile concentration in the intercumulus liquid until it reaches fluid saturation. Separation and upward migration of this fluid lead to an upward-migrating zone of increasingly higher bulk water contents as water degassed from underlying cumulates enriches overlying, fluid-undersaturated interstitial liquids. Sulfide is resorbed from the degassing regions and is reprecipitated in these vapor-undersaturated interstitial liquids, producing a zone of relatively high modal sulfide that also migrates upward with time. Owing to its strong preference for sulfide, Pd is not significantly mobile until all sulfide is resorbed. The result is a zone of increasing PGE enrichment that follows the sulfide resorption front as solidification/degassing continues. In detail, the highest Pd concentrations occur stratigraphically below the peak in S and base metals. The high Pd/S ratio mimics values conventionally interpreted as the result of high (silicate liquid)/(sulfide liquid) mass ratios (``R'' values). However, in this case, the high Pd/S ratio is the result of a chromatographic/reaction front enrichment and not a magmatic sulfide-saturation event.

Cellular Automaton Study of Hydrogen Porosity Evolution Coupled with Dendrite Growth During Solidification in the Molten Pool of Al-Cu Alloys

NASA Astrophysics Data System (ADS)

Gu, Cheng; Wei, Yanhong; Yu, Fengyi; Liu, Xiangbo; She, Lvbo

2017-09-01

Welding porosity defects significantly reduce the mechanical properties of welded joints. In this paper, the hydrogen porosity evolution coupled with dendrite growth during solidification in the molten pool of Al-4.0 wt pct Cu alloy was modeled and simulated. Three phases, including a liquid phase, a solid phase, and a gas phase, were considered in this model. The growth of dendrites and hydrogen gas pores was reproduced using a cellular automaton (CA) approach. The diffusion of solute and hydrogen was calculated using the finite difference method (FDM). Columnar and equiaxed dendrite growth with porosity evolution were simulated. Competitive growth between different dendrites and porosities was observed. Dendrite morphology was influenced by porosity formation near dendrites. After solidification, when the porosities were surrounded by dendrites, they could not escape from the liquid, and they made pores that existed in the welded joints. With the increase in the cooling rate, the average diameter of porosities decreased, and the average number of porosities increased. The average diameter of porosities and the number of porosities in the simulation results had the same trend as the experimental results.

Adapting and Modifying the Apparatus for Students to Accurately Determine the Freezing Point of a Solvent and Solution

ERIC Educational Resources Information Center

Li, Shirong; Guo, Jianzhong; Wang, Kewang; Chen, Lin; Hu, Daodao; Bai, Yunshan

2017-01-01

An improved apparatus for measuring freezing points has been developed. Compared to the traditional Beckmann freezing point instrument, the improved one overcame prior difficulties with solidification of liquid and made the solid-liquid equilibrium reversible with heat compensation from a heating tube. The reliability and accuracy were carefully…

Adjustable Lid Aids Silicon-Ribbon Growth

NASA Technical Reports Server (NTRS)

Mchugh, J. P.; Steidensticker, R. G.; Duncan, C. S.

1985-01-01

Closely-spaced crucible cover speeds up solidification. Growth rate of dendritic-web silicon ribbon from molten silicon increased by controlling distance between crucible susceptor lid and liquid/solid interface. Lid held in relatively high position when crucible newly filled with chunks of polycrystalline silicon. As silicon melts and forms pool of liquid at lower level, lid gradually lowered.

Metastable and unstable cellular solidification of colloidal suspensions

NASA Astrophysics Data System (ADS)

Deville, Sylvain; Maire, Eric; Bernard-Granger, Guillaume; Lasalle, Audrey; Bogner, Agnès; Gauthier, Catherine; Leloup, Jérôme; Guizard, Christian

2009-12-01

Colloidal particles are often seen as big atoms that can be directly observed in real space. They are therefore becoming increasingly important as model systems to study processes of interest in condensed-matter physics such as melting, freezing and glass transitions. The solidification of colloidal suspensions has long been a puzzling phenomenon with many unexplained features. Here, we demonstrate and rationalize the existence of instability and metastability domains in cellular solidification of colloidal suspensions, by direct in situ high-resolution X-ray radiography and tomography observations. We explain such interface instabilities by a partial Brownian diffusion of the particles leading to constitutional supercooling situations. Processing under unstable conditions leads to localized and global kinetic instabilities of the solid/liquid interface, affecting the crystal morphology and particle redistribution behaviour.

The bulk composition and leaching properties of electroplating sludge prior/following the solidification/stabilization by calcium oxide.

PubMed

Orescanin, Visnja; Mikulic, Nenad; Mikelic, Ivanka Lovrencic; Posedi, Mario; Kampic, Stefica; Medunic, Gordana

2009-10-01

Eighteen samples of electroplating sludge were taken from three vertical profiles of waste storage pond of the zinc plating facility. Dry matter and organic matter content, pH value, bulk concentrations and leachate composition were determined. A sludge sample with the highest zinc value in the leachate was treated with calcium oxide (10% to 70%) and the obtained solidificate was repeatedly tested. There were found significant variations of all measured parameters among the profiles of untreated waste. Dry matter content varied from 125 to 455 mgg(-1), organic matter varied from 94.3 to 293.9 mgg(-1), and pH value varied from 3.42 to 5.90 (mean 4.34). Iron content ranged from 38.4 to 191.4 mgg(-1) (mean 136 mgg(-1); RSD 0.25), while zinc ranged from 10.9 to 58.2 mgg(-1) (mean 33.4 mgg(-1); RSD 0.38). According to its DIN38414-S4 leachate composition, this material was not suitable for landfilling of inert waste since zinc and nickel mean values were 10 and 1.5 times higher, respectively, and maximum values 27 and 2.5 times higher, respectively, compared to the upper permissible limit. Maximum values of Cr(VI), Fe, Ni, Cu, and Zn in the DIN38414-S4 leachate were 0.183 mgL(-1), 34.085 mgL(-1), 1.052 mgL(-1), 0.829 mgL(-1) and 107.475 mgL(-1)L, respectively. Following the solidification/stabilization procedure with CaO (sample/CaO = 90/10), concentrations of Cr(VI), Fe, Cu and Zn were reduced 92, 44, 66 and 57 times, respectively, compared to the untreated sample. The addition of 50% of CaO into the sludge reduced zinc and nickel concentrations 79 and 45 times, respectively, in the DIN38414-S4 leachate of the solidified waste compared to the original sludge, thereby converting an hazardous waste into the inert material suitable for landfilling or reuse in the construction processes.

SOLIDIFICATION/STABILIZATION OF SLUDGE AND ASH FROM WASTEWATER TREATMENT PLANTS

EPA Science Inventory

Tests were performed to determine the physical properties and chemical leaching characteristics of the residuals and the stabilized/solidified products from two publicly-owned wastewater treatment works (POTW). The two POTW waste products included in this study were an anaerobic ...

ONSITE ENGINEERING REPORT FOR SOLIDIFICATION/ STABILIZATION TREATMENT TESTING OF CONTAMINATED SOILS

EPA Science Inventory

The EPA's Office of Solid Waste and Emergency Response (OSWER) is currently developing land disposal restrictions (LDRs) for contaminated soil and debris (CS&D). The Office of Research and Development, through its Risk Reduction Engineering Laboratory (RREL), is providing support...

Riser Feeding Evaluation Method for Metal Castings Using Numerical Analysis

NASA Astrophysics Data System (ADS)

Ahmad, Nadiah

One of the design aspects that continues to create a challenge for casting designers is the optimum design of casting feeders (risers). As liquid metal solidifies, the metal shrinks and forms cavities inside the casting. In order to avoid shrinkage cavities, risers are added to the casting shape to supply additional molten metal when shrinkage occurs during solidification. The shrinkage cavities in the casting are compensated by controlling the cooling rate to promote directional solidification. This control can be achieved by designing the casting such that the cooling begins at the sections that are farthest away from the risers and ends at the risers. Therefore, the risers will solidify last and feed the casting with the molten metal. As a result, the shrinkage cavities formed during solidification are in the risers which are later removed from the casting. Since casting designers have to usually go through iterative processes of validating the casting designs which are very costly due to expensive simulation processes or manual trials and errors on actual casting processes, this study investigates more efficient methods that will help casting designers utilize their casting experiences systematically to develop good initial casting designs. The objective is to reduce the casting design method iterations; therefore, reducing the cost involved in that design processes. The aim of this research aims at finding a method that can help casting designers design effective risers used in sand casting process of aluminum-silicon alloys by utilizing the analysis of solidification simulation. The analysis focuses on studying the significance of pressure distribution of the liquid metal at the early stage of casting solidification, when heat transfer and convective fluid flow are taken into account in the solidification simulation. The mathematical model of casting solidification was solved using the finite volume method (FVM). This study focuses to improve our understanding of the feeding behavior in aluminum-silicon alloys and the effective feeding by considering the pressure gradient distribution of the molten metal at casting dendrite coherency point. For this study, we will identify the relationship between feeding efficiency, shrinkage behavior and how the change in riser size affects the pressure gradient in the casting. This understanding will be used to help in the design of effective risers.

Characterizations of mortar-degraded spinney waste composite nominated as solidifying agent for radwastes due to immersion processes

NASA Astrophysics Data System (ADS)

Saleh, H. M.; Eskander, S. B.

2012-11-01

Immobilization process of radioactive wastes is a compromise between economic and reliability factors. It involves the use of inert and cheap matrices to fix the wastes in homogenous monolithic solid forms. The characteristics of the resulting waste form were studied in various disposal options before coming to the final conclusion concerning the solidification process. A proposed mortar composite is formed from a mixture of Portland cement and sand in the weight ratio of 0.33 which by slurry of degraded spinney waste fibers at the ratio of 0.7 relative to the Portland cement. The composite was prepared at the laboratory ambient conditions (25 ± 5 °C). The temperature changes accompanying the hydration process were followed up to 96 h. At the end of 28 days, curing period, the performance of the obtained composite was evaluated under immersion circumstances imitating a flooding scenario that could happen at a disposal site. Compressive strength, porosity and mass changes were investigated under complete static immersion conditions in three different leachants, namely acetic acid, groundwater and seawater for 48 weeks. X-ray and scanning electron microscopy were used to follow and evaluate the changes that may occur for the proposed composite under flooding conditions. Based on the experimental data reached, it could be concluded that the prepared mortar composite can be nominated as a matrix for solidification/stabilization of some radwaste categories, even under the aggressive attacks of various immersion media.

Porosity and environment

NASA Technical Reports Server (NTRS)

Piwonka, T. S.

1984-01-01

Significant progress was achieved when it was realized that porosity could be analyzed successfully by considering not only heat flow, but also fluid flow within the solidifying casting. Sound castings may be produced by lowering pressure during melting (to allow dissolved gas to escape the melt) and increasing pressure during solidification (to force liquid metal into the mushy zone to feed shrinkage). Such techniques are especially effective if they are combined with chilling of parts of the casting to produce progressive solidification, which shortens the mushy zone and, hence, the distance that metal must travel to feed porosity.

A thermodynamic prediction for microporosity formation in aluminum-rich Al-Cu alloys

NASA Technical Reports Server (NTRS)

Poirier, D. R.; Yeum, K.; Maples, A. L.

1987-01-01

A computer model is used to predict the formation and degree of microporosity in a directionally solidified Al-4.5 wt pct Cu alloy, considering the interplay between solidification shrinkage and gas porosity. Macrosegregation theory is used to determine the local pressure within the interdendritic liquid. Results show interdendritic porosity for initial hydrogen contents in the 0.03-1 ppm range, and none below contents of 0.03. An increase in either the thermal gradient or the solidification rate is show to decrease the amount of interdendritic porosity.

Co-treatment of flotation waste, neutralization sludge, and arsenic-containing gypsum sludge from copper smelting: solidification/stabilization of arsenic and heavy metals with minimal cement clinker.

PubMed

Liu, De-Gang; Min, Xiao-Bo; Ke, Yong; Chai, Li-Yuan; Liang, Yan-Jie; Li, Yuan-Cheng; Yao, Li-Wei; Wang, Zhong-Bing

2018-03-01

Flotation waste of copper slag (FWCS), neutralization sludge (NS), and arsenic-containing gypsum sludge (GS), both of which are difficult to dispose of, are major solid wastes produced by the copper smelting. This study focused on the co-treatment of FWCS, NS, and GS for solidification/stabilization of arsenic and heavy metals with minimal cement clinker. Firstly, the preparation parameters of binder composed of FWCS, NS, and cement clinker were optimized to be FWCS dosage of 40%, NS dosage of 10%, cement clinker dosage of 50%, mill time of 1.5 h, and water-to-binder ratio of 0.25. On these conditions, the unconfined compressive strength (UCS) of the binder reached 43.24 MPa after hydration of 28 days. Then, the binder was used to solidify/stabilize the As-containing GS. When the mass ratio of binder-to-GS was 5:5, the UCS of matrix can reach 11.06 MPa after hydration of 28 days, meeting the required UCS level of MU10 brick in China. Moreover, arsenic and other heavy metals in FWCS, NS, and GS were effectively solidified or stabilized. The heavy metal concentrations in leachate were much lower than those in the limits of China standard leaching test (CSLT). Therefore, the matrices were potential to be used as bricks in some constructions. XRD analysis shows that the main hydration products of the matrix were portlandite and calcium silicate hydrate. These hydration products may play a significant role in the stabilization/solidification of arsenic and heavy metals.

Drop spreading and gelation of thermoresponsive polymers.

PubMed

de Ruiter, R; Royon, L; Snoeijer, J H; Brunet, P

2018-04-25

Spreading and solidification of liquid droplets are elementary processes of relevance for additive manufacturing. Here we investigate the effect of heat transfer on spreading of a thermoresponsive solution (Pluronic F127) that undergoes a sol-gel transition above a critical temperature Tm. By controlling the concentration of Pluronic F127 we systematically vary Tm, while also imposing a broad range of temperatures of the solid and the liquid. We subsequently monitor the spreading dynamics over several orders of magnitude in time and determine when solidification stops the spreading. It is found that the main parameter is the difference between the substrate temperature and Tm, pointing to a local mechanism for arrest near the contact line. Unexpectedly, the spreading is also found to stop below the gelation temperature, which we attribute to a local enhancement in polymer concentration due to evaporation near the contact line.

Technetium Getters to Improve Cast Stone Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neeway, James J.; Lawter, Amanda R.; Serne, R. Jeffrey

2015-10-15

The cementitious material known as Cast Stone has been selected as the preferred waste form for solidification of aqueous secondary liquid effluents from the Hanford Tank Waste Treatment and Immobilization Plant (WTP) process condensates and low-activity waste (LAW) melter off-gas caustic scrubber effluents. Cast Stone is also being evaluated as a supplemental immobilization technology to provide the necessary LAW treatment capacity to complete the Hanford tank waste cleanup mission in a timely and cost effective manner. Two radionuclides of particular concern in these waste streams are technetium-99 (99Tc) and iodine-129 (129I). These radioactive tank waste components contribute the most tomore » the environmental impacts associated with the cleanup of the Hanford site. A recent environmental assessment of Cast Stone performance, which assumes a diffusion controlled release of contaminants from the waste form, calculates groundwater in excess of the allowable maximum permissible concentrations for both contaminants. There is, therefore, a need and an opportunity to improve the retention of both 99Tc and 129I in Cast Stone. One method to improve the performance of Cast Stone is through the addition of “getters” that selectively sequester Tc and I, therefore reducing their diffusion out of Cast Stone. In this paper, we present results of Tc and I removal from solution with various getters with batch sorption experiments conducted in deionized water (DIW) and a highly caustic 7.8 M Na Ave LAW simulant. In general, the data show that the selected getters are effective in DIW but their performance is comprised when experiments are performed with the 7.8 M Na Ave LAW simulant. Reasons for the mitigated performance in the LAW simulant may be due to competition with Cr present in the 7.8 M Na Ave LAW simulant and to a pH effect.« less

Effect of a weak transverse magnetic field on the microstructure in directionally solidified peritectic alloys

PubMed Central

Li, Xi; Lu, Zhenyuan; Fautrelle, Yves; Gagnoud, Annie; Moreau, Rene; Ren, Zhongming

2016-01-01

Effect of a weak transverse magnetic field on the microstructures in directionally solidified Fe-Ni and Pb-Bi peritectic alloys has been investigated experimentally. The results indicate that the magnetic field can induce the formation of banded and island-like structures and refine the primary phase in peritectic alloys. The above results are enhanced with increasing magnetic field. Furthermore, electron probe micro analyzer (EPMA) analysis reveals that the magnetic field increases the Ni solute content on one side and enhances the solid solubility in the primary phase in the Fe-Ni alloy. The thermoelectric (TE) power difference at the liquid/solid interface of the Pb-Bi peritectic alloy is measured in situ, and the results show that a TE power difference exists at the liquid/solid interface. 3 D numerical simulations for the TE magnetic convection in the liquid are performed, and the results show that a unidirectional TE magnetic convection forms in the liquid near the liquid/solid interface during directional solidification under a transverse magnetic field and that the amplitude of the TE magnetic convection at different scales is different. The TE magnetic convections on the macroscopic interface and the cell/dendrite scales are responsible for the modification of microstructures during directional solidification under a magnetic field. PMID:27886265

Solid-phase extraction assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet to determine sildenafil and its analogues in dietary supplements.

PubMed

Li, Jing; Roh, Si Hun; Shaodong, Jia; Hong, Ji Yeon; Lee, Dong-Kyu; Shin, Byong-Kyu; Park, Jeong Hill; Lee, Jeongmi; Kwon, Sung Won

2017-08-01

A novel analytical method for the simultaneous determination of the concentration of sildenafil and its five analogues in dietary supplements using solid-phase extraction assisted reversed-phase dispersive liquid-liquid microextraction based on solidification of floating organic droplet combined with ion-pairing liquid chromatography with an ultraviolet detector was developed. Parameters that affect extraction efficiency were systematically investigated, including the type of solid-phase extraction cartridge, pH of the extraction environment, and the type and volume of extraction and dispersive solvent. The method linearity was in the range of 5.0-100 ng/mL for sildenafil, homosildenafil, udenafil, benzylsildenafil, and thiosildenafil and 10-100 ng/mL for acetildenafil. The coefficients of determination were ≥0.996 for all regression curves. The sensitivity values expressed as limit of detection were between 2.5 and 7.5 ng/mL. Furthermore, intraday and interday precisions expressed as relative standard deviations were less than 5.7 and 9.9%, respectively. The proposed method was successfully applied to the analysis of sildenafil and its five analogues in complex dietary supplements. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Application of stabilization/solidification technology on oil refinery sludge contaminated by heavy metals.

PubMed

Karamalidis, Athanasios K; Voudrias, Evangelos A

2004-01-01

The oily sludge produced by petroleum refineries is classified as a solid hazardous waste, according to European regulations. The objective of this work was to investigate whether stabilization/solidification can be used as a management method for the oily sludge. The sludge samples used originated from a petroleum-storing tank and a centrifuge unit of two Greek refineries. The experiments were designed to study the leachability of the heavy metals Pb, Cr, Cd, Ni, and Cu, which are contained in the sludge, using the Toxicity Characteristic Leaching Procedure (TCLP). Despite the fact that the metals were immobilized in a cement-based environment in the presence of organic load, leaching tests have shown a low metal leachability, less than 5%. Acid Neutralizing Capacity (ANC) tests were employed in order to estimate the acid resistance of the stabilized/solidified waste. In addition to ANC, a sequential TCLP test was employed in order to understand how the pH affects the leachability of Ni from the stabilized/solidified specimen.

Free energy change of off-eutectic binary alloys on solidification

NASA Technical Reports Server (NTRS)

Ohsaka, K.; Trinh, E. H.; Lin, J.-C.; Perepezko, J. H.

1991-01-01

A formula for the free energy difference between the undercooled liquid phase and the stable solid phase is derived for off-eutectic binary alloys in which the equilibrium solid/liquid transition takes place over a certain temperature range. The free energy change is then evaluated numerically for a Bi-25 at. pct Cd alloy modeled as a sub-subregular solution.

Dispersive liquid-liquid microextraction based on solidification of floating organic drop for preconcentration and determination of trace amounts of copper by flame atomic absorption spectrometry.

PubMed

Karadaş, Cennet; Kara, Derya

2017-04-01

A novel, simple, rapid, sensitive, inexpensive and environmentally friendly dispersive liquid-liquid microextraction method based on the solidification of a floating organic drop (DLLME-SFO) was developed for the determination of copper by flame atomic absorption spectrometry (FAAS). N-o-Vanillidine-2-amino-p-cresol was used as a chelating ligand and 1-undecanol was selected as an extraction solvent. The main parameters affecting the performance of DLLME-SFO, such as sample pH, volume of extraction solvent, extraction time, concentration of the chelating ligand, salt effect, centrifugation time and sample volume were investigated and optimized. The effect of interfering ions on the recovery of copper was also examined. Under the optimum conditions, the detection limit (3σ) was 0.93μgL -1 for Cu using a sample volume of 20mL, yielding a preconcentration factor of 20. The proposed method was successfully applied to the determination of Cu in tap, river and seawater, rice flour and black tea samples as well as certified reference materials. Copyright © 2016. Published by Elsevier Ltd.

Separation/preconcentration and determination of vanadium with dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) and electrothermal atomic absorption spectrometry.

PubMed

Asadollahi, Tahereh; Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji

2010-06-30

A novel dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) for separation/preconcentration of ultra trace amount of vanadium and its determination with the electrothermal atomic absorption spectrometry (ETAAS) was developed. The DLLME-SFO behavior of vanadium (V) using N-benzoyl-N-phenylhydroxylamine (BPHA) as complexing agent was systematically investigated. The factors influencing the complex formation and extraction by DLLME-SFO method were optimized. Under the optimized conditions: 100 microL, 200 microL and 25 mL of extraction solvent (1-undecanol), disperser solvent (acetone) and sample volume, respectively, an enrichment factor of 184, a detection limit (based on 3S(b)/m) of 7 ng L(-1) and a relative standard deviation of 4.6% (at 500 ng L(-1)) were obtained. The calibration graph using the preconcentration system for vanadium was linear from 20 to 1000 ng L(-1) with a correlation coefficient of 0.9996. The method was successfully applied for the determination of vanadium in water and parsley. Copyright 2010 Elsevier B.V. All rights reserved.

Immobilization of organic radioactive and non-radioactive liquid waste in a composite matrix

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galkin, Anatoliy; Gelis, Artem V.; Castiglioni, Andrew J.

A method for immobilizing liquid radioactive waste is provided, the method having the steps of mixing waste with polymer to form a non-liquid waste; contacting the non-liquid waste with a solidifying agent to create a mixture, heating the mixture to cause the polymer, waste, and filler to irreversibly bind in a solid phase, and compressing the solid phase into a monolith. The invention also provides a method for immobilizing liquid radioactive waste containing tritium, the method having the steps of mixing liquid waste with polymer to convert the liquid waste to a non-liquid waste, contacting the non-liquid waste with amore » solidifying agent to create a mixture, heating the mixture to form homogeneous, chemically stable solid phase, and compressing the chemically stable solid phase into a final waste form, wherein the polymer comprises approximately a 9:1 weight ratio mixture of styrene block co-polymers and cross linked co-polymers of acrylamides.« less

Enviromental impact of a hospital waste incineration plant in Krakow (Poland).

PubMed

Gielar, Agnieszka; Helios-Rybicka, Edeltrauda

2013-07-01

The environmental impact of a hospital waste incineration plant in Krakow was investigated. The objective of this study was to assess the degree of environmental effect of the secondary solid waste generated during the incineration process of medical waste. The analysis of pollution of the air emissions and leaching test of ashes and slag were carried out. The obtained results allowed us to conclude that (i) the hospital waste incineration plant significantly solves the problems of medical waste treatment in Krakow; (ii) the detected contaminant concentrations were generally lower than the permissible values; (iii) the generated ashes and slag contained considerable concentrations of heavy metals, mainly zinc, and chloride and sulfate anions. Ashes and slag constituted 10-15% of the mass of incinerated wastes; they are more harmful for the environment when compared with untreated waste, and after solidification they can be deposited in the hazardous waste disposal.

Determination of organophosphorus pesticides in environmental water samples by dispersive liquid-liquid microextraction with solidification of floating organic droplet followed by high-performance liquid chromatography.

PubMed

Wu, Chunxia; Liu, Huimin; Liu, Weihua; Wu, Qiuhua; Wang, Chun; Wang, Zhi

2010-07-01

A simple dispersive liquid-liquid microextraction based on solidification of floating organic droplet coupled with high-performance liquid chromatography-diode array detection was developed for the determination of five organophosphorus pesticides (OPs) in water samples. In this method, the extraction solvent used is of low density, low toxicity, and proper melting point near room temperature. The extractant droplet could be collected easily by solidifying it in the lower temperature. Some important experimental parameters that affect the extraction efficiencies were optimized. Under the optimum conditions, the calibration curve was linear in the concentration range from 1 to 200 ng mL(-1) for the five OPs (triazophos, parathion, diazinon, phoxim, and parathion-methyl), with the correlation coefficients (r) varying from 0.9991 to 0.9998. High enrichment factors were achieved ranging from 215 to 557. The limits of detection were in the range between 0.1 and 0.3 ng mL(-1). The recoveries of the target analytes from water samples at spiking levels of 5.0 and 50.0 ng mL(-1) were 82.2-98.8% and 83.6-104.0%, respectively. The relative standard deviations fell in the range of 4.4% to 6.3%. The method was suitable for the determination of the OPs in real water samples.

Mixing Dynamics Induced by Traveling Magnetic Fields

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Mazuruk, Konstantin

2000-01-01

Microstructural and compositional homogeneity in metals and alloys can only be achieved if the initial melt is homogeneous prior to the onset of solidification processing. Naturally induced convection may initially facilitate this requirement but upon the onset of solidification significant compositional variations generally arise leading to undesired segregation. Application of alternating magnetic fields to promote a uniform bulk liquid concentration during solidification processing has been suggested. To investigate such possibilities an initial study of using traveling magnetic fields (TMF) to promote melt homogenization is reported in this work. Theoretically, the effect of TMF-induced convection on mixing phenomena is studied in the laminar regime of flow. Experimentally, with and without applied fields, both: mixing dynamics by optically monitoring the spreading of an initially localized dye in transparent fluids and, compositional variations in metal alloys have been investigated.

Mixing Dynamics Induced by Traveling Magnetic Fields

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Mazuruk, Konstantin; Rose, M. Franklin (Technical Monitor)

2001-01-01

Microstructural and compositional homogeneity in metals and alloys can only be achieved if the initial melt is homogeneous prior to the onset of solidification processing. Naturally induced convection may initially facilitate this requirement but upon the onset of solidification significant compositional variations generally arise leading to undesired segregation. Application of alternating magnetic fields to promote a uniform bulk liquid concentration during solidification processing has been suggested. To investigate such possibilities an initial study of using traveling magnetic fields (TMF) to promote melt homogenization is reported in this work. Theoretically, the effect of TMF-induced convection on mixing phenomena is studied in the laminar regime of flow. Experimentally, with and without applied fields, both 1) mixing dynamics by optically monitoring the spreading of an initially localized dye in transparent fluids and, 2) compositional variations in metal alloys have been investigated.

Linear morphological stability analysis of the solid-liquid interface in rapidsolidification of a binary system

NASA Astrophysics Data System (ADS)

Galenko, P. K.; Danilov, D. A.

2004-05-01

The interface stability against small perturbations of the planar solid-liquid interface is considered analytically in linear approximation. Following the analytical procedure of Trivedi and Kurz [

Porous ionic liquids: synthesis and application.

PubMed

Zhang, Shiguo; Dokko, Kaoru; Watanabe, Masayoshi

2015-07-15

Solidification of fluidic ionic liquids into porous materials yields porous ionic networks that combine the unique characteristics of ionic liquids with the common features of polymers and porous materials. This minireview reports the most recent advances in the design of porous ionic liquids. A summary of the synthesis of ordered and disordered porous ionic liquid-based nanoparticles or membranes with or without templates is provided, together with the new concept of room temperature porous ionic liquids. As a versatile platform for functional materials, porous ionic liquids have shown widespread applications in catalysis, adsorption, sensing, actuation, etc. This new research direction towards ionic liquids chemistry is still in its early stages but has great potential.

The influence of the mould cooling temperature on the surface appearance and the internal quality of ESR ingots

NASA Astrophysics Data System (ADS)

Kubin, M.; Ofner, B.; Holzgruber, H.; Schneider, R.; Enzenhofer, D.; Filzwieser, A.; Konetschnik, S.

2016-07-01

One of the main benefits of the ESR process is to obtain an ingot surface which is smooth and allows a subsequent forging operation without any surface dressing. The main influencing factor on surface quality is the precise controlling of the process such as melt rate and electrode immersion depth. However, the relatively strong cooling effect of water as a cooling medium can result in the solidification of the meniscus of the liquid steel on the boundary liquid steel and slag which is most likely the origin of surface defects. The usage of different cooling media like ionic liquids, a salt solution which can be heated up to 250°C operating temperature might diminish the meniscus solidification phenomenon. This paper shows the first results of the usage of an ionic liquid as a mould cooling medium. In doing so, 210mm diameter ESR ingots were produced with the laboratory scale ESR furnace at the university of applied science using an ionic liquid cooling device developed by the company METTOP. For each trial melt different inlet and outlet temperatures of the ionic liquid were chosen and the impact on the surface appearance and internal quality were analyzed. Furthermore the influence on the energy balance is also briefly highlighted. Ultimately, an effect of the usage of ionic liquids as a cooling medium could be determined and these results will be described in detail within the scope of this paper.

Experimental and Theoretical Investigations of the Solidification of Eutectic Al-Si Alloy

NASA Technical Reports Server (NTRS)

Sen, S.; Catalina, A. V.; Rose, M. Franklin (Technical Monitor)

2001-01-01

The eutectic alloys have a wide spectrum of applications due to their good castability and physical and mechanical properties. The interphase spacing resulting during solidification is an important microstructural feature that significantly influences the mechanical behavior of the material. Thus, knowledge of the evolution of the interphase spacing during solidification is necessary in order to properly design the solidification process and optimize the material properties. While the growth of regular eutectics is rather well understood, the irregular eutectics such as Al-Si or Fe-graphite exhibit undercoolings and lamellar spacings much larger than those theoretically predicted. Despite of a considerable amount of experimental and theoretical work a clear understanding of the true mechanism underlying the spacing selection in irregular eutectics is yet to be achieved. A new experimental study of the solidification of the eutectic Al-Si alloy will be reported in this paper. The measured interface undercoolings and lamellar spacing will be compared to those found in the literature in order to get more general information regarding the growth mechanism of irregular eutectics. A modification of the present theory of the eutectic growth is also proposed. The results of the modified mathematical model, accounting for a non-isothermal solid/liquid interface, will be compared to the experimental measurements.

Microstructural analysis of laser weld fusion zone in Haynes 282 superalloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osoba, L.O.; Ding, R.G.; Ojo, O.A., E-mail: ojo@cc.umanitoba.ca

Analytical electron microscopy and spectroscopy analyses of the fusion zone (FZ) microstructure in autogenous laser beam welded Haynes 282 (HY 282) superalloy were performed. The micro-segregation patterns observed in the FZ indicate that Co, Cr and Al exhibited a nearly uniform distribution between the dendrite core and interdendritic regions while Ti and Mo were rejected into the interdendritic liquid during the weld solidification. Transmission electron diffraction analysis and energy dispersive X-ray microanalysis revealed the second phase particles formed along the FZ interdendritic region to be Ti-Mo rich MC-type carbide particles. Weld FZ solidification cracking, which is sometimes associated with themore » formation of {gamma}-{gamma}' eutectic in {gamma}' precipitation strengthened nickel-base superalloys, was not observed in the HY 282 superalloy. Modified primary solidification path due to carbon addition in the newly developed superalloy is used to explain preclusion of weld FZ solidification cracking in the material. - Highlights: Black-Right-Pointing-Pointer A newly developed superalloy was welded by CO{sub 2} laser beam joining technique. Black-Right-Pointing-Pointer Electron microscopy characterization of the weld microstructure was performed. Black-Right-Pointing-Pointer Identified interdendritic microconstituents consist of MC-type carbides. Black-Right-Pointing-Pointer Modification of primary solidification path is used to explain cracking resistance.« less

Solidification and microstructures of binary ice-I/hydrate eutectic aggregates

USGS Publications Warehouse

McCarthy, C.; Cooper, R.F.; Kirby, S.H.; Rieck, K.D.; Stern, L.A.

2007-01-01

The microstructures of two-phase binary aggregates of ice-I + salt-hydrate, prepared by eutectic solidification, have been characterized by cryogenic scanning electron microscopy (CSEM). The specific binary systems studied were H2O-Na2SO4, H2O-MgSO4, H2O-NaCl, and H2O-H2SO4; these were selected based on their potential application to the study of tectonics on the Jovian moon Europa. Homogeneous liquid solutions of eutectic compositions were undercooled modestly (??T - 1-5 ??C); similarly cooled crystalline seeds of the same composition were added to circumvent the thermodynamic barrier to nucleation and to control eutectic growth under (approximately) isothermal conditions. CSEM revealed classic eutectic solidification microstructures with the hydrate phase forming continuous lamellae, discontinuous lamellae, or forming the matrix around rods of ice-I, depending on the volume fractions of the phases and their entropy of dissolving and forming a homogeneous aqueous solution. We quantify aspects of the solidification behavior and microstructures for each system and, with these data articulate anticipated effects of the microstructure on the mechanical responses of the materials.

Macrosegregation Resulting from Directional Solidification Through an Abrupt Change in Cross-Sections

NASA Technical Reports Server (NTRS)

Lauer, M.; Poirier, D. R.; Ghods, M.; Tewari, S. N.; Grugel, R. N.

2017-01-01

Simulations of the directional solidification of two hypoeutectic alloys (Al-7Si alloy and Al-19Cu) and resulting macrosegregation patterns are presented. The casting geometries include abrupt changes in cross-section from a larger width of 9.5 mm to a narrower 3.2 mm width then through an expansion back to a width of 9.5 mm. The alloys were chosen as model alloys because they have similar solidification shrinkages, but the effect of Cu on changing the density of the liquid alloy is about an order of magnitude greater than that of Si. The simulations compare well with experimental castings that were directionally solidified in a graphite mold in a Bridgman furnace. In addition to the simulations of the directional solidification in graphite molds, some simulations were effected for solidification in an alumina mold. This study showed that the mold must be included in numerical simulations of directional solidification because of its effect on the temperature field and solidification. For the model alloys used for the study, the simulations clearly show the interaction of the convection field with the solidifying alloys to produce a macrosegregation pattern known as "steepling" in sections with a uniform width. Details of the complex convection- and segregation-patterns at both the contraction and expansion of the cross-sectional area are revealed by the computer simulations. The convection and solidification through the expansions suggest a possible mechanism for the formation of stray grains. The computer simulations and the experimental castings have been part of on-going ground-based research with the goal of providing necessary background for eventual experiments aboard the ISS. For casting practitioners, the results of the simulations demonstrate that computer simulations should be applied to reveal interactions between alloy solidification properties, solidification conditions, and mold geometries on macrosegregation. The simulations also presents the possibility of engineering the mold-material to avoid, or mitigate, the effects of thermosolutal convection and macrosegregation by selecting a mold material with suitable thermal properties, especially its thermal conductivity.

Benard convection in binary mixtures with Soret effects and solidification

NASA Technical Reports Server (NTRS)

Zimmermann, G.; Mueller, U.; Davis, S. H.

1992-01-01

Benard convection was studied in a two-component liquid which displayed Soret effects (Soret, 1879; DeGroot and Mazur, 1969) and in which the temperatures of the horizontal boundaries spanned the solidification temperature of the mixture. A steady basic state was observed, in which the layer is partly liquid (near the lower, heated plate) and partly solid (near the upper, cooled plate) with the interface being planar, and in which all transport is by conduction and diffusion. Linear stability of the basic state was examined to determine how the presence of solid and the ability of the material to solidify or melt under disturbance affects the critical conditions from the onset of instability. The theoretical results obtained for cases when the phase change is absent and when the Soret effects are absent (but the phase change is present) are compared with an experiment using alcohol-water mixtures.

Atomistic simulations of carbon diffusion and segregation in liquid silicon

NASA Astrophysics Data System (ADS)

Luo, Jinping; Alateeqi, Abdullah; Liu, Lijun; Sinno, Talid

2017-12-01

The diffusivity of carbon atoms in liquid silicon and their equilibrium distribution between the silicon melt and crystal phases are key, but unfortunately not precisely known parameters for the global models of silicon solidification processes. In this study, we apply a suite of molecular simulation tools, driven by multiple empirical potential models, to compute diffusion and segregation coefficients of carbon at the silicon melting temperature. We generally find good consistency across the potential model predictions, although some exceptions are identified and discussed. We also find good agreement with the range of available experimental measurements of segregation coefficients. However, the carbon diffusion coefficients we compute are significantly lower than the values typically assumed in continuum models of impurity distribution. Overall, we show that currently available empirical potential models may be useful, at least semi-quantitatively, for studying carbon (and possibly other impurity) transport in silicon solidification, especially if a multi-model approach is taken.

Application of the Evacuated Canister System for Removing Residual Molten Glass From the West Valley Demonstration Project High-Level Waste Melter

DOE Office of Scientific and Technical Information (OSTI.GOV)

May, Joseph J.; Dombrowski, David J.; Valenti, Paul J.

The principal mission of the West Valley Demonstration Project (WVDP) is to meet a series of objectives defined in the West Valley Demonstration Project Act (Public Law 96-368). Chief among these is the objective to solidify liquid high-level waste (HLW) at the WVDP site into a form suitable for disposal in a federal geologic repository. In 1982, the Secretary of Energy formally selected vitrification as the technology to be used to solidify HLW at the WVDP. One of the first steps in meeting the HLW solidification objective involved designing, constructing and operating the Vitrification (Vit) Facility, the WVDP facility thatmore » houses the systems and subsystems used to process HLW into stainless steel canisters of borosilicate waste-glass that satisfy waste acceptance criteria (WAC) for disposal in a federal geologic repository. HLW processing and canister production began in 1996. The final step in meeting the HLW solidification objective involved ending Vit system operations and shut ting down the Vit Facility. This was accomplished by conducting a discrete series of activities to remove as much residual material as practical from the primary process vessels, components, and associated piping used in HLW canister production before declaring a formal end to Vit system operations. Flushing was the primary method used to remove residual radioactive material from the vitrification system. The inventory of radioactivity contained within the entire primary processing system diminished by conducting the flushing activities. At the completion of flushing activities, the composition of residual molten material remaining in the melter (the primary system component used in glass production) consisted of a small quantity of radioactive material and large quantities of glass former materials needed to produce borosilicate waste-glass. A special system developed during the pre-operational and testing phase of Vit Facility operation, the Evacuated Canister System (ECS), was deployed at the West Valley Demonstration Project to remove this radioactively dilute, residual molten material from the melter before Vit system operations were brought to a formal end. The ECS consists of a stainless steel canister of the same size and dimensions as a standard HLW canister that is equipped with a special L-shaped snorkel assembly made of 304L stainless steel. Both the canister and snorkel assembly fit into a stainless steel cage that allows the entire canister assembly to be positioned over the melter as molten glass is drawn out by a vacuum applied to the canister. This paper describes the process used to prepare and apply the ECS to complete molten glass removal before declaring a formal end to Vit system operations and placing the Vit Facility into a safe standby mode awaiting potential deactivation.« less

Investigation of Artificial Forced Cooling in the Bridgman Crystal Growth of Cadmium Zinc Telluride

NASA Astrophysics Data System (ADS)

Liu, Juncheng; Li, Jiao; Zhang, Guodong; Li, Changxing; Lennon, Craig; Sivananthan, Siva

2007-08-01

The effects of artificial forced cooling on the solid liquid interface and on solute segregation were investigated by modeling the vertical Bridgman method for the single-crystal growth of CdZnTe, taking into consideration effects such as increasing the axial outward heat flux from the crucible bottom, the radial outward heat flux from the crucible wall, and the carbon film thickness on the crucible inner wall. Axial artificially forced cooling noticeably increases convection and the temperature gradient in the melt next to the solid liquid interface, and substantially reduces interface concavity at the initial solidification stage. Interface concavity increases a little when the solidification proceeds further, however. Axial artificially forced cooling reduces radial solute segregation of the initial segment of the grown crystal and slightly increases the solute iso-concentration segment. Radial artificially forced cooling enhances melt convection substantially, affects solid liquid interface concavity only slightly, and hardly affects solute segregation in the grown crystal. Doubling the carbon film thickness weakens convection of the melt in front of the interface, substantially increases interface concavity, and hardly affects solute segregation in the grown crystal.

Effect of wetting on nucleation and growth of D2 in confinement

NASA Astrophysics Data System (ADS)

Zepeda-Ruiz, L. A.; Sadigh, B.; Shin, S. J.; Kozioziemski, B. J.; Chernov, A. A.

2018-04-01

We have performed a computational study to determine how the wetting of liquid deuterium to the walls of the material influences nucleation. We present the development of a pair-wise interatomic potential that includes zero-point motion of molecular deuterium. Deuterium is used in this study because of its importance to inertial confinement fusion and the potential to generate a superfluid state if the solidification can be suppressed. Our simulations show that wetting dominates undercooling compared to the pore geometries. We observe a transition from heterogeneous nucleation at the confining wall to homogeneous nucleation at the bulk of the liquid (and intermediate cases) as the interaction with the confining wall changes from perfect wetting to non-wetting. When nucleation is heterogeneous, the temperature needed for solidification changes by 4 K with decreasing deuterium-wall interaction, but it remains independent (and equal to the one from bulk samples) when homogeneous nucleation dominates. We find that growth and quality of the resulting microstructure also depends on the magnitude of liquid deuterium-wall interaction strength.

Influence of convection on microstructure

NASA Technical Reports Server (NTRS)

Wilcox, William R.; Caram, Rubens; Mohanty, A. P.; Seth, Jayshree

1990-01-01

In eutectic growth, as the solid phases grow they reject atoms to the liquid. This results in a variation of melt composition along the solid/liquid interface. In the past, mass transfer in eutectic solidification, in the absence of convection, was considered to be governed only by the diffusion induced by compositional gradients. However, mass transfer can also be generated by a temperature gradient. This is called thermotransport, thermomigration, thermal diffusion or the Soret effect. A theoretical model of the influence of the Soret effect on the growth of eutectic alloys is presented. A differential equation describing the compositional field near the interface during unidirectional solidification of a binary eutectic alloy was formulated by including the contributions of both compositional and thermal gradients in the liquid. A steady-state solution of the differential equation was obtained by applying appropriate boundary conditions and accounting for heat flow in the melt. Following that, the average interfacial composition was converted to a variation of undercooling at the interface, and consequently to microstructural parameters. The results obtained show that thermotransport can, under certain circumstances, be a parameter of paramount importance.

Directional Solidification of Bi-Sn on USMP-4

NASA Technical Reports Server (NTRS)

Abbaschian, Reza; deGroh, H., III; Leonardi, E.; Timchenko, V.; deVahlDavis, G.

1999-01-01

The experiments used MEPHISTO hardware to study the solidification and melting behavior of bismuth alloyed with 1 at% tin. Three samples, each approximately 900 mm long and 6mm in diameter, were used. A portion of each sample also included a 2 mm diameter growth capillary, to assist in the formation of a single grain. One sample provided the Seebeck voltage generated during melting and freezing processes. Another provided temperature data and Peltier pulsed demarcation of the interface shape for post flight analysis. The third sample provided resistance and growth velocity measurements, as well as additional thermal data. The third sample was also quenched at the end of the mission to preserve the composition of the liquid near the interface for post flight determination. A total of 450mm of directionally solidified samples were preserved for post mission structural and compositional characterization. Substantial differences were observed in the Seebeck signal between the ground-based experiments and the space-based experiments. The temperature gradient in the liquid for the ground-based experiments was significantly lower than the temperature gradient in the liquid for the space-based experiments.

Solidification of undercooled liquids

NASA Technical Reports Server (NTRS)

Perepezko, J. H.; Shiohara, Y.; Paik, J. S.; Flemmings, M. C.

1982-01-01

During rapid solidification processing (RSP) the amount of liquid undercooling is an important factor in determining microstructural development by controlling phase selection during nucleation and morphological evolution during crystal growth. While undercooling is an inherent feature of many techniques of RSP, the deepest undercoolings and most controlled studies have been possible in carefully prepared fine droplet samples. From past work and recent advances in studies of nucleation kinetics it has become clear that the initiation of crystallization during RSP is governed usually by heterogeneous sites located at surfaces. With known nucleant sites, it has been possible to identify specific pathways of metastable phase formation and microstructural development in alloys. These advances have allowed for a clearer assessment of the interplay between undercooling, cooling rate and particle size statistics in structure formation. New approaches to the examination of growth processes have been developed to follow the thermal behavior and morphology in small samples in the period of rapid crystallization and recalescence. Based upon the new experimental information from these studies, useful models can be developed for the overall solidification process to include nucleation behavior, thermodynamic constraints, thermal history, growth kinetics, solute redistribution and resulting structures. From the refinement of knowledge concerning the underlying factors that govern RSP a basis is emerging for an effective alloy design and processing strategy.

Liquidus Projections of Bi-Se-Ga and Bi-Se-Te Ternary Systems

NASA Astrophysics Data System (ADS)

Lin, Po-han; Chen, Sinn-wen; Hwang, Jenn-dong; Chu, Hsu-shen

2016-12-01

This study determines the liquidus projections of both Bi-Se-Ga and Bi-Se-Te ternary systems which are constituent ternary systems of promising Bi-Se-Te-Ga thermoelectric materials. Ternary Bi-Se-Ga and Bi-Se-Te alloys are prepared. Their primary solidification phases are experimentally determined, and thermal analysis experiments are carried out. The liquidus projections are determined based on the ternary experimental results and phase diagrams of constituent binary systems. The Bi-Se-Ga system includes seven primary solidification phases, Bi, Ga, GaSe, Ga2Se3, Se, Bi2Se3, and (Bi2)n(Bi2Se3)m. In the Bi-Se-Te system, there are five primary solidification phases, Bi, (Bi2)n(Bi2Te3)m, Bi2(Se,Te)3, (Se,Te), and (Bi2)n(Bi2Se3)m. Both the (Bi2)n(Bi2Te3)m and (Bi2)n(Bi2Se3)m phases are not a single phase, but a collection of series undetermined phases. Large miscibility gaps are observed in the Bi-Se-Ga system. The temperatures of the invariant reactions, Liquid + Bi + GaSe = Ga and Liquid + Ga2Se3 = Bi + GaSe, are at 495 K (222 °C) and 533 K (260 °C), respectively.

Modelling of crater formation on anode surface by high-current vacuum arcs

NASA Astrophysics Data System (ADS)

Tian, Yunbo; Wang, Zhenxing; Jiang, Yanjun; Ma, Hui; Liu, Zhiyuan; Geng, Yingsan; Wang, Jianhua; Nordlund, Kai; Djurabekova, Flyura

2016-11-01

Anode melting and crater formation significantly affect interruption of high-current vacuum arcs. The primary objective of this paper is to theoretically investigate the mechanism of anode surface crater formation, caused by the combined effect of surface heating during the vacuum arc and pressure exerted on the molten surface by ions and electrons from the arc plasma. A model of fluid flow and heat transfer in the arc anode is developed and combined with a magnetohydrodynamics model of the vacuum arc plasma. Crater formation is observed in simulation for a peak arcing current higher than 15 kA on 40 mm diam. Cu electrodes spaced 10 mm apart. The flow of liquid metal starts after 4 or 5 ms of arcing, and the maximum velocities are 0.95 m/s and 1.39 m/s for 20 kA and 25 kA arcs, respectively. This flow redistributes thermal energy, and the maximum temperature of the anode surface does not remain in the center. Moreover, the condition for the liquid droplet formation on the anode surfaces is developed. The solidification process after current zero is also analyzed. The solidification time has been found to be more than 3 ms after 25 kA arcing. The long solidification time and sharp features on crater rims induce Taylor cone formation.

Convection-induced distortion of a solid-liquid interface

NASA Technical Reports Server (NTRS)

Schaefer, R. J.; Coriell, S. R.

1984-01-01

Measurements of convective flow fields and solid-liquid interface shapes during the solidification of a pure and a slightly alloyed transparent material reveal that the convective transport of solute can cause a macroscopic depression to develop in the solid-liquid interface. This effect occurs under conditions close to those which are predicted to produce morphological instability of a planar interface. A cellular or dendritic microstructure later develops within the interface depression. The convection is attributed to the effect of radial temperature gradients in the crystal growth apparatus.

Silicon web process development

NASA Technical Reports Server (NTRS)

Duncan, C. S.; Seidensticker, R. G.; Mchugh, J. P.; Skutch, M. E.; Driggers, J. M.; Hopkins, R. H.

1981-01-01

The silicon web process takes advantage of natural crystallographic stabilizing forces to grow long, thin single crystal ribbons directly from liquid silicon. The ribbon, or web, is formed by the solidification of a liquid film supported by surface tension between two silicon filaments, called dendrites, which border the edges of the growing strip. The ribbon can be propagated indefinitely by replenishing the liquid silicon as it is transformed to crystal. The dendritic web process has several advantages for achieving low cost, high efficiency solar cells. These advantages are discussed.

Equipment evaluation for low density polyethylene encapsulated nitrate salt waste at the Rocky Flats Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamada, W.I.; Faucette, A.M.; Jantzen, R.C.

1993-08-30

Mixed wastes at the Rocky Flats Plant (RFP) are subject to regulation by the Resource Conservation and Recovery Act (RCRA). Polymer solidification is being developed as a final treatment technology for several of these mixed wastes, including nitrate salts. Encapsulation nitrate salts with low density polyethylene (LDPE) has been the preliminary focus of the RFP polymer solidification effort. Literature reviews, industry surveys, and lab-scale and pilot-scale tests have been conducted to evaluate several options for encapsulating nitrate salts with LDPE. Most of the effort has focused on identifying compatible drying and extrusion technologies. Other processing options, specifically meltration and non-heatedmore » compounding machines, were also investigated. The best approach appears to be pretreatment of the nitrate salt waste brine in either a vertical or horizontal thin film evaporator followed by compounding of the dried waste with LDPE in an intermeshing, co-rotating, twin-screw extruder. Additional pilot-scale tests planned for the fall of 1993 should further support this recommendation. Preliminary evaluation work indicates that meltration is not possible at atmospheric pressure with the LDPE (Chevron PE-1409) provided by RFP. However, meltration should be possible at atmospheric pressure using another LDPE formulation with altered physical and rheological properties: Lower molecular weight and lower viscosity (Epoline C-15). Contract modifications are now in process to allow a follow-on pilot scale demonstration. Questions regarding changed safety and physical properties of the resultant LDPE waste form due to use of the Epoline C-15 will be addressed. No additional work with non-heated mixer compounder machines is planned at this time.« less

A study of waste liquid crystal display generation in mainland China.

PubMed

Liu, Zhifeng; Xu, Zeying; Huang, Haihong; Li, Bingbing

2016-01-01

The generation of liquid crystal display waste is becoming a serious social problem. Predicting liquid crystal display waste status is the foundation for establishing a recycling network; however, the difficulty in predicting liquid crystal display waste quantity lies in data mining. In order to determine the quantity and the distribution of liquid crystal display waste in China, the four top-selling liquid crystal display products (liquid crystal display TVs, desktop PCs, notebook PCs, and mobile phones) were selected as study objects. Then, the extended logistic model and market supply A method was used to predict the quantity of liquid crystal display waste products. Moreover, the distribution of liquid crystal display waste products in different regions was evaluated by examining the consumption levels of household equipment. The results revealed that the quantity of waste liquid crystal displays would increase rapidly in the next decade. In particular, the predicted quantity of waste liquid crystal displays would rise to approximately 4.262 × 10(9) pieces in 2020, and the total display area (i.e. the surface area of liquid crystal display panels) of waste liquid crystal displays would reach 5.539 × 10(7) m(2). The prediction on the display area of waste liquid crystal display TVs showed that it would account for 71.5% of the total display area by 2020. Meanwhile, the quantity of waste mobile phones would significantly grow, increasing 5.8 times from 2012 to 2020. In terms of distribution, Guangdong is the top waste liquid crystal display-generating province in China, followed by Jiangsu, Shandong, Henan, Zhejiang, and Sichuan. Considering its regional characteristics, Guangdong has been proposed to be the most important location of the recycling network. © The Author(s) 2015.

Appearance of metastable B2 phase during solidification of Ni 50 Zr 50 alloy: electrostatic levitation and molecular dynamics simulation studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quirinale, D. G.; Rustan, G. E.; Wilson, S. R.

2015-02-04

High-energy x-ray diffraction measurements of undercooled, electrostatically levitated Ni 50Zr 50 liquid droplets were performed. The observed solidification pathway proceeded through the nucleation and growth of the metastable B2 phase, which persisted for several seconds before the rapid appearance of the stable B33 phase. This sequence is shown to be consistent with predictions from classical nucleation theory using data obtained from molecular dynamics (MD) simulations. A plausible mechanism for the B2–B33 transformation is proposed and investigated through further MD simulations.

Dendrite Array Disruption by Bubbles during Re-melting in a Microgravity Environment

NASA Technical Reports Server (NTRS)

Grugel, Richard N.

2012-01-01

As part of the Pore Formation and Mobility Investigation (PFMI), Succinonitrile Water alloys consisting of aligned dendritic arrays were re-melted prior to conducting directional solidification experiments in the microgravity environment aboard the International Space Station. Thermocapillary convection initiated by bubbles at the solid-liquid interface during controlled melt back of the alloy was observed to disrupt the initial dendritic alignment. Disruption ranged from detaching large arrays to the transport of small dendrite fragments at the interface. The role of bubble size and origin is discussed along with subsequent consequences upon reinitiating controlled solidification.

Low-gravity homogenization and solidification of aluminum antimonide. [Apollo-Soyuz test project

NASA Technical Reports Server (NTRS)

Ang, C.-Y.; Lacy, L. L.

1976-01-01

The III-V semiconducting compound AlSb shows promise as a highly efficient solar cell material, but it has not been commercially exploited because of difficulties in compound synthesis. Liquid state homogenization and solidification of AlSb were carried out in the Apollo-Soyuz Test Project Experiment MA-044 in the hope that compositional homogeneity would be improved by negating the large density difference between the two constituents. Post-flight analysis and comparative characterization of the space-processed and ground-processed samples indicate that there are major homogeneity improvements in the low-gravity solidified material.

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet followed by high-performance liquid chromatography with ultraviolet detection and liquid chromatography-tandem mass spectrometry for the determination of triclosan and 2,4-dichlorophenol in water samples.

PubMed

Zheng, Cao; Zhao, Jing; Bao, Peng; Gao, Jin; He, Jin

2011-06-24

A novel, simple and efficient dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) technique coupled with high-performance liquid chromatography with ultraviolet detection (HPLC-UV) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of triclosan and its degradation product 2,4-dichlorophenol in real water samples. The extraction solvent used in this work is of low density, low volatility, low toxicity and proper melting point around room temperature. The extractant droplets can be collected easily by solidifying it at a lower temperature. Parameters that affect the extraction efficiency, including type and volume of extraction solvent and dispersive solvent, salt effect, pH and extraction time, were investigated and optimized in a 5 mL sample system by HPLC-UV. Under the optimum conditions (extraction solvent: 12 μL of 1-dodecanol; dispersive solvent: 300 of μL acetonitrile; sample pH: 6.0; extraction time: 1 min), the limits of detection (LODs) of the pretreatment method combined with LC-MS/MS were in the range of 0.002-0.02 μg L(-1) which are lower than or comparable with other reported approaches applied to the determination of the same compounds. Wide linearities, good precisions and satisfactory relative recoveries were also obtained. The proposed technique was successfully applied to determine triclosan and 2,4-dichlorophenol in real water samples. Copyright © 2011 Elsevier B.V. All rights reserved.

Treatment Of Arsenic-Contaminated Materials Using Selected Stabilization And Solidification Technologies

EPA Science Inventory

Arsenic contamination of soil, sediment and groundwater is a widespread problem in certain areas and has caused great public concern due to increased awareness of the health risks. Often the contamination is naturally occurring, but it can also be a result of waste generated fro...

Cement-based stabilization/solidification of oil refinery sludge: Leaching behavior of alkanes and PAHs.

PubMed

Karamalidis, Athanasios K; Voudrias, Evangelos A

2007-09-05

Stabilization/solidification is a process widely applied for the immobilization of inorganic constituents of hazardous wastes, especially for metals. Cement is usually one of the most common binders for that purpose. However, limited results have been presented on immobilization of hydrocarbons in cement-based stabilized/solidified petroleum solid waste. In this study, real oil refinery sludge samples were stabilized and solidified with various additions of I42.5 and II42.5 cement (Portland and blended cement, respectively) and subject to leaching. The target analytes were total petroleum hydrocarbons, alkanes and 16 polycyclic aromatic hydrocarbons of the EPA priority pollutant list. The experiments showed that the waste was confined in the cement matrix by macroencapsulation. The rapture of the cement structure led to the increase of leachability for most of the hydrocarbons. Leaching of n-alkanes from II42.5 cement-solidified samples was lower than that from I42.5 solidified samples. Leaching of alkanes in the range of n-C(10) to n-C(27) was lower than that of long chain alkanes (>n-C(27)), regardless the amount of cement addition. Generally, increasing the cement content in the solidified waste samples, increased individual alkane leachability. This indicated that cement addition resulted in destabilization of the waste. Addition of I42.5 cement favored immobilization of anthracene, benzo[a]anthracene, benzo[b]fluoroanthene, benzo[k]fluoroanthene, benzo[a]pyrene and dibenzo[a,h]anthracene. However, addition of II42.5 favored 5 out of 16, i.e., naphthalene, anthracene, benzo[b]fluoroanthene, benzo[k]fluoroanthene and dibenzo[a,h]anthracene.

Microstructure selection in thin-sample directional solidification of an Al-Cu alloy: In situ X-ray imaging and phase-field simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clarke, A. J.; Tourret, D.; Song, Y.

We study microstructure selection during during directional solidification of a thin metallic sample. We combine in situ X-ray radiography of a dilute Al-Cu alloy solidification experiments with three-dimensional phase-field simulations. Here we explore a range of temperature gradient G and growth velocity V and build a microstructure selection map for this alloy. We investigate the selection of the primary dendritic spacing Λ and tip radius ρ. While ρ shows a good agreement between experimental measurements and dendrite growth theory, with ρ~V $-$1/2, Λ is observed to increase with V (∂Λ/∂V > 0), in apparent disagreement with classical scaling laws formore » primary dendritic spacing, which predict that ∂Λ/∂V<0. We show through simulations that this trend inversion for Λ(V) is due to liquid convection in our experiments, despite the thin sample configuration. We use a classical diffusion boundary-layer approximation to semi-quantitatively incorporate the effect of liquid convection into phase-field simulations. This approximation is implemented by assuming complete solute mixing outside a purely diffusive zone of constant thickness that surrounds the solid-liquid interface. This simple method enables us to quantitatively match experimental measurements of the planar morphological instability threshold and primary spacings over an order of magnitude in V. Lastly, we explain the observed inversion of ∂Λ/∂V by a combination of slow transient dynamics of microstructural homogenization and the influence of the sample thickness.« less

Microstructure selection in thin-sample directional solidification of an Al-Cu alloy: In situ X-ray imaging and phase-field simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clarke, A. J.; Tourret, D.; Song, Y.

We study microstructure selection during directional solidification of a thin metallic sample. We combine in situ X-ray radiography of a dilute Al-Cu alloy solidification experiments with three-dimensional phase-field simulations. We explore a range of temperature gradient G and growth velocity V and build a microstructure selection map for this alloy. We investigate the selection of the primary dendritic spacing Lambda and tip radius rho. While rho shows a good agreement between experimental measurements and dendrite growth theory, with rho similar to V-1/2, Lambda is observed to increase with V (partial derivative Lambda/partial derivative V > 0), in apparent disagreement withmore » classical scaling laws for primary dendritic spacing, which predict that partial derivative Lambda/partial derivative V <0. We show through simulations that this trend inversion for Lambda(V) is due to liquid convection in our experiments, despite the thin sample configuration. We use a classical diffusion boundary-layer approximation to semi-quantitatively incorporate the effect of liquid convection into phase-field simulations. This approximation is implemented by assuming complete solute mixing outside a purely diffusive zone of constant thickness that surrounds the solid-liquid interface. This simple method enables us to quantitatively match experimental measurements of the planar morphological instability threshold and primary spacings over an order of magnitude in V. We explain the observed inversion of partial derivative Lambda/partial derivative V by a combination of slow transient dynamics of microstructural homogenization and the influence of the sample thickness.« less

Microstructure selection in thin-sample directional solidification of an Al-Cu alloy: In situ X-ray imaging and phase-field simulations

DOE PAGES

Clarke, A. J.; Tourret, D.; Song, Y.; ...

2017-05-01

We study microstructure selection during during directional solidification of a thin metallic sample. We combine in situ X-ray radiography of a dilute Al-Cu alloy solidification experiments with three-dimensional phase-field simulations. Here we explore a range of temperature gradient G and growth velocity V and build a microstructure selection map for this alloy. We investigate the selection of the primary dendritic spacing Λ and tip radius ρ. While ρ shows a good agreement between experimental measurements and dendrite growth theory, with ρ~V $-$1/2, Λ is observed to increase with V (∂Λ/∂V > 0), in apparent disagreement with classical scaling laws formore » primary dendritic spacing, which predict that ∂Λ/∂V<0. We show through simulations that this trend inversion for Λ(V) is due to liquid convection in our experiments, despite the thin sample configuration. We use a classical diffusion boundary-layer approximation to semi-quantitatively incorporate the effect of liquid convection into phase-field simulations. This approximation is implemented by assuming complete solute mixing outside a purely diffusive zone of constant thickness that surrounds the solid-liquid interface. This simple method enables us to quantitatively match experimental measurements of the planar morphological instability threshold and primary spacings over an order of magnitude in V. Lastly, we explain the observed inversion of ∂Λ/∂V by a combination of slow transient dynamics of microstructural homogenization and the influence of the sample thickness.« less

Use of cement-fly ash-based stabilization techniques for the treatment of waste containing aromatic contaminants

NASA Astrophysics Data System (ADS)

Banaszkiewicz, Kamil; Marcinkowski, Tadeusz

2017-11-01

Research on evaluation of evaporation rate of volatile organic compounds from soil beds during processing is presented. For the experiment, soil samples were prepared with the same amounts of benzene and stabilized using a mixture of CEMI 42.5R cement and fly ash from pit-coal combustion. Solidification of soils contaminated with BTEX hydrocarbons using hydraulic binders involves a risk of releasing vapours of these compounds during homogenization of waste with stabilizing mixture introduced and its dilution with water. The primary purposes of the research were: analysis of benzene volume emitted from soil during stabilization/solidification process and characterization of factors that may negatively affect the quality of measurements/the course of stabilization process. Analysis of benzene emission intensity during the process was based on concentration (C6H6) values, recorded with flame-ionization detector above the surface of reacting mixture. At the same time, gaseous contaminants emitted during waste stabilization were passed through pipes filled with activated carbon (SCK, Anasorb CSC). Benzene vapours adsorbed on activated carbon were subjected to analysis using gas chromatograph Varian 450-GC. Evaporation characteristics of benzene during processing contaminated soils revealed the stages creating the highest danger to workers' health, as well as a need for actions connected with modification of technological line.

Numerical Simulation and Experimental Casting of Nickel-Based Single-Crystal Superalloys by HRS and LMC Directional Solidification Processes

NASA Astrophysics Data System (ADS)

Yan, Xuewei; Wang, Run'nan; Xu, Qingyan; Liu, Baicheng

2017-04-01

Mathematical models for dynamic heat radiation and convection boundary in directional solidification processes are established to simulate the temperature fields. Cellular automaton (CA) method and Kurz-Giovanola-Trivedi (KGT) growth model are used to describe nucleation and growth. Primary dendritic arm spacing (PDAS) and secondary dendritic arm spacing (SDAS) are calculated by the Ma-Sham (MS) and Furer-Wunderlin (FW) models respectively. The mushy zone shape is investigated based on the temperature fields, for both high-rate solidification (HRS) and liquid metal cooling (LMC) processes. The evolution of the microstructure and crystallographic orientation are analyzed by simulation and electron back-scattered diffraction (EBSD) technique, respectively. Comparison of the simulation results from PDAS and SDAS with experimental results reveals a good agreement with each other. The results show that LMC process can provide both dendritic refinement and superior performance for castings due to the increased cooling rate and thermal gradient.

Macrosegregation Caused by Convection Associated with Directional Solidification through Cross-Section Change

NASA Technical Reports Server (NTRS)

Ghods, M.; Lauer, M.; Tewari, S. N.; Poirier, D. R..; Grugel, R. N.

2015-01-01

Al-7 wt% Si and Pb-6 wt% Sb alloy samples were directionally solidified (DS), with liquid above and solid below and gravity pointing down, in cylindrical graphite crucibles through an abrupt cross-section change. Fraction eutectic distribution in the microstructure, primary dendrite spacing and primary dendrite trunk diameters have been measured in the DS samples in the vicinity of section change in order to examine the effect of convection associated with the combined influence of thermosolutal factors and solidification shrinkage. It is observed that convection not only produces extensive radial and axial macrosegregation near cross-section change, it also affects the dendritic array morphology. Primary dendrite spacing and primary dendrite trunk diameter, both, are influenced by this convection. In addition to the experimental results, preliminary results from a numerical model which includes solidification shrinkage and thermosolutal convection in the mushy zone in its analysis will also be presented

Proposal of a sequential treatment methodology for the safe reuse of oil sludge-contaminated soil.

PubMed

Mater, L; Sperb, R M; Madureira, L A S; Rosin, A P; Correa, A X R; Radetski, C M

2006-08-25

In this study sequential steps were used to treat and immobilize oil constituents of an oil sludge-contaminated soil. Initially, the contaminated soil was oxidized by a Fenton type reaction (13 wt% for H(2)O(2); 10mM for Fe(2+)). The oxidative treatment period of 80 h was carried out under three different pH conditions: 20 h at pH 6.5, 20 h at pH 4.5, and 40 h at pH 3.0. The oxidized contaminated sample (3 kg) was stabilized and solidified for 2h with clay (1 kg) and lime (2 kg). Finally, this mixture was solidified by sand (2 kg) and Portland cement (4 kg). In order to evaluate the efficiency of different processes to treat and immobilize oil contaminants of the oil sludge-contaminated soil, leachability and solubility tests were performed and extracts were analyzed according to the current Brazilian waste regulations. Results showed that the Fenton oxidative process was partially efficient in degrading the oil contaminants in the soil, since residual concentrations were found for the PAH and BTEX compounds. Leachability tests showed that clay-lime stabilization/solidification followed by Portland cement stabilization/solidification was efficient in immobilizing the recalcitrant and hazardous constituents of the contaminated soil. These two steps stabilization/solidification processes are necessary to enhance environmental protection (minimal leachability) and to render final product economically profitable. The treated waste is safe enough to be used on environmental applications, like roadbeds blocks.

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet for the determination of triazine and triazoles in mineral water samples.

PubMed

Bolzan, Cátia M; Caldas, Sergiane S; Guimarães, Bruno S; Primel, Ednei G

2016-09-01

A simple, rapid, and sensitive method for the determination of atrazine, simazine, cyproconazole, tebuconazole, and epoxiconazole in mineral water employing the dispersive liquid-liquid microextraction with solidification of a floating organic drop with determination by liquid chromatography tandem mass spectrometry has been developed. A mixed solution of 250 μL 1-dodecanol and 1250 μL methanol was injected rapidly into 10 mL aqueous solution (pH 7.0) with 2% w/v NaCl. After centrifugation for 5 min at 2000 rpm, the organic solvent droplets floated on the surface of the aqueous solution and the floating solvent solidified. The method limits of detection were between 3.75 and 37.5 ng/L and limits of quantification were between 12.5 and 125 ng/L. The recoveries ranged from 70 to 118% for repeatability and between 76 and 95% for intermediate precision with a relative standard deviation from 2 to 18% for all compounds. Low matrix effect was observed. The proposed method can be successfully applied in routine analysis for determination of pesticide residues in mineral water samples, allowing for monitoring of triazine and triazoles at levels below the regulatory limits set by international and national legislations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An investigation of the elevated temperature cracking susceptibility of alloy C-22 weld-metal

NASA Astrophysics Data System (ADS)

Gallagher, Morgan Leo

Alloy C-22 is one of the most corrosion resistant Ni-Cr-Mo alloys available today, and is particularly versatile. As a result, Alloy C-22 is being considered for use in the construction of storage canisters for permanent disposal of radioactive waste in the Yucca Mountain Project. However, in such a critical application, weld related defects (such as these two forms of cracking) are simply unacceptable. Solidification cracking occurs when weld shrinkage strains are applied to liquid films that result from microsegregation during solidification. Many nickel-base alloys are susceptible to solidification cracking since they solidify as austenite and many of their alloying additions partition during solidification and form low melting eutectic constituents. The transvarestraint test was used to quantify the susceptibility of Alloy C-22 to solidification cracking. The solidification cracking temperature range (SCTR) was found to be approximately 50°C (90°F); this SCTR predicts that Alloy-C-22 will have only slightly higher susceptibility than known crack-resistant alloys, such as duplex stainless-steel 2205 and austenitic stainless-steel Type 304 (FN6). Ductility-dip cracking (DDC) is a solid-state cracking phenomenon that occurs below the effective solidus temperature in highly restrained austenitic alloys. Although this type of cracking is relatively uncommon, it can be costly in critical applications where there is a low tolerance for defects. This investigation used two separate tests to quantify the susceptibility of the alloy to DDC: the hot-ductility test and the strain-to-fracture (STF) test. The hot-ductility test revealed that Alloy C-22 weld-metal exhibits an intermediate temperature ductility-dip, with ductility recovery at the upper end of the testing temperature range. The ductility minimum in the hot-ductility tests occurred around 950°C (1742°F) in both the on-heating and on-cooling tests. The strain-to-fracture test also revealed Alloy C-22 to be susceptible to ductility-dip cracking. Alloy C-22 displayed a low threshold strain necessary to initiate cracking, a wide temperature range over which cracking occurred, and no recovery of ductility at the upper end of the testing temperature range. The recovery of ductility at the upper end of the testing temperature range in the hotductility test, and the absence of this recovery in the STF test, is explained by the recrystallization behavior of the metal. Alloy C-22 has a low stacking-fault-energy, as compared to other DDC susceptible nickel-base alloys, and accordingly requires higher levels of deformation before recrystallization begins. With the relatively low strains experienced by the samples in the STF test (less than ten-percent), cracking will occur before enough strain is accumulated to cause recrystallization. In the hot-ductility test, where the sample is pulled to failure, sufficient strain (forty-percent or greater) is applied such that recrystallization occurs. This recrystallization is responsible for the recovery of ductility at the high end of the testing temperature range in the hot-ductility test. The low threshold strain that is observed in the STF test is in part explained by the behavior of the metal during the thermal cycle of the test. Experimental observations indicate that tortuous (wavy) solidification grain boundaries (SGB) migrate, or straighten, during the temperature upslope and hold period of the STF test. This migration of the grain boundaries reduces the mechanical locking effect that tortuous grain boundaries provide, allowing cracking to occur at lower applied strains. Button-melting experiments were conducted to examine the effect of compositional variation on both solidification cracking and ductility-dip cracking susceptibility of the alloy. Molybdenum, tungsten, and iron were selected for variation, as previous research has shown these three elements to be significantly enriched or depleted in the terminal solidification products of Alloy C-22 weld-metal. The solidification temperature range and volume fraction of secondary phases were used as indicators of the susceptibility of the experimental alloys to solidification cracking and ductility-dip cracking, respectively. Previous research on nickel-base alloys has demonstrated that the solidification temperature range of an alloy is directly proportional to the susceptibility of the alloy to solidification cracking. Experiments conducted within this investigation indicate that increasing the volume fraction of secondary phases in Alloy C-22 acts to increase the elevated temperature cracking-resistance and ductility of the alloy. The solidification temperature ranges of the Alloy C-22 variants examined within the button-melting experiments did not significantly widen or narrow with increases in composition. These same compositional variations demonstrated that increasing amounts of molybdenum, tungsten, and iron increased the volume fraction of secondary phases, with each element having relatively the same potency. Based on the button melting experiments and thermodynamic simulations, it is expected that Alloy C-22 will have good resistance to weld solidification cracking over its entire composition range. (Abstract shortened by UMI.)

Characterization of air pollution control residues produced in a municipal solid waste incinerator in Portugal.

PubMed

Quina, Margarida J; Santos, Regina C; Bordado, João C; Quinta-Ferreira, Rosa M

2008-04-01

This study is mainly related with the physical and chemical characterization of a solid waste, produced in a municipal solid waste (MSW) incineration process, which is usually referred as air pollution control (APC) residue. The moisture content, loss on ignition (LOI), particle size distribution, density, porosity, specific surface area and morphology were the physical properties addressed here. At the chemical level, total elemental content (TC), total availability (TA) and the leaching behaviour with compliance tests were determined, as well as the acid neutralization capacity (ANC). The main mineralogical crystalline phases were identified, and the thermal behaviour of the APC residues is also shown. The experimental work involves several techniques such as laser diffraction spectrometry, mercury porosimetry, helium pycnometry, gas adsorption, flame atomic absorption spectrometry (FAAS), ion chromatography, scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD) and simultaneous thermal analysis (STA). The results point out that the APC residues do not comply with regulations in force at the developed countries, and therefore the waste should be considered hazardous. Among the considered heavy metals, lead, zinc and chromium were identified as the most problematic ones, and their total elemental quantities are similar for several samples collected in an industrial plant at different times. Moreover, the high amount of soluble salts (NaCl, KCl, calcium compounds) may constitute a major problem and should be taken into account for all management strategies. The solubility in water is very high (more than 24% for a solid/liquid ratio of 10) and thus the possible utilizations of this residue are very limited, creating difficulties also in the ordinary treatments, such as in solidification/stabilization with binders.

FNAS modify matric and transparent experiments

NASA Technical Reports Server (NTRS)

Smith, Guy A.; Kosten, Sue E.; Workman, Gary L.

1992-01-01

Monotectic alloy materials are created by rapid melt/rapid solidification processing on the NASA KC-135. Separation of the uniform liquid into two liquids may occur by either of two processes; spinodal decomposition or nucleation followed by growth. In the first case, the liquid is unstable to composition waves, which form and grow, giving liquids of two different compositions. In the latter process discrete particles of the second liquid phase form via thermal fluctuations and then grow by diffusion. The two processes are very different, with the determining process being dictated by temperature, composition, and thermodynamic characteristics of the alloy. The first two quantities are process variables, while the third is determined by electronic interactions between the atoms in the alloy. In either case the initial alloy decomposition is followed by coarsening, resulting in growth of the particle size at nearly constant volume fraction. In particular, reduced gravity experiments on monotectic solutions have shown a number of interesting results in the KC-135. Monotectic solutions exhibit a miscibility gap in the liquid state, and consequently, gravity driven forces can dominate the solidification parameters at 1 g. In reduced gravity however, the distribution of the phases is different, resulting in new and interesting microstructures. The Rapid Melt/Rapid Quench Furnace allows one to melt a sample and resolidify it in one parabola of the KC-135's flight path, thus eliminating any accumulative influence of multiple parabolas to affect the microstructure of the material.

Approximate formula for recalescence in binary eutectic alloys

NASA Technical Reports Server (NTRS)

Ohsaka, K.; Trinh, E. H.

1993-01-01

Supercooling of a liquid prior to the nucleation of a solid and the subsequent rapid growth are necessary conditions for producing novel microstructures including metastable phases which are not formed by conventional solidification processes. Since containerless techniques, such as levitation and free fall of a sample, are capable of achieving a significant supercooling level of liquids, they are under consideration as possible techniques for material processing on earth and in space.

Grain Refining and Microstructural Modification during Solidification.

DTIC Science & Technology

1983-10-01

was found to be insensitive to the iron concentration in the samples solidified in the levitated state but not in samples quenched from the liquid . The... liquid . The preliminary * results with niobium additions indicate that no appreciable grain refinement * is achieved when the samples are levitated in an...to the critical examination of the Cr-Ni phase diagram, by using high purity starting materials, and a containerless electromagnetic levitation

Direct observation of spatially isothermal equiaxed solidification of an Al-Cu alloy in microgravity on board the MASER 13 sounding rocket

NASA Astrophysics Data System (ADS)

Murphy, A. G.; Mathiesen, R. H.; Houltz, Y.; Li, J.; Lockowandt, C.; Henriksson, K.; Melville, N.; Browne, D. J.

2016-11-01

For the first time, isothermal equiaxed solidification of a metallic alloy has been observed in situ in space, providing unique benchmark experimental data. The experiment was completed on board the MASER 13 sounding rocket, launched in December 2015, using a newly developed isothermal solidification furnace. A grain-refined Al-20 wt%Cu sample was fully melted and solidified during 360 s of microgravity and the solidification sequence was recorded using time-resolved X-radiography. Equiaxed nucleation, dendritic growth, solutal impingement, and eutectic transformation were thus observed in a gravity-free environment. Equiaxed nucleation was promoted through application of a controlled cooling rate of -0.05 K/s producing a 1D grain density of 6.5 mm-1, uniformly distributed throughout the field of view (FOV). Primary growth slowed to a visually imperceptible level at an estimated undercooling of 7 K, after which the cooling rate was increased to -1.0 K/s for the remainder of solidification and eutectic transformation, ensuring the sample was fully solidified inside the microgravity time window. The eutectic transformation commenced at the centre of the FOV proceeding radially outwards covering the entire FOV in 3 s Microgravity-based solidification is compared to an identical pre-flight ground-based experiment using the same sample and experiment timeline. The ground experiment was designed to minimise gravity effects, by choice of a horizontal orientation for the sample, so that any differences would be subtle. The first equiaxed nucleation occurred at an apparent undercooling of 0.6 K less than the equivalent event during microgravity. During primary equiaxed solidification, as expected, no buoyant grain motion was observed during microgravity, compared to modest grain rotation and reorientation observed during terrestrial-based solidification. However, when the cooling rate was increased from -0.05 K/s to -1.0 K/s during the latter stages of solidification, in both 1g and micro-g environments, some grain movement was apparent due to liquid feeding and mechanical impingement of neighbouring grains.

EVALUATION OF CONTAMINANT LEACHABILITY FACTORS BY COMPARISON OF TREATABILITY STUDY DATA FOR MULTIPLE SOLIDIFIED/STABILIZED MATERIALS

EPA Science Inventory

Solidification/stabilization (S/S) technology is widely used in the treatment of hazardous waste and contaminated soil in the US. In a project sponsored by the US Navy and the USEPA, treatability test data were compiled into a data base listing contaminant concentration and matri...

Removal of actinide elements from liquid scintillation cocktail wastes using liquid-liquid extraction and demulsification techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foltz, K.; Landsberger, S.; Srinivasan, B.

1994-12-31

A method for the separation of radionuclides with Z greater than 88, from lower-level radioactive wastes (liquid scintillation cocktail or LSC wastes), is described. The method is liquid-liquid extraction (LLX) and demulsification. The actinide elements are removed from the LSC wastes by extraction into an aqueous phase after the cocktail has been demulsified. The aqueous and organic phases are separated, then the wastes type remaining may be incinerated. Future experiments will be performed to study the effects of pH and temperature and to extend the study to wastes containing americium.

Crystal Growth Using MEPHISTO

NASA Technical Reports Server (NTRS)

deGroh, Henry C., III

1999-01-01

The shuttle flight experiment "In Situ Monitoring of Crystal Growth Using MEPHISTO" was accomplished during STS-87 as part of the fourth flight of the United States Microgravity Payload (USMP-4), which was flown from November 19 to December 5, 1997. The data returned from that flight are just now beginning to yield quantitative results. This project is an international collaboration: the furnace system known as MEPHISTO was built in France by CNES (French National Space Agency) and CEA (French Atomic Energy Commission); the principal investigator, Prof. Reza Abbaschian, is from the University of Florida at Gainesville; and numerical and analytical modeling support includes collaborators from the University of New South Wales, Australia, the University of Wisconsin at Milwaukee, the National Institute of Standards and Technology, and the NASA Lewis Research Center. MEPHISTO is a French acronym that translates into English as Materials for the Study of Interesting Phenomena of Solidification on Earth and in Orbit. Since this was the fourth flight of the MEPHISTO furnace, the experiment is referred to as MEPHISTO-4. MEPHISTO-4 was a directional solidification experiment that studied the liquid-to-solid transformation of bismuth alloyed with tin. Directional solidification is a freezing technique common to the processing of the electronic materials used in integrated circuits and detectors, such as silicon and germanium. When liquids are frozen on Earth, they must be cooled. The cooling causes stirring because of density variations in the liquid. This stirring, known as natural convection, influences the quality of the resulting solid. During freezing, regions of high and low concentrations of tin are created. This introduces another important phenomenon: diffusion, or the movement by molecular action of matter from regions of high concentration to regions of lower concentration. In MEPHISTO-4, it is tin that diffuses from the high-concentration region in front of the solid-liquid interface to more distant low-concentration regions.

Solidification of Savannah River plant high level waste

NASA Astrophysics Data System (ADS)

Maher, R.; Shafranek, L. F.; Kelley, J. A.; Zeyfang, R. W.

1981-11-01

Authorization for construction of the Defense Waste Processing Facility (DWPF) is expected in FY-83. The optimum time for stage 2 authorization is about three years later. Detailed design and construction will require approximately five years for stage 1, with stage 2 construction completed about two to three years later. Production of canisters of waste glass would begin in 1988, and the existing backlog of high level waste sludge stored at SRP would be worked off by about the year 2000. Stage 2 operation could begin in 1990. The technology and engineering are ready for construction and eventual operation of the DWPF for immobilizing high level radioactive waste at Savannah River Plant (SRP). Proceeding with this project will provide the public, and the leadership of this country, with a crucial demonstration that a major quanitity of existing high level nuclear wastes can be safely and permanently immobilized.

Experiments with the Kema cyclone incinerator for radioactive waste

NASA Astrophysics Data System (ADS)

Matteman, J. L.; Tigchelaar, P.

A cyclone incinerator for the treatment of solid waste at a nuclear power station was developed to reduce volume and weight of the final waste; reductions by factors of 7 and 80 respectively are possible (after solidification). For burnable waste the throughput is 23 kg/hr for 6 hr runs. About 7000 kg of nonradioactive waste were treated in total. The behavior of potentially dangerous radionuclides (Co, Cs, Mn and Sr) was studied by tracers. It appears that Co, Mn and Sr are concentrated in the resulting ashes, where 55% of the Cs is also found; the remaining Cs is unaccounted for. The ashes were solidified by mixing them with concrete in a 1:1 ratio. Due to the flexibility of the facility, start-up and turn-down periods are short. Since the process can be controlled automatically, the operation can be run by one employee, to load the waste and handle the ashes.

Containerless drop tube solidification and grain refinement of NiAl3

NASA Technical Reports Server (NTRS)

Ethridge, E. C.; Curreri, P. A.; Kelly, M.; Workman, G.; Smith, A. M.; Bond, R.

1984-01-01

The possibility of undercooling Ni-Al alloys below the liquidus in order to produce a single phase peritectic structure by containerless drop tube solidification was studied. Containerless process is a technique for both high purity contamination free studies as well as for investigating the undercooling and rapid solidification of alloys by suppression of heterogeneous nucleation on container walls. In order to achieve large undercoolings one must avoid heterogeneous nucleation of crystallization. It was shown that the Marshall Space Flight Center drop tubes ae unique facilities for containerless solidification experiments and large undercoolings are possible with some alloys. The original goal of undercooling the liquid metal well below the liquidus to the peritectic temperature during containerless free to form primarily NiAl3 was achieved. The microstructures were interesting from another point of view. The microstructure from small diameter samples is greatly refined. Small dendrite arm spacings such as these could greatly facilitate the annealing and solid state transformation of the alloy to nearly 10% NiAl3 by reducing the distance over which diffusion needs to occur. This could minimize annealing time and might make it economically feasible to produce NiAl3 alloy.

Heat transfer enhancement in triplex-tube latent thermal energy storage system with selected arrangements of fins

NASA Astrophysics Data System (ADS)

Zhao, Liang; Xing, Yuming; Liu, Xin; Rui, Zhoufeng

2018-01-01

The use of thermal energy storage systems can effectively reduce energy consumption and improve the system performance. One of the promising ways for thermal energy storage system is application of phase change materials (PCMs). In this study, a two-dimensional numerical model is presented to investigate the heat transfer enhancement during the melting/solidification process in a triplex tube heat exchanger (TTHX) by using fluent software. The thermal conduction and natural convection are all taken into account in the simulation of the melting/solidification process. As the volume fraction of fin is kept to be a constant, the influence of proposed fin arrangement on temporal profile of liquid fraction over the melting process is studied and reported. By rotating the unit with different angle, the simulation shows that the melting time varies a little, which means that the installation error can be reduced by the selected fin arrangement. The proposed fin arrangement also can effectively reduce time of the solidification of the PCM by investigating the solidification process. To summarize, this work presents a shape optimization for the improvement of the thermal energy storage system by considering both thermal energy charging and discharging process.

Progress on Numerical Modeling of the Dispersion of Ceramic Nanoparticles During Ultrasonic Processing and Solidification of Al-Based Nanocomposites

NASA Astrophysics Data System (ADS)

Zhang, Daojie; Nastac, Laurentiu

2016-12-01

In present study, 6061- and A356-based nano-composites are fabricated by using the ultrasonic stirring technology (UST) in a coreless induction furnace. SiC nanoparticles are used as the reinforcement. Nanoparticles are added into the molten metal and then dispersed by ultrasonic cavitation and acoustic streaming assisted by electromagnetic stirring. The applied UST parameters in the current experiments are used to validate a recently developed magneto-hydro-dynamics (MHD) model, which is capable of modeling the cavitation and nanoparticle dispersion during UST processing. The MHD model accounts for turbulent fluid flow, heat transfer and solidification, and electromagnetic field, as well as the complex interaction between the nanoparticles and both the molten and solidified alloys by using ANSYS Maxwell and ANSYS Fluent. Molecular dynamics (MD) simulations are conducted to analyze the complex interactions between the nanoparticle and the liquid/solid interface. The current modeling results demonstrate that a strong flow can disperse the nanoparticles relatively well during molten metal and solidification processes. MD simulation results prove that ultrafine particles (10 nm) will be engulfed by the solidification front instead of being pushed, which is beneficial for nano-dispersion.

Instabilities in rapid solidification of multi-component alloys

NASA Astrophysics Data System (ADS)

Altieri, Anthony L.; Davis, Stephen H.

2017-10-01

Rapid solidification of multi-component liquids occurs in many modern applications such as additive manufacturing. In the present work the interface departures from equilibrium consist of the segregation coefficient and liquidus slope depending on front speed, the one-sided, frozen-temperature approximation, and the alloy behaving as the superposition of individual components. Linear-stability theory is applied, showing that the cellular and oscillatory instabilities of the binary case are modified. The addition of components tends to destabilize the interface while the addition of a single large-diffusivity material can entirely suppress the oscillatory mode. Multiple minima in the neutral curve for the cellular mode occur.

Heat of mixing and morphological stability

NASA Technical Reports Server (NTRS)

Nandapurkar, P.; Poirier, D. R.

1988-01-01

A mathematical model, which incorporates heat of mixing in the energy balance, has been developed to analyze the morphological stability of a planar solid-liquid interface during the directional solidification of a binary alloy. It is observed that the stability behavior is almost that predicted by the analysis of Mullins and Sekerka (1963) at low growth velocities, while deviations in the critical concentration of about 20-25 percent are observed under rapid solidification conditions for certain systems. The calculations indicate that a positive heat of mixing makes the planar interface more unstable, whereas a negative heat of mixing makes it more stable, in terms of the critical concentration.

Waste management technology development and demonstration programs at Brookhaven National Laboratory

NASA Technical Reports Server (NTRS)

Kalb, Paul D.; Colombo, Peter

1991-01-01

Two thermoplastic processes for improved treatment of radioactive, hazardous, and mixed wastes were developed from bench scale through technology demonstration: polyethylene encapsulation and modified sulfur cement encapsulation. The steps required to bring technologies from the research and development stage through full scale implementation are described. Both systems result in durable waste forms that meet current Nuclear Regulatory Commission and Environmental Protection Agency regulatory criteria and provide significant improvements over conventional solidification systems such as hydraulic cement. For example, the polyethylene process can encapsulate up to 70 wt pct. nitrate salt, compared with a maximum of about 20 wt pct. for the best hydraulic cement formulation. Modified sulfur cement waste forms containing as much as 43 wt pct. incinerator fly ash were formulated, whereas the maximum quantity of this waste in hydraulic cement is 16 wt pct.

Getting in shape: molten wax drop deformation and solidification at an immiscible liquid interface.

PubMed

Beesabathuni, Shilpa N; Lindberg, Seth E; Caggioni, Marco; Wesner, Chris; Shen, Amy Q

2015-05-01

The controlled production of non-spherical shaped particles is important for many applications such as food processing, consumer goods, adsorbents, drug delivery, and optical sensing. In this paper, we investigated the deformation and simultaneous solidification of millimeter size molten wax drops as they impacted an immiscible liquid interface of higher density. By varying initial temperature and viscoelasticity of the molten drop, drop size, impact velocity, viscosity and temperature of the bath fluid, and the interfacial tension between the molten wax and bath fluid, spherical molten wax drops impinged on a cooling water bath and were arrested into non-spherical solidified particles in the form of ellipsoid, mushroom, disc, and flake-like shapes. We constructed cursory phase diagrams for the various particle shapes generated over a range of Weber, Capillary, Reynolds, and Stefan numbers, governed by the interfacial, inertial, viscous, and thermal effects. We solved a simplified heat transfer problem to estimate the time required to initiate the solidification at the interface of a spherical molten wax droplet and cooling aqueous bath after impact. By correlating this time with the molten wax drop deformation history captured from high speed imaging experiments, we elucidate the delicate balance of interfacial, inertial, viscous, and thermal forces that determine the final morphology of wax particles. Copyright © 2015 Elsevier Inc. All rights reserved.

Grain Refinement and Improvement of Solidification Defects in Direct-Chill Cast Billets of A4032 Alloy by Melt Conditioning

NASA Astrophysics Data System (ADS)

Li, Hu-Tian; Zhao, Pizhi; Yang, Rongdong; Patel, Jayesh B.; Chen, Xiangfu; Fan, Zhongyun

2017-10-01

Melt-conditioned, direct-chill (MC-DC) casting is an emerging technology to manipulate the solidification process by melt conditioning via intensive shearing in the sump during DC casting to tailor the solidification microstructure and defect formation. When using MC-DC casting technology in an industrial scale DC cast billet of an A4032 aluminum alloy, significant grain refinement and uniform microstructure can be achieved in the primary α-Al phase with fine secondary dendritic arm spacing (SDAS). Improved macrosegregation is quantitatively characterized and correlated with the suppression of channel segregation. The mechanisms for the prevention of channel segregation are attributed to the increased local cooling rate in the liquid-solid phase region in the sump and the formation of fine equiaxed dendritic grains under intensive melt shearing during MC-DC casting. A critical cooling rate has been identified to be around 0.5 to 1 K/s (°C/s) for the channel segregation to happen in the investigated alloy based on quantitative metallographic results of SDAS. Reduction and refinement of microporosity is attributed to the improved permeability in the liquid-solid phase region estimated by the Kozeny-Carman relationship. The potential improvement in the mechanical properties achievable in MC-DC cast billets is indicated by the finer and more uniform forging streamline in the forgings of MC-DC cast billet.

Dilatant shear bands in solidifying metals.

PubMed

Gourlay, C M; Dahle, A K

2007-01-04

Compacted granular materials expand in response to shear, and can exhibit different behaviour from that of the solids, liquids and gases of which they are composed. Application of the physics of granular materials has increased the understanding of avalanches, geological faults, flow in hoppers and silos, and soil mechanics. During the equiaxed solidification of metallic alloys, there exists a range of solid fractions where the microstructure consists of a geometrically crowded disordered assembly of crystals saturated with liquid. It is therefore natural to ask if such a microstructure deforms as a granular material and what relevance this might have to solidification processing. Here we show that partially solidified alloys can exhibit the characteristics of a cohesionless granular material, including Reynolds' dilatancy and strain localization in dilatant shear bands 7-18 mean crystals wide. We show that this behaviour is important in defect formation during high pressure die casting of Al and Mg alloys, a global industry that contributes over $7.3 billion to the USA's economy alone and is used in the manufacture of products that include mobile-phone covers and steering wheels. More broadly, these findings highlight the potential to apply the principles and modelling approaches developed in granular mechanics to the field of solidification processing, and also indicate the possible benefits that might be gained from exploring and exploiting further synergies between these fields.

Liquid and Gaseous Waste Operations Department annual operating report CY 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maddox, J.J.; Scott, C.B.

1997-03-01

This annual report summarizes operating activities dealing with the process waste system, the liquid low-level waste system, and the gaseous waste system. It also describes upgrade activities dealing with the process and liquid low-level waste systems, the cathodic protection system, a stack ventilation system, and configuration control. Maintenance activities are described dealing with nonradiological wastewater treatment plant, process waste treatment plant and collection system, liquid low-level waste system, and gaseous waste system. Miscellaneous activities include training, audits/reviews/tours, and environmental restoration support.

Interactions between solidification and compositional convection in mushy layers

NASA Technical Reports Server (NTRS)

Worster, M. Grae

1994-01-01

Mushy layers are ubiquitous during the solidification of alloys. They are regions of mixed phase wherein solid crystals are bathed in the melt from which they grew. The matrix of crystals forms a porous medium through which the melt can flow, driven either by external forces or by its own buoyancy in a gravitational field. Buoyancy-driven convection of the melt depends both on temperature gradients, which are necessary for solidification, and on compositional gradients, which are generated as certain components of the alloy are preferentially incorporated in the solid phase and the remaining components are expelled into the melt. In fully liquid regions, the combined action of temperature and concentration on the density of the liquid can cause various forms of double-diffusive convection. However, in the interior of mushy regions the temperature and concentration are thermodynamically coupled so only single-diffusive convection can occur. Typically, the effect of composition on the buoyancy of the melt is much greater than the effect of temperature, and thus convection in mushy layers in driven primarily by the computational gradients within them. The rising interstitial liquid is relatively dilute, having come from colder regions of the mushy layer, where the liquidus concentration is lower, and can dissolve the crystal matrix through which it flows. This is the fundamental process by which chimneys are formed. It is a nonlinear process that requires the convective velocities to be sufficiently large, so fully fledged chimneys (narrow channels) might be avoided by means that weaken the flow. Better still would be to prevent convection altogether, since even weak convection will cause lateral, compositional inhomogeneities in castings. This report outlines three studies that examine the onset of convection within mushy layers.

Apparatus for melt growth of crystalline semiconductor sheets

DOEpatents

Ciszek, Theodore F.; Hurd, Jeffery L.

1986-01-01

An economical method is presented for forming thin sheets of crystalline silicon suitable for use in a photovoltaic conversion cell by solidification from the liquid phase. Two spatially separated, generally coplanar filaments wettable by liquid silicon and joined together at the end by a bridge member are immersed in a silicon melt and then slowly withdrawn from the melt so that a silicon crystal is grown between the edge of the bridge and the filaments.

Solidification and loss of hydrostaticity in liquid media used for pressure measurements

DOE PAGES

Torikachvili, M. S.; Kim, S. K.; Colombier, E.; ...

2015-12-16

We carried out a study of the pressure dependence of the solidification temperature in nine pressure transmitting media that are liquid at ambient temperature, under pressures up to 2.3 GPa. These fluids are 1:1 isopentane/n-pentane, 4:6 light mineral oil/n-pentane, 1:1 isoamyl alcohol/n-pentane, 4:1 methanol/ethanol, 1:1 FC72/FC84 (Fluorinert), Daphne 7373, isopentane, and Dow Corning PMX silicone oils 200 and 60,000 cS. We relied on the high sensitivity of the electrical resistivity of Ba(Fe 1–xRu x) 2As 2 single crystals to the freezing of the pressure media and cross-checked with corresponding anomalies observed in the resistance of the manganin coil that servedmore » as the ambient temperature resistive manometer. In addition to establishing the temperature-pressure line separating the liquid (hydrostatic) and frozen (non-hydrostatic) phases, these data permit rough estimates of the freezing pressure of these media at ambient temperature. As a result, this pressure establishes the extreme limit for the medium to be considered hydrostatic. For higher applied pressures, the medium has to be treated as non-hydrostatic.« less

Solidification and loss of hydrostaticity in liquid media used for pressure measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Torikachvili, M. S.; Kim, S. K.; Colombier, E.

We carried out a study of the pressure dependence of the solidification temperature in nine pressure transmitting media that are liquid at ambient temperature, under pressures up to 2.3 GPa. These fluids are 1:1 isopentane/n-pentane, 4:6 light mineral oil/n-pentane, 1:1 isoamyl alcohol/n-pentane, 4:1 methanol/ethanol, 1:1 FC72/FC84 (Fluorinert), Daphne 7373, isopentane, and Dow Corning PMX silicone oils 200 and 60,000 cS. We relied on the high sensitivity of the electrical resistivity of Ba(Fe 1–xRu x) 2As 2 single crystals to the freezing of the pressure media and cross-checked with corresponding anomalies observed in the resistance of the manganin coil that servedmore » as the ambient temperature resistive manometer. In addition to establishing the temperature-pressure line separating the liquid (hydrostatic) and frozen (non-hydrostatic) phases, these data permit rough estimates of the freezing pressure of these media at ambient temperature. As a result, this pressure establishes the extreme limit for the medium to be considered hydrostatic. For higher applied pressures, the medium has to be treated as non-hydrostatic.« less

40 CFR 60.2875 - What definitions must I know?

Code of Federal Regulations, 2012 CFR

2012-07-01

... burn liquid wastes material and gas (Liquid/gas),” “Energy recovery unit designed to burn solid..., liquid fuel or gaseous fuels. Energy recovery unit designed to burn liquid waste material and gas (Liquid/gas) means an energy recovery unit that burns a liquid waste with liquid or gaseous fuels not combined...

40 CFR 60.2875 - What definitions must I know?

Code of Federal Regulations, 2011 CFR

2011-07-01

... burn liquid wastes material and gas (Liquid/gas),” “Energy recovery unit designed to burn solid..., liquid fuel or gaseous fuels. Energy recovery unit designed to burn liquid waste material and gas (Liquid/gas) means an energy recovery unit that burns a liquid waste with liquid or gaseous fuels not combined...

Partially melted zone in aluminum welds

NASA Astrophysics Data System (ADS)

Huang, Chen-Che

The partially melted zone (PMZ) is a region immediately outside the weld metal where grain boundary (GB) liquation can occur and cause intergranular cracking. Aluminum alloys are known to be susceptible to liquation and liquation cracking. The PMZ of alloy 2219 (essentially Al-6.3Cu) was studied. Liquation is initiated eutectically. Solidification of the GB liquid was directional---upward and toward the weld as a result of the temperature gradients across the PMZ. The liquated material solidifies with severe segregation into a low-strength, low-ductility structure consisting of a solute-depleted ductile phase and a solute-rich brittle eutectic. In tensile testing the maximum load and displacement before failure were both far below those of the base metal. The GB eutectic fractured while the adjacent Cu-depleted a deformed readily under tension. The solidification mode of the grain boundary liquid was mostly planar. However, cellular solidification was also observed near the bottom of partial-penetration welds, where temperature gradients were lowest. The liquation mechanisms in wrought multicomponent aluminum alloys during welding were also studied. Three mechanisms were identified. They cover most, if not all, wrought aluminum alloys. Liquation cracking in the PMZ was investigated in full-penetration aluminum welds. Liquation cracking occurs because the solidifying PMZ is pulled by a solidifying and thus contracting weld metal that is stronger than the PMZ. Liquation cracking can occur if there is significant liquation in the PMZ, if there is no solidification cracking in the adjacent weld metal, and if the PMZ becomes lower in solid fraction (and hence strength) during its terminal solidification than the solidifying weld metal. Liquation cracking in the PMZ was also investigated in partial-penetration aluminum welds. The papillary (nipple) type penetration common in welding with spray transfer of the filler wire actually oscillates along the weld and promotes cracking regardless of the filler metal used. The fast-solidifying weld metal immediately behind the penetration tip contracts and pulls the PMZ near the tip and, regardless of the weld-metal composition, cracking can occur if PMZ liquation is significant.

Approximate analysis of the formation of a buoyant solid sphere in a supercooled melt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solomon, A.D.; Wilson, D.G.; Alexiades, V.

1986-03-01

A mathematical model is presented for the idealized formation and development of a buoyant sphere solidifying in an infinite pool of supercooled liquid. The solid and liquid are of the same pure material and the solid is less dense than the liquid. Initially the liquid is at a uniform temperature that is below its equilibrium freezing temperature, T/sub cr/, but above the so called hypercooled temperature, T/sub cr/ - H/c/sub L/. Here H and c/sub L/ are the latent heat of solidification and the specific heat of the liquid, respectively. An approximate solution is derived based on the Megerlin approximationmore » method. 11 refs.« less

Determination of ochratoxin A in fruit juice by high-performance liquid chromatography after vortex-assisted emulsification microextraction based on solidification of floating organic drop.

PubMed

Asadi, Mohammad

2018-03-01

A rapid, simple, and green vortex-assisted emulsification microextraction method based on solidification of floating organic drop was developed for the extraction and determination of ochratoxin A (OTA) with high-performance liquid chromatography. Some factors influencing the extraction efficiency of OTA such as the type and volume of extraction solvent, sample pH, salt concentration, vortex time, and sample volume were optimized. Under optimized conditions, the calibration curve exhibited linearity in the range of 50.0-500 ng L -1 with a coefficient of determination higher than 0.999. The limit of detection was 15.0 ng L -1 . The inter- and intra-assays relative standard deviations were in a range of 4.7-8.7%. The accuracy of the developed method was investigated through recovery experiments, and it was successfully used for the quantification of OTA in 40 samples of fruit juice.

Preferred growth orientation and microsegregation behaviors of eutectic in a nickel-based single-crystal superalloy

PubMed Central

Ma, Dexin; Bührig-Polaczek, Andreas

2015-01-01

A nickel-based single-crystal superalloy was employed to investigate the preferred growth orientation behavior of the (γ + γ′) eutectic and the effect of these orientations on the segregation behavior. A novel solidification model for the eutectic island was proposed. At the beginning of the eutectic island’s crystallization, the core directly formed from the liquid by the eutectic reaction, and then preferably grew along [100] direction. The crystallization of the eutectic along [110] always lagged behind that in [100] direction. The eutectic growth in [100] direction terminated on impinging the edge of the dendrites or another eutectic island. The end of the eutectic island’s solidification terminates due to the encroachment of the eutectic liquid/solid interface at the dendrites or another eutectic island in [110] direction. The distribution of the alloying elements depended on the crystalline axis. The degree of the alloying elements’ segregation was lower along [100] than [110] direction with increasing distance from the eutectic island’s center. PMID:27877773

Surface Structure Formation in Direct Chill (DC) Casting of Al Alloys

NASA Astrophysics Data System (ADS)

Bayat, Nazlin; Carlberg, Torbjörn

2014-05-01

The aim of this study is to increase the understanding of the surface zone formation during direct chill (DC) casting of aluminum billets produced by the air slip technology. The depth of the shell zone, with compositions deviating from the bulk, is of large importance for the subsequent extrusion productivity and quality of final products. The surface microstructures of 6060 and 6005 aluminum alloys in three different surface appearances—defect free, wavy surface, and spot defects—were studied. The surface microstructures and outer appearance, segregation depth, and phase formation were investigated for the mentioned cases. The results were discussed and explained based on the exudation of liquid metal through the mushy zone and the fact that the exudated liquid is contained within a surface oxide skin. Outward solidification in the surface layer was quantitatively analyzed, and the oxide skin movements explained meniscus line formation. Phases forming at different positions in the segregation zone were analyzed and coupled to a cellular solidification in the exudated layer.

The Faceted Discrete Growth and Phase Differentiation During the Directional Solidification of 20SiMnMo5 Steel

NASA Astrophysics Data System (ADS)

Ma, Xiaoping; Li, Dianzhong

2018-07-01

The microstructures, segregation and cooling curve were investigated in the directional solidification of 20SiMnMo5 steel. The typical characteristic of faceted growth is identified. The microstructures within the single cellular and within the single dendritic arm, together with the contradictive segregation distribution against the cooling curve, verify the discrete crystal growth in multi-scales. Not only the single cellular/dendritic arm but also the single martensite zone within the single cellular/dendritic arm is produced by the discrete growth. In the viewpoint of segregation, the basic domain following continuous growth has not been revealed. Along with the multi-scale faceted discrete growth, the phase differentiation happens for both the solid and liquid. The differentiated liquid phases appear and evolve with different sizes, positions, compositions and durations. The physical mechanism for the faceted discrete growth is qualitatively established based on the nucleation of new faceted steps induced by the composition gradient and temperature gradient.

The Faceted Discrete Growth and Phase Differentiation During the Directional Solidification of 20SiMnMo5 Steel

NASA Astrophysics Data System (ADS)

Ma, Xiaoping; Li, Dianzhong

2018-03-01

The microstructures, segregation and cooling curve were investigated in the directional solidification of 20SiMnMo5 steel. The typical characteristic of faceted growth is identified. The microstructures within the single cellular and within the single dendritic arm, together with the contradictive segregation distribution against the cooling curve, verify the discrete crystal growth in multi-scales. Not only the single cellular/dendritic arm but also the single martensite zone within the single cellular/dendritic arm is produced by the discrete growth. In the viewpoint of segregation, the basic domain following continuous growth has not been revealed. Along with the multi-scale faceted discrete growth, the phase differentiation happens for both the solid and liquid. The differentiated liquid phases appear and evolve with different sizes, positions, compositions and durations. The physical mechanism for the faceted discrete growth is qualitatively established based on the nucleation of new faceted steps induced by the composition gradient and temperature gradient.

Specific heat and related thermophysical properties of liquid Fe-Cu-Mo alloy

NASA Astrophysics Data System (ADS)

Wang, Haipeng; Luo, Bingchi; Chang, Jian; Wei, Bingbo

2007-08-01

The specific heat and related thermophysical properties of liquid Fe77.5Cu13Mo9.5 monotectic alloy were investigated by an electromagnetic levitation drop calorimeter over a wide temperature range from 1482 to 1818 K. A maximum undercooling of 221 K (0.13 T m) was achieved and the specific heat was determined as 44.71 J·mol-1·K-1. The excess specific heat, enthalpy change, entropy change and Gibbs free energy difference of this alloy were calculated on the basis of experimental results. It was found that the calculated results by traditional estimating methods can only describe the solidification process under low undercooling conditions. Only the experimental results can reflect the reality under high undercooling conditions. Meanwhile, the thermal diffusivity, thermal conductivity, and sound speed were derived from the present experimental results. Furthermore, the solidified microstructural morphology was examined, which consists of (Fe) and (Cu) phases. The calculated interface energy was applied to exploring the correlation between competitive nucleation and solidification microstructure within monotectic alloy.

The Particle Distribution in Liquid Metal with Ceramic Particles Mould Filling Process

NASA Astrophysics Data System (ADS)

Dong, Qi; Xing, Shu-ming

2017-09-01

Adding ceramic particles in the plate hammer is an effective method to increase the wear resistance of the hammer. The liquid phase method is based on the “with the flow of mixed liquid forging composite preparation of ZTA ceramic particle reinforced high chromium cast iron hammer. Preparation method for this system is using CFD simulation analysis the particles distribution of flow mixing and filling process. Taking the 30% volume fraction of ZTA ceramic composite of high chromium cast iron hammer as example, by changing the speed of liquid metal viscosity to control and make reasonable predictions of particles distribution before solidification.

40 CFR 761.269 - Sampling liquid PCB remediation waste.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Sampling liquid PCB remediation waste..., AND USE PROHIBITIONS Cleanup Site Characterization Sampling for PCB Remediation Waste in Accordance with § 761.61(a)(2) § 761.269 Sampling liquid PCB remediation waste. (a) If the liquid is single phase...

Risk assessment and quality improvement of liquid waste management in Taiwan University chemical laboratories.

PubMed

Ho, Chao-Chung; Chen, Ming-Shu

2018-01-01

The policy of establishing new universities across Taiwan has led to an increase in the number of universities, and many schools have constructed new laboratories to meet students' academic needs. In recent years, there has been an increase in the number of laboratory accidents from the liquid waste in universities. Therefore, how to build a safety system for laboratory liquid waste disposal has become an important issue in the environmental protection, safety, and hygiene of all universities. This study identifies the risk factors of liquid waste disposal and presents an agenda for practices to laboratory managers. An expert questionnaire is adopted to probe into the risk priority procedures of liquid waste disposal; then, the fuzzy theory-based FMEA method and the traditional FMEA method are employed to analyze and improve the procedures for liquid waste disposal. According to the research results, the fuzzy FMEA method is the most effective, and the top 10 potential disabling factors are prioritized for improvement according to the risk priority number (RNP), including "Unclear classification", "Gathering liquid waste without a funnel or a drain pan", "Lack of a clearance and transport contract", "Liquid waste spill during delivery", "Spill over", "Decentralized storage", "Calculating weight in the wrong way", "Compatibility between the container material and the liquid waste", "Lack of dumping and disposal tools", and "Lack of a clear labels for liquid waste containers". After tracking improvements, the overall improvement rate rose to 60.2%. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mercury recovery from mercury-containing wastes using a vacuum thermal desorption system.

PubMed

Lee, Woo Rim; Eom, Yujin; Lee, Tai Gyu

2017-02-01

Mercury (Hg)-containing waste from various industrial facilities is commonly treated by incineration or stabilization/solidification and retained in a landfill at a managed site. However, when highly concentrated Hg waste is treated using these methods, Hg is released into the atmosphere and soil environment. To eliminate these risks, Hg recovery technology using thermal treatment has been developed and commercialized to recover Hg from Hg-containing waste for safe disposal. Therefore, we developed Hg recovery equipment to treat Hg-containing waste under a vacuum of 6.67kPa (abs) at 400°C and recover the Hg. In addition, the dust generated from the waste was separated by controlling the temperature of the dust filtration unit to 230°C. Additionally, water and Hg vapors were condensed in a condensation unit. The Hg removal rate after waste treatment was 96.75%, and the Hg recovery rate as elemental Hg was 75.23%. Copyright © 2016 Elsevier Ltd. All rights reserved.

A calorimetric and microstructural study of solidified toxic wastes. Part 1: A classification of OPC/waste interference effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hills, C.D.; Sollars, C.J.; Perry, R.

1994-01-01

Ordinary Portland cement (OPC) has been used to solidify hazardous waste for about 25 years. The effects of waste components on the hydraulic activity of his binder have been subject to increasing research. Under certain circumstances, as yet to be defined, the hydration reactions thought responsible for solidification can be poisoned and appear to be retarded indefinitely. In this study, a number of wastes known to be capable of poisoning hydration were added to OPC and the effects were examined by conduction calorimetry and microstructural analysis techniques. A comparison of results showed that it was possible to classify waste/OPC interactionsmore » by phase development and the heat of hydration evolved. During the second part of this work, which is reported separately, the individual wastes were characterized, and the individual components identified as significant were added to OPC in single and combined additions. A comparison of results showed that it was possible to reproduce the poisoning effects observed.« less

Instant freezing of impacting wax drops

NASA Astrophysics Data System (ADS)

Ponomarenko, Alexandre; Virot, Emmanuel; Rubinstein, Shmuel

2015-11-01

We present the impact of hot liquid drops of wax on surfaces whose temperature is below the solidifying temperature of the drops. During the fall the drops remain mostly liquid, but upon impact, their temperature quickly decreases resulting in the solidification of the drop. Depending on the impact energy, drops size and the temperature difference between the drop and the surface this results in plethora of solid shapes: simple lenses, triangular drops, spherical caps and popped popcorn shapes.

Method and apparatus for melt growth of crystalline semiconductor sheets

DOEpatents

Ciszek, T.F.; Hurd, J.L.

1981-02-25

An economical method is presented for forming thin sheets of crystalline silicon suitable for use in a photovoltaic conversion cell by solidification from the liquid phase. Two spatially separated, generally coplanar filaments wettable by liquid silicon and joined together at the end by a bridge member are immersed in a silicon melt and then slowly withdrawn from the melt so that a silicon crystal is grown between the edge of the bridge and the filaments.

Atomistic to continuum modeling of solidification microstructures

DOE PAGES

Karma, Alain; Tourret, Damien

2015-09-26

We summarize recent advances in modeling of solidification microstructures using computational methods that bridge atomistic to continuum scales. We first discuss progress in atomistic modeling of equilibrium and non-equilibrium solid–liquid interface properties influencing microstructure formation, as well as interface coalescence phenomena influencing the late stages of solidification. The latter is relevant in the context of hot tearing reviewed in the article by M. Rappaz in this issue. We then discuss progress to model microstructures on a continuum scale using phase-field methods. We focus on selected examples in which modeling of 3D cellular and dendritic microstructures has been directly linked tomore » experimental observations. Finally, we discuss a recently introduced coarse-grained dendritic needle network approach to simulate the formation of well-developed dendritic microstructures. The approach reliably bridges the well-separated scales traditionally simulated by phase-field and grain structure models, hence opening new avenues for quantitative modeling of complex intra- and inter-grain dynamical interactions on a grain scale.« less

Particle Engulfment and Pushing by Solidification Interfaces. Part 1; Ground Experiments

NASA Technical Reports Server (NTRS)

Juretzko, Frank R.; Dhindaw, Brij K.; Stefanescu, Doru M.; Sen, subhayu; Curreri, Peter A.

1998-01-01

Directional solidification experiments have been carried out to determine the pushing/engulfment transition for two different metal/particle systems. The systems chosen were aluminum/zirconia particles and zinc/zirconia particles. Pure metals (99.999% Al and 99.95% Zn) and spherical particles (500 microns in diameter) were used. The particles were non-reactive with the matrices within the temperature range of interest. The experiments were conducted such as to insure a planar solid/liquid interface during solidification. Particle location before and after processing was evaluated by X-ray transmission microscopy for the Al/ZrO2 samples. All samples were characterized by optical metallography after processing. A clear methodology for the experiment evaluation was developed to unambiguously interpret the occurrence of the pushing/engulfment transition. It was found that the critical velocity for engulfment ranges from 1.9 to 2.4 micron/s for Al/ZrO2 and from 1.9 to 2.9 microns/s for Zn/ZrO2.

The melting and solidification of nanowires

NASA Astrophysics Data System (ADS)

Florio, B. J.; Myers, T. G.

2016-06-01

A mathematical model is developed to describe the melting of nanowires. The first section of the paper deals with a standard theoretical situation, where the wire melts due to a fixed boundary temperature. This analysis allows us to compare with existing results for the phase change of nanospheres. The equivalent solidification problem is also examined. This shows that solidification is a faster process than melting; this is because the energy transfer occurs primarily through the solid rather than the liquid which is a poorer conductor of heat. This effect competes with the energy required to create new solid surface which acts to slow down the process, but overall conduction dominates. In the second section, we consider a more physically realistic boundary condition, where the phase change occurs due to a heat flux from surrounding material. This removes the singularity in initial melt velocity predicted in previous models of nanoparticle melting. It is shown that even with the highest possible flux the melting time is significantly slower than with a fixed boundary temperature condition.

Convection Effects During Bulk Transparent Alloy Solidification in DECLIC-DSI and Phase-Field Simulations in Diffusive Conditions

NASA Astrophysics Data System (ADS)

Mota, F. L.; Song, Y.; Pereda, J.; Billia, B.; Tourret, D.; Debierre, J.-M.; Trivedi, R.; Karma, A.; Bergeon, N.

2017-08-01

To study the dynamical formation and evolution of cellular and dendritic arrays under diffusive growth conditions, three-dimensional (3D) directional solidification experiments were conducted in microgravity on a model transparent alloy onboard the International Space Station using the Directional Solidification Insert in the DEvice for the study of Critical LIquids and Crystallization. Selected experiments were repeated on Earth under gravity-driven fluid flow to evidence convection effects. Both radial and axial macrosegregation resulting from convection are observed in ground experiments, and primary spacings measured on Earth and microgravity experiments are noticeably different. The microgravity experiments provide unique benchmark data for numerical simulations of spatially extended pattern formation under diffusive growth conditions. The results of 3D phase-field simulations highlight the importance of accurately modeling thermal conditions that strongly influence the front recoil of the interface and the selection of the primary spacing. The modeling predictions are in good quantitative agreements with the microgravity experiments.

Thermosolutal convection during dendritic solidification

NASA Technical Reports Server (NTRS)

Heinrich, J. C.; Nandapurkar, P.; Poirier, D. R.; Felicelli, S.

1989-01-01

This paper presents a mathematical model for directional solidification of a binary alloy including a dendritic region underlying an all-liquid region. It is assumed initially that there exists a nonconvecting state with planar isotherms and isoconcentrates solidifying at a constant velocity. The stability of this system has been analyzed and nonlinear calculations are performed that show the effect of convection in the solidification process when the system is unstable. Results of calculations for various cases defined by the initial temperature gradient at the dendrite tips and varying strength of the gravitational field are presented for systems involving lead-tin alloys. The results show that the systems are stable for a gravitational constant of 0.0001 g(0) and that convection can be suppressed by appropriate choice of the container's size for higher values of the gravitational constant. It is also concluded that for the lead-tin systems considered, convection in the mushy zone is not significant below the upper 20 percent of the dendritic zone, if al all.

The growth of metastable peritectic compounds

NASA Technical Reports Server (NTRS)

Pirich, R. G.

1984-01-01

The effects of directional solidification processing on the microstructural, compositional, and magnetic properties of high-melting-temperature, commercially important alloys which form from the liquid state via peritectic or eutectic type reactions were determined. Emphasis was placed on ferromagnetic compounds of the commercially important Co-Sm and Al-Mn systems. The primary dendrite spacing for eutectic Sm2Co17/Co scaled with negative square root of V and varied from approximately 50 microns for V 20 cm/h to hundreds of microns for V 10 cm/h. Since the crystal growth mechanism was dendritic rather than cooperative, the assoicated permanent magnet properties were rather poor. Magnetization as a function of sample orientation indicates that the easy axis of magnetization was primarily along the direction of solidification for the eutectic Sm2Co17/Co and peritectic SmCo5/Sm2Co17 compositions. For the Al-Mn case, magnetization and microstructural characterization suggest isotropic, polycrystalling growth for all solidification velocities studied.

Rapid solidification of high-conductivity copper alloys. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Bloom, Theodore Atlas

1989-01-01

The main objective was to develop improved copper alloys of high strength and high thermal and electric conductivity. Chill block melt spinning was used to produce binary alloys of Cu-Cr and Cu-Zr, and ternary alloys of Cu-Cr-Ag. By quenching from the liquid state, up to 5 atomic percent of Cr and Zr were retained in metastable extended solid solution during the rapid solidification process. Eutectic solidification was avoided and the full strengthening benefits of the large volume fraction of precipitates were realized by subsequent aging treatment. The very low solid solubility of Cr and Zr in Cu result in a high conductivity Cu matrix strengthened by second phase precipitates. Tensile properties on as-cast and aged ribbons were measured at room and elevated temperatures. Precipitate coarsening of Cr in Cu was studied by changes in electrical resistance during aging. X-ray diffraction was used to measure the lattice parameter and the degree of supersaturation of the matrix. The microstructures were characterized by optical and electron microscopy.

Influence of Pressure Field in Melts on the Primary Nucleation in Solidification Processing

NASA Astrophysics Data System (ADS)

Rakita, Milan; Han, Qingyou

2017-10-01

It is well known that external fields applied to melts can cause nucleation at lower supercoolings, fragmentation of growing dendrites, and forced convection around the solidification front. All these effects contribute to a finer microstructure of solidified material. In this article, we analyze how the pressure field created with ultrasonic vibrations influences structure refinement in terms of supercooling. It is shown that only high cavitation pressures of the order of 104 atmospheres are capable of nucleating crystals at minimal supercoolings. We demonstrate the possibility of sononucleation even in superheated liquid. Simulation and experiments with water samples show that very high cavitation pressures occur in a relatively narrow zone where the drive acoustic field has an appropriate combination of pressure amplitude and frequency. In order to accurately predict the microstructure formed by ultrasonically assisted solidification of metals, this article calls for the development of equations of state that would describe the pressure-dependent behavior of molten metals.

An Electron Microscopy Study of Graphite Growth in Nodular Cast Irons

NASA Astrophysics Data System (ADS)

Laffont, L.; Jday, R.; Lacaze, J.

2018-04-01

Growth of graphite during solidification and high-temperature solid-state transformation has been investigated in samples cut out from a thin-wall casting which solidified partly in the stable (iron-graphite) and partly in the metastable (iron-cementite) systems. Transmission electron microscopy has been used to characterize graphite nodules in as-cast state and in samples having been fully graphitized at various temperatures in the austenite field. Nodules in the as-cast material show a twofold structure characterized by an inner zone where graphite is disoriented and an outer zone where it is well crystallized. In heat-treated samples, graphite nodules consist of well-crystallized sectors radiating from the nucleus. These observations suggest that the disoriented zone appears because of mechanical deformation when the liquid contracts during its solidification in the metastable system. During heat-treatment, the graphite in this zone recrystallizes. In turn, it can be concluded that nodular graphite growth mechanism is the same during solidification and solid-state transformation.

Analysis of X-Ray Microradiographs of Al-Au Interface Quench Profile using Modeling of Solidification Including Double-Diffusion and Convection in the Melt

NASA Technical Reports Server (NTRS)

Bune, Andris V.; Kaukler, William

1999-01-01

Experimental data on Al-0.8Au horizontal solidification of a 1 mm thick specimen in a BN crucible shows the effect of growth rate on the solidification interface shape. For translation rates below 0.5 micron/s the interface maintains a plain and flat shape. When the translation rate is 3 to 5 micron/s or more, the interface appearance changes to two planar zones, with the zone closer to the bottom having higher inclination. The interface shapes were measured by first quenching in place during growth. X-ray microscopy shows the interface shape within the quenched sample by viewing through the side of the specimen. In order to provide theoretical explanation of the phenomena, numerical modeling was undertaken using finite element code FIDAP. Double diffusion convection in Al-0.8Au melt and crystal-melt interface curvature during directional solidification was analyzed numerically. Actual thermophysical properties of Al-0.8Au including the binary Al-Au phase diagram were used. Although convection in the sample is weak, for the slower translation rate convection and diffusion is sufficient for the redistribution of initial compositional stratification caused by gravity. When translation rate is raised, neither convection nor diffusion can provide proper mixing so that solidification temperatures differ significantly near the bottom within the bulk of the sample. As a result, the solid-liquid interface appears to have two planar zones with different inclination.

Comparison of solidification of floating drop and homogenous liquid-liquid microextractions for the extraction of two plasticizers from the water kept in PET-bottles.

PubMed

Yamini, Yadollah; Ghambarian, Mahnaz; Khalili-Zanjani, Mohammad Reza; Faraji, Mohammad; Shariati, Shahab

2009-09-01

Two approaches based on solidification of floating drop microextraction (SFDME) and homogenous liquid-liquid microextraction (HLLE) were compared for the extraction and preconcentration of di-(2-ethylhexyl) phthalate (DEHP) and di-(2-ethylhexyl) adipate (DEHA) from the mineral water samples. In SFDME, a floated drop of the mixture of acetophenone/1-undecanol (1:8) was exposed on the surface of the aqueous solution and extraction was permitted to occur. In HLLE, a homogenous ternary solvent system was used by water/methanol/chloroform and the phase separation phenomenon occurred by salt addition. Under the optimal conditions, the LODs for the two target plasticizers (DEHA and DEHP), obtained by SFDME-GC-FID and HLLE-GC-FID, were ranged from 0.03 to 0.01 microg/L and 0.02 to 0.01 microg/L, respectively. HLLE provided higher preconcentration factors (472.5- and 551.2-fold) within the shorter extraction time as well as better RSDs (4.5-6.9%). While, in SFDME, high preconcentration factors in the range of 162-198 and good RSDs in the range of 5.2-9.6% were obtained. Both methods were applied for the analysis of two plasticizers in different water samples and two target plasticizers were found in the bottled mineral water after the expiring time and the boiling water was exposed to a polyethylene vial.

30 CFR 250.217 - What solid and liquid wastes and discharges information and cooling water intake information must...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 2 2011-07-01 2011-07-01 false What solid and liquid wastes and discharges... of Exploration Plans (ep) § 250.217 What solid and liquid wastes and discharges information and cooling water intake information must accompany the EP? The following solid and liquid wastes and...

Strength characteristics of lightly solidified dredged marine clay admixed with bentonite

NASA Astrophysics Data System (ADS)

Ariffin, Syazwana Tajul; Chan, Chee-Ming

2017-11-01

Strength characteristic is a significant parameter in measuring the effect of soil improvement and effective composition of solidification. In this study, the dredged marine sediment (DMS) collected from Kuala Perlis (Malaysia) was examined to determine its strength characteristics under light cement solidification with bentonite. Dredged marine clay generally has the low shear strength and high void ratio, and consists mainly of soil particles of the fine-grained type. As a discarded geo-waste, it can be potentially treated to for reuse as a backfill material instead of being disposed of, hence reducing the negative impact on the environment. Physico-chemical parameters of the dredged sample were first determined, then solidification was carried out to improve the engineering properties by admixing ordinary Portland cement (OPC) as the binder and bentonite as a volume enhancer to the soil. The DMS was treated with the addition of 3 % and 6 % cement and bentonite within the range of 0-30 %. The specimens were cured at room temperature for 3, 7 and 14 days. The strength gain was measured by unconfined compression test and vane shear test. The laboratory test results were analyzed to establish the relationship between strength properties and solidification specifications. In summary, the strength of specimens increased with the increase of the quantity of bentonite and cement to get the effective composition of the specimen.

Effect of Microstructure on Diffusional Solidification of 4343/3005/4343 Multi-Layer Aluminum Brazing Sheet

NASA Astrophysics Data System (ADS)

Tu, Yiyou; Tong, Zhen; Jiang, Jianqing

2013-04-01

The effect of microstructure on clad/core interactions during the brazing of 4343/3005/4343 multi-layer aluminum brazing sheet was investigated employing differential scanning calorimetry (DSC) and electron back-scattering diffraction (EBSD). The thickness of the melted clad layer gradually decreased during the brazing operation. It could be completely removed isothermally as a result of diffusional solidification at the brazing temperature. During the brazing cycle, the rate of loss of the melt in the brazing sheet, with small equiaxed grains' core layer, was higher than that with the core layer consisting of elongated large grains. The difference in microstructure affected the amount of liquid formed during brazing.

Microstructural properties and evolution of nanoclusters in liquid Si during a rapid cooling process

NASA Astrophysics Data System (ADS)

Gao, T.; Hu, X.; Li, Y.; Tian, Z.; Xie, Q.; Chen, Q.; Liang, Y.; Luo, X.; Ren, L.; Luo, J.

2017-11-01

The formation of amorphous structures in Si during the rapid quenching process was studied based on molecular dynamics simulation by using the Stillinger-Weber potential. The evolution characteristics of nanoclusters during the solidification were analyzed by several structural analysis methods. The amorphous Si has been formed with many tetrahedral clusters and few nanoclusters. During the solidification, tetrahedral polyhedrons affect the local structures by their different positions and connection modes. The main kinds of polyhedrons randomly linked with one another to form an amorphous network structures in the system. The structural evolution of crystal nanocluster demonstrates that the nanocluster has difficulty to growth because of the high cooling rate of 1012 K/s.

The factors that have correlation with student behavior to dispose liquid waste

NASA Astrophysics Data System (ADS)

Kusmawaningtyas, Rieneke; Darmajanti, Linda; Soesilo, Tri Edhi Budhi

2017-03-01

Students majoring in chemistry could produce toxic liquid waste in their laboratory practices. They are not allowed to dispose of hazardous laboratory liquid into the environment. The formulation of problem in this study is that not all students have good behavior to dispose liquid waste properly according to their type and chemical properties while it is expected that all students have good behavior to dispose liquid waste with the type and chemical properties in container vessel, even though all students are expected to have behavior to dispose waste in the container vessel with the support of the predisposing factors, enabling factors, and driving factors. The aim of this study is to analyze the type and chemical properties of liquid waste and the relationship between three factors forming behavior with student behavior. The relationship between three factors forming behavior with student behavior was analyzed by correlative analysis. Type and chemical properties known through observation and qualitative analysis. The results of this research is found that enabling factors and driving behavior have a weak relation with student behavior. Nevertheless, predisposing factors has no relation with student behavior. The result of analysis of waste laboratory are known that laboratory liquid waste contains Cu, Fe, and methylene blue which potentially pollute the environment. The findings show that although generally the laboratory use chemicals in small quantities, but the total quantity of laboratory liquid waste produced from all laboratories in some regions must be considered. Moreover, the impact of the big quantity of liquid waste to environment must be taken into account. Thus, it is recommended that students should raise awareness of the risks associated with laboratory liquid waste and, we should provide proper management for a laboratory and policy makers.

40 CFR 761.340 - Applicability.

Code of Federal Regulations, 2011 CFR

2011-07-01

... leaching characteristics for storage or disposal. (a) Existing accumulations of non-liquid, non-metal PCB bulk product waste. (b) Non-liquid, non-metal PCB bulk product waste from processes that continuously generate new waste. (c) Non-liquid PCB remediation waste from processes that continuously generate new...

Microstructural development and segregation effects in directionally solidified nickel-based superalloy PWA 1484

NASA Astrophysics Data System (ADS)

Li, Lichun

2002-09-01

These studies were performed to investigate the effects of thermal gradient (G) and growth velocity (V) on the microstructure development and solidification behavior of directionally solidified nickel-based superalloy PWA 1484. Directional solidification (DS) experiments were conducted using a Bridgman crystal growth facility. The solidification velocity ranged from 0.00005 to 0.01 cm/sec and thermal gradients ranged from 12 to 108°C/cm. The as-cast microstructures of DS samples were characterized by using conventional metallography; chemical composition and segregation of directionally solidified samples were analyzed with energy dispersive spectroscopy in SEM. A range of aligned solidification microstructures is exhibited by the alloy when examined as-cast at room temperature: dendrites, flanged cells, cells. The microstructure transitions from cellular to dendritic as the growth velocity increases. The experimental data for PWA1484 exhibits excellent agreement with the well-known exponential equation (lambda1 ∝ G -1/2V-1/4). However, the constant of proportionality is different depending upon the solidification microstructure: (1) dendritic growth with secondary arms leads to a marked dependence of lambda1 on G-1/2 V-1/4; (2) flanged cellular growth with no secondary arms leads to much lower dependence of lambda 1 on G-1/2V -1/4. The primary dendritic arm spacing results were also compared to recent theoretical models. The model of Hunt and Lu and the model of Ma and Sahm provided excellent agreement at medium to high thermal gradients and a wide range of solidification velocities. The anomalous behavior of lambda 1 with high growth velocity V at low G is analyzed based on the samples' microstructures. Off-axis heat flows were shown to cause radial non-uniformity in the dendrite arm spacing data for low thermal gradients and large withdrawal velocities. Various precipitates including gamma', (gamma ' + gamma) eutectic pool or divorced eutectic gamma ', and metal carbides were characterized. Processing conditions (growth velocity V and thermal gradient G) exert significant influence on both morphology and size of precipitates present. Freckle defects were observed on the surface of nickel-based superalloy MM247 cylindrical samples but not on the surface of cylindrical PWA 1484 samples. The Rayleigh number (Ra) that represents liquid instability at the interface was evaluated for MM247 and PWA 1484 in terms of a recently proposed theoretical equation. The effects of segregation, sloped solid/liquid interface and the morphology of dendritic/cellular trunks on the mushy zone convective flow and freckle formation are also discussed.

30 CFR 250.248 - What solid and liquid wastes and discharges information and cooling water intake information must...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 2 2011-07-01 2011-07-01 false What solid and liquid wastes and discharges...) § 250.248 What solid and liquid wastes and discharges information and cooling water intake information must accompany the DPP or DOCD? The following solid and liquid wastes and discharges information and...

NBS: Materials measurements

NASA Technical Reports Server (NTRS)

Manning, J. R.

1981-01-01

Measurement of materials properties and thermophysical properties is described. The topics discussed are: surface tensions and their variations with temperature and impurities; convection during unidirectional solidification: measurement of high temperature thermophysical properties of tungsten liquid and solid; thermodynamic properties of refractory materials at high temperatures; and experimental and theoretical studies in wetting and multilayer adsorption.

Study of the Formation Mechanism of A-Segregation Based on Microstructural Morphology

NASA Astrophysics Data System (ADS)

Zhang, Zhao; Bao, Yuchong; Liu, Lin; Pian, Song; Li, Ri

2018-04-01

A model that combines a cellular automaton (CA) and lattice Boltzmann method (LBM) is presented. The mechanism of A-segregation in an Fe-0.34 wt pct C alloy ingot is analyzed on the basis of microstructural morphology calculations. The CA is used to capture the solid/liquid interface, while the LBM is used to calculate the transport phenomena. (1) The solidification of global columnar dendrites was simulated, and two obvious A-segregation bands appeared in the middle-radius region between the ingot wall surface and the centerline. In addition, the angle of deflection to the centerline increased with the increasing heat dissipation rate of the wall surface. When natural convection was ignored, the A-segregation disappeared, and only positive segregation was present in the center and bottom corner of the ingot. (2) Mixed columnar-equiaxed solidification was simulated. Many A-segregation bands appeared in the ingot. (3) Global equiaxed solidification was simulated, and no A-segregation bands were found. The results show that the upward movement of the high-concentration melt is the key to the formation of A-segregation bands, and remelting and the emergence of equiaxed grains are not necessary conditions to develop these bands. However, the appearance of equiaxed grains accelerates the formation of vortexes; thus, many A-segregation bands appear during columnar-equiaxed solidification.

Numerical Analysis of Temperature Gradients and Interface Shape During Directional Solidification of Al and Al-Cu Alloy Under Microgravity Conditions

NASA Technical Reports Server (NTRS)

Bune, Andris V.; Sen, Subhayu; Mukherjee, Sundeep; Catalina, Adrian; Stefanescu, Doru M.

1999-01-01

Numerical modeling was undertaken to analyze the influence of radial thermal gradient on solid/liquid (s/1) interface shape and convection patterns during solidification of pure Al and Al-4 wt% Cu alloy. The objective of the numerical task was to predict the influence of convective velocity on an insoluble particle near a s/l interface. These predictions would then be used to define the minimum gravity level (g) required to investigate the fundamental physics of interaction between a particle and a s/I interface. To satisfy this objective, steady state calculations were performed for different gravity levels and orientations with the gravity vector. ne furnace configuration used in this analysis is the proposed International Space Station Furnace, Quench Module Insert (QMI) 1. Results from a thermal model of the furnace core were used as initial boundary conditions for solidification modeling. General model of binary alloy solidification was based on the finite element code FIDAP. It was found that for the worst case orientation of 90 degrees with the gravity vector and a g level of 10(exp -4)g(sub o) (g(sub o) = 9.8 m/s(exp 2)) the dominant forces acting on the particle would be the fundamental drag and interfacial forces.

Microstructure formation in partially melted zone during gas tungsten arc welding of AZ91 Mg cast alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu Tianping; Chen, Zhan W.; Gao Wei

2008-11-15

During gas tungsten arc (GTA) welding of AZ91 Mg cast alloy, constitutional liquid forms locally in the original interdendritic regions in the partially melted zone (PMZ). The PMZ re-solidification behaviour has not been well understood. In this study, the gradual change of the re-solidification microstructure within PMZ from base metal side to weld metal side was characterised. High cooling rate experiments using Gleeble thermal simulator were also conducted to understand the morphological change of the {alpha}-Mg/{beta}-Mg{sub 17}Al{sub 12} phase interface formed during re-solidification after partial melting. It was found that the original partially divorced eutectic structure has become a moremore » regular eutectic phase in most of the PMZ, although close to the fusion boundary the re-solidified eutectic is again a divorced one. Proceeding the eutectic re-solidification, if the degree of partial melting is sufficiently high, {alpha}-Mg re-solidified with a cellular growth, resulting in a serrated interface between {alpha}-Mg and {alpha}-Mg/{beta}-Mg{sub 17}Al{sub 12} in the weld sample and between {alpha}-Mg and {beta}-Mg{sub 17}Al{sub 12} (fully divorced eutectic) in Gleeble samples. The morphological changes affected by the peak temperature and cooling rate are also explained.« less

DWPF Safely Dispositioning Liquid Waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2016-01-05

The only operating radioactive waste glassification plant in the nation, the Defense Waste Processing Facility (DWPF) converts the liquid radioactive waste currently stored at the Savannah River Site (SRS) into a solid glass form suitable for long-term storage and disposal. Scientists have long considered this glassification process, called “vitrification,” as the preferred option for treating liquid radioactive waste.

Stabilization/solidification of an alkyd paint waste by carbonation of waste-lime based formulations.

PubMed

Arce, R; Galán, B; Coz, A; Andrés, A; Viguri, J R

2010-05-15

The application of solvent-based paints by spraying in paint booths is extensively used in a wide range of industrial activities for the surface treatment of a vast array of products. The wastes generated as overspray represent an important environmental and managerial problem mainly due to the hazardous characteristics of the organic solvent, rendering it necessary to appropriately manage this waste. In this paper a solidification/stabilization (S/S) process based on accelerated carbonation was investigated as an immobilization pre-treatment prior to the disposal, via landfill, of an alkyd solvent-based paint waste coming from the automotive industry; the purpose of this S/S process was to immobilize the contaminants and reduce their release into the environment. Different formulations of paint waste with lime, lime-coal fly-ash and lime-Portland cement were carbonated to study the effect of the water/solid ratio and carbonation time on the characteristics of the final product. To assess the efficiency of the studied S/S process, metals, anions and dissolved organic carbon (DOC) were analyzed in the leachates obtained from a battery of compliance and characterization leaching tests. Regarding the carbonation of paint waste-lime formulations, a mathematical expression has been proposed to predict the results of the leachability of DOC from carbonated mixtures working at water/solid ratios from 0.2 to 0.6. However, lower DOC concentrations in leachates (400mg/kg DOC in L/S=10 batch leaching test) were obtained when carbonation of paint waste-lime-fly-ash mixtures was used at 10h carbonation and water to solid ratio of 0.2. The flammability characteristics, the total contents of contaminants and the contaminant release rate in compliance leaching tests provide evidence for a final product suitable for deposition in non-hazardous landfills. The characterization of this carbonated sample using a dynamic column leaching test shows a high stabilization of metals, partial immobilization of Cl(-), SO(4)(2-), F(-) and limited retention of DOC. However, the obtained results improve the previous findings obtained after the paint waste S/S using uncarbonated formulations and would be a useful pre-treatment technique of the alkyd paint waste prior to its disposal in a landfill. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Particle Engulfment and Pushing Micro-Gravity Experiments and Mathematical Modeling

NASA Technical Reports Server (NTRS)

Stefanescu, Doru M.; Catalina, A. V.; Juretzko, F.; Mukherjee, S.; Sen, S.

2000-01-01

The phenomenon of interaction of particles with solid-liquid interfaces that results in particle engulfment or pushing (PEP) has been Studied since mid 1960's. While the original interest stemmed from geology applications (frost heaving in soil), it was recognized early that understanding particle behavior at solidifying interfaces mi ht yield 9 practical benefits in other fields. In metallurgical applications the issue is the location of particles with respect to grain boundaries at the end of solidification. Considerable amount of experimental and theoretical research was lately focused on applications to metal matrix composites produced by casting; or spray forming techniques. Another application of PEP is in the growing of Y1Ba2CU3O7-delta(123) superconductor crystals from an undercooled liquid. The oxide melt contains Y2Ba1CU1O5 (211) precipitates, which act as flux pinning sites. The paper presents results of PEP micro-gravity research performed by the authors on two shuttle missions using metallic and polymeric materials. In addition. a discussion on the theoretical aspects of the physics of PEP is offered. Analytical and numerical models for planar solidification interfaces developed by the authors are used to explain the experimental results. Shortcomings of steady-state models are emphasized. A numerical model that includes the effect of the solutal field and of natural convection is introduced. A discussion of phenomena associated with dendritic solidification based on experimental observations is also offered. A mechanism of engulfment is proposed.

Preliminary assessment of the aquatic impacts of a proposed defense waste processing facility at the Savannah River Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mackey, H.E. Jr.

1979-01-01

A review of the literature indicates that a significant body of descriptive information exists concerning the aquatic ecology of Upper Three Runs Creek and Four Mile Creek of the Savannah River Plant south of Aiken, South Carolina. This information is adequate for preparation of an environmental document evaluating these streams. These streams will be impacted by construction and operation of a proposed Defense Waste Processing Facility for solidification of high level defense waste. Potential impacts include (1) construction runoff, erosion, and siltation, (2) effluents from a chemical and industrial waste treatment facility, and (3) radionuclide releases. In order to bettermore » evaluate potential impacts, recommend mitigation methods, and comply with NEPA requirements, additional quantitative biological information should be obtained through implementation of an aquatic baseline program.« less

Liquid foam templating - A route to tailor-made polymer foams.

PubMed

Andrieux, Sébastien; Quell, Aggeliki; Stubenrauch, Cosima; Drenckhan, Wiebke

2018-06-01

Solid foams with pore sizes between a few micrometres and a few millimetres are heavily exploited in a wide range of established and emerging applications. While the optimisation of foam applications requires a fine control over their structural properties (pore size distribution, pore opening, foam density, …), the great complexity of most foaming processes still defies a sound scientific understanding and therefore explicit control and prediction of these parameters. We therefore need to improve our understanding of existing processes and also develop new fabrication routes which we understand and which we can exploit to tailor-make new porous materials. One of these new routes is liquid templating in general and liquid foam templating in particular, to which this review article is dedicated. While all solid foams are generated from an initially liquid(-like) state, the particular notion of liquid foam templating implies the specific condition that the liquid foam has time to find its "equilibrium structure" before it is solidified. In other words, the characteristic time scales of the liquid foam's stability and its solidification are well separated, allowing to build on the vast know-how on liquid foams established over the last 20 years. The dispersed phase of the liquid foam determines the final pore size and pore size distribution, while the continuous phase contains the precursors of the desired porous scaffold. We review here the three key challenges which need to be addressed by this approach: (1) the control of the structure of the liquid template, (2) the matching of the time scales between the stability of the liquid template and solidification, and (3) the preservation of the structure of the template throughout the process. Focusing on the field of polymer foams, this review gives an overview of recent research on the properties of liquid foam templates and summarises a key set of studies in the emerging field of liquid foam templating. It finishes with an outlook on future developments. Occasional references to non-polymeric foams are given if the analogy provides specific insight into a physical phenomenon. Copyright © 2018 Elsevier B.V. All rights reserved.

Cooling and solidification of heavy hydrocarbon liquid streams

DOEpatents

Antieri, Salvatore J.; Comolli, Alfred G.

1983-01-01

A process and apparatus for cooling and solidifying a stream of heavy hydrocarbon material normally boiling above about 850.degree. F., such as vacuum bottoms material from a coal liquefaction process. The hydrocarbon stream is dropped into a liquid bath, preferably water, which contains a screw conveyor device and the stream is rapidly cooled, solidified and broken therein to form discrete elongated particles. The solid extrudates or prills are then dried separately to remove substantially all surface moisture, and passed to further usage.

Simulation of the bimetal cast in the case of milling rolls

NASA Astrophysics Data System (ADS)

Mihut, G.; Popa, E.

2015-06-01

In the paper it is proposed, in main, to obtain of a model of numerical simulation, valid general and applicable the whole peculiars cases of bimetal casting, model with which help can be studied through the computer, the optimization possibility of flowing working condition of liquid alloy of the distribution of temperatures field, of the liquid phase and contraction during the solidification, with the minimum price (necessary reimbursement of the software and calculus equipment) in very short time etc.

Analysis of the free-fall behavior of liquid-metal drops in a gaseous atmosphere

NASA Technical Reports Server (NTRS)

Mccoy, J. Kevin; Markworth, Alan J.; Collings, E. W.; Brodkey, Robert S.

1987-01-01

The free-fall of a liquid-metal drop and heat transfer from the drop to its environment are described for both a gaseous atmosphere and vacuum. A simple model, in which the drop is assumed to fall rectilinearly with behavior like that of a rigid particle, is developed first, then possible causes of deviation from this behavior are discussed. The model is applied to describe solidification of drops in a drop tube. Possible future developments of the model are suggested.

Existing data on the 216-Z liquid waste sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Owens, K.W.

1981-05-01

During 36 years of operation at the Hanford Site, the ground has been used for disposal of liquid and solid transuranic and/or low-level wastes. Liquid waste was disposed in surface and subsurface cribs, trenches, French drains, reverse wells, ditches and ponds. Disposal structures associated with Z Plant received liquid waste from plutonium finishing and reclamation, waste treatment and laboratory operations. The nineteen 216-Z sites have received 83% of the plutonium discharged to 325 liquid waste facilities at the Hanford Site. The purpose of this document is to support the Hanford Defense Waste Environmental Impact Statement by drawing the existing datamore » together for the 216-Z liquid waste disposal sites. This document provides an interim reference while a sitewide Waste Information Data System (WIDS) is developed and put on line. Eventually these and additional site data for all Hanford waste disposal sites will be available on WIDS. Compilation of existing data is the first step in evaluating the need and developing the technology for long-term management of these waste sites. The scope of this document is confined to data describing the status of the 216-Z waste sites as of December 31, 1979. Information and sketches are taken from existing documents and drawings.« less

Computer simulation of liquid metals

NASA Astrophysics Data System (ADS)

Belashchenko, D. K.

2013-12-01

Methods for and the results of the computer simulation of liquid metals are reviewed. Two basic methods, classical molecular dynamics with known interparticle potentials and the ab initio method, are considered. Most attention is given to the simulated results obtained using the embedded atom model (EAM). The thermodynamic, structural, and diffusion properties of liquid metal models under normal and extreme (shock) pressure conditions are considered. Liquid-metal simulated results for the Groups I - IV elements, a number of transition metals, and some binary systems (Fe - C, Fe - S) are examined. Possibilities for the simulation to account for the thermal contribution of delocalized electrons to energy and pressure are considered. Solidification features of supercooled metals are also discussed.

Evaluation of Technetium Getters to Improve the Performance of Cast Stone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neeway, James J.; Qafoku, Nikolla P.; Serne, R. Jeffrey

2015-11-01

Cast Stone has been selected as the preferred waste form for solidification of aqueous secondary liquid effluents from the Hanford Tank Waste Treatment and Immobilization Plant (WTP) process condensates and low-activity waste (LAW) melter off-gas caustic scrubber effluents. Cast Stone is also being evaluated as a supplemental immobilization technology to provide the necessary LAW treatment capacity to complete the Hanford tank waste cleanup mission in a timely and cost effective manner. One of the major radionuclides that Cast Stone has the potential to immobilize is technetium (Tc). The mechanism for immobilization is through the reduction of the highly mobile Tc(VII)more » species to the less mobile Tc(IV) species by the blast furnace slag (BFS) used in the Cast Stone formulation. Technetium immobilization through this method would be beneficial because Tc is one of the most difficult contaminants to address at the U.S. Department of Energy (DOE) Hanford Site due to its complex chemical behavior in tank waste, limited incorporation in mid- to high-temperature immobilization processes (vitrification, steam reformation, etc.), and high mobility in subsurface environments. In fact, the Tank Closure and Waste Management Environmental Impact Statement for the Hanford Site, Richland, Washington (TC&WM EIS) identifies technetium-99 ( 99Tc) as one of the radioactive tank waste components contributing the most to the environmental impact associated with the cleanup of the Hanford Site. The TC&WM EIS, along with an earlier supplemental waste-form risk assessment, used a diffusion-limited release model to estimate the release of different contaminants from the WTP process waste forms. In both of these predictive modeling exercises, where effective diffusivities based on grout performance data available at the time, groundwater at the 100-m down-gradient well exceeded the allowable maximum permissible concentrations for 99Tc. (900 pCi/L). Recent relatively short-term (63 day) leach tests conducted on both LAW and secondary waste Cast Stone monoliths indicated that 99Tc diffusivities were at or near diffusivities where the groundwater at the 100-m down-gradient well would exceed the allowable maximum permissible 99Tc concentrations. There is, therefore, a need and an opportunity to improve the retention of Tc in the Cast Stone waste form. One method to improve the performance of the Cast Stone waste form is through the addition of “getters” that selectively sequester Tc inside Cast Stone.« less

Nasreya: a treatment and disposal facility for industrial hazardous waste in Alexandria, Egypt: phase I.

PubMed

Ramadan, Adham R; Kock, Per; Nadim, Amani

2005-04-01

A facility for the treatment and disposal of industrial hazardous waste has been established in Alexandria, Egypt. Phase I of the facility encompassing a secure landfill and solar evaporation ponds is ready to receive waste, and Phase II encompassing physico-chemical treatment, solidification, and interim storage is underway. The facility, the Nasreya Centre, is the first of its kind in Egypt, and represents the nucleus for the integration, improvement and further expansion of different hazardous waste management practices and services in Alexandria. It has been developed within the overall legal framework of the Egyptian Law for the Environment, and is expected to improve prospects for enforcement of the regulatory requirements specified in this law. It has been developed with the overall aim of promoting the establishment of an integrated industrial hazardous waste management system in Alexandria, serving as a demonstration to be replicated elsewhere in Egypt. For Phase I, the Centre only accepts inorganic industrial wastes. In this respect, a waste acceptance policy has been developed, which is expected to be reviewed during Phase II, with an expansion of the waste types accepted.

49 CFR 173.197 - Regulated medical waste.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (bio) medical waste must be rigid containers meeting the provisions of subpart B of this part. (b) Non... medical waste or clinical waste or (bio) medical waste must be UN standard packagings conforming to the... filled. (2) Liquids. Liquid regulated medical waste or clinical waste or (bio) medical waste transported...

DWPF Safely Dispositioning Liquid Waste

ScienceCinema

None

2018-06-21

The only operating radioactive waste glassification plant in the nation, the Defense Waste Processing Facility (DWPF) converts the liquid radioactive waste currently stored at the Savannah River Site (SRS) into a solid glass form suitable for long-term storage and disposal. Scientists have long considered this glassification process, called “vitrification,” as the preferred option for treating liquid radioactive waste.

Solidification of floating organic droplet in dispersive liquid-liquid microextraction as a green analytical tool.

PubMed

Mansour, Fotouh R; Danielson, Neil D

2017-08-01

Dispersive liquid-liquid microextraction (DLLME) is a special type of microextraction in which a mixture of two solvents (an extracting solvent and a disperser) is injected into the sample. The extraction solvent is then dispersed as fine droplets in the cloudy sample through manual or mechanical agitation. Hence, the sample is centrifuged to break the formed emulsion and the extracting solvent is manually separated. The organic solvents commonly used in DLLME are halogenated hydrocarbons that are highly toxic. These solvents are heavier than water, so they sink to the bottom of the centrifugation tube which makes the separation step difficult. By using solvents of low density, the organic extractant floats on the sample surface. If the selected solvent such as undecanol has a freezing point in the range 10-25°C, the floating droplet can be solidified using a simple ice-bath, and then transferred out of the sample matrix; this step is known as solidification of floating organic droplet (SFOD). Coupling DLLME to SFOD combines the advantages of both approaches together. The DLLME-SFOD process is controlled by the same variables of conventional liquid-liquid extraction. The organic solvents used as extractants in DLLME-SFOD must be immiscible with water, of lower density, low volatility, high partition coefficient and low melting and freezing points. The extraction efficiency of DLLME-SFOD is affected by types and volumes of organic extractant and disperser, salt addition, pH, temperature, stirring rate and extraction time. This review discusses the principle, optimization variables, advantages and disadvantages and some selected applications of DLLME-SFOD in water, food and biomedical analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Air-assisted liquid-liquid microextraction by solidifying the floating organic droplets for the rapid determination of seven fungicide residues in juice samples.

PubMed

You, Xiangwei; Xing, Zhuokan; Liu, Fengmao; Zhang, Xu

2015-05-22

A novel air assisted liquid-liquid microextraction using the solidification of a floating organic droplet method (AALLME-SFO) was developed for the rapid and simple determination of seven fungicide residues in juice samples, using the gas chromatography with electron capture detector (GC-ECD). This method combines the advantages of AALLME and dispersive liquid-liquid microextraction based on the solidification of floating organic droplets (DLLME-SFO) for the first time. In this method, a low-density solvent with a melting point near room temperature was used as the extraction solvent, and the emulsion was rapidly formed by pulling in and pushing out the mixture of aqueous sample solution and extraction solvent for ten times repeatedly using a 10-mL glass syringe. After centrifugation, the extractant droplet could be easily collected from the top of the aqueous samples by solidifying it at a temperature lower than the melting point. Under the optimized conditions, good linearities with the correlation coefficients (γ) higher than 0.9959 were obtained and the limits of detection (LOD) varied between 0.02 and 0.25 μgL(-1). The proposed method was applied to determine the target fungicides in juice samples and acceptable recoveries ranged from 72.6% to 114.0% with the relative standard deviations (RSDs) of 2.3-13.0% were achieved. Compared with the conventional DLLME method, the newly proposed method will neither require a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly. Copyright © 2015 Elsevier B.V. All rights reserved.

Structural Study of Liquid Lithium Niobate by Neutron Diffraction Role of the Li Atom in the Clustering Near Solidification

NASA Astrophysics Data System (ADS)

Andonov, P.; Fischer, H. E.; Palleau, P.; Kimura, S.

2001-05-01

The structure of liquid LiNbO3 has been investigated by neutron diffraction using samples with different isotopic composition of lithium. The intensity scattered by these samples has been measured for momentum transfers 0.4 Å-1 T> 1500 K, which include the undercooling domain. From an analysis of the correlation functions Gij(r) of the atomic pairs Li-Li, Li-Nb, Li-O and their structural evolutions, given by Δ Gi-j (r) = Gi-j(r)1500 -Gi-j(r)1550 made with reference to the crystalline LiNbO3 ferroelectric structure, it was possible to confirm a local ordering similar to that of the crystal. The presence of clusters (groupings of NbO3 octahedra) is confirmed. Both regular and irregular N b06 octahedra are observed in the liquid near solidification. With its high mobil­ity in the melt, the Li atom plays an important role in the clustering: the Li-O and Li-Nb bonds make possible the staking of four octahedra groups into clusters of eight octahedra or more. The Li-Li bonds join these groups. The diameter of the clusters is a least 22 Å in the undercooling regime.

Dewetting and Segregation of Zn-Doped InSb in Microgravity Experiments

NASA Technical Reports Server (NTRS)

Ostrogorsky, A. G.; Marin, C.; Duffar, T.; Volz, M.

2009-01-01

In directional solidification, dewetting is characterized by the lack of contact between the crystal and the crucible walls, due to the existence of a liquid meniscus at the level of the solid-liquid interface. This creates a gap of a few tens of micrometers between the crystal and the crucible. One of the immediate consequences of this phenomenon is the dramatic improvement of the quality of the crystal. This improvement is partly due to the modification of the solid-liquid interface curvature and partly to the absence of sticking and spurious nucleation at the crystal-crucible interface. Dewetting has been, commonly observed during the growth of semiconductors in crucibles under microgravity conditions where it appears to be very stable: the gap between the crystal and the crucible remains constant along several centimetres of growth. The physical models of the phenomenon are well established and they predict that dewetting should not occur in microgravity, if sufficient static pressure is imposed on the melt, pushing it towards the crucible. We present the results of InSb(Zn) solidification experiments conducted at the International Space Station (ISS) where, in spite of a spring exerting a pressure on the liquid, partial dewetting did occur. This surprising result is discussed in terms of force exerted .by the spring on the liquid and of possibility that the spring did not work properly. Furthermore, it appears that the segregation of the Zn was not affected by the occurrence of the dewetting. The data suggest that there was no significant interference of convection with segregation of Zn in InSb.

Treatability Variance for Containerised Liquids in Mixed Debris Waste - 12101

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alstatt, Catherine M.

2012-07-01

The TRU Waste Processing Center (TWPC) is a Department of Energy facility whose mission is to receive and process for appropriate disposal legacy Contact Handled (CH) and Remote Handled (RH) waste, including debris waste stored at various DOE Oak Ridge facilities. Acceptable Knowledge (AK) prepared for the waste characterizes the waste as mixed waste, meaning it is both radioactive and regulated under the Resource Conservation and Recovery Act (RCRA). The AK also indicates that a number of the debris waste packages contain small amounts of containerised liquids. The documentation indicates liquid wastes generated in routine lab operations were typically collectedmore » for potential recovery of valuable isotopes. However, during activities associated with decontamination and decommissioning (D and D), some containers with small amounts of liquids were placed into the waste containers with debris waste. Many of these containers now hold from 2.5 milliliters (ml) to 237 ml of liquid; a few contain larger volumes. At least some of these containers were likely empty at the time of generation, but documentation of this condition is lacking. Since WIPP compliant AK is developed on a waste stream basis, rather than an individual container basis, and includes every potential RCRA hazardous constituent within the waste stream, it is insufficient for the purpose of characterizing individual containers of liquid. Debris waste is defined in 40 CFR 268.2(g) as 'solid material exceeding a 60 mm particle size that is intended for disposal and that is: a manufactured object; or plant or animal matter; or natural geologic material'. The definition further states that intact containers of hazardous waste that are not ruptured and that retain at least 75% of their original volume are not debris. The prescribed treatment is removal of intact containers from the debris waste, and treatment of their contents to meet specific Land Disposal Restrictions (LDR) standards. This is true for containers with incidental amounts of liquids, even if the liquid is less than 50% of the total waste volume. Under the proposed variance, all free or containerised liquids (up to 3.8 liters(L)) found in the debris would be treated and returned in solid form to the debris waste stream from which they originated. The waste would then be macro-encapsulated. (author)« less

West Valley feasibility study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pirro, J.

This report presents the results of a technical assessment of decontamination alternative prepared for the Western New York Nuclear Service Center (WNYNSC). The purpose of the assessment is to determine the recommended method for decontamination of cell surfaces and decontamination and removal of fuel reprocessing cell equipment to permit manual entry into the cells for the installation of waste solidification equipment. The primary cells of interest are the PMC, GPC, and CPC because they offer the largest usable volume for the solidification program. The secondary cells include XC-1, XC-2, XC-3 and the PPC which may be needed to support themore » solidification program. Five decontamination assessments were evaluated (A-E). The assessments included the estimated cost, occupational exposure, duration, manpower, waste volume generated, and final cell radiation levels achieved with the alternative decontamination methods. The methods varied from thorough destructive decontamination to equipment removal without decontamination followed by cell wall and floor decontamination. The recommended method for the primary cells is to utilize the remote manipulators and cranes to the maximum extent possible to decontaminate equipment and cell surfaces remotely, and to remove the equipment for temporary on-site storage. The recommended method for secondary cell decontamination is to remotely decontaminate the cells to the maximum extent possible prior to manned entry for contact-removal of the fuel reprocessing equipment (Assessment D). Assessment A is expected to cost $8,713,500 in 1980 dollars (including a 25% contingency) and will result in an occupational exposure of 180.3 manRem. Assessment D is expected to cost $11,039,800 and will result in an occupational exposure of 259 manRems.« less

Solidification of arsenic and heavy metal containing tailings using cement and blast furnace slag.

PubMed

Kim, Jung-Wook; Jung, Myung Chae

2011-01-01

The objective of this study is to examine the solidification of toxic elements in tailings by the use of cement and blast furnace slag. Tailings samples were taken at an Au-Ag mine in Korea. To examine the best mixing ratio of tailings and the mixture of ordinary Portland cement (OPC) and blast furnace slag (SG) of 5:5, 6:6, 7:3, and 8:2, the 7:3 ratio of tailings and OPC+SG was adapted. In addition, the mixing ratios of water and OPC + SG were applied to 10, 20, and 30 wt%. After 7, 14, and 28 days' curing, the UCS test was undertaken. A relatively high strength of solidified material (137.2 kg cm⁻² in average of 3 samples) at 28 days' curing was found in 20 wt% of water content (WC). This study also examined the leachability of arsenic and heavy metals (Cd, Cu, Pb, and Zn) under the Korean Standard Leaching Test, and it showed that the reductions in leachabilities of As and heavy metals of solidified samples were ranged from 76 to 99%. Thus, all the solidified samples were within the guidelines for special and hazardous waste materials by the Waste Management Act in Korea. In addition, the result of freeze-thaw cycle test of the materials indicated that the durability of the materials was sufficient. In conclusion, solidification using a 7:3 mixing ratio of tailings and a 1:1 mixture of OPC + SG with 20% of WC is one of the best methods for the remediation of arsenic and heavy metals in tailings and other contaminated materials.

Process for removing sulfate anions from waste water

DOEpatents

Nilsen, David N.; Galvan, Gloria J.; Hundley, Gary L.; Wright, John B.

1997-01-01

A liquid emulsion membrane process for removing sulfate anions from waste water is disclosed. The liquid emulsion membrane process includes the steps of: (a) providing a liquid emulsion formed from an aqueous strip solution and an organic phase that contains an extractant capable of removing sulfate anions from waste water; (b) dispersing the liquid emulsion in globule form into a quantity of waste water containing sulfate anions to allow the organic phase in each globule of the emulsion to extract and absorb sulfate anions from the waste water and (c) separating the emulsion including its organic phase and absorbed sulfate anions from the waste water to provide waste water containing substantially no sulfate anions.

Real-time alpha monitoring of a radioactive liquid waste stream at Los Alamos National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, J.D.; Whitley, C.R.; Rawool-Sullivan, M.

1995-12-31

This poster display concerns the development, installation, and testing of a real-time radioactive liquid waste monitor at Los Alamos National Laboratory (LANL). The detector system was designed for the LANL Radioactive Liquid Waste Treatment Facility so that influent to the plant could be monitored in real time. By knowing the activity of the influent, plant operators can better monitor treatment, better segregate waste (potentially), and monitor the regulatory compliance of users of the LANL Radioactive Liquid Waste Collection System. The detector system uses long-range alpha detection technology, which is a nonintrusive method of characterization that determines alpha activity on themore » liquid surface by measuring the ionization of ambient air. Extensive testing has been performed to ensure long-term use with a minimal amount of maintenance. The final design was a simple cost-effective alpha monitor that could be modified for monitoring influent waste streams at various points in the LANL Radioactive Liquid Waste Collection System.« less

Determination of service standard time for liquid waste parameter in certification institution

NASA Astrophysics Data System (ADS)

Sembiring, M. T.; Kusumawaty, D.

2018-02-01

Baristand Industry Medan is a technical implementation unit under the Industrial and Research and Development Agency, the Ministry of Industry. One of the services often used in Baristand Industry Medan is liquid waste testing service. The company set the standard of service 9 working days for testing services. At 2015, 89.66% on testing services liquid waste does not meet the specified standard of services company. The purpose of this research is to specify the standard time of each parameter in testing services liquid waste. The method used is the stopwatch time study. There are 45 test parameters in liquid waste laboratory. The measurement of the time done 4 samples per test parameters using the stopwatch. From the measurement results obtained standard time that the standard Minimum Service test of liquid waste is 13 working days if there is testing E. coli.

Analysis of Radial Segregation in Directionally Solidified Hg(0.89)Mn(0.11)Te

NASA Technical Reports Server (NTRS)

Price, M. W.; Scripa, R. N.; Szofran, F. R.; Motakef, S.; Hanson, B.

2003-01-01

Bridgman growth experiments were performed on Hg(0.89)Mn(0.11)Te (MMT) to determine the extent of radial Manganese segregation during directional solidification. MMT crystals were directionally solidified at rates of 0.09 and 0.18 p d s and in axial thermal gradients of 83 and 68"C/cm. Wavelength Dispersive Spectroscopy (WDS) and Fourier Transform Infra-Red (FTIR) analytical techniques were used to determine the radial homogeneity in all boules and the deflection of the solid-liquid interface (SLI) in two boules that were rapidly quenched after 5 to 6 cm of directional solidification. For all growth runs, the measured radial coinpositional variations were on the order of 0.01 molar percent MnTe in the steady state region of growth. Comparison of the measured radial compositional results of the crystals to predicted values in the diffusion-limited regime indicate a strong influence of convection near the solid-liquid interface. This conclusion is supported by the weak influence of the translation rates and axial thermal gradients utilized in this study upon radial compositional homogeneity.

In Situ Synchrotron X-ray Study of Ultrasound Cavitation and Its Effect on Solidification Microstructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mi, Jiawei; Tan, Dongyue; Lee, Tung Lik

2014-12-11

Considerable progress has been made in studying the mechanism and effectiveness of using ultrasound waves to manipulate the solidification microstructures of metallic alloys. However, uncertainties remain in both the underlying physics of how microstructures evolve under ultrasonic waves, and the best technological approach to control the final microstructures and properties. We used the ultrafast synchrotron X-ray phase contrast imaging facility housed at the Advanced Photon Source, Argonne National Laboratory, US to study in situ the highly transient and dynamic interactions between the liquid metal and ultrasonic waves/bubbles. The dynamics of ultrasonic bubbles in liquid metal and their interactions with themore » solidifying phases in a transparent alloy were captured in situ. The experiments were complemented by the simulations of the acoustic pressure field, the pulsing of the bubbles, and the associated forces acting onto the solidifying dendrites. The study provides more quantitative understanding on how ultrasonic waves/bubbles influence the growth of dendritic grains and promote the grain multiplication effect for grain refinement.« less

Mechanical Fracturing of Core-Shell Undercooled Metal Particles for Heat-Free Soldering.

PubMed

Çınar, Simge; Tevis, Ian D; Chen, Jiahao; Thuo, Martin

2016-02-23

Phase-change materials, such as meta-stable undercooled (supercooled) liquids, have been widely recognized as a suitable route for complex fabrication and engineering. Despite comprehensive studies on the undercooling phenomenon, little progress has been made in the use of undercooled metals, primarily due to low yields and poor stability. This paper reports the use of an extension of droplet emulsion technique (SLICE) to produce undercooled core-shell particles of structure; metal/oxide shell-acetate ('/' = physisorbed, '-' = chemisorbed), from molten Field's metal (Bi-In-Sn) and Bi-Sn alloys. These particles exhibit stability against solidification at ambient conditions. Besides synthesis, we report the use of these undercooled metal, liquid core-shell, particles for heat free joining and manufacturing at ambient conditions. Our approach incorporates gentle etching and/or fracturing of outer oxide-acetate layers through mechanical stressing or shearing, thus initiating a cascade entailing fluid flow with concomitant deformation, combination/alloying, shaping, and solidification. This simple and low cost technique for soldering and fabrication enables formation of complex shapes and joining at the meso- and micro-scale at ambient conditions without heat or electricity.

Effect of a High Magnetic Field on γ' Phase for Ni-Based Single Crystal Superalloy During Directional Solidification

NASA Astrophysics Data System (ADS)

Xuan, Weidong; Lan, Jian; Zhao, Dengke; Li, Chuanjun; Shang, Xingfu; Zhong, Yunbo; Li, Xi; Ren, Zhongming

2018-05-01

The effect of a high magnetic field on the γ' phase of Ni-based single crystal superalloy during directional solidification is investigated experimentally. The results clearly indicate that the magnetic field significantly reduces the γ' phase size. Further, the quenching experiment is carried out, and the results found that the length of mushy zone is obviously decreased under a high magnetic field. Based on both experimental results and nucleation mechanism, it is found that the decrease of γ' phase size should be attributed to the fact that a high magnetic field causes the increase of temperature gradient in front of solid/liquid interface and leads to the increase of undercooling of γ' phase.

Thermoelectric and morphological effects of Peltier pulsing on directional solidification of eutectic Bi-Mn

NASA Technical Reports Server (NTRS)

Silberstein, R. P.; Larson, D. J., Jr.; Dressler, B.

1984-01-01

Extensive in situ thermal measurements using Peltier Interface Demarcation (PID) during directional solidification of eutectic Bi/MnBi were carried out. Observations indicate that significant thermal transients occur throughout the sample as a result of the Peltier pulsing. The contributions of the Peltier, Thomson, and Joule heats were separated and studied as a function of pulse intensity and polarity. The Joule and the combined Peltier and Thomson thermal contributions were determined as a function of time during and after the current pulses, close to the solid/liquid interface. Variations of the Bi/MnBi particle morphology clearly reveal the interface shape, changes in interface velocity, meltback, and temporary loss of cooperative growth, as a result of the pulsing.

Exploiting the Temperature/Concentration Dependence of Magnetic Susceptibility to Control Convection in Fundamental Studies of Solidification Phenomena

NASA Technical Reports Server (NTRS)

Evans, J. W.; Xu, Dong; Jones, W. Kinzy, Jr.; Szofran, Frank R.

1999-01-01

The objective of this new research project is to demonstrate by experiment, supplemented by mathematical modeling and physical property measurement, that the effects of buoyancy driven convection can be largely eliminated in ground-based experiments, and further reduced in flight, by applying a new technique. That technique exploits the dependence of magnetic susceptibility on composition or temperature. It is emphasized at the outset that the phenomenon to be exploited is fundamentally and practically different from the magnetic damping of convection in conducting liquids that has been the subject of much prior research. The concept suggesting this research is that all materials, even non-conductors, when placed in a magnetic field gradient, experience a force. Of particular interest here are paramagnetic and diamagnetic materials, classes which embrace the "model alloys", such as succinonitrile-acetone, that have been used by others investigating the fundamentals of solidification. Such alloys will exhibit a dependence of susceptibility on composition. The consequence is that, with a properly oriented field (gradient) a force will arise that can be made to be equal to, but opposite, the buoyancy force arising from concentration (or temperature) gradients. In this way convection can be stilled. The role of convection in determining the microstructure, and thereby properties, of materials is well known. Elimination of that convection has both scientific and technological consequences. Our knowledge of diffusive phenomena in solidification, phenomena normally hidden by the dominance of convection, is enhanced if we can study solidification of quiescent liquids. Furthermore, the microstructure, microchemistry and properties of materials (thereby practical value) are affected by the convection occurring during their solidification. Hitherto the method of choice for elimination of convection has been experimentation in microgravity. However, even in low Earth orbit, residual convection has effects. That residual convection arises from acceleration (drag on the spacecraft), displacement from the center of mass or transients in the gravitational field (g-jitter). There is therefore a need for both further reducing buoyancy driven flow in flight and allowing the simulation of microgravity during ground based experiments. Previous investigations, the research project description, theory behind the study and experimental methods as well as plots of magnetic fields and forces are presented.

Physico-chemical treatment of liquid waste on an industrial plant for electrocoagulation.

PubMed

Mlakar, Matej; Levstek, Marjetka; Stražar, Marjeta

2017-10-01

Wastewater from washing, oil separators, the metal processing and detergent industries, was tested and treated for treatment of different types of liquid waste at industrial level at Domžale-Kamnik Wastewater Treatment Plant (WWTP). The effect of implementing the electrocoagulation (EC) and flotation processes, respectively, is analysed and includes the duration of the EC implementation, voltage, number of electrodes, and chemical addition, as well as the pH effect and conductivity. The tests were performed not only on various types of liquid waste, but also on different mixtures of liquid waste. Laboratory analysis of the samples before and after EC have shown an effective reduction not only in organic loads in accordance with the COD (chemical oxygen demand) parameter, but also in mineral oil content, toxic metal concentration, and surfactants. The COD in liquid waste from the detergent industry was reduced by 73% and the content of surfactants by 64%. In liquid waste from the metal processing industry, the COD decreased by up to 95%, while the content of toxic metals decreased from 59 to 99%. Similar phenomena were shown in liquid waste from oil separators, where the COD was reduced to 33% and the concentration of mineral oils by 99%. Some of the liquid wastes were mixed together in the ratio 1:1, thus allowing testing of the operation of EC technology in heterogeneous liquid waste, where the final result proved to be effective cleaning as well. After treatment in the process of EC, the limit values of the treated water proved appropriate for discharge into the sewerage system.

Double-sided electromagnetic pump with controllable normal force for rapid solidification of liquid metals

DOEpatents

Kuznetsov, Stephen B.

1987-01-01

A system for casting liquid metals is provided with an electromagnetic pump which includes a pair of primary blocks each having a polyphase winding and being positioned to form a gap through which a movable conductive heat sink passes. A solidifying liquid metal sheet is deposited on the heat sink and the heat sink and sheet are held in compression by forces produced as a result of current flow through the polyphase windings. Shaded-pole interaction between the primary windings, heat sink and solidifying strip produce transverse forces which act to center the strip on the heat sink.

Double-sided electromagnetic pump with controllable normal force for rapid solidification of liquid metals

DOEpatents

Kuznetsov, S.B.

1987-01-13

A system for casting liquid metals is provided with an electromagnetic pump which includes a pair of primary blocks each having a polyphase winding and being positioned to form a gap through which a movable conductive heat sink passes. A solidifying liquid metal sheet is deposited on the heat sink and the heat sink and sheet are held in compression by forces produced as a result of current flow through the polyphase windings. Shaded-pole interaction between the primary windings, heat sink and solidifying strip produce transverse forces which act to center the strip on the heat sink. 5 figs.

The velocity, refractive index, and equation of state of liquid ammonia at high temperatures and high pressures.

PubMed

Li, Fangfei; Li, Min; Cui, Qiliang; Cui, Tian; He, Zhi; Zhou, Qiang; Zou, Guangtian

2009-10-07

The high temperature and high pressure Brillouin scattering studies of liquid ammonia have been performed in a diamond anvil cell. Acoustic velocity, refractive index, adiabatic bulk modulus, and the equation of state of liquid ammonia were determined at temperatures up to 410 K and at pressures up to the solidification point. Velocity and refractive index increase smoothly with increasing pressure along isothermals but decrease slightly with the temperature increase. The bulk modulus increases linearly with pressure and its slope dB/dP decreases slightly with increasing temperature from 6.67 at 297 K to 5.94 at 410 K.

Utilization of air pollution control residues for the stabilization/solidification of trace element contaminated soil.

PubMed

Travar, I; Kihl, A; Kumpiene, J

2015-12-01

The aim of this study was to evaluate the stabilization/solidification (S/S) of trace element-contaminated soil using air pollution control residues (APCRs) prior to disposal in landfill sites. Two soil samples (with low and moderate concentrations of organic matter) were stabilized using three APCRs that originated from the incineration of municipal solid waste, bio-fuels and a mixture of coal and crushed olive kernels. Two APCR/soil mixtures were tested: 30% APCR/70% soil and 50% APCR/50% soil. A batch leaching test was used to study immobilization of As and co-occurring metals Cr, Cu, Pb and Zn. Solidification was evaluated by measuring the unconfined compression strength (UCS). Leaching of As was reduced by 39-93% in APCR/soil mixtures and decreased with increased amounts of added APCR. Immobilization of As positively correlated with the amount of Ca in the APCR and negatively with the amount of soil organic matter. According to geochemical modelling, the precipitation of calcium arsenate (Ca3(AsO4)2/4H2O) and incorporation of As in ettringite (Ca6Al2(SO4)3(OH)12 · 26H2O) in soil/APCR mixtures might explain the reduced leaching of As. A negative effect of the treatment was an increased leaching of Cu, Cr and dissolved organic carbon. Solidification of APCR/soil was considerably weakened by soil organic matter.

A calorimetric and microstructural study of solidified toxic wastes. Part 2: A model for poisoning of OPC hydration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hills, C.D.; Sollars, C.J.; Perry, R.

1994-01-01

During cement-based processing of certain hazardous wastes the hydration reactions thought to be responsible for solidification can be poisoned and appear to be retarded indefinitely. A number of wastes known to be capable of poisoning hydration were added to ordinary Portland cement (OPC) and classified on the basis of interference effects observed. This paper reports the results from a characterization of these wastes and the subsequent addition to OPC of waste components identified as significant in single and combined additions. The effects of these additions were examined by conduction calorimetry and microstructural techniques. A comparison of results showed that itmore » was possible to reproduce the poisoning effects observed previously with real wastes by an addition of combined metal hydroxides only. These results suggest that poisoning results from the synergistic effects of compounds contained in the waste. A model, representing the early hydration of OPC, has been modified and is presented and its application in explaining poisoning of hydration is discussed.« less

Performance evaluation of rotating pump jet mixing of radioactive wastes in Hanford Tanks 241-AP-102 and -104

DOE Office of Scientific and Technical Information (OSTI.GOV)

Onishi, Y.; Recknagle, K.P.

The purpose of this study was to confirm the adequacy of a single mixer pump to fully mix the wastes that will be stored in Tanks 241-AP-102 and -104. These Hanford double-shell tanks (DSTs) will be used as staging tanks to receive low-activity wastes from other Hanford storage tanks and, in turn, will supply the wastes to private waste vitrification facilities for eventual solidification. The TEMPEST computer code was applied to Tanks AP-102 and -104 to simulate waste mixing generated by the 60-ft/s rotating jets and to determine the effectiveness of the single rotating pump to mix the waste. TEMPESTmore » simulates flow and mass/heat transport and chemical reactions (equilibrium and kinetic reactions) coupled together. Section 2 describes the pump jet mixing conditions the authors evaluated, the modeling cases, and their parameters. Section 3 reports model applications and assessment results. The summary and conclusions are presented in Section 4, and cited references are listed in Section 5.« less

Regulation of the Deposition Morphology of Inkjet-Printed Crystalline Materials via Polydopamine Functional Coatings for Highly Uniform and Electrically Conductive Patterns.

PubMed

Liu, Liang; Ma, Siyuan; Pei, Yunheng; Xiong, Xiao; Sivakumar, Preeth; Singler, Timothy J

2016-08-24

We report a method to achieve highly uniform inkjet-printed silver nitrate (AgNO3) and a reactive silver precursor patterns on rigid and flexible substrates functionalized with polydopamine (PDA) coatings. The printed AgNO3 patterns on PDA-coated substrates (glass and polyethylene terephthalate (PET)) exhibit a narrow thickness distribution ranging between 0.9 and 1 μm in the line transverse direction and uniform deposition profiles in the line axial direction. The deposited reactive silver precursor patterns on PDA-functionalized substrates also show "dome-shaped" morphology without "edge-thickened" structure due to "coffee-stain" effect. We posit that the highly uniform functional ink deposits formed on PDA-coated substrates are attributable to the strong binding interaction between the abundant catecholamine moieties at the PDA surface and the metallic silver cations (Ag(+) or Ag(NH3)(2+)) in the solutal inks. During printing of the ink rivulet and solvent evaporation, the substrate-liquid ink (S-L) interface is enriched with the silver-based cations and a solidification at the S/L interface is induced. The preferential solidification initiated at the S-L interface is further verified by the in situ visualization of the dynamic solidification process during solvent evaporation, and results suggest an enhanced crystal nucleation and growth localized at the S-L interface on PDA functionalized substrates. This interfacial interaction mediates solute transport in the liquid phase, resulting in the controlled enrichment of solute at the S-L interface and mitigated solute precipitation in both the contact line region and the liquid ink-vapor (L-V) interface due to evaporation. This mediated transport contributes to the final uniform solid deposition for both types of ink systems. This technique provides a complementary strategy for achieving highly uniform inkjet-printed crystalline structures, and can serve as an innovative foundation for high-precision additive delivery of functional materials.

In Situ Monitoring of Crystal Growth Using MEPHISTO, Mission STS 87-Program USMP-4: Experimental Analysis

NASA Technical Reports Server (NTRS)

Abbaschian, Reza; Chen, F.; Mileham, J. R.; deGroh, H., III; Timchenko, V.; Leonardi, E.; deVahlDavis, G.; Coriell, S.; Cambon, G.

1999-01-01

This report summarizes the results of the In situ Monitoring of Crystal Growth Using MEPHISTO (Material por l'Etude des Phenomenes Interessant de la Solidification sur Terre et en Orbite) experiment on USMP-4. The report includes microstructural and compositional data obtained during the first year of the post flight analysis, as well as numerical simulation of the flight experiment. Additional analyses are being continued and will be reported in the near future. The experiments utilized MEPHISTO hardware to study the solidification and melting behavior of bismuth alloyed with 1 at% tin. The experiments involved repeated melting and solidification of three samples, each approximately 90 cm long and 6mm in diameter. Half of each sample also included a 2 mm. diameter growth capillary, to assist in the formation of single grain inside. One sample provided the Seebeck voltage generated during melting and freezing processes. Another one provided temperature data and Peltier pulsed demarcation of the interface shape for post flight analysis. The third sample provided resistance and velocity measurements, as well as additional thermal data. The third sample was also quenched at the end of the mission to preserve the interface composition for post flight determination. A total of more than 45cm of directionally solidified alloy were directionally solidified at the end of the flight for post mission structural and compositional characterization. Metallurgical analysis of the samples has shown that the interfacial kinetics play a key role in controlling the morphological stability of faceted alloys. Substantial differences were observed in the Seebeck signal between the ground-based experiments and the space-based experiments. The temperature gradient in the liquid for the ground-based experiments was also significantly lower than the temperature gradient in the liquid for the space-based experiments. Both of these observations indicate significant influence of liquid convection for the ground-based experiments.

Thermomechanical Simulation of the Splashing of Ceramic Droplets on a Rigid Substrate

NASA Astrophysics Data System (ADS)

Bertagnolli, Mauro; Marchese, Maurizio; Jacucci, Gianni; St. Doltsinis, Ioannis; Noelting, Swen

1997-05-01

Finite element simulation techniques have been applied to the spreading process of single ceramic liquid droplets impacting on a flat cold surface under plasma-spraying conditions. The goal of the present investigation is to predict the geometrical form of the splat as a function of technological process parameters, such as initial temperature and velocity, and to follow the thermal field developing in the droplet up to solidification. A non-linear finite element programming system has been utilized in order to model the complex physical phenomena involved in the present impact process. The Lagrangean description of the motion of the viscous melt in the drops, as constrained by surface tension and the developing contact with the target, has been coupled to an analysis of transient thermal phenomena accounting also for the solidification of the material. The present study refers to a parameter spectrum as from experimental data of technological relevance. The significance of process parameters for the most pronounced physical phenomena is discussed as are also the consequences of modelling. We consider the issue of solidification as well and touch on the effect of partially unmelted material.

A thermodynamic approach to obtain materials properties for engineering applications

NASA Technical Reports Server (NTRS)

Chang, Y. Austin

1993-01-01

With the ever increases in the capabilities of computers for numerical computations, we are on the verge of using these tools to model manufacturing processes for improving the efficiency of these processes as well as the quality of the products. One such process is casting for the production of metals. However, in order to model metal casting processes in a meaningful way it is essential to have the basic properties of these materials in their molten state, solid state as well as in the mixed state of solid and liquid. Some of the properties needed may be considered as intrinsic such as the density, heat capacity or enthalpy of freezing of a pure metal, while others are not. For instance, the enthalpy of solidification of an alloy is not a defined thermodynamic quantity. Its value depends on the micro-segregation of the phases during the course of solidification. The objective of the present study is to present a thermodynamic approach to obtain some of the intrinsic properties and combining thermodynamics with kinetic models to estimate such quantities as the enthalpy of solidification of an alloy.

Natural diatomite process for removal of radioactivity from liquid waste.

PubMed

Osmanlioglu, Ahmet Erdal

2007-01-01

Diatomite has a number of unique physical properties and has found diversified industrial utilization. The filtration characteristics are particularly significant in the purification of liquids. The purpose of this study was to test natural diatomaceous earth (diatomite) as an alternative material that could be used for removal of radioactivity from liquid waste. A pilot-scale column-type device was designed. Natural diatomite samples were ground, sieved and prepared to use as sorption media. In this study, real waste liquid was used as radioactive liquid having special conditions. The liquid waste contained three radionuclides (Cs-137, Cs-134 and Co-60). Following the treatment by diatomite, the radioactivity of liquid waste was reduced from the initial 2.60 Bq/ml to less than 0.40 Bq/ml. The results of this study show that most of the radioactivity was removed from the solution by processing with diatomite.

40 CFR 258.28 - Liquids restrictions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 258.28 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.28 Liquids restrictions. (a) Bulk or... (Paint Filter Liquids Test), included in “Test Methods for Evaluating Solid Waste, Physical/Chemical...

40 CFR 258.28 - Liquids restrictions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 258.28 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.28 Liquids restrictions. (a) Bulk or... (Paint Filter Liquids Test), included in “Test Methods for Evaluating Solid Waste, Physical/Chemical...

DEM simulation of dendritic grain random packing: application to metal alloy solidification

NASA Astrophysics Data System (ADS)

Olmedilla, Antonio; Založnik, Miha; Combeau, Hervé

2017-06-01

The random packing of equiaxed dendritic grains in metal-alloy solidification is numerically simulated and validated via an experimental model. This phenomenon is characterized by a driving force which is induced by the solid-liquid density difference. Thereby, the solid dendritic grains, nucleated in the melt, sediment and pack with a relatively low inertia-to-dissipation ratio, which is the so-called Stokes number. The characteristics of the particle packed porous structure such as solid packing fraction affect the final solidified product. A multi-sphere clumping Discrete Element Method (DEM) approach is employed to predict the solid packing fraction as function of the grain geometry under the solidification conditions. Five different monodisperse noncohesive frictionless particle collections are numerically packed by means of a vertical acceleration: a) three dendritic morphologies; b) spheres and c) one ellipsoidal geometry. In order to validate our numerical results with solidification conditions, the sedimentation and packing of two monodisperse collections (spherical and dendritic) is experimentally carried out in a viscous quiescent medium. The hydrodynamic similarity is respected between the actual phenomenon and the experimental model, that is a low Stokes number, o(10-3). In this way, the experimental average solid packing fraction is employed to validate the numerical model. Eventually, the average packing fraction is found to highly depend on the equiaxed dendritic grain sphericity, with looser packings for lower sphericity.

A&M. Hot liquid waste holding tanks. Camera faces southeast. Located ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

A&M. Hot liquid waste holding tanks. Camera faces southeast. Located in vicinity of TAN-616, hot liquid waste treatment plant. Date: November 13, 1953. INEEL negative no. 9159 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

Modeling of macrosegregation caused by volumetric deformation in a coherent mushy zone

NASA Astrophysics Data System (ADS)

Nicolli, Lilia C.; Mo, Asbjørn; M'hamdi, Mohammed

2005-02-01

A two-phase volume-averaged continuum model is presented that quantifies macrosegregation formation during solidification of metallic alloys caused by deformation of the dendritic network and associated melt flow in the coherent part of the mushy zone. Also, the macrosegregation formation associated with the solidification shrinkage (inverse segregation) is taken into account. Based on experimental evidence established elsewhere, volumetric viscoplastic deformation (densification/dilatation) of the coherent dendritic network is included in the model. While the thermomechanical model previously outlined (M. M’Hamdi, A. Mo, and C.L. Martin: Metall. Mater. Trans. A, 2002, vol. 33A, pp. 2081-93) has been used to calculate the temperature and velocity fields associated with the thermally induced deformations and shrinkage driven melt flow, the solute conservation equation including both the liquid and a solid volume-averaged velocity is solved in the present study. In modeling examples, the macrosegregation formation caused by mechanically imposed as well as by thermally induced deformations has been calculated. The modeling results for an Al-4 wt pct Cu alloy indicate that even quite small volumetric strains (≈2 pct), which can be associated with thermally induced deformations, can lead to a macroscopic composition variation in the final casting comparable to that resulting from the solidification shrinkage induced melt flow. These results can be explained by the relatively large volumetric viscoplastic deformation in the coherent mush resulting from the applied constitutive model, as well as the relatively large difference in composition for the studied Al-Cu alloy in the solid and liquid phases at high solid fractions at which the deformation takes place.

Calorimetric Investigation of Thermal Stability of 304H Cu (Fe-17.7Cr-9.3Ni-2.95Cu-0.91Mn-0.58Nb-0.24Si-0.1C-0.12N-Wt Pct) Austenitic Stainless Steel

NASA Astrophysics Data System (ADS)

Tripathy, Haraprasanna; Subramanian, Raju; Hajra, Raj Narayan; Rai, Arun Kumar; Rengachari, Mythili; Saibaba, Saroja; Jayakumar, Tammana

2016-12-01

The sequence of phase instabilities that take place in a Fe-17.7Cr-9.3Ni-0.58Nb-2.95Cu-0.12N (wt pct) austenitic stainless steel (304H Cu grade) as a function of temperature has been investigated using dynamic calorimetry. The results obtained from this investigation are supplemented by Thermocalc-based equilibrium and Scheil-Gulliver nonequilibrium solidification simulation. The following phase transformation sequence is found upon slow cooling from liquid: L → L + γ → L + γ + MX → γ + MX + δ → γ +MX + M23C6 → γ + MX + M23C6 + Cu. Under slow cooling, the solidification follows austenite + ferrite (AF) mode, which is in accordance with Thermocalc prediction and Scheil-Gulliver simulation. However, higher cooling rates result in skeletal δ-ferrite formation, due to increased segregation tendency of Nb and Cr to segregate to interdendritic liquid. The solidification mode is found to depend on combined Nb + Cu content. Experimental estimates of enthalpy change associated with melting and secondary phase precipitation are also obtained. In addition a semi-quantitative study on the dissolution kinetics of M23C6 type carbides has also been investigated. The standard solution treatment at 1413 K (1140 °C) is found to be adequate to dissolve both Cu and M23C6 into γ-austenite; but the complete dissolution of MX type carbonitrides occurs near the melting region.

Microgravity

NASA Image and Video Library

2000-07-29

Angie Jackman, a NASA project manager in microgravity research, demonstrates the enhanced resilience of undercooled metal alloys as compared to conventional alloys. Experiments aboard the Space Shuttle helped scientists refine their understanding of the physical properties of certain metal alloys when undercooled (i.e., kept liquid below their normal solidification temperature). This new knowledge then allowed scientists to modify a terrestrial production method so they can now make limited quantities marketed under the Liquid Metal trademark. The exhibit was a part of the NASA outreach activity at AirVenture 2000 sponsored by the Experimental Aircraft Association in Oshkosh, WI.

Ternary liquid-liquid equilibria for the phenolic compounds extraction from artificial textile industrial waste

NASA Astrophysics Data System (ADS)

Fardhyanti, Dewi Selvia; Prasetiawan, Haniif; Hermawan, Sari, Lelita Sakina

2017-03-01

Liquid waste in textile industry contains large amounts of dyes and chemicals which are capable of harming the environment and human health. It is due to liquid waste characteristics which have high BOD, COD, temperature, dissolved and suspended solid. One of chemical compound which might be harmful for environment when disposed in high concentration is phenol. Currently, Phenol compound in textile industrial waste has reached 10 ppm meanwhile maximum allowable phenol concentration is not more than 0.2 ppm. Otherwise, Phenol also has economic value as feedstock of plastic, pharmaceutical and cosmetic industry. Furthermore, suitable method to separate phenol from waste water is needed. In this research, liquid - liquid extraction method was used with extraction time for 70 minutes. Waste water sample was then separated into two layers which are extract and raffinate. Thereafter, extract and raffinate were then tested by using UV-Vis Spectrophotometer to obtained liquid - liquid equilibrium data. Aim of this research is to study the effect of temperature, stirring speed and type of solvent to obtain distribution coefficient (Kd), phenol yield and correlation of Three-Suffix Margules model for the liquid - liquid extraction data equilibrium. The highest extraction yield at 80.43 % was found by using 70% methanol as solvent at extraction temperature 50 °C with stirring speed 300 rpm, coefficient distribution was found 216.334. From this research it can be concluded that Three-Suffix Margules Model is suitable to predict liquid - liquid equilibrium data for phenol system.

Effects of Undercooling and Cooling Rate on Peritectic Phase Crystallization Within Ni-Zr Alloy Melt

NASA Astrophysics Data System (ADS)

Lü, P.; Wang, H. P.

2018-04-01

The liquid Ni-16.75 at. pct Zr peritectic alloy was substantially undercooled and containerlessly solidified by an electromagnetic levitator and a drop tube. The dependence of the peritectic solidification mode on undercooling was established based on the results of the solidified microstructures, crystal growth velocity, as well as X-ray diffraction patterns. Below a critical undercooling of 124 K, the primary Ni7Zr2 phase preferentially nucleates and grows from the undercooled liquid, which is followed by a peritectic reaction of Ni7Zr2+L → Ni5Zr. The corresponding microstructure is composed of the Ni7Zr2 dendrites, peritectic Ni5Zr phase, and inter-dendritic eutectic. Nevertheless, once the liquid undercooling exceeds the critical undercooling, the peritectic Ni5Zr phase directly precipitates from this undercooled liquid. However, a negligible amount of residual Ni7Zr2 phase still appears in the microstructure, indicating that nucleation and growth of the Ni7Zr2 phase are not completely suppressed. The micromechanical property of the peritectic Ni5Zr phase in terms of the Vickers microhardness is enhanced, which is ascribed to the transition of the peritectic solidification mode. To suppress the formation of the primary phase completely, this alloy was also containerlessly solidified in free fall experiments. Typical peritectic solidified microstructure forms in large droplets, while only the peritectic Ni5Zr phase appears in smaller droplets, which gives an indication that the peritectic Ni5Zr phase directly precipitates from the undercooled liquid by completely suppressing the growth of the primary Ni7Zr2 phase and the peritectic reaction due to the combined effects of the large undercooling and high cooling rate.

Dispersive liquid-liquid microextraction method based on solidification of floating organic droplet for the determination of thiamphenicol and florfenicol in environmental water samples.

PubMed

Peng, Guilong; He, Qiang; Al-Hamadani, Sulala M Z F; Zhou, Guangming; Liu, Mengzi; Zhu, Hui; Chen, Junhua

2015-05-01

Dispersive liquid-liquid microextraction with solidification of a floating organic droplet (DLLME-SFO) followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection was applied for the determination of thiamphenicol (TAP), florfenicol (FF) in water samples. 1-Undecanol was used as the extraction solvent which has lower density than water, low toxicity, and low melting point (19°C). A mixture of 800mL acetone (disperser solvent) and 80µL of 1-undecanol (extraction solvent) was injected into 20mL of aqueous solution. After 5min, 0.6g of NaCl was added and the sample vial was shaken. After 5min, the sample was centrifuged at 3500rpm for 3min, and then placed in an ice bath. When the extraction solvent floating on the aqueous solution had solidified, it was transferred into another conical vial where it was melted quickly at room temperature, and was diluted with methanol to 1mL, and analyzed by HPLC-UV detection. Parameters influencing the extraction efficiency were thoroughly examined and optimized. The extraction recoveries (ER) and the enrichment factors (EF) ranged from 67% to 72% and 223 to 241, respectively. The limits of detection (LODs) (S/N=3) were 0.33 and 0.56µgL(-1) for TAP and FF, respectively. Linear dynamic range (LDR) was in the range of 1.0-550µgL(-1) for TAP and 1.5-700µgL(-1) for FF, the relative standard deviations (RSDs) were in the range of 2.6-3.5% and the recoveries of spiked samples ranged from 94% to 106%. Copyright © 2015 Elsevier Inc. All rights reserved.

Capabilities and limitations of dispersive liquid-liquid microextraction with solidification of floating organic drop for the extraction of organic pollutants from water samples.

PubMed

Vera-Avila, Luz E; Rojo-Portillo, Tania; Covarrubias-Herrera, Rosario; Peña-Alvarez, Araceli

2013-12-17

Dispersive liquid-liquid microextraction with solidification of floating organic drop (DLLME-SFO) is one of the most interesting sample preparation techniques developed in recent years. Although several applications have been reported, the potentiality and limitations of this simple and rapid extraction technique have not been made sufficiently explicit. In this work, the extraction efficiency of DLLME-SFO for pollutants from different chemical families was determined. Studied compounds include: 10 polycyclic aromatic hydrocarbons, 5 pesticides (chlorophenoxy herbicides and DDT), 8 phenols and 6 sulfonamides, thus, covering a large range of polarity and hydrophobicity (LogKow 0-7, overall). After optimization of extraction conditions using 1-dodecanol as extractant, the procedure was applied for extraction of each family from 10-mL spiked water samples, only adjusting sample pH as required. Absolute recoveries for pollutants with LogKow 3-7 were >70% and recovery values within this group (18 compounds) were independent of structure or hydrophobicity; the precision of recovery was very acceptable (RSD<12%) and linear behavior was observed in the studied concentration range (r(2)>0.995). Extraction recoveries for pollutants with LogKow 1.46-2.8 were in the range 13-62%, directly depending on individual LogKow values; however, good linearity (r(2)>0.993) and precision (RSD<6.5%) were also demonstrated for these polar solutes, despite recovery level. DLLME-SFO with 1-dodecanol completely failed for extraction of compounds with LogKow≤1 (sulfa drugs), other more polar extraction solvents (ionic liquids) should be explored for highly hydrophilic pollutants. Copyright © 2013 Elsevier B.V. All rights reserved.

Method for stabilizing low-level mixed wastes at room temperature

DOEpatents

Wagh, A.S.; Singh, D.

1997-07-08

A method to stabilize solid and liquid waste at room temperature is provided comprising combining solid waste with a starter oxide to obtain a powder, contacting the powder with an acid solution to create a slurry, said acid solution containing the liquid waste, shaping the now-mixed slurry into a predetermined form, and allowing the now-formed slurry to set. The invention also provides for a method to encapsulate and stabilize waste containing cesium comprising combining the waste with Zr(OH){sub 4} to create a solid-phase mixture, mixing phosphoric acid with the solid-phase mixture to create a slurry, subjecting the slurry to pressure; and allowing the now pressurized slurry to set. Lastly, the invention provides for a method to stabilize liquid waste, comprising supplying a powder containing magnesium, sodium and phosphate in predetermined proportions, mixing said powder with the liquid waste, such as tritium, and allowing the resulting slurry to set. 4 figs.

Method for stabilizing low-level mixed wastes at room temperature

DOEpatents

Wagh, Arun S.; Singh, Dileep

1997-01-01

A method to stabilize solid and liquid waste at room temperature is provided comprising combining solid waste with a starter oxide to obtain a powder, contacting the powder with an acid solution to create a slurry, said acid solution containing the liquid waste, shaping the now-mixed slurry into a predetermined form, and allowing the now-formed slurry to set. The invention also provides for a method to encapsulate and stabilize waste containing cesium comprising combining the waste with Zr(OH).sub.4 to create a solid-phase mixture, mixing phosphoric acid with the solid-phase mixture to create a slurry, subjecting the slurry to pressure; and allowing the now pressurized slurry to set. Lastly, the invention provides for a method to stabilize liquid waste, comprising supplying a powder containing magnesium, sodium and phosphate in predetermined proportions, mixing said powder with the liquid waste, such as tritium, and allowing the resulting slurry to set.

Solid and Liquid Waste Drying Bag

NASA Technical Reports Server (NTRS)

Litwiller, Eric (Inventor); Hogan, John A. (Inventor); Fisher, John W. (Inventor)

2009-01-01

Method and system for processing waste from human activities, including solids, liquids and vapors. A fluid-impermeable bag, lined with a liquid-impermeable but vapor-permeable membrane, defining an inner bag, is provided. A vacuum force is provided to extract vapors so that the waste is moved toward a selected region in the inner bag, extracted vapors, including the waste vapors and vaporized portions of the waste liquids are transported across the membrane, and most or all of the solids remain within the liner. Extracted vapors are filtered, and sanitized components thereof are isolated and optionally stored. The solids remaining within the liner are optionally dried and isolated for ultimate disposal.

Hydrothermal solidification of municipal solid waste incineration bottom ash with slag addition.

PubMed

Jing, Zhenzi; Ran, Xianqiang; Jin, Fangming; Ishida, Emile H

2010-01-01

Hydrothermal solidification of municipal solid waste incineration (MSWI) bottom ash has been carried out under saturated steam pressure (1.56 MPa) at 200 degrees C for up to 24 h by mixing quartz, slaked lime and water-cooled blast furnace slag (WBFS). The strength enhancement for the WBFS addition was best. The strength development was shown to be due mainly to tobermorite formation, and the tobermorite formation densified matrix, thus promoting the strength development. WBFS seemed to have a higher reactivity than the quartz during the initial hydrothermal process, which provided more silica available to harden the solidified specimens. However, a longer curing time (24 h) was favorable to the quartz dissolution for tobermorite formation, which in turn, enhanced the strength for quartz addition. Curing time affected the crystal morphology evolution, and the stubby plate of tobermorite seemed to result in a high strength enhancement in this study. Laboratory leaching tests were conducted to determine the amount of heavy metals dissolved from the final solidified specimens, and the leaching results showed that after hydrothermal processing the heavy metals dissolved from the solidified specimens were reduced effectively. As such, the hydrothermal processing may have a high potential for recycling/reusing MSWI ash on a large scale. 2010 Elsevier Ltd. All rights reserved.

WEST VALLEY DEMONSTRATION PROJECT ANNUAL SITE ENVIRONMENTAL REPORT CALENDAR YEAR 2002

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2003-09-12

This annual environmental monitoring report for the West Valley Demonstration Project (WVDP or Project) is published to inform those with interest about environmental conditions at the WVDP. In accordance with U.S. Department of Energy (DOE) Order 231.1, Environment, Safety, and Health Reporting, the report summarizes calendar year (CY) 2002 environmental monitoring data so as to describe the performance of the WVDP's environmental management system, confirm compliance with standards and regulations, and highlight important programs. In 2002, the West Valley Demonstration Project, the site of a DOE environmental cleanup activity operated by West Valley Nuclear Services Co. (WVNSCO), was in themore » final stages of stabilizing high-level radioactive waste (HLW) that remained at the site after commercial nuclear fuel reprocessing had been discontinued in the early 1970s. The Project is located in western New York State, about 30 miles south of Buffalo, within the New York State-owned Western New York Nuclear Service Center (WNYNSC). The WVDP is being conducted in cooperation with the New York State Energy Research and Development Authority (NYSERDA). Ongoing work activities at the WVDP during 2002 included: (1) completing HLW solidification and melter shutdown; (2) shipping low-level radioactive waste off-site for disposal; (3) constructing a facility where large high-activity components can be safely packaged for disposal; (4) packaging and removing spent materials from the vitrification facility; (5) preparing environmental impact statements for future activities; (6) removing as much of the waste left behind in waste tanks 8D-1 and 8D-2 as was reasonably possible; (7) removing storage racks, canisters, and debris from the fuel receiving and storage pool, decontaminating pool walls, and beginning shipment of debris for disposal; (8) ongoing decontamination in the general purpose cell and the process mechanical cell (also referred to as the head end cells); (9) planning for cleanup of waste in the plutonium purification cell (south) and extraction cell number 2 in the main plant; (10) ongoing characterization of facilities such as the waste tank farm and process cells; (11) monitoring the environment and managing contaminated areas within the Project facility premises; and (12) flushing and rinsing HLW solidification facilities.« less

Thermodynamic properties derived from the free volume model of liquids

NASA Technical Reports Server (NTRS)

Miller, R. I.

1974-01-01

An equation of state and expressions for the isothermal compressibility, thermal expansion coefficient, heat capacity, and entropy of liquids have been derived from the free volume model partition function suggested by Turnbull. The simple definition of the free volume is used, and it is assumed that the specific volume is directly related to the cube of the intermolecular separation by a proportionality factor which is found to be a function of temperature and pressure as well as specific volume. When values of the proportionality factor are calculated from experimental data for real liquids, it is found to be approximately constant over ranges of temperature and pressure which correspond to the dense liquid phase. This result provides a single-parameter method for calculating dense liquid thermodynamic properties and is consistent with the fact that the free volume model is designed to describe liquids near the solidification point.

TREATMENT OF METAL-LADEN HAZARDOUS WASTES WITH ADVANCED CLEAN COAL TECHNOLOGY BY-PRODUCTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

James T. Cobb, Jr.

2003-09-12

Metal-laden wastes can be stabilized and solidified using advanced clean coal technology by-products (CCTBs)--fluid bed combustor ash and spray drier solids. These utility-generated treatment chemicals are available for purchase through brokers, and commercial applications of this process are being practiced by treaters of metal-laden hazardous waste. A complex of regulations governs this industry, and sensitivities to this complex has discouraged public documentation of treatment of metal-laden hazardous wastes with CCTBs. This report provides a comprehensive public documentation of laboratory studies that show the efficacy of the stabilization and solidification of metal-laden hazardous wastes--such as lead-contaminated soils and sandblast residues--through treatmentmore » with CCTBs. It then describes the extensive efforts that were made to obtain the permits allowing a commercial hazardous waste treater to utilize CCTBs as treatment chemicals and to install the equipment required to do so. It concludes with the effect of this lengthy process on the ability of the treatment company to realize the practical, physical outcome of this effort, leading to premature termination of the project.« less

Studies of Thermophysical Properties of Metals and Semiconductors by Containerless Processing Under Microgravity

NASA Technical Reports Server (NTRS)

Seidel, A.; Soellner, W.; Stenzel, C.

2012-01-01

Electromagnetic levitation under microgravity provides unique opportunities for the investigation of liquid metals, alloys and semiconductors, both above and below their melting temperatures, with minimized disturbances of the sample under investigation. The opportunity to perform such experiments will soon be available on the ISS with the EML payload which is currently being integrated. With its high-performance diagnostics systems EML allows to measure various physical properties such as heat capacity, enthalpy of fusion, viscosity, surface tension, thermal expansion coefficient, and electrical conductivity. In studies of nucleation and solidification phenomena the nucleation kinetics, phase selection, and solidification velocity can be determined. Advanced measurement capabilities currently being studied include the measurement and control of the residual oxygen content of the process atmosphere and a complementary inductive technique to measure thermophysical properties.

Particle Engulfment and Pushing by Solidifying Interfaces LMS Mission Results

NASA Technical Reports Server (NTRS)

Juretzko, Frank R.; Catalina, Adrian V.; Stefanescu, Doru M.; Dhindaw, Brij K.; Sen, Subhayu; Curreri, Peter A.; Mullins, Jennifer

1998-01-01

Results of the directional solidification experiments on Particle Engulfment and Pushing by Solidifying Interfaces (PEP) conducted on the space shuttle Columbia are reported. The experiment was manifested as part of The Life and Microgravity Science Mission. Two pure aluminum (99.999%) 9 mm cylindrical rods, loaded with about 2 vol.% 500 microns diameter zirconia particles were melted and directionally solidified in the microgravity (micro-g) environment of the shuttle. The particles were non-reactive with the matrices within the temperature range of interest. The experiments were conducted such as to insure a planar solid/liquid interface during solidification. Two different cartridge - crucible - sample designs were used: a spring-piston and expansion void. Both resulted in sound samples. Samples were evaluated post-flight for soundness by X-ray computer tomography (XCT).

Crucible de-wetting during bridgman growth of semiconductors in microgravity

NASA Astrophysics Data System (ADS)

Duffar, T.; Paret-Harter, I.; Dusserre, P.

1990-02-01

After a literature survey and observations made during a space experiment, the phenomenon of crucible de-wetting by the crystal during Bridgman solidification in microgravity is explained by a model involving composite wetting of the crucible by the liquid, crystal angle of growth and interface advance. A ground experiment was run in order to validate this model which also explains why a crystal detaches from the crucible surface when a sand blasted crucible is used in Bridgman solidification on the ground. It is shown that de-wetting leads to enhanced quality of the crystal produced and that capillary-induced convection effects are not to be feared in this case. Consequently, it is highly advisable to use rough-surface crucibles for crystal growth both in microgravity and on the ground.

The Orbital Workshop Waste Management Compartment

NASA Technical Reports Server (NTRS)

1972-01-01

This image is a wide-angle view of the Orbital Workshop waste management compartment. The waste management facilities presented a unique challenge to spacecraft designers. In addition to collection of liquid and solid human wastes, there was a medical requirement to dry all solid human waste products and to return the residue to Earth for examination. Liquid human waste (urine) was frozen for return to Earth. Total quantities of each astronaut's liquid and solid wastes were precisely measured. Cabin air was drawn into the toilet, shown on the wall at right in this photograph, and over the waste products to generate a flow of the waste in the desired direction. The air was then filtered for odor control and antiseptic purposes prior to being discharged back into the cabin.

Detection of free liquid in containers of solidified radioactive waste

DOEpatents

Greenhalgh, W.O.

Nondestructive detection of the presence of free liquid within a sealed enclosure containing solidified waste is accomplished by measuring the levels of waste at two diametrically opposite locations while slowly tilting the enclosure toward one of said locations. When the measured level remains constant at the other location, the measured level at said one location is noted and any measured difference of levels indicates the presence of liquid on the surface of the solifified waste. The absence of liquid in the enclosure is verified when the measured levels at both locations are equal.

Detection of free liquid in containers of solidified radioactive waste

DOEpatents

Greenhalgh, Wilbur O.

1985-01-01

A method of nondestructively detecting the presence of free liquid within a sealed enclosure containing solidified waste by measuring the levels of waste at two diametrically opposite locations while slowly tilting the enclosure toward one of said locations. When the measured level remains constant at the other location, the measured level at said one location is noted and any measured difference of levels indicates the presence of liquid on the surface of the solidified waste. The absence of liquid in the enclosure is verified when the measured levels at both locations are equal.

Solidification and stabilization of the incinerated wastewater sludge from textile industry

NASA Astrophysics Data System (ADS)

Aziz, Hamidi Abdul; Ghazali, Miskiah Fadzilah; Omran, Abdelnaser; Umar, Muhammad

2017-10-01

This paper describes the investigation of solidification and stabilization (S/S) process for the safe disposal of incinerated wastewater sludge produced from a textile industry in Penang, Malaysia. Physical and chemical properties of the samples were first characterized. Various ratios of ordinary Portland cement (OPC) as a binder were used to immobilize the metals. The leachability of metals in these cement-based waste materials was studied by standard toxicity characteristic leaching procedure (TCLP) and the mechanical strength was tested by a compressive strength test. TCLP results showed the ability of OPC to immobilize various metals such as Zn, Cu, Fe, Al, Ti, and K within the limits set by USEPA and Malaysia Environment Quality Act, 1974. However, the strength of the solidified matrixes was generally lower than the control specimens, ranging from 1-23 Mpa, which was well above the specified limit of 414 kPa for such matrices for their disposal in landfills.

Development of Axial Continuous Metal Expeller for melt conditioning of alloys

NASA Astrophysics Data System (ADS)

Cassinath, Z.; Prasada Rao, A. K.

2016-02-01

ACME (Axial, centrifugal metal expeller) is a novel processing technology developed independently for conditioning liquid metal prior to solidification processing. The ACME process is based on an axial compressor and uses a rotor stator mechanism to impose a high shear rate and a high intensity of turbulence to the liquid metal, so that the conditioned liquid metal has uniform temperature and uniform chemical composition as it is expelled. The microstructural refinement is achieved through the process of dendrite fragmentation while taking advantage of the thixotropic property of semisolid metal slurry so that it can be conveyed for further downstream operations. This paper introduces the concept and its advantages over current technologies.

Radwaste desk reference - Volume 3, Part 2: Liquid waste management. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deltete, D.; Fisher, S.; Kelly, J.J.

1994-05-01

EPRI began, in late in 1987, to produce a Radwaste Desk Reference that would allow each of the member utilities access to the available information and expertise on radwaste management. EPRI considers this important because radwaste management involves a wide variety of scientific and engineering disciplines. These include chemical and mechanical engineering, chemistry, and health physics. Radwaste management also plays a role in implementing a wide variety of regulatory requirements. These include plant-specific technical specifications, NRC standards for protection against radiation, DOT transportation regulations and major environmental legislation such as the Resource Conservation and Recovery Act. EPRI chose a questionmore » and answer format because it could be easily accessed by radwaste professionals with a variety of interests. The questions were generated at two meetings of utility radwaste professionals and EPRI contractors. Volume 1, which is already in publication, addresses dry active waste generation, processing and measurement. Volume 2 addresses low level waste storage, transportation and disposal. This volume, Volume 3, is being issued in two parts. Part 1 concentrates on the processing of liquid radioactive waste, whereas Part 2, included here, addresses liquid waste management. It includes extensive information and operating practices related to liquid waste generation and control, liquid waste processing systems at existing U.S. nuclear plants, processes for managing wet wastes (handling, dewatering, solidifying, processing, and packaging), and liquid waste measurement and analysis.« less

Microgravity

NASA Image and Video Library

2000-07-29

An entranced youngster watches a demonstration of the enhanced resilience of undercooled metal alloys as compared to conventional alloys. Steel bearings are dropped onto plates made of steel, titanium alloy, and zirconium liquid metal alloy, so-called because its molecular structure is amorphous and not crystalline. The bearing on the liquid metal plate bounces for a minute or more longer than on the other plates. Experiments aboard the Space Shuttle helped scientists refine their understanding of the physical properties of certain metal alloys when undercooled (i.e., kept liquid below their normal solidification temperature). This new knowledge then allowed scientists to modify a terrestrial production method so they can now make limited quantities marketed under the Liquid Metal trademark. The exhibit was a part of the NASA outreach activity at AirVenture 2000 sponsored by the Experimental Aircraft Association in Oshkosh, WI.

49 CFR 173.150 - Exceptions for Class 3 (flammable and combustible liquids).

Code of Federal Regulations, 2010 CFR

2010-10-01

... the material meets the definition of a hazardous substance, hazardous waste, marine pollutant, or are... waste, or a marine pollutant. (3) A combustible liquid that is in a bulk packaging or a combustible liquid that is a hazardous substance, a hazardous waste, or a marine pollutant is not subject to the...

49 CFR 173.150 - Exceptions for Class 3 (flammable and combustible liquids).

Code of Federal Regulations, 2011 CFR

2011-10-01

... material meets the definition of a hazardous substance, hazardous waste, marine pollutant, or is offered... that is a hazardous substance, a hazardous waste, or a marine pollutant is not subject to the... liquid in a non-bulk packaging unless the combustible liquid is a hazardous substance, a hazardous waste...

78 FR 6149 - Final Interim Staff Guidance Assessing the Radiological Consequences of Accidental Releases of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-29

... Accidental Releases of Radioactive Materials From Liquid Waste Tanks in Ground and Surface Waters for... Radioactive Materials from Liquid Waste Tanks in Ground and Surface Waters for Combined License Applications... Radioactive Materials from Liquid Waste Tanks in Ground and Surface Waters for Combined License Applications...

Skylab

NASA Image and Video Library

1972-05-01

This image is a wide-angle view of the Orbital Workshop waste management compartment. The waste management facilities presented a unique challenge to spacecraft designers. In addition to collection of liquid and solid human wastes, there was a medical requirement to dry all solid human waste products and to return the residue to Earth for examination. Liquid human waste (urine) was frozen for return to Earth. Total quantities of each astronaut's liquid and solid wastes were precisely measured. Cabin air was drawn into the toilet, shown on the wall at right in this photograph, and over the waste products to generate a flow of the waste in the desired direction. The air was then filtered for odor control and antiseptic purposes prior to being discharged back into the cabin.

Studies of Nucleation and Growth, Specific Heat and Viscosity of Undercooled Melts of Quasicrystals and Polytetrehedral-Phase-Forming Alloys

NASA Technical Reports Server (NTRS)

2003-01-01

By investigating the properties of quasicrystals and quasicrystal-forming liquid alloys, we may determine the role of ordering of the liquid phase in the formation of quasicrystals, leading to a better fundamental understanding of both the quasicrystal and the liquid. A quasicrystal is solid characterized by a symmetric but non-periodic arrangement of atoms, usually in the form of an icosahedron (12 atoms, 20 triangular faces). It is theorized that the short-range order in liquids takes this same form. The degree of ordering depends on the temperature of the liquid, and affects many of the liquid s properties, including specific heat, viscosity, and electrical resistivity. The MSFC role in this project includes solidification studies, phase diagram determination, and thermophysical property measurements on the liquid quasicrystal-forming alloys, all by electrostatic levitation (ESL). The viscosity of liquid quasicrystal-forming alloys is measured by the oscillating drop method, both in the stable and undercooled liquid state. The specific heat of solid, undercooled liquid, and stable liquid are measured by the radiative cooling rate of the droplets.

Towards wall functions for the prediction of solute segregation in plane front directional solidification

NASA Astrophysics Data System (ADS)

Chatelain, M.; Rhouzlane, S.; Botton, V.; Albaric, M.; Henry, D.; Millet, S.; Pelletier, D.; Garandet, J. P.

2017-10-01

The present paper focuses on solute segregation occurring in directional solidification processes with sharp solid/liquid interface, like silicon crystal growth. A major difficulty for the simulation of such processes is their inherently multi-scale nature: the impurity segregation problem is controlled at the solute boundary layer scale (micrometers) while the thermal problem is ruled at the crucible scale (meters). The thickness of the solute boundary layer is controlled by the convection regime and requires a specific refinement of the mesh of numerical models. In order to improve numerical simulations, wall functions describing solute boundary layers for convecto-diffusive regimes are derived from a scaling analysis. The aim of these wall functions is to obtain segregation profiles from purely thermo-hydrodynamic simulations, which do not require solute boundary layer refinement at the solid/liquid interface. Regarding industrial applications, various stirring techniques can be used to enhance segregation, leading to fully turbulent flows in the melt. In this context, the scaling analysis is further improved by taking into account the turbulent solute transport. The solute boundary layers predicted by the analytical model are compared to those obtained by transient segregation simulations in a canonical 2D lid driven cavity configuration for validation purposes. Convective regimes ranging from laminar to fully turbulent are considered. Growth rate and molecular diffusivity influences are also investigated. Then, a procedure to predict concentration fields in the solid phase from a hydrodynamic simulation of the solidification process is proposed. This procedure is based on the analytical wall functions and on solute mass conservation. It only uses wall shear-stress profiles at the solidification front as input data. The 2D analytical concentration fields are directly compared to the results of the complete simulation of segregation in the lid driven cavity configuration. Finally, an additional output from the analytical model is also presented. We put in light the correlation between different species convecto-diffusive behaviour; we use it to propose an estimation method for the segregation parameters of various chemical species knowing segregation parameters of one specific species.

Molecular interactions in high conductive gel electrolytes based on low molecular weight gelator.

PubMed

Bielejewski, Michał; Łapiński, Andrzej; Demchuk, Oleg

2017-03-15

Organic ionic gel (OIG) electrolytes, also known as gel electrolytes or ionogels are one example of modern functional materials with the potential to use in wide range of electrochemical applications. The functionality of OIGs arises from the thermally reversible solidification of electrolytes or ionic liquids and their superior ionic conductivity. To understand and to predict the properties of these systems it is important to get the knowledge about the interactions on molecular level between the solid gelator matrix and the electrolyte solution. This paper reports the spectroscopic studies (FT-IR, UV-Vis and Raman) of the gel electrolyte based on low molecular weight gelator methyl-4,6-O-(p-nitrobenzylidene)-α-d-glucopyranoside and solution of quaternary ammonium salt, tetramethylammonium bromide. The solidification process was based on sol-gel technique. Below characteristic temperature, defined as gel to sol phase transition temperature, T gs , the samples were solid-like and showed high conductivity values of the same order as observed for pure liquid electrolytes. The investigations were performed for a OIGs in a wide range of molar concentrations of the electrolyte solution. Copyright © 2016 Elsevier Inc. All rights reserved.

Mechanical Fracturing of Core-Shell Undercooled Metal Particles for Heat-Free Soldering

PubMed Central

Çınar, Simge; Tevis, Ian D.; Chen, Jiahao; Thuo, Martin

2016-01-01

Phase-change materials, such as meta-stable undercooled (supercooled) liquids, have been widely recognized as a suitable route for complex fabrication and engineering. Despite comprehensive studies on the undercooling phenomenon, little progress has been made in the use of undercooled metals, primarily due to low yields and poor stability. This paper reports the use of an extension of droplet emulsion technique (SLICE) to produce undercooled core-shell particles of structure; metal/oxide shell-acetate (‘/’ = physisorbed, ‘-’ = chemisorbed), from molten Field’s metal (Bi-In-Sn) and Bi-Sn alloys. These particles exhibit stability against solidification at ambient conditions. Besides synthesis, we report the use of these undercooled metal, liquid core-shell, particles for heat free joining and manufacturing at ambient conditions. Our approach incorporates gentle etching and/or fracturing of outer oxide-acetate layers through mechanical stressing or shearing, thus initiating a cascade entailing fluid flow with concomitant deformation, combination/alloying, shaping, and solidification. This simple and low cost technique for soldering and fabrication enables formation of complex shapes and joining at the meso- and micro-scale at ambient conditions without heat or electricity. PMID:26902483

Waste Management Facilities Cost Information report for Greater-Than-Class C and DOE equivalent special case waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feizollahi, F.; Shropshire, D.

This Waste Management Facility Cost Information (WMFCI) report for Greater-Than-Class C low-level waste (GTCC LLW) and DOE equivalent special case waste contains preconceptual designs and planning level life-cycle cost (PLCC) estimates for treatment, storage, and disposal facilities needed for management of GTCC LLW and DOE equivalent waste. The report contains information on 16 facilities (referred to as cost modules). These facilities are treatment facility front-end and back-end support functions (administration support, and receiving, preparation, and shipping cost modules); seven treatment concepts (incineration, metal melting, shredding/compaction, solidification, vitrification, metal sizing and decontamination, and wet/air oxidation cost modules); two storage concepts (enclosedmore » vault and silo); disposal facility front-end functions (disposal receiving and inspection cost module); and four disposal concepts (shallow-land, engineered shallow-land, intermediate depth, and deep geological cost modules). Data in this report allow the user to develop PLCC estimates for various waste management options. A procedure to guide the U.S. Department of Energy (DOE) and its contractor personnel in the use of estimating data is also included in this report.« less

Immobilization of iodine in concrete

DOEpatents

Clark, Walter E.; Thompson, Clarence T.

1977-04-12

A method for immobilizing fission product radioactive iodine recovered from irradiated nuclear fuel comprises combining material comprising water, Portland cement and about 3-20 wt. % iodine as Ba(IO.sub.3).sub.2 to provide a fluid mixture and allowing the fluid mixture to harden, said Ba(IO.sub.3).sub.2 comprising said radioactive iodine. An article for solid waste disposal comprises concrete prepared by this method. BACKGROUND OF THE INVENTION This invention was made in the course of, or under a contract with the Energy Research and Development Administration. It relates in general to reactor waste solidification and more specifically to the immobilization of fission product radioactive iodine recovered from irradiated nuclear fuel for underground storage.

Remediation by in-situ solidification/stabilisation of Ardeer landfill, Scotland

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wyllie, M.; Esnault, A.; Barker, P.

1997-12-31

The Ardeer Landfill site at ICI Explosives factory on the west coast of Scotland had been a repository for waste from the site for 40 years. In order to safeguard the local environment ICI Explosives, with approval of Local Authorities and the Clyde River Purification Board put into action a programme of investigation and planning which culminated in the in-situ treatment of 10,000 m3 of waste within the landfill by a deep mixing method using the {open_quotes}Colmix{close_quotes} system. The paper describes in varying degrees of detail the remediation from investigation to the execution of the in-situ stabilisation and presents themore » post construction monitoring results.« less

Thermoelectric energy harvesting for a solid waste processing toilet

NASA Astrophysics Data System (ADS)

Stokes, C. David; Baldasaro, Nicholas G.; Bulman, Gary E.; Stoner, Brian R.

2014-06-01

Over 2.5 billion people do not have access to safe and effective sanitation. Without a sanitary sewer infrastructure, self-contained modular systems can provide solutions for these people in the developing world and remote areas. Our team is building a better toilet that processes human waste into burnable fuel and disinfects the liquid waste. The toilet employs energy harvesting to produce electricity and does not require external electrical power or consumable materials. RTI has partnered with Colorado State University, Duke University, and Roca Sanitario under a Bill and Melinda Gates Foundation Reinvent the Toilet Challenge (RTTC) grant to develop an advanced stand-alone, self-sufficient toilet to effectively process solid and liquid waste. The system operates through the following steps: 1) Solid-liquid separation, 2) Solid waste drying and sizing, 3) Solid waste combustion, and 4) Liquid waste disinfection. Thermoelectric energy harvesting is a key component to the system and provides the electric power for autonomous operation. A portion of the exhaust heat is captured through finned heat-sinks and converted to electricity by thermoelectric (TE) devices to provide power for the electrochemical treatment of the liquid waste, pumps, blowers, combustion ignition, and controls.

Solidification of a binary alloy: Finite-element, single-domain simulation and new benchmark solutions

NASA Astrophysics Data System (ADS)

Le Bars, Michael; Worster, M. Grae

2006-07-01

A finite-element simulation of binary alloy solidification based on a single-domain formulation is presented and tested. Resolution of phase change is first checked by comparison with the analytical results of Worster [M.G. Worster, Solidification of an alloy from a cooled boundary, J. Fluid Mech. 167 (1986) 481-501] for purely diffusive solidification. Fluid dynamical processes without phase change are then tested by comparison with previous numerical studies of thermal convection in a pure fluid [G. de Vahl Davis, Natural convection of air in a square cavity: a bench mark numerical solution, Int. J. Numer. Meth. Fluids 3 (1983) 249-264; D.A. Mayne, A.S. Usmani, M. Crapper, h-adaptive finite element solution of high Rayleigh number thermally driven cavity problem, Int. J. Numer. Meth. Heat Fluid Flow 10 (2000) 598-615; D.C. Wan, B.S.V. Patnaik, G.W. Wei, A new benchmark quality solution for the buoyancy driven cavity by discrete singular convolution, Numer. Heat Transf. 40 (2001) 199-228], in a porous medium with a constant porosity [G. Lauriat, V. Prasad, Non-darcian effects on natural convection in a vertical porous enclosure, Int. J. Heat Mass Transf. 32 (1989) 2135-2148; P. Nithiarasu, K.N. Seetharamu, T. Sundararajan, Natural convective heat transfer in an enclosure filled with fluid saturated variable porosity medium, Int. J. Heat Mass Transf. 40 (1997) 3955-3967] and in a mixed liquid-porous medium with a spatially variable porosity [P. Nithiarasu, K.N. Seetharamu, T. Sundararajan, Natural convective heat transfer in an enclosure filled with fluid saturated variable porosity medium, Int. J. Heat Mass Transf. 40 (1997) 3955-3967; N. Zabaras, D. Samanta, A stabilized volume-averaging finite element method for flow in porous media and binary alloy solidification processes, Int. J. Numer. Meth. Eng. 60 (2004) 1103-1138]. Finally, new benchmark solutions for simultaneous flow through both fluid and porous domains and for convective solidification processes are presented, based on the similarity solutions in corner-flow geometries recently obtained by Le Bars and Worster [M. Le Bars, M.G. Worster, Interfacial conditions between a pure fluid and a porous medium: implications for binary alloy solidification, J. Fluid Mech. (in press)]. Good agreement is found for all tests, hence validating our physical and numerical methods. More generally, the computations presented here could now be considered as standard and reliable analytical benchmarks for numerical simulations, specifically and independently testing the different processes underlying binary alloy solidification.

Identification of Gravity-Related Effects on Crystal Growth From Melts With an Immiscibility Gap

NASA Technical Reports Server (NTRS)

Kassemi, M.; Sayir, A.; Farmer, S.

1999-01-01

This work involves an experimental-numerical approach to study the effects of natural and Marangoni convections on solidification of single crystals from a silicate melt with a liquid-liquid immiscibility gap. Industrial use of crystals grown from silicate melts is becoming increasingly important in electronic, optical, and high temperature structural applications. Even the simplest silicate systems like Al203-SiO2 have had, and will continue to have, a significant role in the development of traditional and advanced ceramics. A unique feature of crystals grown from the silicate systems is their outstanding linear electro-optic properties. They also exhibit exceptionally high optical rotativity. As a result, these crystals are attractive materials for dielectric, optical, and microwave applications. Experimental work in our laboratory has indicated that directional solidification of a single crystal mullite appears to be preceded by liquid-liquid phase separation in the melt. Disruption of the immiscible state results in crystallization of a two phase structure. There is also evidence that mixing in the melt caused by density-driven convection can significantly affect the stability of the immiscible liquid layers and result in poly-crystalline growth. On earth, the immiscible state has only been observed for small diameter crystals grown in float zone systems where natural convection is almost negligible. Therefore, it is anticipated that growth of large single crystals from silicate melts would benefit from microgravity conditions because of the reduction of the natural convective mixing. The main objective of this research is to determine the effects of transport processes on the phase separation in the melt during growth of a single crystal while addressing the following issues: (1) When do the immiscible layers form and are they real?; (2) What are the main physical characteristics of the immiscible liquids?; and (3) How mixing by natural or Marangoni convection affects the stability of the phase separated melt.

Design of model experiments for melt flow and solidification in a square container under time-dependent magnetic fields

NASA Astrophysics Data System (ADS)

Meier, D.; Lukin, G.; Thieme, N.; Bönisch, P.; Dadzis, K.; Büttner, L.; Pätzold, O.; Czarske, J.; Stelter, M.

2017-03-01

This paper describes novel equipment for model experiments designed for detailed studies on electromagnetically driven flows as well as solidification and melting processes with low-melting metals in a square-based container. Such model experiments are relevant for a validation of numerical flow simulation, in particular in the field of directional solidification of multi-crystalline photovoltaic silicon ingots. The equipment includes two square-shaped electromagnetic coils and a melt container with a base of 220×220 mm2 and thermostat-controlled heat exchangers at top and bottom. A system for dual-plane, spatial- and time-resolved flow measurements as well as for in-situ tracking of the solid-liquid interface is developed on the basis of the ultrasound Doppler velocimetry. The parameters of the model experiment are chosen to meet the scaling laws for a transfer of experimental results to real silicon growth processes. The eutectic GaInSn alloy and elemental gallium with melting points of 10.5 °C and 29.8 °C, respectively, are used as model substances. Results of experiments for testing the equipment are presented and discussed.

Dimensionless numbers in additive manufacturing

NASA Astrophysics Data System (ADS)

Mukherjee, T.; Manvatkar, V.; De, A.; DebRoy, T.

2017-02-01

The effects of many process variables and alloy properties on the structure and properties of additively manufactured parts are examined using four dimensionless numbers. The structure and properties of components made from 316 Stainless steel, Ti-6Al-4V, and Inconel 718 powders for various dimensionless heat inputs, Peclet numbers, Marangoni numbers, and Fourier numbers are studied. Temperature fields, cooling rates, solidification parameters, lack of fusion defects, and thermal strains are examined using a well-tested three-dimensional transient heat transfer and fluid flow model. The results show that lack of fusion defects in the fabricated parts can be minimized by strengthening interlayer bonding using high values of dimensionless heat input. The formation of harmful intermetallics such as laves phases in Inconel 718 can be suppressed using low heat input that results in a small molten pool, a steep temperature gradient, and a fast cooling rate. Improved interlayer bonding can be achieved at high Marangoni numbers, which results in vigorous circulation of liquid metal, larger pool dimensions, and greater depth of penetration. A high Fourier number ensures rapid cooling, low thermal distortion, and a high ratio of temperature gradient to the solidification growth rate with a greater tendency of plane front solidification.

A Review of Permanent Magnet Stirring During Metal Solidification

NASA Astrophysics Data System (ADS)

Zeng, Jie; Chen, Weiqing; Yang, Yindong; Mclean, Alexander

2017-12-01

Rather than using conventional electromagnetic stirring (EMS) with three-phase alternating current, permanent magnet stirring (PMS), based on the use of sintered NdFeB material which has excellent magnetic characteristics, can be employed to generate a magnetic field for the stirring of liquid metal during solidification. Recent experience with steel casting indicates that PMS requires less than 20 pct of the total energy compared with EMS. Despite the excellent magnetic density properties and low power consumption, this relatively new technology has received comparatively little attention by the metal casting community. This paper reviews simulation modeling, experimental studies, and industrial trials of PMS conducted during recent years. With the development of magnetic simulation software, the magnetic field and associated flow patterns generated by PMS have been evaluated. Based on the results obtained from laboratory experiments, the effects of PMS on metal solidification structures and typical defects such as surface pinholes and center cavities are summarized. The significance of findings obtained from trials of PMS within the metals processing sector, including the continuous casting of steel, are discussed with the aim of providing an overview of the relevant parameters that are of importance for further development and industrial application of this innovative technology.

Solidification of nanosuspensions for the production of solid oral dosage forms and inhalable dry powders.

PubMed

Malamatari, Maria; Somavarapu, Satyanarayana; Taylor, Kevin M G; Buckton, Graham

2016-01-01

Nanosuspensions combine the advantages of nanotherapeutics (e.g. increased dissolution rate and saturation solubility) with ease of commercialisation. Transformation of nanosuspensions to solid oral and inhalable dosage forms minimises the physical instability associated with their liquid state, enhances patient compliance and enables targeted oral and pulmonary drug delivery. This review outlines solidification methods for nanosuspensions. It includes spray and freeze drying as the most widely used techniques. Fluidised-bed coating, granulation and pelletisation are also discussed as they yield nanocrystalline formulations with more straightforward downstream processing to tablets or capsules. Spray-freeze drying, aerosol flow reactor and printing of nanosuspensions are also presented as promising alternative solidification techniques. Results regarding the solid state, in vitro dissolution and/or aerosolisation efficiency of the nanocrystalline formulations are given and combined with available in vivo data. Focus is placed on the redispersibility of the solid nanocrystalline formulations, which is a prerequisite for their clinical application. A few solidified nanocrystalline products are already on the market and many more are in development. Oral and inhalable nanoparticle formulations are expected to have great potential especially in the areas of personalised medicine and delivery of high drug doses (e.g. antibiotics) to the lungs, respectively.