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Sample records for solidification vrs system

  1. WasteChem Corporation's Volume Reduction and Solidification (VRS) system for low-level radwaste treatment: Final report

    International Nuclear Information System (INIS)

    1988-01-01

    Since 1965, low and medium level radwastes from nuclear power stations, reprocessing plants and nuclear research centers have been stabilized using the Volume Reduction and Solidification (VRS) system. The VRS system uses an extruder/evaporator to evaporate the liquids from waste influents, while simultaneously incorporating the remaining radioactive solids in an asphalt binder. In the period 1965 to 1986 a minimum of 700,000 cubic feet of wastes have been processed with the VRS system. This report provides current operating data from various systems including the volume reduction factors achieved, and the progress of start-ups in the US. The report also provides previously unpublished experience with mixed wastes including uranium raffinate and nitrate-bearing sludges from surface impoundments. VRS systems in the US are currently operating at the Palisades and Hope Creek nuclear stations. These systems produce a variety of waste types including boric acid, bead resin, sodium sulfate and powdered resins. There are three start-ups of VRS systems scheduled in the US in 1987. These systems are at Fermi 2, Seabrook, and Nine Mile Point 2. Overseas, the startup of new systems continues with three VRS process lines coming on-line at the LaHague Reprocessing Center in France in 1986 and a start-up scheduled for 1987 at the Laguna Verde plant in Mexico. The US systems are operating continuously and with little required maintenance. Data on maintenance and the operator exposure are provided in this report. 6 refs., 11 figs., 13 tabs

  2. Process gas solidification system

    International Nuclear Information System (INIS)

    1980-01-01

    A process for withdrawing gaseous UF 6 from a first system and directing same into a second system for converting the gas to liquid UF 6 at an elevated temperature, additionally including the step of withdrawing the resulting liquid UF 6 from the second system, subjecting it to a specified sequence of flash-evaporation, cooling and solidification operations, and storing it as a solid in a plurality of storage vessels. (author)

  3. Plastic solidification system for radioactive waste

    International Nuclear Information System (INIS)

    Kani, Jiro; Irie, Hiromitsu; Obu, Etsuji; Nakayama, Yasuyuki; Matsuura, Hiroyuki.

    1979-01-01

    The establishment of a new solidification system is an important theme for recent radioactive-waste disposal systems. The conditions required of new systems are: (1) the volume of the solidified product to be reduced, and (2) the property of the solidified product to be superior to the conventional ones. In the plastic solidification system developed by Toshiba, the waste is first dried and then solidified with thermosetting resin. It has been confirmed that the property of the plastic solidified product is superior to that of the cement-or bitumen-solidified product. Investigation from various phases is being carried on for the application of this method to commercial plants. (author)

  4. Retrofit of radwaste solidification systems in Spain

    International Nuclear Information System (INIS)

    Rorcillo, R.; Virzi, E.

    1983-01-01

    In order to meet current Spanish engineering criteria as well as to provide for likely future Spanish Regulatory requirements, utilities committed to a major policy change in the preferred radwaste solidification media. In the early 1970's Spanish utilities, following the United States experience, purchased inexpensive solidification systems which used urea formaldehyde (UF) as the binding matrix. By the late 1970's the Spanish utilities, seeing the deterioration of the UF position and slow progress toward its improvement, unilaterally changed their binding matrix to cement. This paper illustrates the implementation of this change at the ASCO Nuclear Plant. The problems of layout modifications, shortened delivery schedule and criteria unique for Spain are addressed. Also presented is the operating experience acquired during the pre-operational start-up of the ASCO I Radwaste System

  5. Solidification in Multicomponent Multiphase Systems (SIMMS)

    Science.gov (United States)

    Rex, S.; Hecht, U.

    2005-06-01

    The multiphase microstructures that evolve during the solidification of multicomponent alloys are attracting widespread interest for industrial applications and fundamental research.Thermodynamic databases are now well-established for many alloy systems. Thermodynamic calculations provide all the required information about phase equilibria, forming an integral part of both dedicated and comprehensive microstructure models. Among the latter, phase-field modelling has emerged as the method of choice. Solidification experiments are intended to trigger model development or to serve as benchmarks for model validation. For benchmarking, microgravity conditions offer a unique opportunity for avoiding buoyancy-induced convection and buoyancy forces in bulk samples. However, diffusion and the free-energy of interfaces and its anisotropy need to be determined.The measurement of chemical diffusivities in the liquid state can equally benefit from microgravity experiments.

  6. Modular radwaste volume reduction and solidification systems

    International Nuclear Information System (INIS)

    Miller, E.L.

    1986-01-01

    This paper describes both the modular transportable and the modular mobile liquid radwaste volume reduction and solidification units based on a General Electric Company developed and patented process called AZTECH (a trademark of GE). An AZTECH system removes all water by azeotropic distillation and encapsulates the remaining solids in a polyester compound. The resulting monolith is suitable for either long term above ground storage or shallow land burial. Pilot and demonstration plant testing has confirmed the design parameters. The three processing modules are covered together with data which resulted in Nuclear Regulatory Commission approval on Dec. 30, 1985

  7. The cement solidification systems at LANL

    International Nuclear Information System (INIS)

    Veazey, G.W.

    1990-01-01

    There are two major cement solidification systems at Los Alamos National Laboratory. Both are focused primarily around treating waste from the evaporator at TA-55, the Plutonium Processing Facility. The evaporator receives the liquid waste stream from TA-55's nitric acid-based, aqueous-processing operations and concentrates the majority of the radionuclides in the evaporator bottoms solution. This is sent to the TA-55 cementation system. The evaporator distillate is sent to the TA-50 facility, where the radionuclides are precipitated and then cemented. Both systems treat TRU-level waste, and so are operated according to the criteria for WIPP-destined waste, but they differ in both cement type and mixing method. The TA-55 systems uses Envirostone, a gypsum-based cement and in-drum prop mixing; the TA-50 systems uses Portland cement and drum tumbling for mixing

  8. Mobile concrete solidification systems for power reactor waste

    International Nuclear Information System (INIS)

    Tchemitcheff, E.; Bordas, Y.

    1990-01-01

    In late 1988 SGN received an order from Electricite de France (EDF) for the construction of a mobile concrete solidification system to process secondary system resins generated by the P'4 and N4 series PWR power plants in France. This order was placed in view of SGN's experience with low- and medium-level radioactive waste treatment and conditioning over a period of almost 20 years. In addition to the construction of fixed waste processing facilities using more conventional technologies, SGN has been involved in application of the mobile system concept to the bituminization process in the United States, which led to the construction and commissioning of two transportable systems in collaboration with its American licensee US Ecology. It has also conducted large-scale R ampersand D on LLW/MLW concrete solidification, particularly for ion exchange resins. 5 figs

  9. Halo Formation During Solidification of Refractory Metal Aluminide Ternary Systems

    Science.gov (United States)

    D'Souza, N.; Feitosa, L. M.; West, G. D.; Dong, H. B.

    2018-02-01

    The evolution of eutectic morphologies following primary solidification has been studied in the refractory metal aluminide (Ta-Al-Fe, Nb-Al-Co, and Nb-Al-Fe) ternary systems. The undercooling accompanying solid growth, as related to the extended solute solubility in the primary and secondary phases can be used to account for the evolution of phase morphologies during ternary eutectic solidification. For small undercooling, the conditions of interfacial equilibrium remain valid, while in the case of significant undercooling when nucleation constraints occur, there is a departure from equilibrium leading to unexpected phases. In Ta-Al-Fe, an extended solubility of Fe in σ was observed, which was consistent with the formation of a halo of μ phase on primary σ. In Nb-Al-Co, a halo of C14 is formed on primary CoAl, but very limited vice versa. However, in the absence of a solidus projection it was not possible to definitively determine the extended solute solubility in the primary phase. In Nb-Al-Fe when nucleation constraints arise, the inability to initiate coupled growth of NbAl3 + C14 leads to the occurrence of a two-phase halo of C14 + Nb2Al, indicating a large undercooling and departure from equilibrium.

  10. Solidification of eutectic system alloys in space (M-19)

    Science.gov (United States)

    Ohno, Atsumi

    1993-01-01

    It is well known that in the liquid state eutectic alloys are theoretically homogeneous under 1 g conditions. However, the homogeneous solidified structure of this alloy is not obtained because thermal convection and non-equilibrium solidification occur. The present investigators have clarified the solidification mechanisms of the eutectic system alloys under 1 g conditions by using the in situ observation method; in particular, the primary crystals of the eutectic system alloys never nucleated in the liquid, but instead did so on the mold wall, and the crystals separated from the mold wall by fluid motion caused by thermal convection. They also found that the equiaxed eutectic grains (eutectic cells) are formed on the primary crystals. In this case, the leading phase of the eutectic must agree with the phase of the primary crystals. In space, no thermal convection occurs so that primary crystals should not move from the mold wall and should not appear inside the solidified structure. Therefore no equiaxed eutectic grains will be formed under microgravity conditions. Past space experiments concerning eutectic alloys were classified into two types of experiments: one with respect to the solidification mechanisms of the eutectic alloys and the other to the unidirectional solidification of this alloy. The former type of experiment has the problem that the solidified structures between microgravity and 1 g conditions show little difference. This is why the flight samples were prepared by the ordinary cast techniques on Earth. Therefore it is impossible to ascertain whether or not the nucleation and growth of primary crystals in the melt occur and if primary crystals influence the formation of the equiaxed eutectic grains. In this experiment, hypo- and hyper-eutectic aluminum copper alloys which are near eutectic point are used. The chemical compositions of the samples are Al-32.4mass%Cu (Hypo-eutectic) and Al-33.5mass%Cu (hyper-eutectic). Long rods for the samples are

  11. Plastic solidification system at Hamaoka Nuclear Power Station

    International Nuclear Information System (INIS)

    Okajima, Hiroyuki; Iokibe, Hiroyuki; Tsukiyama, Shigeru; Suzuki, Michio; Yamaguchi, Masato

    1987-01-01

    In Unit 1 and 2 of the Hamaoka Nuclear Power Station, radioactive waste was previously solidified in cement. By this method, the quantity of waste thus treated is relatively small, resulting in large number of the solidified drums. In order to solve this problem, the solidification facility using a thermosetting resin was employed, which is in operation since January 1986 for Unit 1, 2 and 3. As compared with the cement solidification, the solidified volume of concentrated liquid is about 1/12 and of spent-resin slurry is about 1/4 in plastic solidification. The following are described: course leading to the employment, the plastic solidification facility, features of the facility, operation results so far with the facility, etc. (Mori, K.)

  12. Directional Solidification and Liquidus Projection of the Sn-Co-Cu System

    Science.gov (United States)

    Chen, Sinn-Wen; Chang, Jui-Shen; Pan, Kevin; Hsu, Chia-Ming; Hsu, Che-Wei

    2013-04-01

    This study investigates the Sn-Co-Cu ternary system, which is of interest to the electronics industry. Ternary Sn-Co-Cu alloys were prepared, their as-solidified microstructures were examined, and their primary solidification phases were determined. The primary solidification phases observed were Cu, Co, Co3Sn2, CoSn, CoSn2, Cu6Sn5, Co3Sn2, γ, and β phases. Although there are ternary compounds reported in this ternary system, no ternary compound was found as the primary solidification phase. The directional solidification technique was applied when difficulties were encountered using the conventional quenching method to distinguish the primary solidification phases, such as Cu6Sn5, Cu3Sn, and γ phases. Of all the primary solidification phases, the Co3Sn2 and Co phases have the largest compositional regimes in which alloys display them as the primary solidification phases. There are four class II reactions and four class III reactions. The reactions with the highest and lowest reaction temperatures are both class III reactions, and are L + CoSn2 + Cu6Sn5 = CoSn3 at 621.5 K (348.3 °C) and L + Co3Sn2 + CoSn = Cu6Sn5 at 1157.8 K (884.6 °C), respectively.

  13. Calculation of solidification microstructure maps for the system Al-Fe-Si

    International Nuclear Information System (INIS)

    Gilgien, P.

    1996-01-01

    Computer programs have been developed in order to calculate solidification microstructure maps for binary and ternary alloys. These programs are based on recent analytical models for the constrained growth of dendrites and eutectics. Due to the importance of phase diagrams data, programs for the calculation of growth kinetics are coupled with ThermoCalc, a commercial software for phase diagram calculations. These programs have been used to calculate a solidification microstructure map for the Al-Fe system from 0 to 4 at%Fe. Comparison of the calculated results with an experimental solidification microstructure map from the literature shows that all microstructure transitions were predicted. Nevertheless there remain significant discrepancies between some calculated and experimental transition velocities. The programs were also used to calculate solidification microstructure maps in the Al-rich corner of the Al-Fe-Si system (0 to 8 at% Fe and 0 to 8 at% Si). In this case also, calculated results were in satisfactory agreement with experimental solidification microstructure maps, although the comparison was only partial since experimental ternary microstructure maps are less complete than for the binary system, and because the available thermodynamic database does not, as yet, include metastable phases. Laser surface remelting experiments were carried out on an Al-4 at% Fe alloy in order to link results from the literature, obtained at high solidification rates by laser surface remelting and at low solidification rates by Bridman experiments. Finally, Bridman experiments were carried out with an Al-2.63 wt% Fe alloy in order to determine the critical velocity at which a planar Al-Al 13 Fe 4 eutectic front is destabilised in a cellular eutectic by a small amount of Si. The critical solidification velocity thus obtained was in agreement with a criterion of constitutional undercooling. (author) figs., tabs., refs

  14. 47 CFR 64.606 - VRS and IP Relay provider and TRS program certification.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false VRS and IP Relay provider and TRS program... Services and Related Customer Premises Equipment for Persons With Disabilities § 64.606 VRS and IP Relay... including notification in the Federal Register. (2) VRS and IP Relay provider. Any entity desiring to...

  15. Directional solidification and characterization of the Al Nb2 - Al3 Nb eutectic system

    International Nuclear Information System (INIS)

    Trevisan, Eduardo A.O.; Andreotti, Fabio; Caram, Rubens

    1996-01-01

    The manufacturing of components to operate at high temperatures requires the use of metallic materials which can keep satisfactory mechanical and chemical properties, even at temperatures beyond 1000 deg C. An interesting alternative is the use of directionally solidified eutectic alloys. The eutectic alloy solidification makes possible the production of 'in situ' composite. A potentially useful system for manufacturing structural materials is the Al-Nb eutectic system. The aim of this work is to present the directional solidification of the Al-Nb eutectic alloy. (author)

  16. 78 FR 63488 - 60-Day Notice of Proposed Information Collection: Grant Drawdown Payment Request/LOCCS/VRS Voice...

    Science.gov (United States)

    2013-10-24

    .... Public and Indian Housing Grant recipients use the payment vouchers to request funds from HUD through the... system. The information collected on the payment voucher will also be used as an internal control measure... Information Collection: Grant Drawdown Payment Request/LOCCS/VRS Voice Activated AGENCY: Office of the...

  17. Determination of Systems Suitable for Study as Monotectic Binary Metallic Alloy Solidification Models

    Science.gov (United States)

    Smith, J. E., Jr.

    1983-01-01

    Succinonitrile-water and diethylene glycol-ethyl salicylate are two transparent systems which have been studied as monotectic binary metallic alloy solidification models. Being transparent, these systems allow for the direct observations of phase transformations and solidification reactions. The objective was to develop a screening technique to find systems of interest and then experimentally measure those systems. The succinonitrile-water system was used to check the procedures. To simulate the phase diagram of the system, two computer programs which determine solid-liquid and liquid-liquid equilibria were obtained. These programs use the UNIFAC method to determine activity coefficients and together with several other programs were used to predict the phase diagram. An experimental apparatus was developed and the succinonitrile-water phase diagram measured. The diagram was compared to both the simulation and literature data. Substantial differences were found in the comparisons which serve to demonstrate the need for this procedure.

  18. Economic analysis of a volume reduction/polyethylene solidification system for low-level radioactive wastes

    International Nuclear Information System (INIS)

    Kalb, P.D.; Colombo, P.

    1985-01-01

    A study was conducted at Brookhaven National Laboratory to determine the economic feasibility of a fluidized bed volume reduction/polyethylene solidification system for low-level radioactive wastes. These results are compared with the ''null'' alternative of no volume reduction and solidification of aqueous waste streams in hydraulic cement. The economic analysis employed a levelized revenue requirement (LRR) technique conducted over a ten year period. An interactive computer program was written to conduct the LRR calculations. Both of the treatment/solidification options were considered for a number of scenarios including type of plant (BWR or PWR) and transportation distance to the disposal site. If current trends in the escalation rates of cost components continue, the volume reduction/polyethylene solidification option will be cost effective for both BWRs and PWRs. Data indicate that a minimum net annual savings of $0.8 million per year (for a PWR shipping its waste 750 miles) and a maximum net annual savings of $9 million per year (for a BWR shipping its waste 2500 miles) can be achieved. A sensitivity analysis was performed for the burial cost escalation rate, which indicated that variation of this factor will impact the total levelized revenue requirement. The burial cost escalation rate which yields a break-even condition was determined for each scenario considered. 11 refs., 8 figs., 39 tabs

  19. Development of Mitsui/Juelich Incineration System and hydro-thermal ash solidification

    International Nuclear Information System (INIS)

    Suzuki, S.; Kamada, S.; Nakamori, Y.; Katakura, M.; Yamazaki, N.

    1988-01-01

    This paper summarizes the developing program for Mitsui/Juelich Incinerated System combined with Hydrothermal ash solidification. The system is an integrated one and capable for volume reduction of various kind of radioactive waste and safe disposal of residual incinerator ash. The system also has an advantage of reducing construction and operation cost. An outline of the incineration plant is also presented in this paper

  20. Retrofit of existing Dow solidification system at quad cities nuclear station

    International Nuclear Information System (INIS)

    Dekitis, L.; Jarvis, N.; Petri, R.; Testa, J.

    1983-01-01

    Over the past year ATCOR has been involved in the design, testing and supply of an In-container Mixing System Retrofit for Commonwealth Edison's Quad Cities Nuclear Station Solidification System. The system supplied by DOW, itself a retrofit of a urea formaldehyde system, was based upon use of 50 cubic foot containers (liners). ATCOR's retrofit increased liner capacity to 170 cubic feet and allowed in-cask solidification of highly radioactive material. This paper discusses the reasons for the decision to replace equipment within the originally furnished system and the development of the ATCOR plan to proof-test this equipment prior to delivery at the site. Results of this pre-testing, and a comparison between pre-tested conditions and the actual in-plan start-up tests are presented. Development of improved instrumentation and mechanical modifications which enhance the reliability of the ATCOR/DOW process In-container Mixing System was provided as a part of this project. Test results are presented on instruments, controls and the unique method of mechanical attachment of the Mixing Head to the solidification container

  1. Solidification of high temperature molten salts for thermal energy storage systems

    Science.gov (United States)

    Sheffield, J. W.

    1981-01-01

    The solidification of phase change materials for the high temperature thermal energy storage system of an advanced solar thermal power system has been examined theoretically. In light of the particular thermophysical properties of candidate phase change high temperature salts, such as the eutectic mixture of NaF - MgF2, the heat transfer characteristics of one-dimensional inward solidification for a cylindrical geometry have been studied. The Biot number for the solidified salt is shown to be the critical design parameter for constant extraction heat flux. A fin-on-fin design concept of heat transfer surface augmentation is proposed in an effort to minimize the effects of the salt's low thermal conductivity and large volume change upon fusing.

  2. Solidification microstructure development

    Indian Academy of Sciences (India)

    Unknown

    A majority of manufacturing processes involve melting and solidification of metals and ... In such a case (for example, chill casting), the solidification thickness (S) is ... (5). Here, LX is the system length scale in one dimension and DS is the solute diffusivity in solid. Thermal and solutal diffusivities are finite and usually very ...

  3. High-level waste solidification system for the Western New York Nuclear Service Center

    International Nuclear Information System (INIS)

    Carrell, J.R.; Holton, L.K.; Siemens, D.H.

    1982-01-01

    A preconceptual design for a waste conditioning and solidification system for the immobilization of the high-level liquid wastes (HLLW) stored at the Western New York Nuclear Service Center (WNYNSC), West Valley, New York was completed in 1981. The preconceptual design was conducted as part of the Department of Energy's (DOE) West Valley Demonstration Project, which requires a waste management demonstration at the WNYNSC. This paper summarizes the bases, assumptions, results and conclusions of the preconceptual design study

  4. A Real Time Investigation of Morphological Evolution During Solidification of Different Alloy Systems

    Science.gov (United States)

    Sen, S.; Kaukler, W. F.; Curreri, P. A.

    1999-01-01

    Solidification phenomenon which occur at the solid/liquid (s/I) interface play a major role in the determination of structure and hence the technologically important properties of a casting. However, metals being opaque, conclusions related to several important phenomenon such as boundary layer thickness, morphological evolution, and eutectic and cell spacing are deduced from quenching experiments and subsequent post solidification metallographic analysis. Consequently, limited information is obtained about the dynamics of the process. This paper will discuss the recent efforts at the Space Science Laboratory, NASA Marshall Space Flight Center, to view and quantify in-situ and in real time the dynamics of the solidification process and to measure interfacial undercooling. First, a high resolution x-ray transmission microscope (XTM) has been developed to monitor fundamental interfacial phenomena during directional solidification of metals and alloys. The XTM operates in the range of 10-100 KeV and through projection is capable of achieving magnification of up to 16OX. Secondly, an innovative collapsible furnace has been designed to quantify interfacial undercooling by measuring the temperature of a moving s/I interface in reference to a fixed s/l interface. This measurement technique is non-intrusive in nature and is based on the Seebeck principle. In this paper real time results obtained to characterize the dynamics of irregular eutectic spacing will be presented. As an example fiber to lamella or plate transition in the Al-Al2Au eutectic system will be discussed. Further, a resolution limit of 25 micron has permitted viewing in real time morphological instability and cellular growth in Al-Au and Al-Ag systems. Simultaneously, a systematic investigation has been carried out to measure interfacial undercooling for Pb-1 wt.% Sn at and near the marginal stability regime. In conjunction with the XTM observations this study attempts to validate existing relationships

  5. Solidification interface shape control in a continuous Czochralski silicon growth system

    Science.gov (United States)

    Wang, Chenlei; Zhang, Hui; Wang, Tihu; Zheng, Lili

    2006-01-01

    In a continuous Czochralski (CCZ) growth system with a shallow and replenished melt proposed earlier, large-diameter crystals may be grown at a high pull rate and reduced melt convection. The proposed system consists of two heaters. In this paper, the relationship between the solidification interface and the power levels is established. An interface control algorithm is developed to achieve the desired interface shape by adjusting the power level of the bottom heater. The control algorithm is incorporated into an existing process model, and the efficiency of the control algorithm is tested.

  6. Chemical radwaste solidification processes

    International Nuclear Information System (INIS)

    Malloy, C.W.

    1979-01-01

    Some of these processes and their problems are briefly reviewed: early cement systems; urea-formaldehyde; Dow solidification process; low-viscosity chemical agents (POLYPAC); and water-extensible polyester. 9 refs

  7. The modelling of heat, mass and solute transport in solidification systems

    Science.gov (United States)

    Voller, V. R.; Brent, A. D.; Prakash, C.

    1989-01-01

    The aim of this paper is to explore the range of possible one-phase models of binary alloy solidification. Starting from a general two-phase description, based on the two-fluid model, three limiting cases are identified which result in one-phase models of binary systems. Each of these models can be readily implemented in standard single phase flow numerical codes. Differences between predictions from these models are examined. In particular, the effects of the models on the predicted macro-segregation patterns are evaluated.

  8. Influence of additional heat exchanger block on directional solidification system for growing multi-crystalline silicon ingot - A simulation investigation

    Science.gov (United States)

    Nagarajan, S. G.; Srinivasan, M.; Aravinth, K.; Ramasamy, P.

    2018-04-01

    Transient simulation has been carried out for analyzing the heat transfer properties of Directional Solidification (DS) furnace. The simulation results revealed that the additional heat exchanger block under the bottom insulation on the DS furnace has enhanced the control of solidification of the silicon melt. Controlled Heat extraction rate during the solidification of silicon melt is requisite for growing good quality ingots which has been achieved by the additional heat exchanger block. As an additional heat exchanger block, the water circulating plate has been placed under the bottom insulation. The heat flux analysis of DS system and the temperature distribution studies of grown ingot confirm that the established additional heat exchanger block on the DS system gives additional benefit to the mc-Si ingot.

  9. Análise de modelos troposféricos no posicionamento baseado em redes usando o conceito de VRS

    Directory of Open Access Journals (Sweden)

    Adeliton Da Fonseca De Oliveira

    Full Text Available Nos últimos anos, várias técnicas de posicionamento GPS (Global Positioning System vêm sendo desenvolvidas e/ou aprimoradas com interesse de alcançar alta acurácia e produtividade em tempo real. O conceito de redes de estações de referência além de possibilitar aos usuários das comunidades civis e científicas qualidade e confiabilidade no posicionamento, permite estudos sobre a modelagem da refração troposférica na região da rede. Além disso, dentre as formas de transmissão das correções geradas pela rede ao usuário, destaca-se o conceito de VRS (Virtual Reference Station. Neste método, os dados de uma estação virtual são gerados nas proximidades do usuário, permitindo realizar posicionamento relativo em linhas de base curta com receptor de simples frequência. Neste artigo é descrita a metodologia para geração de dados da VRS com diferentes modelos troposféricos. Foram realizados testes comparativos nas quatro estações do ano com os modelos troposféricos de PNT/INPE (Previsão Numérica de Tempo/Instituto Nacional de Pesquisas Espaciais e Hopfield. Na análise de qualidade dos dados da VRS, o método PPP (Posicionamento por Ponto Preciso proporcionou resultados satisfatórios. Foram observadas melhorias entre os modelos de PNT/INPE e Hopfield de 9,75% e 24,2% em média para dias secos e úmidos, respectivamente.

  10. Solidification of liquid concentrate and solid waste generated as by-products of the liquid radwaste treatment systems in light-water reactors

    International Nuclear Information System (INIS)

    Neilson, R.M. Jr.; Colombo, P.

    1977-01-01

    The treatment of liquid concentrate and solid waste produced in light-water reactors as by-products of liquid radwaste treatment systems consists of five basic operations: waste collection, waste pretreatment, solidification agent handling, mixing/packaging (solidification) and waste package handling. This paper will concern itself primarily with the solidification operation, however, the other operations enumerated as well as the types of wastes treated and their origins will be briefly described, especially with regards to their effects on solidification. During solidification, liquid concentrate and solid wastes are incorporated with a solidification agent to form a monolithic, free-standing solid. The basic solidification agent types either currently used in the United States or proposed for use include absorbants, hydraulic cement, urea-formaldehyde, other polymer systems, and bitumen. The operation, formulations and limitations of these agents as used for radwaste solidification will be discussed. Properties relevant to the evaluation of solidified waste forms will be identified and relative comparisons made for wastes solidified by various processes

  11. Production-scale LLW and RMW solidification system operational testing at Argonne National Laboratory-East (ANL-E)

    International Nuclear Information System (INIS)

    Wescott, J.; Wagh, A.; Singh, D.; Nelson, R.; No, H.

    1997-01-01

    Argonne National Laboratory-East (ANL-E) has begun production-scale testing of a low-level waste and radioactive mixed waste solidification system. This system will be used to treat low-level and mixed radioactive waste to meet land burial requirements. The system can use any of several types of solidification media, including a chemically bonded phosphate ceramic developed by ANL-E scientists. The final waste product will consist of a solidified mass in a standard 208-liter drum. The system uses commercial equipment and incorporates several unique process control features to ensure proper treatment. This paper will discuss the waste types requiring treatment, the system configuration, and operation results for these waste streams

  12. A conceptual chemical solidification/stabilization system to remediate radioactive raffinate sludge

    International Nuclear Information System (INIS)

    Carpenter, D.J.; Ansted, J.P.; Foldyna, J.T.

    1994-01-01

    Past operations at the U.S. Department of Energy's (DOE) Weldon Spring, Missouri, Superfund Site included the manufacture of nitroaromatic-based munitions and the production of uranium and thorium metal from ore concentrates. These operations generated a large quantity of diverse contaminated waste media including raffinate sludge, soil, sediment, and building debris. These various waste media are contaminated with varying amounts of radionuclides nitroaromatics, metals, metalloids, non-metals, polychlorinated biphenyls (PCBs) and asbestos. The volumes and diversity of contaminants and waste media pose significant challenges in identifying applicable remedial technologies, particularly for the excavation and treatment of the water-rich raffinate sludge. This paper presents the results of comprehensive efforts to develop a conceptual chemical solidification/stabilization (CSS) system to treat a variety of waste media. The emphasis of this paper is the treatment of a water-rich refractory raffinate sludge and site contaminated soils both radioactive and nonradioactive. The conceptual system design includes raffinate sludge excavation, dewatering, and CSS processing (reagent selection and formulation, reagent and waste storage and metering, and product mixing). Many innovations were incorporated into the design, producing a system that can process the various waste types. Additionally, the radioactive and hazardous constituents are sufficiently immobilized to allow the secured disposal in a waste cell of the treated product. The conceptual CSS system can also produce a variety of treated product types, ranging from a monolithic form to a compactible soil-like medium. The advantages of this system flexibility are also presented

  13. Low-level radwaste solidification

    International Nuclear Information System (INIS)

    Naughton, M.D.; Miller, C.C.; Nelson, R.A.; Tucker, R.F.

    1983-01-01

    This paper reports on a study of ''Advanced Low-Level Radioactive Waste Treatment Systems'' conducted under an EPRI contract. The object of the study is to identify advanced lowlevel radwaste treatment systems that are commercially available or are expected to be in the near future. The current state-ofthe-art in radwaste solidification technology is presented. Related processing technologies, such as the compaction of dry active waste (DAW), containers available for radwaste disposal, and the regulatory aspects of radwaste transportation and solidification, are described. The chemical and physical properties of the currently acceptable solidification agents, as identified in the Barnwell radwaste burial site license, are examined. The solidification agents investigated are hydraulic cements, thermoplastic polymers, and thermosetting polymers. It is concluded that solidification processes are complex and depend not only on the chemical and physical properties of the binder material and the waste, but also on how these materials are mixed

  14. Evaluating the Correctness of Airborne Laser Scanning Data Heights Using Vehicle-Based RTK and VRS GPS Observations

    Directory of Open Access Journals (Sweden)

    Martin Vermeer

    2011-08-01

    Full Text Available In this study, we describe a system in which a GPS receiver mounted on the roof of a car is used to provide reference information to evaluate the elevation accuracy and georeferencing of airborne laser scanning (ALS point clouds. The concept was evaluated in the Klaukkala test area where a number of roads were traversed to collect real-time kinematic data. Two test cases were evaluated, including one case using the real-time kinematic (RTK method with a dedicated GPS base station at a known benchmark in the area and another case using the GNSSnet virtual reference station service (VRS. The utility of both GPS methods was confirmed. When all test data were included, the mean difference between ALS data and GPS-based observations was −2.4 cm for both RTK and VRS GPS cases. The corresponding dispersions were ±4.5 cm and ±5.9 cm, respectively. In addition, our examination did not reveal the presence of any significant rotation between ALS and GPS data.

  15. Solidification method of radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Tsutomu; Chino, Koichi; Sasahira, Akira; Ikeda, Takashi

    1992-07-24

    Metal solidification material can completely seal radioactive wastes and it has high sealing effect even if a trace amount of evaporation should be caused. In addition, the solidification operation can be conducted safely by using a metal having a melting point of lower than that of the decomposition temperature of the radioactive wastes. Further, the radioactive wastes having a possibility of evaporation and scattering along with oxidation can be solidified in a stable form by putting the solidification system under an inert gas atmosphere. Then in the present invention, a metal is selected as a solidification material for radioactive wastes, and a metal, for example, lead or tin having a melting point of lower than that of the decomposition temperature of the wastes is used in order to prevent the release of the wastes during the solidification operation. Radioactive wastes which are unstable in air and scatter easily, for example, Ru or the like can be converted into a stable solidification product by conducting the solidification processing under an inert gas atmosphere. (T.M.).

  16. Design of DGPS Receiver Based on the Net of VRS

    Directory of Open Access Journals (Sweden)

    Yun XU

    2014-02-01

    Full Text Available To improve the positioning accuracy of the GPS system, the differential technology based on real time kinematic is utilized. Comparing with the conventional differential technology, the differential technology based on the virtual reference station can minimize the size of the rover station which is of great significance for the small system such as the mini-type unmanned vehicle, smart ammunitions and so on. Due to the high cost of the GPS receivers in the market which can’t be redeveloped and the limitation of their interface, it is not suitable for the application of the embedded system. In this paper, the receiver based on the aforementioned method is proposed to realize the real time differential positioning. Firstly, the concept of differential positioning based on real time kinematic is explained. Next, the composition of the virtual reference system and its working principle are introduced. And then, the design of differential GPS receiver based on the virtual reference system for rover station is illustrated. Finally, from the repeatability test, the result shows that by means of getting the differential corrections from the virtual reference station, the designed differential GPS receiver can correct the errors caused by ionosphere, troposphere and atmospheric refraction. Moreover, it can improve the positioning accuracy to centimeter-level. With low cost, small size and convertibility of the interface of the designed differential GPS receiver according to the embedded system, it will be popular in the future market.

  17. Self-consistent theory of steady-state lamellar solidification in binary eutectic systems

    International Nuclear Information System (INIS)

    Nash, G.E.; Glicksman, M.E.

    1976-01-01

    The potential theoretic methods developed recently at NRL for solving the diffusion equation are applied to the free-boundary problem describing lamellar eutectic solidification. Using these techniques, the original boundary value problem is reduced to a set of coupled integro-differential equations for the shape of the solid/liquid interface and various quantities defined on the interface. The behavior of the solutions is discussed in a qualitative fashion, leading to some interesting inferences regarding the nature of the eutectic solidification process. Using the information obtained from the analysis referred to above, an approximate theory of the lamellar-rod transition is formulated. The predictions of the theory are shown to be in qualitative agreement with experimental observations of this transition. In addition, a simplified version of the general integro-differential equations is developed and is used to assess the effect of interface curvature on the interfacial solute concentrations, and to check the new theory for consistency with experiment

  18. Thermodynamic description of the Al-Cu-Mg-Mn-Si quinary system and its application to solidification simulation

    International Nuclear Information System (INIS)

    Chang, Keke; Liu, Shuhong; Zhao, Dongdong; Du, Yong; Zhou, Liangcai; Chen, Li

    2011-01-01

    By means of the first-principles calculations, the enthalpy of formation for the quaternary phase in the Al-Cu-Mg-Si system was computed. A set of self-consistent thermodynamic parameters for the Al-Cu-Mg-Si and Al-Cu-Mn-Si systems was then obtained using CALPHAD approach taking into account the reliable experimental data and the first-principles calculations. The thermodynamic database for the Al-Cu-Mg-Mn-Si system was developed based on the constituent binary, ternary, and quaternary systems. Comprehensive comparisons between the calculated and measured phase diagrams and invariant reactions showed that the experimental information was satisfactorily accounted for by the present thermodynamic description. The obtained database was used to describe the solidification behavior of Al alloys B319.1 (90.2Al-6Si-3.5Cu-0.3Mg, in wt.%) and B319.1 + xMn (x = 0.5-2, in wt.%) under Gulliver-Scheil non-equilibrium condition. The reliability of the present thermodynamic database was also verified by the good agreement between calculation and experiment for Gulliver-Scheil non-equilibrium solidification.

  19. Solidification paths of multicomponent monotectic aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mirkovic, Djordje; Groebner, Joachim [Clausthal University of Technology, Institute of Metallurgy, Robert-Koch-Street 42, D-38678 Clausthal-Zellerfeld (Germany); Schmid-Fetzer, Rainer [Clausthal University of Technology, Institute of Metallurgy, Robert-Koch-Street 42, D-38678 Clausthal-Zellerfeld (Germany)], E-mail: schmid-fetzer@tu-clausthal.de

    2008-10-15

    Solidification paths of three ternary monotectic alloy systems, Al-Bi-Zn, Al-Sn-Cu and Al-Bi-Cu, are studied using thermodynamic calculations, both for the pertinent phase diagrams and also for specific details concerning the solidification of selected alloy compositions. The coupled composition variation in two different liquids is quantitatively given. Various ternary monotectic four-phase reactions are encountered during solidification, as opposed to the simple binary monotectic, L' {yields} L'' + solid. These intricacies are reflected in the solidification microstructures, as demonstrated for these three aluminum alloy systems, selected in view of their distinctive features. This examination of solidification paths and microstructure formation may be relevant for advanced solidification processing of multicomponent monotectic alloys.

  20. Characterization for solidification and phase transformations of pure-titanium steel weld metal with time-resolved X-ray diffraction system

    International Nuclear Information System (INIS)

    Terasaki, Hidenori; Komizo, Yu-ichi; Nishino, Fumihiro; Ikeda, Masahiko

    2007-01-01

    Understanding and controlling solidification and phase transformation process of weld metal is essential for forming the microstructure with superior mechanical property. Recent evolution of analysis technique makes for solidification and phase transformation process to be in-situ analyzed, in direct and reciprocal lattice space. In the present work, unidirectional-solidification and phase transformation in the weld metal of commercial pure-titanium in Gas Tungsten Arc welding was in-situ observed by using Time-Resolved X-Ray Diffraction system with two-dimensional pixel detector. An undulator beam was used as a probe. Larger diffraction area could be detected in the time-resolution of 0.05 seconds, in unidirectional solidification and subsequent phase transformation process of pure-titanium weld metal. Furthermore, the microstructure formation during β-α phase transformation was in situ observed with High temperature Laser Scanning Confocal Microscopy. The crystal configurations in unidirectional solidification of weld metal and rapid change of phase ratio in reconstructive phase transformation were clearly analyzed. (author)

  1. β-phase melting and solidification phenomena in the niobium-hydrogen system

    International Nuclear Information System (INIS)

    Schober, T.; Linke, U.; Wenzl, H.

    1975-01-01

    The morphology of the decomposition and formation (or the melting and solidifcation in the lattice gas description) of the ordered NbH β-phase is investigated with polarized light and interference contrast techniques. Melting occurs in the absence of temperature gradients by the growth of droplets of the liquid phase α' nucleated at the domain boundaries. Solidification of the α'-phase involves the formation of single-domain β-phase plates, subsequent repeated twinning and the growth of 'elastic closure domains'. The solidus and liquidus lines of the α → α' transformation are determined in the range from 70 to 95 at. %H/Nb where the transition temperatures vary from 84 0 C (triple line of α-, α'- and β-phase) to 145 0 C. (orig.) [de

  2. Pattern selection in single-component systems coupling Benard convection and solidification

    International Nuclear Information System (INIS)

    Davis, S.H.; Mueller, U.; Dietsche, C.

    1983-12-01

    A horizontal layer is heated from below and cooled from above so that the enclosed single-component liquid is frozen in the upper part of the layer. When the imposed temperature difference is such that the Rayleigh number across the liquid is supercritical, there is Benard convection coupled with the dynamics of the solidification interface. An experiment is presented which shows that the interfacial corrugations that result are two-dimensional when this ''ice'' is thin but hexagonal when the ''ice'' is thick. A weakly-nonlinear convective instability theory is presented which explains this behavior, and isolates the mechanism of the pattern selection. Jump behavior is seen in the liquid-layer thickness at the onset of hexagonal convection. (orig.) [de

  3. Accelerating solidification process simulation for large-sized system of liquid metal atoms using GPU with CUDA

    Energy Technology Data Exchange (ETDEWEB)

    Jie, Liang [School of Information Science and Engineering, Hunan University, Changshang, 410082 (China); Li, KenLi, E-mail: lkl@hnu.edu.cn [School of Information Science and Engineering, Hunan University, Changshang, 410082 (China); National Supercomputing Center in Changsha, 410082 (China); Shi, Lin [School of Information Science and Engineering, Hunan University, Changshang, 410082 (China); Liu, RangSu [School of Physics and Micro Electronic, Hunan University, Changshang, 410082 (China); Mei, Jing [School of Information Science and Engineering, Hunan University, Changshang, 410082 (China)

    2014-01-15

    Molecular dynamics simulation is a powerful tool to simulate and analyze complex physical processes and phenomena at atomic characteristic for predicting the natural time-evolution of a system of atoms. Precise simulation of physical processes has strong requirements both in the simulation size and computing timescale. Therefore, finding available computing resources is crucial to accelerate computation. However, a tremendous computational resource (GPGPU) are recently being utilized for general purpose computing due to its high performance of floating-point arithmetic operation, wide memory bandwidth and enhanced programmability. As for the most time-consuming component in MD simulation calculation during the case of studying liquid metal solidification processes, this paper presents a fine-grained spatial decomposition method to accelerate the computation of update of neighbor lists and interaction force calculation by take advantage of modern graphics processors units (GPU), enlarging the scale of the simulation system to a simulation system involving 10 000 000 atoms. In addition, a number of evaluations and tests, ranging from executions on different precision enabled-CUDA versions, over various types of GPU (NVIDIA 480GTX, 580GTX and M2050) to CPU clusters with different number of CPU cores are discussed. The experimental results demonstrate that GPU-based calculations are typically 9∼11 times faster than the corresponding sequential execution and approximately 1.5∼2 times faster than 16 CPU cores clusters implementations. On the basis of the simulated results, the comparisons between the theoretical results and the experimental ones are executed, and the good agreement between the two and more complete and larger cluster structures in the actual macroscopic materials are observed. Moreover, different nucleation and evolution mechanism of nano-clusters and nano-crystals formed in the processes of metal solidification is observed with large

  4. General characteristics of eutectic alloy solidification mechanisms

    International Nuclear Information System (INIS)

    Lemaignan, Clement.

    1977-01-01

    The eutectic alloy sodification was studied in binary systems: solidification of non facetted - non facetted eutectic alloy (theoretical aspects, variation of the lamellar spacing, crystallographic relation between the various phases); solidification of facetted - non facetted eutectic alloy; coupled growth out of eutectic alloy; eutectic nucleation [fr

  5. Solidification of metal chloride waste from pyrochemical process via dechlorination-chlorination reaction system

    Energy Technology Data Exchange (ETDEWEB)

    Park, H.S.; Cho, I.H.; Lee, K.R.; Choi, J.H.; Eun, H.C.; Kim, I.T.; Park, G.I. [Korea Atomic Energy Research Inst., Deajeon (Korea, Republic of)

    2014-07-01

    The metal chloride wastes generated from the pyro-chemical process to recover uranium and TRUs has been considered as a problematic waste due to the high volatility and low compatibility with conventional silicate glass. Our research group has suggested the dechlorination approach for the solidification of this kind of waste by using a synthetic composite, SAP (SiO{sub 2}-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5}). During the dechlorination, metal elements are chemically interacted with the inorganic composite, SAP, while chlorine is vaporized as gaseous chlorine. Metal elements in the salt were immobilized into phosphate and silicate glass which are uniformly distributed in tens of nm scale. During the dechlorination, gaseous chlorine is captured by Li{sub 2}O-Li{sub 2}O{sub 2} composite that can be converted into metal chloride (LiCl). About 98wt% of oxide composite was converted into LiCl that can be used as an electrolyte in the electrochemical process. The method suggested in this study can provide a chance to minimize the waste volume for the final disposal of salt wastes from a pyro-chemical process. (author)

  6. Radioactive gas solidification apparatus

    International Nuclear Information System (INIS)

    Kobayashi, Yoshihiro; Seki, Eiji; Yabu, Tomohiko; Matsunaga, Hiroyuki.

    1990-01-01

    Handling of a solidification container from the completion for the solidifying processing to the storage of radioactive gases by a remote control equipment such as a manipulator requires a great cost and is difficult to realize. In a radioactive gas solidification device for injection and solidification in accumulated layers of sputtered metals by glow discharge, radiation shieldings are disposed surrounding the entire container, and cooling water is supplied to a cooling vessel formed between the container and the shielding materials. The shielding materials are divided into upper and lower shielding materials, so that solidification container can be taken out from the shielding materials. As a result, the solidification container after the solidification of radioactive gases can be handled with ease. Further, after-heat can be removed effectively from the ion injection electrode upon solidifying treatment upon storage, to attain a radioactive gas solidifying processing apparatus which is safe, economical and highly reliable. (N.H.)

  7. 77 FR 30546 - Notice of Proposed Information Collection: Comment Request; Form HUD-40221(rev) “LOCCS/VRS Self...

    Science.gov (United States)

    2012-05-23

    ... Program Payment Voucher'' AGENCY: Office of the Assistant Secretary for Community Planning and Development... must complete a ``LOCCS/VRS Self-help Homeownership Opportunity Program Payment Voucher'' prior to...-help Homeownership Opportunity Program Payment Voucher''. OMB Control Number: 2506-0157. Description of...

  8. Fundamental Metallurgy of Solidification

    DEFF Research Database (Denmark)

    Tiedje, Niels

    2004-01-01

    The text takes the reader through some fundamental aspects of solidification, with focus on understanding the basic physics that govern solidification in casting and welding. It is described how the first solid is formed and which factors affect nucleation. It is described how crystals grow from...

  9. Development of a hybrid genetic algorithm based decision support system for vehicle routing and scheduling in supply chain logistics managment

    OpenAIRE

    Khanian, Seyed Mohammad Shafi

    2007-01-01

    Vehicle Routing and Scheduling (VRS) constitute an important part of logistics management. Given the fact that the worldwide cost on physical distribution is evermore increasing, the global competition and the complex nature of logistics problems, one area, which determines the efficiency of all others, is the VRS activities. The application of Decision Support Systems (DSS) to assist logistics management with an efficient VRS could be of great benefit. Although the benefits of DSS in VRS are...

  10. Integrated System of Thermal/Dimensional Analysis for Quality Control of Metallic Melt and Ductile Iron Casting Solidification

    Science.gov (United States)

    Stan, Stelian; Chisamera, Mihai; Riposan, Iulian; Neacsu, Loredana; Cojocaru, Ana Maria; Stan, Iuliana

    2018-03-01

    The main objective of the present work is to introduce a specific experimental instrument and technique for simultaneously evaluating cooling curves and expansion or contraction of cast metals during solidification. Contraction/expansion analysis illustrates the solidification parameters progression, according to the molten cast iron characteristics, which are dependent on the melting procedure and applied metallurgical treatments, mold media rigidity and thermal behavior [heat transfer parameters]. The first part of the paper summarizes the performance of this two-mold device. Its function is illustrated by representative shrinkage tendency results in ductile cast iron as affected by mold rigidity (green sand and furan resin sand molds) and inoculant type (FeSi-based alloys), published in part previously. The second part of the paper illustrates an application of this equipment adapted for commercial foundry use. It conducts thermal analysis and volume change measurements in a single ceramic cup so that mold media as well as solidification conditions are constants, with cast iron quality as the variable. Experiments compared gray and ductile cast iron solidification patterns. Gray iron castings are characterized by higher undercooling at the beginning and at the end of solidification and lower graphitic expansion. Typically, ductile cast iron exhibits higher graphitic, initial expansion, conducive for shrinkage formation in soft molds.

  11. Fluid bed dryer and Aeropep solidification system. Amendment 1 to topical report

    International Nuclear Information System (INIS)

    1975-01-01

    Information is presented on interfaces between the aerojet fluid bed dryer and the liquid radwaste system, plant ventilation system, and radioactive solid waste handling system for BWR and PWR type reactors. (U.S.)

  12. Advances in Solidification Processing

    Directory of Open Access Journals (Sweden)

    Hugo F. Lopez

    2015-08-01

    Full Text Available Melt solidification is the shortest and most viable route to obtain components, starting from the design to the finished products. Hence, a sound knowledge of the solidification of metallic materials is essential for the development of advanced structural metallic components that drive modern technological societies. As a result, there have been innumerable efforts and full conferences dedicated to this important subject [1–6]. In addition, there are various scientific journals fully devoted to investigating the various aspects which give rise to various solidification microstructures [7–9]. [...

  13. Micro-scale thermocapillary convection with solidification

    International Nuclear Information System (INIS)

    Yang, W.J.; Liu, J.C.; Chai, A.T.

    1991-01-01

    This paper reports on an experimental study performed on heat transfer in sessile drops of lysozyme solutions with solidification. Solidification inside the sessile drop is initiated by means of the center cooling method. The internal flow behavior and solidification front movement are observed using a microscope-video monitor system. Results are obtained for lysozyme, and buffer solutions, and water, representing media possessing surface tension coefficients. It is disclosed that the time history of the solidification front movement can be divided into two stages; initial and stable. In the stable stage, the front movement x follows the power-law behavior x = Ct n . C is an empirical constant, and t denotes time. The exponent n takes on a value close to unity in the stable stage

  14. Solidification and casting

    CERN Document Server

    Cantor, Brian

    2002-01-01

    INDUSTRIAL PERSPECTIVEDirect chillcasting of aluminium alloysContinuous casting of aluminium alloysContinuous casting of steelsCastings in the automotive industryCast aluminium-silicon piston alloysMODELLING AND SIMULATIONModelling direct chill castingMold filling simulation of die castingThe ten casting rulesGrain selection in single crystal superalloy castingsDefects in aluminium shape castingPattern formation during solidificationPeritectic solidificationSTRUCTURE AND DEFECTSHetergeneous nucleation in aluminium alloysCo

  15. Physico-mechanical properties of naphthalene-acenaphthene eutectic system by different modes of solidification

    International Nuclear Information System (INIS)

    Sharma, B.L.; Gupta, S.; Tandon, S.; Kant, R.

    2008-01-01

    Anisotropic crystal growth kinetics from compositional melts encompassing the entire naphthalene-acenaphthene eutectic system, evidentially, evinces the dislocation mechanism. Rheological properties of eutectic phase melts at different temperatures explore the occurrence of molecular interactions emanating molecular clusters, rich in one phase or the other, in the eutectic melt. Microscopic studies confirm the crystalline faceted-faceted structure of the naphthalene-acenaphthene eutectic system. Implicit in the present work is the concept of strength-growth relationship that follows an identical form of the Weibull probability distribution curve. The curve exhibits two cut-off points corresponding to a lower strength limit in the slow and fast growth regions, and an upper strength limit in the moderate growth region. Relational essence between microstructural parameters essentially structuring morphology and excess thermodynamic functions implicitly governing molten state of the naphthalene-acenaphthene eutectic system is extracted

  16. Inspection method for solidification product of radioactive waste and method of preparing solidification product of radiation waste

    International Nuclear Information System (INIS)

    Izumida, Tatsuo; Tamada, Shin; Matsuda, Masami; Kamata, Shoji; Kikuchi, Makoto.

    1993-01-01

    A powerful X-ray generation device using an electron-ray accelerator is used for inspecting presence or absence of inner voids in solidification products of radioactive wastes during or after solidification. By installing the X-ray CT system and the radioactive waste solidifying facility together, CT imaging for solidification products is conducted in a not-yet cured state of solidifying materials during or just after the injection. If a defect that deteriorates the durability of the solidification products should be detected, the solidification products are repaired, for example, by applying vibrations to the not-yet cured solidification products. Thus, since voids or cracks in the radioactive wastes solidification products, which were difficult to be measured so far, can be measured in a short period of time accurately thereby enabling to judge adaptability to the disposal standards, inspection cost for the radioactive waste solidification product can be saved remarkably. Further, the inside of the radioactive waste solidification products can be evaluated correctly and visually, so that safety in the ground disposal storage of the radioactive solidification products can be improved remarkably. (N.H.)

  17. Parametric study of ternary ettringite-based systems for radwaste solidification and stabilization

    International Nuclear Information System (INIS)

    Martin, I.; Patapy, C.; Cyr, M.; Boher, C.; Avril, D.

    2015-01-01

    Currently, there is a demand in furthering technological solutions to embed radioactive waste. A kind of this waste produced during the reprocessing of nuclear fuel is characterized by high pH sensitivity. Some organic matrixes (e.g. bitumen) developed to condition this waste are currently reconsidered by nuclear safety regulators. Therefore the cementation in ettringite systems might be a promising solution to solidify and stabilize this radioactive waste. Calcium Aluminate Cement (CAC) are planned to be used, instead of Ordinary Portland Cement (OPC), to form a significant amount of ettringite able to catch water molecules when forming. Moreover, due to the low pH of CAC-based matrixes, the latter have a good compatibility with the compounds used to stabilize active elements. However, the heat generated by hydration and the chemistry of waste require additional components. This paper details the investigations carried out on the CAC systems combined with Supplementary Cementing Materials. First theoretical studies show the main characteristics of reaction for the blends - especially: kinetics and type of hydrates formed, pH and chemistry of pore solution. Formulations are optimized to be in accordance with the stability of high pH sensitivity radioactive waste. Thereafter, parametric experiments including simulated waste are realized to study the rheological and the heat properties of the mixes. It appears that an increase in sulfate content ensures the formation and stability of ettringite and can greatly decrease the pH of pore solutions due to the formation of ettringite/AH 3 in a larger extent. Results show that increasing slag content in the CAC system reduces the heat generated during hydration and that the addition of quartz filler in simulated wastes has increased the nucleation surface

  18. Sufficient condition for generation of multiple solidification front in one-dimensional solidification of binary alloys

    International Nuclear Information System (INIS)

    Bobula, E.; Kalicka, Z.

    1981-10-01

    In the paper we consider the one-dimensional solidification of binary alloys in the finite system. The authors present the sufficient condition for solidification in the liquid in front of the moving solid-liquid interface. The effect may produce a fluctuating concentration distributin in the solid. The convection in the liquid and supercooling required for homogeneous nucleation are omitted. A local-equilibrium approximation at the liquid-solid interface is supposed. (author)

  19. Radioactive waste solidification material

    International Nuclear Information System (INIS)

    Nishihara, Yukio; Wakuta, Kuniharu; Ishizaki, Kanjiro; Koyanagi, Naoaki; Sakamoto, Hiroyuki; Uchida, Ikuo.

    1992-01-01

    The present invention concerns a radioactive waste solidification material containing vermiculite cement used for a vacuum packing type waste processing device, which contains no residue of calcium hydroxide in cement solidification products. No residue of calcium hydroxide means, for example, that peak of Ca(OH) 2 is not recognized in an X ray diffraction device. With such procedures, since calcium sulfoaluminate clinker and Portland cement themselves exhibit water hardening property, and slugs exhibit hydration activity from the early stage, the cement exhibits quick-hardening property, has great extension of long term strength, further, has no shrinking property, less dry- shrinkage, excellent durability, less causing damages such as cracks and peeling as processing products of radioactive wastes, enabling to attain highly safe solidification product. (T.M.)

  20. Polymer solidification national program

    International Nuclear Information System (INIS)

    Kalb, P.D.; Colombo, P.

    1993-04-01

    Brookhaven National Laboratory (BNL) has developed several new and innovative polymer processes for the solidification of low-level radioactive, hazardous and mixed wastes streams. Polyethylene and modified sulfur cement solidification technologies have undergone steady, gradual development at BNL over the past nine years. During this time they have progressed through each of the stages necessary for logical technology maturation: from process conception, parameter optimization, waste form testing, evaluation of long-term durability, economic analysis, and scale-up feasibility. This technology development represents a significant investment which can potentially provide DOE with both short- and long-term savings

  1. Radioactive gas solidification treatment device

    International Nuclear Information System (INIS)

    Igarashi, Ryokichi; Watanabe, Yu; Seki, Eiji.

    1992-01-01

    In a radioactive gas solidification treatment device by using sputtering, spiral pipelines are disposed with a gap therebetween for cooling an ion injection electrode by passing cooling water during operation of the solidification treatment. During the operation of the solidification treatment, cooling water is passed in the pipelines to cool the ion injection electrode. During storage, a solidification vessel is cooled by natural heat dissipation from an exposed portion at the surface of the solidification vessel. Accordingly, after-heat of radioactive gas solidified in a metal accumulation layer can be removed efficiently, safely and economically to improve the reliability. (N.H.)

  2. Thermosolutal convection during dendritic solidification

    Science.gov (United States)

    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.

  3. Enthalpies of a binary alloy during solidification

    Science.gov (United States)

    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.

  4. Experimental and thermodynamic assessments of substitutions in the AlFeSi, FeMnSi, FeSiZr and AlCaFeSi systems (65 wt % Si) - solidification simulation

    International Nuclear Information System (INIS)

    Gueneau, C.; Ansara, I.

    1994-01-01

    The substitutions of Al Si, Fe Mn and Fe Zr in some intermetallic compounds of the Al-Fe-Si, Fe-Mn-Si and Fe-Si-Zr systems are modelled in the Si-rich corner using a two sublattice model. The solidification paths of the studied alloys are determined at equilibrium. The ascalculated phase volume fractions of the alloys are compared to the experimental ones. Finally, a solidification simulation using the Gulliver-Scheil's model is performed in order to explain the formation of some precipitates experimentally observed. (authors). 14 figs., 19 refs

  5. Nuclear waste solidification

    Science.gov (United States)

    Bjorklund, William J.

    1977-01-01

    High level liquid waste solidification is achieved on a continuous basis by atomizing the liquid waste and introducing the atomized liquid waste into a reaction chamber including a fluidized, heated inert bed to effect calcination of the atomized waste and removal of the calcined waste by overflow removal and by attrition and elutriation from the reaction chamber, and feeding additional inert bed particles to the fluidized bed to maintain the inert bed composition.

  6. Nuclear waste solidification

    International Nuclear Information System (INIS)

    Bjorklund, W.J.

    1977-01-01

    High level liquid waste solidification is achieved on a continuous basis by atomizing the liquid waste and introducing the atomized liquid waste into a reaction chamber including a fluidized, heated inert bed to effect calcination of the atomized waste and removal of the calcined waste by overflow removal and by attrition and elutriation from the reaction chamber, and feeding additional inert bed particles to the fluidized bed to maintain the inert bed composition

  7. Microwave solidification project overview

    Energy Technology Data Exchange (ETDEWEB)

    Sprenger, G.

    1993-01-01

    The Rocky Flats Plant Microwave Solidification Project has application potential to the Mixed Waste Treatment Project and the The Mixed Waste Integrated Program. The technical areas being addressed include (1) waste destruction and stabilization; (2) final waste form; and (3) front-end waste handling and feed preparation. This document covers need for such a program; technology description; significance; regulatory requirements; and accomplishments to date. A list of significant reports published under this project is included.

  8. Microwave solidification project overview

    International Nuclear Information System (INIS)

    Sprenger, G.

    1993-01-01

    The Rocky Flats Plant Microwave Solidification Project has application potential to the Mixed Waste Treatment Project and the The Mixed Waste Integrated Program. The technical areas being addressed include (1) waste destruction and stabilization; (2) final waste form; and (3) front-end waste handling and feed preparation. This document covers need for such a program; technology description; significance; regulatory requirements; and accomplishments to date. A list of significant reports published under this project is included

  9. Advanced modeling of solidification

    International Nuclear Information System (INIS)

    Bousquet-Melou, P.; Fichot, F.; Goyeau, B.; Gobin, D.; Quintard, M.

    2001-01-01

    A theoretical and numerical macroscopic modeling of the solidification of binary mixtures is presented. The growth of a solid-liquid region (mushy zone), represented by a non-homogeneous porous medium, is considered. A macroscopic model for momentum, heat and mass transfer during solidification is derived using the volume averaging method, and the effective transport properties (permeability, effective diffusivities, mass exchange coefficients) are defined by associated closure problems (set of microscopic balance equations). Consequently, the effects of the dendritic geometry (tortuosity) and of microscopic transfer phenomena (dispersion, interfacial exchange) are introduced in the averaged balance equations and in the representation of the effective transport coefficients. This closure method provides an original approach of solidification modeling. The resulting macroscopic model is based on the local thermal equilibrium assumption (one-temperature model) while a two-phase description of macroscopic species transfer is introduced using solid and liquid mass exchange coefficients. The phase diagram is used to predict the solid and liquid equilibrium concentrations at the solid-liquid interface. This two-phase approach extends the classical limiting cases that correspond to the lever-rule and Scheil descriptions. (authors)

  10. The solidification behaviour of the UO{sub 2}–ThO{sub 2} system in a laser heating study

    Energy Technology Data Exchange (ETDEWEB)

    Böhler, R. [European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany); Delft University of Technology, Faculty of Applied Sciences, Department of Radiation Science and Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Quaini, A. [Politecnico di Milano, Department of Energy, Enrico Fermi Center for Nuclear Studies (CeSNEF), via La Masa 34, 20156 Milano (Italy); Capriotti, L. [Politecnico di Milano, Department of Energy, Enrico Fermi Center for Nuclear Studies (CeSNEF), via La Masa 34, 20156 Milano (Italy); European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany); Çakır, P. [Ege Univerity, Institute of Nuclear Sciences, 35100 Bornova Izmir (Turkey); European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany); Beneš, O.; Boboridis, K.; Guiot, A. [European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany); Luzzi, L. [Politecnico di Milano, Department of Energy, Enrico Fermi Center for Nuclear Studies (CeSNEF), via La Masa 34, 20156 Milano (Italy); Konings, R.J.M. [European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany); Manara, D., E-mail: dario.manara@ec.europa.eu [European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany)

    2014-12-15

    Highlights: • Melting of the full UO{sub 2}–ThO{sub 2} system was studied by laser heating. • A minimum melting point was found around 5 mol% ThO{sub 2} and T = 3098 K. • Ideal solution behaviour near melting was observed for compositions richer in ThO{sub 2}. • These compounds were also studied by Raman spectroscopy before and after melting. - Abstract: The high-temperature phase diagram of the UO{sub 2}–ThO{sub 2} system has been experimentally revisited in the present study for the first time since 1970, using a laser heating approach combined with fast pyrometry in a thermal arrest method. The melting/solidification temperature, which is of fundamental information for a reactor design was studied here. It was found that low addition of ThO{sub 2} to UO{sub 2} would result in a slight decrease of the solidification temperature. A minimum was found at 3098 K around a composition of 5 mol% ThO{sub 2}. The solid/liquid transition temperature was then observed to increase again with increasing ThO{sub 2} fraction. The literature value of pure ThO{sub 2} (around 3630 K) was well reproduced here. Important experimental difficulties, stemming from the high temperatures reached during the measurements, as well as a complete investigation with electron microscopy, Raman spectroscopy and powder X-ray diffraction, are extensively discussed. These results show the importance of the high-temperature oxygen chemistry in this actinide oxide compound.

  11. Solidification process for sludge residue

    International Nuclear Information System (INIS)

    Pearce, K.L.

    1998-01-01

    This report investigates the solidification process used at 100-N Basin to solidify the N Basin sediment and assesses the N Basin process for application to the K Basin sludge residue material. This report also includes a discussion of a solidification process for stabilizing filters. The solidified matrix must be compatible with the Environmental Remediation Disposal Facility acceptance criteria

  12. Plastic solidification of radioactive wastes

    International Nuclear Information System (INIS)

    Moriyama, Noboru

    1981-01-01

    Over 20 years have elapsed after the start of nuclear power development, and the nuclear power generation in Japan now exceeds the level of 10,000 MW. In order to meet the energy demands, the problem of the treatment and disposal of radioactive wastes produced in nuclear power stations must be solved. The purpose of the plastic solidification of such wastes is to immobilize the contained radionuclides, same as other solidification methods, to provide the first barrier against their move into the environment. The following matters are described: the nuclear power generation in Japan, the radioactive wastes from LWR plants, the position of plastic solidification, the status of plastic solidification in overseas countries and in Japan, the solidification process for radioactive wastes with polyethylene, and the properties of solidified products, and the leachability of radionuclides in asphalt solids. (J.P.N.)

  13. Microwave solidification development for Rocky Flats waste

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, D.; Erle, R.; Eschen, V. [and others

    1994-04-01

    The Microwave Engineering Team at the Rocky Flats Plant has developed a production-scale system for the treatment of hazardous, radioactive, and mixed wastes using microwave energy. The system produces a vitreous final form which meets the acceptance criteria for shipment and disposal. The technology also has potential for application on various other waste streams from the public and private sectors. Technology transfer opportunities are being identified and pursued for commercialization of the microwave solidification technology.

  14. Microwave solidification development for Rocky Flats waste

    International Nuclear Information System (INIS)

    Dixon, D.; Erle, R.; Eschen, V.

    1994-04-01

    The Microwave Engineering Team at the Rocky Flats Plant has developed a production-scale system for the treatment of hazardous, radioactive, and mixed wastes using microwave energy. The system produces a vitreous final form which meets the acceptance criteria for shipment and disposal. The technology also has potential for application on various other waste streams from the public and private sectors. Technology transfer opportunities are being identified and pursued for commercialization of the microwave solidification technology

  15. Rock solidification method

    International Nuclear Information System (INIS)

    Nakaya, Iwao; Murakami, Tadashi; Miyake, Takafumi; Funakoshi, Toshio; Inagaki, Yuzo; Hashimoto, Yasuhide.

    1985-01-01

    Purpose: To convert radioactive wastes into the final state for storage (artificial rocks) in a short period of time. Method: Radioactive burnable wastes such as spent papers, cloths and oils and activated carbons are burnt into ashes in a burning furnace, while radioactive liquid wastes such as liquid wastes of boric acid, exhausted cleaning water and decontaminating liquid wastes are powderized in a drying furnace or calcining furnace. These powders are joined with silicates as such as white clay, silica and glass powder and a liquid alkali such as NaOH or Ca(OH) 2 and transferred to a solidifying vessel. Then, the vessel is set to a hydrothermal reactor, heated and pressurized, then taken out about 20 min after and tightly sealed. In this way, radioactive wastes are converted through the hydrothermal reactions into aqueous rock stable for a long period of time to obtain solidification products insoluble to water and with an extremely low leaching rate. (Ikeda, J.)

  16. Method of storing solidification products

    International Nuclear Information System (INIS)

    Tani, Yutaro.

    1985-01-01

    Purpose: To enable to efficiently and satisfactorily cool and store solidification products of liquid wastes generated from the reactor spent fuel reprocessing process by a simple facility. Method: Liquid wastes generated from the reactor spent fuel reprocessing process are caused to flow from the upper opening to the inside of a spherical canistor. The opening of the spherical canistor is welded with a lid by a remote control and the liquid wastes are tightly sealed within the spherical canistor as glass solidification products. Spherical canistors having the solidification products tightly sealed therein are sent into and stored in a hopper by the remote control. Further, a blower is driven upon storing to suck cooling air from the cooling air intake port to the inside of the hopper to absorb the decay heat of radioactive materials in the solidification products and the air is discharged from the duct and through the stack to the atmosphere. (Kawakami, Y.)

  17. Visitor Registration System

    Data.gov (United States)

    US Agency for International Development — Visitor Registration System (VRS) streamlines visitor check-in and check-out process for expediting visitors into USAID. The system captures visitor information...

  18. Centralized cement solidification technique for low-level radioactive wastes

    International Nuclear Information System (INIS)

    Matsuda, Masami; Nishi, Takashi; Izumida, Tatsuo; Tsuchiya, Hiroyuki.

    1996-01-01

    A centralized cement solidification system has been developed to enable a single facility to solidify such low-level radioactive wastes as liquid waste, spent ion exchange resin, incineration ash, and miscellaneous solid wastes. Since the system uses newly developed high-performance cement, waste loading is raised and deterioration of waste forms after land burial prevented. This paper describes the centralized cement solidification system and the features of the high-performance cement. Results of full-scale pilot plant tests are also shown from the viewpoint of industrial applicability. (author)

  19. Altering the cooling rate dependence of phase formation during rapid solidification in the Nd{sub 2}Fe{sub 14}B system

    Energy Technology Data Exchange (ETDEWEB)

    Branagan, D.J. [USDOE, Ames, IA (United States). Ames Lab.]|[Iowa State Univ. of Science and Technology, Ames, IA (United States). Dept. of Materials Science and Engineering; McCallum, R.W. [USDOE, Ames, IA (United States). Ames Lab.]|[Iowa State Univ. of Science and Technology, Ames, IA (United States). Dept. of Materials Science and Engineering

    1995-04-26

    In order to evaluate the effects of additions on the solidification behavior of Nd{sub 2}Fe{sub 14}B, a stoichiometric alloy was modified with elemental additions of Ti or C and a compound addition of Ti with C. For each alloy, a series of wheel speed runs was undertaken, from which the optimum wheel speeds and optimum energy products were determined. On the BH{sub max} versus wheel speed plots, regions were identified in order to analyze the changes with cooling rates leading to phase formation brought about by the alloy modifications. The compilation of the regional data of the modified alloys showed their effects on altering the cooling rate dependence of phase formation. It was found that the regions of properitectic iron formation, glass formation, and the optimum cooling rate can be changed by more than a factor of two through appropriate alloying additions. The effects of the alloy modifications can be visualized in a convenient fashion through the use of a model continuous cooling transformation (CCT) diagram which represents phase formation during the solidification process under continuous cooling conditions for a wide range of cooling rates from rapid solidification to equilibrium cooling. ((orig.)).

  20. UNCONSTRAINED MELTING AND SOLIDIFICATION INSIDE ...

    African Journals Online (AJOL)

    2015-09-01

    Sep 1, 2015 ... There is a large number of experimental and numerical works on melting and solidification of PCM[6-10], and also its usage as thermal management in building [11-14], electronic devices [15-16] and solar energy. [17-20].Most investigated geometries in melting and freezing process are sphere (spherical.

  1. Linear Stability of Binary Alloy Solidification for Unsteady Growth Rates

    Science.gov (United States)

    Mazuruk, K.; Volz, M. P.

    2010-01-01

    An extension of the Mullins and Sekerka (MS) linear stability analysis to the unsteady growth rate case is considered for dilute binary alloys. In particular, the stability of the planar interface during the initial solidification transient is studied in detail numerically. The rapid solidification case, when the system is traversing through the unstable region defined by the MS criterion, has also been treated. It has been observed that the onset of instability is quite accurately defined by the "quasi-stationary MS criterion", when the growth rate and other process parameters are taken as constants at a particular time of the growth process. A singular behavior of the governing equations for the perturbed quantities at the constitutional supercooling demarcation line has been observed. However, when the solidification process, during its transient, crosses this demarcation line, a planar interface is stable according to the linear analysis performed.

  2. Species redistribution during solidification of nuclear fuel waste metal castings

    Energy Technology Data Exchange (ETDEWEB)

    Naterer, G F; Schneider, G E [Waterloo Univ., ON (Canada)

    1994-12-31

    An enthalpy-based finite element model and a binary system species redistribution model are developed and applied to problems associated with solidification of nuclear fuel waste metal castings. Minimal casting defects such as inhomogeneous solute segregation and cracks are required to prevent container corrosion and radionuclide release. The control-volume-based model accounts for equilibrium solidification for low cooling rates and negligible solid state diffusion for high cooling rates as well as intermediate conditions. Test problems involving nuclear fuel waste castings are investigated and correct limiting cases of species redistribution are observed. (author). 11 refs., 1 tab., 13 figs.

  3. Microstructural investigation of D2 tool steel during rapid solidification

    Science.gov (United States)

    Delshad Khatibi, Pooya

    Solidification is considered as a key processing step in developing the microstructure of most metallic materials. It is, therefore, important that the solidification process can be designed and controlled in such a way so as to obtain the desirable properties in the final product. Rapid solidification refers to the system's high undercooling and high cooling rate, which can yield a microstructure with unique chemical composition and mechanical properties. An area of interest in rapid solidification application is high-chromium, high-carbon tool steels which experience considerable segregation of alloying elements during their solidification in a casting process. In this dissertation, the effect of rapid solidification (undercooling and cooling rate) of D2 tool steel on the microstructure and carbide precipitation during annealing was explored. A methodology is described to estimate the eutectic and primary phase undercooling of solidifying droplets. The estimate of primary phase undercooling was confirmed using an online measurement device that measured the radiation energy of the droplets. The results showed that with increasing primary phase and eutectic undercooling and higher cooling rate, the amount of supersaturation of alloying element in metastable retained austenite phase also increases. In the case of powders, the optimum hardness after heat treatment is achieved at different temperatures for constant periods of time. Higher supersaturation of austenite results in obtaining secondary hardness at higher annealing temperature. D2 steel ingots generated using spray deposition have high eutectic undercooling and, as a result, high supersaturation of alloying elements. This can yield near net shape D2 tool steel components with good mechanical properties (specifically hardness). The data developed in this work would assist in better understanding and development of near net shape D2 steel spray deposit products with good mechanical properties.

  4. Particle Trapping and Banding in Rapid Colloidal Solidification

    KAUST Repository

    Elliott, J. A. W.

    2011-10-11

    We derive an expression for the nonequilibrium segregation coefficient of colloidal particles near a moving solid-liquid interface. The resulting kinetic phase diagram has applications for the rapid solidification of clay soils, gels, and related colloidal systems. We use it to explain the formation of bandlike defects in rapidly solidified alumina suspensions. © 2011 American Physical Society.

  5. Modelling of solidification processing and continuous strip casting for copper-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoudi, Jafar [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Materials Processing

    2000-04-01

    An experimental and numerical study was carried out to investigate the solidification process in a copper continuous strip casting process. Heat flow and solidification process has been experimentally studied. Cooling curves during solidification were registered using a thermocouple of type K connected to a data acquisition system. Temperature measurements in the mould and cooling water were also performed. The numerical model considers a generalized set of mass, momentum and heat equations that is valid for the solid, liquid and solidification interval in the cast. A k-{epsilon} turbulence model, produced with the commercial program CFX, is used to analyse the solidification process of pure copper in the mould region of the caster. The fluid flow, temperature and heat flux distributions in the mould region of the caster were computed. The shape and location of the solidification front were also determined. The effects of the parameters such as heat transfer coefficient, casting speed, casting temperature, heat of fusion and specific heat on the shape and location of the solidification front and the heat transport at the mould-cast interface were investigated. The predicted temperature and heat flux distributions were compared with experimental measurements, and reasonable agreement was obtained. The solidification behaviour of pure copper and different copper base alloys has been studied. A series of solidification experiments using DTA furnace, mirror furnace and levitation technique were performed on different copper-base alloys. The undercooling, cooling rates of the liquid and the solid states, solidification times and temperatures were evaluated from the curves. The cooling curves for different samples were simulated using a FEM solidification program. It was found that the calculated values of the heat of fusion were much lower than the tabulated ones. The fraction of solid formed before quenching, in the DTA experiments, has been observed to be much higher

  6. Solidification Sequence of Spray-Formed Steels

    Science.gov (United States)

    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.

  7. Solidification processing of high-Tc superconductors

    CERN Document Server

    Shiohara, Y; Nakamura, Y; Izumi, T

    2001-01-01

    Recent progress in the solidification processing of RE-system (RE:Y, Sm, Nd etc.) oxide superconducting materials is reviewed. The superconducting YBa/sub 2/Cu/sub 3/O/sub y/(Y123) phase is solidified from Y/sub 2/BaCuO/sub 5/(Y211) and liquid phases, by a peritectic reaction. The solidified micro and macro structure can not be explained by the peritectic reaction with diffusion in the solid but rather by diffusion in the liquid. A solidification model for this reaction is developed. It is confirmed that the prediction from the model calculation is in good agreement with the experimental results. Furthermore, the basic idea is expanded to develop a novel single crystal pulling process. Y211 powders were placed at the bottom of the crucible as the solute source for the growth and a BaO-CuO composite (Ba to Cu cation ratio was 3 to 5) was placed on the layer of Y211 powders. Temperature gradient was provided in the melt. Large bulk single crystals were obtained by this technique, and the growth mechanism was al...

  8. Decontamination impacts on solidification

    International Nuclear Information System (INIS)

    Piciulo, P.L.; Davis, M.S.

    1985-01-01

    The increased occupational exposure resulting from the accumulation of activated corrosion products in the primary system of LWRs has led to the development of chemical methods to remove the contamination. In the past, the problem of enhanced migration of radionuclides away from trenches used to dispose of low-level radioactive waste, has been linked to the presence, at the disposal unit, of chelating or complexing agents such as those used in decontamination processes. These agents have further been found to reduce the normal sorptive capacity of soils for radionuclides. The degree to which these agents inhibit the normal sorptive processes is dependent on the type of complexing agent, the radionuclide of concern, the soil properties and whether the nuclide is present as a complex or is already sorbed to the soil. Since the quantity of reagent employed in a full system decontamination is large (200 to 25,000 kg), the potential for enhanced migration of radionuclides from a site used to dispose of the decontamination wastes should be addressed and guidelines established for the safe disposal of these wastes

  9. Microstructural Development in Al-Si Powder During Rapid Solidification

    Energy Technology Data Exchange (ETDEWEB)

    Genau, Amber Lynn [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    Powder metallurgy has become an increasingly important form of metal processing because of its ability to produce materials with superior mechanical properties. These properties are due in part to the unique and often desirable microstructures which arise as a result of the extreme levels of undercooling achieved, especially in the finest size powder, and the subsequent rapid solidification which occurs. A better understanding of the fundamental processes of nucleation and growth is required to further exploit the potential of rapid solidification processing. Aluminum-silicon, an alloy of significant industrial importance, was chosen as a model for simple eutectic systems displaying an unfaceted/faceted interface and skewed coupled eutectic growth zone, Al-Si powder produced by high pressure gas atomization was studied to determine the relationship between microstructure and alloy composition as a function of powder size and atomization gas. Critical experimental measurements of hypereutectic (Si-rich) compositions were used to determine undercooling and interface velocity, based on the theoretical models which are available. Solidification conditions were analyzed as a function of particle diameter and distance from nucleation site. A revised microstructural map is proposed which allows the prediction of particle morphology based on temperature and composition. It is hoped that this work, by providing enhanced understanding of the processes which govern the development of the solidification morphology of gas atomized powder, will eventually allow for better control of processing conditions so that particle microstructures can be optimized for specific applications.

  10. Solidification at the High and Low Rate Extreme

    Energy Technology Data Exchange (ETDEWEB)

    Meco, Halim [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    The microstructures formed upon solidification are strongly influenced by the imposed growth rates on an alloy system. Depending on the characteristics of the solidification process, a wide range of growth rates is accessible. The prevailing solidification mechanisms, and thus the final microstructure of the alloy, are governed by these imposed growth rates. At the high rate extreme, for instance, one can have access to novel microstructures that are unattainable at low growth rates. While the low growth rates can be utilized for the study of the intrinsic growth behavior of a certain phase growing from the melt. Although the length scales associated with certain processes, such as capillarity, and the diffusion of heat and solute, are different at low and high rate extremes, the phenomena that govern the selection of a certain microstructural length scale or a growth mode are the same. Consequently, one can analyze the solidification phenomena at both high and low rates by using the same governing principles. In this study, we examined the microstructural control at both low and high extremes. For the high rate extreme, the formation of crystalline products and factors that control the microstructure during rapid solidification by free-jet melt spinning are examined in Fe-Si-B system. Particular attention was given to the behavior of the melt pool at different quench-wheel speeds. Since the solidification process takes place within the melt-pool that forms on the rotating quench-wheel, we examined the influence of melt-pool dynamics on nucleation and growth of crystalline solidification products and glass formation. High-speed imaging of the melt-pool, analysis of ribbon microstructure, and measurement of ribbon geometry and surface character all indicate upper and lower limits for melt-spinning rates for which nucleation can be avoided, and fully amorphous ribbons can be achieved. Comparison of the relevant time scales reveals that surface-controlled melt

  11. Finite element modelling of solidification phenomena

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The process of solidification process is complex in nature and the simulation of such process is required in industry before it is actually undertaken. Finite element method is used to simulate the heat transfer process accompanying the solidification process. The metal and the mould along with the air gap formation ...

  12. Solidification control in continuous casting of steel

    Indian Academy of Sciences (India)

    Unknown

    Solidification in continuous casting (CC) technology is initiated in a water- ..... to fully austenitic solidification, and FP between 0 and 1 indicates mixed mode. ... the temperature interval (LIT – TSA) corresponding to fs = 0⋅9 → 1, is in reality the.

  13. Melting, solidification, remelting, and separation of glass and metal

    International Nuclear Information System (INIS)

    Ebadian, M.A.; Xin, R.C.; Liu, Y.Z.

    1998-01-01

    Several high-temperature vitrification technologies have been developed for the treatment of a wide range of mixed waste types in both the low-level waste and transuranic (TRU) mixed waste categories currently in storage at DOE sites throughout the nation. The products of these processes are an oxide slag phase and a reduced metal phase. The metal phase has the potential to be recycled within the DOE Complex. Enhanced slag/metal separation methods are needed to support these processes. This research project involves an experimental investigation of the melting, solidification, remelting, and separation of glass and metal and the development of an efficient separation technology. The ultimate goal of this project is to find an efficient way to separate the slag phase from the metal phase in the molten state. This two-year project commenced in October 1995 (FY96). In the first fiscal year, the following tasks were accomplished: (1) A literature review and an assessment of the baseline glass and metal separation technologies were performed. The results indicated that the baseline technology yields a high percentage of glass in the metal phase, requiring further separation. (2) The main melting and solidification system setup was established. A number of melting and solidification tests were conducted. (3) Temperature distribution, solidification patterns, and flow field in the molten metal pool were simulated numerically for the solidification processes of molten aluminum and iron steel. (4) Initial designs of the laboratory-scale DCS and CS technologies were also completed. The principal demonstration separation units were constructed. (5) An application for a patent for an innovative liquid-liquid separation technology was submitted and is pending

  14. Characteristics of Cement Solidification of Metal Hydroxide Waste

    Directory of Open Access Journals (Sweden)

    Dae-Seo Koo

    2017-02-01

    Full Text Available To perform the permanent disposal of metal hydroxide waste from electro-kinetic decontamination, it is necessary to secure the technology for its solidification. The integrity tests on the fabricated solidification should also meet the criteria of the Korea Radioactive Waste Agency. We carried out the solidification of metal hydroxide waste using cement solidification. The integrity tests such as the compressive strength, immersion, leach, and irradiation tests on the fabricated cement solidifications were performed. It was also confirmed that these requirements of the criteria of Korea Radioactive Waste Agency on these cement solidifications were met. The microstructures of all the cement solidifications were analyzed and discussed.

  15. Characteristics of cement solidification of metal hydroxide waste

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Dae Seo; Sung, Hyun Hee; Kim, Seung Soo; Kim, Gye Nam; Choi, Jong Won [Dept. of Decontemination Decommission Technology Development, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-02-15

    To perform the permanent disposal of metal hydroxide waste from electro-kinetic decontamination, it is necessary to secure the technology for its solidification. The integrity tests on the fabricated solidification should also meet the criteria of the Korea Radioactive Waste Agency. We carried out the solidification of metal hydroxide waste using cement solidification. The integrity tests such as the compressive strength, immersion, leach, and irradiation tests on the fabricated cement solidifications were performed. It was also confirmed that these requirements of the criteria of Korea Radioactive Waste Agency on these cement solidifications were met. The microstructures of all the cement solidifications were analyzed and discussed.

  16. Interface Pattern Selection Criterion for Cellular Structures in Directional Solidification

    Science.gov (United States)

    Trivedi, R.; Tewari, S. N.; Kurtze, D.

    1999-01-01

    The aim of this investigation is to establish key scientific concepts that govern the selection of cellular and dendritic patterns during the directional solidification of alloys. We shall first address scientific concepts that are crucial in the selection of interface patterns. Next, the results of ground-based experimental studies in the Al-4.0 wt % Cu system will be described. Both experimental studies and theoretical calculations will be presented to establish the need for microgravity experiments.

  17. Low level waste solidification practice in Japan

    International Nuclear Information System (INIS)

    Sakata, S.; Kuribayashi, H.; Kono, Y.

    1981-01-01

    Both sea dumping and land isolation are planned to be accomplished for low level waste disposal in Japan. The conceptual design of land isolation facilities has been completed, and site selection will presently get underway. With respect to ocean dumping, safety surveys are being performed along the lines of the London Dumping Convention and the Revised Definitions and Recommendations of the IAEA, and the review of Japanese regulations and applicable criteria is being expedited. This paper discusses the present approach to waste solidification practices in Japan. It reports that the bitumen solidification process and the plastic solidification process are being increasingly used in Japan. Despite higher investment costs, both processes have advantages in operating cost, and are comparable to the cement solidification process in overall costs

  18. Evolution of solidification texture during additive manufacturing

    Science.gov (United States)

    Wei, H. L.; Mazumder, J.; DebRoy, T.

    2015-01-01

    Striking differences in the solidification textures of a nickel based alloy owing to changes in laser scanning pattern during additive manufacturing are examined based on theory and experimental data. Understanding and controlling texture are important because it affects mechanical and chemical properties. Solidification texture depends on the local heat flow directions and competitive grain growth in one of the six preferred growth directions in face centered cubic alloys. Therefore, the heat flow directions are examined for various laser beam scanning patterns based on numerical modeling of heat transfer and fluid flow in three dimensions. Here we show that numerical modeling can not only provide a deeper understanding of the solidification growth patterns during the additive manufacturing, it also serves as a basis for customizing solidification textures which are important for properties and performance of components. PMID:26553246

  19. Method of reprocessing radioactive asphalt solidification products

    International Nuclear Information System (INIS)

    Nakaya, Iwao; Murakami, Tadashi; Miyake, Takafumi; Inagaki, Yuzo.

    1986-01-01

    Purpose: To obtain heat-stable solidification products and decrease the total volume thereof by modifying the solidified form by the reprocessing of existent radioactive asphalt solidification products. Method: Radioactive asphalt solidification products are heated into a fluidized state. Then, incombustible solvents such as perchloroethylene or trichloroethylene are added to a dissolving tank to gradually dissolve the radioactive asphalt solidification products. Thus, organic materials such as asphalts are transferred into the solvent layer, while inorganic materials containing radioactive materials remain as they are in the separation tank. Then, the inorganic materials containing the radioactive materials are taken out and then solidified, for example, by converting them into a rock or glass form. (Kawakami, Y.)

  20. Efficient estimation of diffusion during dendritic solidification

    Science.gov (United States)

    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.

  1. A Comparative study of solidification of Al-Cu alloy under flow of cylindrical radial heat and the unidirectional vertically

    Directory of Open Access Journals (Sweden)

    Jean Robert P. Rodrigues

    2014-09-01

    Full Text Available In spite of technological importance of solidification of metallic alloys under radial heat flow, relatively few studies have been carried out in this area. In this work the solidification of Al 4.5 wt% Cu cylinders against a steel massive mold is analyzed and compared with unidirectional solidification against a cooled mold. Initially temperature variations at different positions in the casting and in the mold were measured during solidification using a data acquisition system. These temperature variations were introduced in a numerical method in order to determine the variation of heat transfer coefficient at metal/mold interface by inverse method. The primary and secondary dendrite arm spacing variations were measured through optical microscopy. Comparisons carried out between experimental and numerical data showed that the numerical method describes well the solidification processes under radial heat flux.

  2. Modeling of solidification of MMC composites during gravity casting process

    Directory of Open Access Journals (Sweden)

    R. Zagórski

    2013-04-01

    Full Text Available The paper deals with computer simulation of gravity casting of the metal matrix composites reinforced with ceramics (MMC into sand mold. The subject of our interest is aluminum matrix composite (AlMMC reinforced with ceramic particles i.e. silicon carbide SiC and glass carbon Cg. The created model describes the process taking into account solidification and its influence on the distribution of reinforcement particles. The computer calculation has been carried out in 2D system with the use of Navier-Stokes equations using ANSYS FLUENT 13. The Volume of Fluid approach (VOF and enthalpy method have been used to model the air-fluid free surface (and also volume fraction of particular continuous phases and the solidification of the cast, respectively.

  3. Metastable and unstable cellular solidification of colloidal suspensions

    Science.gov (United States)

    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.

  4. Numerical model for dendritic solidification of binary alloys

    Science.gov (United States)

    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.

  5. Method of plastic solidification of radioactive wastes

    International Nuclear Information System (INIS)

    Oikawa, Yasuo; Tokimitsu, Fujio.

    1986-01-01

    Purpose: To prevent occurrence of deleterious cracks to the inside and the surface of solidification products, as well as eliminate gaps between the products and the vessel inner wall upon plastic solidification processing for powdery or granular radioactive wastes. Method: An appropriate amount of thermoplastic resins such as styrenic polymer or vinyl acetate type polymer as a low shrinking agent is added and mixed with unsaturated polyester resins to be mixed with radioactive wastes so as to reduce the shrinkage-ratio to 0 % upon curing reaction. Thus, a great shrinkage upon hardening the mixture is suppressed to prevent the occurrence of cracks to the surface and the inside of the solidification products, as well as prevent the gaps between the inner walls of a drum can vessel and the products upon forming solidification products to the inside of the drum can. The resultant solidification products have a large compression strength and can sufficiently satisfy the evaluation standards as the plastic solidification products of radioactive wastes. (Horiuchi, T.)

  6. Geomechanical characterization of volcanic rocks using empirical systems and data mining techniques

    OpenAIRE

    T. Miranda; L.R. Sousa; A.T. Gomes; J. Tinoco; C. Ferreira

    2018-01-01

    This paper tries to characterize volcanic rocks through the development and application of an empirical geomechanical system. Geotechnical information was collected from the samples from several Atlantic Ocean islands including Madeira, Azores and Canarias archipelagos. An empirical rock classification system termed as the volcanic rock system (VRS) is developed and presented in detail. Results using the VRS are compared with those obtained using the traditional rock mass rating (RMR) system....

  7. Solidification of high-level radioactive wastes. Final report

    International Nuclear Information System (INIS)

    1979-06-01

    A panel on waste solidification was formed at the request of the Nuclear Regulatory Commission to study the scientific and technological problems associated with the conversion of liquid and semiliquid high-level radioactive wastes into a stable form suitable for transportation and disposition. Conclusions reached and recommendations made are as follows. Many solid forms described in this report could meet standards as stringent as those currently applied to the handling, storage, and transportation of spent fuel assemblies. Solid waste forms should be selected only in the context of the total radioactive waste management system. Many solid forms are likely to be satisfactory for use in an appropriately designed system, The current United States policy of deferring the reprocessing of commercial reactor fuel provides additional time for R and D solidification technology for this class of wastes. Defense wastes which are relatively low in radioactivity and thermal power density can best be solidified by low-temperature processes. For solidification of fresh commercial wastes that are high in specific activity and thermal power density, the Panel recommends that, in addition to glass, the use of fully-crystalline ceramics and metal-matrix forms be actively considered. Preliminary analysis of the characteristics of spent fuel pins indicates that they may be eligible for consideration as a waste form. Because the differences in potential health hazards to the public resulting from the use of various solid form and disposal options are likely to be small, the Panel concludes that cost, reliability, and health hazards to operating personnel will be major considerations in choosing among the options that can meet safety requiremens. The Panel recommends that responsibility for all radioactive waste management operations (including solidification R and D) should be centralized

  8. Geomechanical characterization of volcanic rocks using empirical systems and data mining techniques

    Directory of Open Access Journals (Sweden)

    T. Miranda

    2018-02-01

    Full Text Available This paper tries to characterize volcanic rocks through the development and application of an empirical geomechanical system. Geotechnical information was collected from the samples from several Atlantic Ocean islands including Madeira, Azores and Canarias archipelagos. An empirical rock classification system termed as the volcanic rock system (VRS is developed and presented in detail. Results using the VRS are compared with those obtained using the traditional rock mass rating (RMR system. Data mining (DM techniques are applied to a database of volcanic rock geomechanical information from the islands. Different algorithms were developed and consequently approaches were followed for predicting rock mass classes using the VRS and RMR classification systems. Finally, some conclusions are drawn with emphasis on the fact that a better performance was achieved using attributes from VRS.

  9. Solidification of radioactive aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Aikawa, Hideaki; Kato, Kiyoshi; Wadachi, Yoshiki

    1970-09-07

    A process for solidifying a radioactive waste solution is provided, using as a solidifying agent a mixture of calcined gypsum and burnt vermiculite. The quantity ratio of the mixture is preferred to be 1:1 by volume. The quantity of impregnation is 1/2 of the volume of the total quantity of the solidifying agent. In embodiments, 10 liters of plutonium waste solution was mixed with a mixture of 1:1 calcined gypsum and burnt vermiculite contained in a 20-liter cylindrical steel container lined with asphalt. The plutonium waste solution from the laboratory was neutralized with a caustic soda aqueous solution to prevent explosion due to the nitration of organic compounds. The neutralization is not always necessary. A market available dental gypsum was calcined at 400 to 500/sup 0/C and a vermiculite from Illinois was burnt at 1,100/sup 0/C to prepare the agents. The time required for the impregnation with 10 liters of plutonium solution was four minutes. After impregnation, the temperature rose to 40/sup 0/C within 30 minutes to one hour. Next, it was cooled to room temperature by standing for 3-4 hours. Solidification time was about 1 hour. The Japan Atomic Energy Research Insitute had treated and disposed about 1,000 tons of plutonium waste by this process as of August 19, 1970.

  10. Improved cement solidification of low and intermediate level radioactive wastes

    International Nuclear Information System (INIS)

    1993-01-01

    Cementation was the first and is still the most widely applied technique for the conditioning of low and intermediate level radioactive wastes. Compared with other solidification techniques, cementation is relatively simple and inexpensive. However, the quality of the final cemented waste forms depends very much on the composition of the waste and the type of cement used. Different kinds of cement are used for different kinds of waste and the compatibility of a specific waste with a specific cement type should always be carefully evaluated. Cementation technology is continuously being developed in order to improve the characteristics of cemented waste in accordance with the increasing requirements for quality of the final solidified waste. Various kinds of additives and chemicals are used to improve the cemented waste forms in order to meet all safety requirements. This report is meant mainly for engineers and designers, to provide an explanation of the chemistry of cementation systems and to facilitate the choice of solidification agents and processing equipment. It reviews recent developments in cementation technology for improving the quality of cemented waste forms and provides a brief description of the various cement solidification processes in use. Refs, figs and tabs

  11. Sandia solidification process: a broad range aqueous waste solidification method

    International Nuclear Information System (INIS)

    Lynch, R.W.; Dosch, R.G.; Kenna, B.T.; Johnstone, J.K.; Nowak, E.J.

    1976-01-01

    New ion-exchange materials of the hydrous oxide type were developed for solidifying aqueous radioactive wastes. These materials have the general formula M[M'/sub x/O/sub y/H/sub z/]/sub n/, where M is an exchangeable cation of charge +n and M' may be Ti; Nb; Zr, or Ta. Affinities for polyvalent cations were found to be very high and ion-exchange capacities large (e.g., 4.0--4.5 meq/g for NaTi 2 O 5 H depending on moisture content). The effectiveness of the exchangers for solidifying high-level waste resulting from reprocessing light-water reactor fuel was demonstrated in small-scale tests. Used in conjunction with anion exchange resin, these materials reduced test solution radioactivity from approximately 0.2 Ci/ml to as low as approximately 2 nCi/ml. The residual radioactivity was almost exclusively due to 106 Ru and total α-activity was only a few pCi/ml. Alternative methods of consolidating the solidified waste were evaluated using nonradioactive simulants. Best results were obtained by pressure-sintering which yielded essentially fully dense ceramics, e.g., titanate/titania ceramics with bulk density as high as 4.7 g/cm 3 , waste oxide content as high as 1.2 g/cm 3 , and leach resistance comparable to good borosilicate glass. Based on the above results, a baseline process for solidifying high-level waste was defined and approximate economic analyses indicated costs were not prohibitive. Additional tests have demonstrated that, if desired, operating conditions could be modified to allow recovery of radiocesium (and perhaps other isotopes) during solidification of the remaining constituents of high-level waste. Preliminary tests have also shown that these materials offer promise for treating tank-stored neutralized wastes

  12. Properties and solidification of decontamination wastes

    International Nuclear Information System (INIS)

    Davis, M.S.; Piciulo, P.L.; Bowerman, B.S.; Adams, J.W.; Milian, L.

    1983-01-01

    LWRs will require one or more chemical decontaminations to achieve their designed lifetimes. Primary system decontamination is designed to lower radiation fields in areas where plant maintenance personnel must work. Chemical decontamination methods are either hard (concentrated chemicals, approximately 5 to 25 weight percent) or soft (dilute chemicals less than 1 percent by weight). These methods may have different chemical reagents, some tailor-made to the crud composition and many methods are and will be proprietary. One factor common to most commercially available processes is the presence of organic acids and chelates. These types of organic reagents are known to enhance the migration of radionuclides after disposal in a shallow land burial site. The NRC sponsors two programs at Brookhaven National Laboratory that are concerned with the management of decontamination wastes which will be generated by the full system decontamination of LWRs. These two programs focus on potential methods for degrading or converting decontamination wastes to more acceptable forms prior to disposal and the impact of disposing of solidified decontamination wastes. The results of the solidification of simulated decontamination resin wastes will be presented. Recent results on combustion of simulated decontamintion wastes will be described and procedures for evaluating the release of decontamination reagents from solidified wastes will be summarized

  13. Interface Pattern Selection in Directional Solidification

    Science.gov (United States)

    Trivedi, Rohit; Tewari, Surendra N.

    2001-01-01

    The central focus of this research is to establish key scientific concepts that govern the selection of cellular and dendritic patterns during the directional solidification of alloys. Ground-based studies have established that the conditions under which cellular and dendritic microstructures form are precisely where convection effects are dominant in bulk samples. Thus, experimental data can not be obtained terrestrially under pure diffusive regime. Furthermore, reliable theoretical models are not yet possible which can quantitatively incorporate fluid flow in the pattern selection criterion. Consequently, microgravity experiments on cellular and dendritic growth are designed to obtain benchmark data under diffusive growth conditions that can be quantitatively analyzed and compared with the rigorous theoretical model to establish the fundamental principles that govern the selection of specific microstructure and its length scales. In the cellular structure, different cells in an array are strongly coupled so that the cellular pattern evolution is controlled by complex interactions between thermal diffusion, solute diffusion and interface effects. These interactions give infinity of solutions, and the system selects only a narrow band of solutions. The aim of this investigation is to obtain benchmark data and develop a rigorous theoretical model that will allow us to quantitatively establish the physics of this selection process.

  14. Solidification microstructures of aluminium-uranium alloys

    International Nuclear Information System (INIS)

    Ambrozio Filho, F.; Vieira, R.R.

    1976-01-01

    The solidification of microstrutures of aluminium-uranium alloys in the range of 4 to 20% uranium is investigated. The solidification was obtained both in ingot molds and under controlled directional solidification. The conditions for the presence of primary crystals and eutectic are discussed and an analysis of the influence of variables (growth rate and thermal gradient in the liquid) on the alloy structure is made. The effect of cooling rate on the alloy structures has been determined. It is found that the resulting structure can be derived from the kinectics concept, as required by the coupled-zone theory. Suggestions on the qualitative intervals of composition and temperatures with eutectic growth are presented [pt

  15. Solidification of HLLW by glass-ceramic process

    International Nuclear Information System (INIS)

    Oguino, N.; Masuda, S.; Tsunoda, N.; Yamanaka, T.; Ninomiya, M.; Sakane, T.; Nakamura, S.; Kawamura, S.

    1979-01-01

    The compositions of glass-ceramics for the solidification of HLLW were studied, and the glass-ceramics in the diopside system was concluded to be the most suitable. Compared with the properties of HLW borosilicate glasses, those of diopside glass-ceramic were thought to be almost equal in leach rate and superior in thermal stability and mechanical strength. It was also found that the glass in this system can be crystallized simply by pouring it into a thermally insulated canister and then allowing it to cool to room temperature. 2 figures, 5 tables

  16. Defect generation during solidification of aluminium foams

    International Nuclear Information System (INIS)

    Mukherjee, M.; Garcia-Moreno, F.; Banhart, J.

    2010-01-01

    The reason for the frequent occurrence of cell wall defects in metal foams was investigated. Aluminium foams often expand during solidification, a process which is referred as solidification expansion (SE). The effect of SE on the structure of aluminium foams was studied in situ by X-ray radioscopy and ex situ by X-ray tomography. A direct correlation between the magnitude of SE and the number of cell wall ruptures during SE and finally the number of defects in the solidified foams was found.

  17. Incorporating interfacial phenomena in solidification models

    Science.gov (United States)

    Beckermann, Christoph; Wang, Chao Yang

    1994-01-01

    A general methodology is available for the incorporation of microscopic interfacial phenomena in macroscopic solidification models that include diffusion and convection. The method is derived from a formal averaging procedure and a multiphase approach, and relies on the presence of interfacial integrals in the macroscopic transport equations. In a wider engineering context, these techniques are not new, but their application in the analysis and modeling of solidification processes has largely been overlooked. This article describes the techniques and demonstrates their utility in two examples in which microscopic interfacial phenomena are of great importance.

  18. A basic study on capture and solidification of rare earth nuclide (Nd) in LiCl-KCl eutectic salt using an inorganic composite with Li{sub 2}OAl{sub 2}O{sub 3}- SiO{sub 2}-B{sub 2}O{sub 3} systems

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Na Young; Eum, Hee Chul; Park, Hwan Seo; Ahn, Do Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-03-15

    The pyroprocessing of spent nuclear fuel generates LiCl-KCl eutectic waste salt containing radioactive rare earth nuclides. It is necessary to develop a simple process for the treatment of LiCl-KCl eutectic waste in a hot-cell facility. In this study, capture and solidification of a rare earth nuclide (Nd) in LiCl-KCl eutectic salt using an inorganic composite with a Li{sub 2}OAl{sub 2}O{sub 3}- SiO{sub 2}-B{sub 2}O{sub 3} system was conducted to simplify the existing separation and solidification process of rare earth nuclides in LiCl-KCl eutectic waste salt from the pyroprocessing of spent nuclear fuel. More than 98wt% of Nd in LiCl-KCl eutectic salt was captured when the mass ratio of the composite was 0.67 over NdCl3 in the eutectic salt. The content of Nd{sub 2}O{sub 3} in the Nd captured-composite reached about 50wt%, and this composite was directly fabricated into a homogeneous and chemical resistant glass waste in a monolithic form. These results will be utilized in designing a process to simplify the existing separation and solidification process.

  19. Quantification of Urine Elimination Behaviors in Cats with a Video Recording System

    OpenAIRE

    R. Dulaney, D.; Hopfensperger, M.; Malinowski, R.; Hauptman, J.; Kruger, J.M.

    2017-01-01

    Background Urinary disorders in cats often require subjective caregiver quantification of clinical signs to establish a diagnosis and monitor therapeutic outcomes. Objective To investigate use of a video recording system (VRS) to better assess and quantify urination behaviors in cats. Animals Eleven healthy cats and 8 cats with disorders potentially associated with abnormal urination patterns. Methods Prospective study design. Litter box urination behaviors were quantified with a VRS for 14 d...

  20. Solidification of oils and organic liquids

    International Nuclear Information System (INIS)

    Clark, D.E.; Colombo, P.; Neilson, R.M. Jr.

    1982-07-01

    The suitability of selected solidification media for application in the disposal of low-level oil and other organic liquid wastes has been investigated. In the past, these low-level wastes (LLWs) have commonly been immobilized by sorption onto solid absorbents such as vermiculite or diatomaceous earth. Evolving regulations regarding the disposal of these materials encourage solidification. Solidification media which were studied include Portland type I cement; vermiculite plus Portland type I cement; Nuclear Technology Corporation's Nutek 380-cement process; emulsifier, Portland type I cement-sodium silicate; Delaware Custom Materiel's cement process; and the US Gypsum Company's Envirostone process. Waste forms have been evaluated as to their ability to reliably produce free standing monolithic solids which are homogeneous (macroscopically), contain < 1% free standing liquids by volume and pass a water immersion test. Solidified waste form specimens were also subjected to vibratory shock testing and flame testing. Simulated oil wastes can be solidified to acceptable solid specimens having volumetric waste loadings of less than 40 volume-%. However, simulated organic liquid wastes could not be solidified into acceptable waste forms above a volumetric loading factor of about 10 volume-% using the solidification agents studied

  1. NPP radioactive waste processing and solidification

    International Nuclear Information System (INIS)

    Nikiforov, A.S.; Polyakov, A.S.; Zakharova, K.P.

    1983-01-01

    The problems of proce-sing NPP intermediate level- and low-level liquid radioactive wastes (LRW) are considered. Various methods are compared of LWR solidification on the base of bituminization, cement grouting and inclusion into synthetic resins. It is concluded that the considered methods ensure radioactive radionuclides effluents into open hydronetwork at the level below the sanitary, standards

  2. Solidification of highly active liquid waste

    International Nuclear Information System (INIS)

    Morris, J.B.

    1985-03-01

    This document contains the annual progress reports on the following subjects: Joule ceramic melter; microwave vitrification; glass technology; identification, evaluation and review of potential alternative solidification processes; rotary kiln calcination; alternative glass feedstocks; volatile ruthenium trapping by solid adsorbents; irrigated baffle column dust scrubber. (author)

  3. Current high-level waste solidification technology

    International Nuclear Information System (INIS)

    Bonner, W.F.; Ross, W.A.

    1976-01-01

    Technology has been developed in the U.S. and abroad for solidification of high-level waste from nuclear power production. Several processes have been demonstrated with actual radioactive waste and are now being prepared for use in the commercial nuclear industry. Conversion of the waste to a glass form is favored because of its high degree of nondispersibility and safety

  4. Polymer Solidification Technology - Technical Issues and Challenges

    International Nuclear Information System (INIS)

    Jensen, Charles; Kim, Juyoul

    2010-01-01

    Many factors come into play, most of which are discovered and resolved only during full-scale solidification testing of each of the media commonly used in nuclear power plants. Each waste stream is unique, and must be addressed accordingly. This testing process is so difficult that Diversified's Vinyl Ester Styrene and Advanced Polymer Solidification are the only two approved processes in the United States today. This paper summarizes a few of the key obstacles that must be overcome to achieve a reliable, repeatable process for producing an approved Stable Class B and C waste form. Before other solidification and encapsulation technologies can be considered compliant with the requirements of a Stable waste form, the tests, calculations and reporting discussed above must be conducted for both the waste form and solidification process used to produce the waste form. Diversified's VERI TM and APS TM processes have gained acceptance in the UK. These processes have also been approved and gained acceptance in the U. S. because we have consistently overcome technical hurdles to produce a complaint product. Diversified Technologies processes are protected intellectual property. In specific instances, we have patents pending on key parts of our process technology

  5. Solidification at the micro-scale

    International Nuclear Information System (INIS)

    Howe, A.

    2003-01-01

    The experimental determination and computer simulation of the micro-segregation accompanying the solidification of alloys continues to be a subject of much academic and industrial interest. Both are subject to progressively more sophisticated analyses, and a discussion is offered regarding the development and practical use of such studies. Simple steels are particularly difficult targets for such work: solidification does not end conveniently in a eutectic, the rapid diffusion particularly in the delta-ferrite phase obscures most evidence of what had occurred at the micro-scale during solidification, and one or more subsequent solid state phase transformations further obscure such details. Also, solidification at the micro-scale is inherently variable: the usual, dendrite morphologies encountered are, after all, instabilities in growth behaviour, and therefore such variability should be expected. For questions such as the relative susceptibility of different grades to particular problems, it is the average, typical behaviour that is of interest, whereas for other questions such as the on-set of macro-segregation, the local variability is paramount. Depending on the question being asked, and indeed the accuracy with which validatory data are available, simple pseudo-analytical equations employing various limiting assumptions, or sophisticated models which remove the need for most such limitations, could be appropriate. This paper highlights the contribution to such studies of various collaborative research forums within the European Union with which the author is involved. (orig.) [de

  6. Method of processing solidification product of radioactive waste

    International Nuclear Information System (INIS)

    Daime, Fumiyoshi.

    1988-01-01

    Purpose: To improve the long-time stability of solidification products by providing solidification products with liquid tightness, gas tightness, abrasion resistance, etc., of the products in the course of the solidification for the treatment of radioactive wastes. Method: The surface of solidification products prepared by mixing solidifying agents with powder or pellets is entirely covered with high molecular polymer such as epoxy resin. The epoxy resin has excellent properties such as radiation-resistance, heat resistance, water proofness and chemical resistance, as well as have satisfactory mechanical properties. This can completely isolate the solidification products of radioactive wastes from the surrounding atmosphere. (Yoshino, Y.)

  7. Fractal growth in impurity-controlled solidification in lipid monolayers

    DEFF Research Database (Denmark)

    Fogedby, Hans C.; Sørensen, Erik Schwartz; Mouritsen, Ole G.

    1987-01-01

    A simple two-dimensional microscopic model is proposed to describe solidifcation processes in systems with impurities which are miscible only in the fluid phase. Computer simulation of the model shows that the resulting solids are fractal over a wide range of impurity concentrations and impurity...... diffusional constants. A fractal-forming mechanism is suggested for impurity-controlled solidification which is consistent with recent experimental observations of fractal growth of solid phospholipid domains in monolayers. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

  8. Densities of Pb-Sn alloys during solidification

    Science.gov (United States)

    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.

  9. Long-lived magnetism from solidification-driven convection on the pallasite parent body

    DEFF Research Database (Denmark)

    Bryson, James F.J.; Nichols, Claire I. O.; Herrero-Albillos, Julia

    2015-01-01

    of long-lived magnetic activity on the pallasite parent body, capturing the decay and eventual shutdown of the magnetic field as core solidification completed.We demonstrate that magnetic activity driven by progressive solidification of an inner core is consistent with our measuredmagnetic field......Palaeomagnetic measurements of meteorites suggest that, shortly after the birth of the Solar System, themolten metallic cores ofmany small planetary bodies convected vigorously and were capable of generating magnetic fields. Convection on these bodies is currently thought to have been thermally...... characteristics and cooling rates. Solidification-driven convectionwas probably commonamong small body cores, and, in contrast to thermally driven convection, will have led to a relatively late (hundreds of millions of years after accretion), long-lasting, intense and widespread epoch of magnetic activity among...

  10. On the role of solidification modelling in Integrated Computational Materials Engineering “ICME”

    International Nuclear Information System (INIS)

    Schmitz, G J; Böttger, B; Apel, M

    2016-01-01

    Solidification during casting processes marks the starting point of the history of almost any component or product. Integrated Computational Materials Engineering (ICME) [1-4] recognizes the importance of further tracking the history of microstructure evolution along the subsequent process chain. Solidification during joining processes in general happens quite late during production, where the parts to be joined already have experienced a number of processing steps which affected their microstructure. Reliable modelling of melting and dissolution of these microstructures represents a key issue before eventually modelling ‘re’-solidification e.g. during welding or soldering. Some instructive examples of microstructure evolution during a joining process obtained on the basis of synthetic and simulated initial microstructures of an Al-Cu binary model system are discussed. (paper)

  11. Feasibility study on the solidification of liquid low-level radioactive mixed waste in the inactive tank system at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    International Nuclear Information System (INIS)

    Trussell, S.

    1993-01-01

    A literature survey was conducted to help determine the feasibility of solidifying a liquid low-level radioactive mixed waste in the inactive tank system at Oak Ridge National Laboratory (ORNL). The goal of this report is to facilitate a decision on the disposition of these wastes by identifying any waste constituents that might (1) compromise the strength or stability of the waste form or (2) be highly leachable. Furthermore, its goal is to identify ways to circumvent interferences and to decrease the leachability of the waste constituents. This study has sought to provide an understanding of inhibition of cement set by identifying the fundamental chemical mechanisms by which this inhibition takes place. From this fundamental information, it is possible to draw some conclusions about the potential effects of waste constituents, even in the absence of particular studies on specific compounds

  12. Solidification processing of monotectic alloy matrix composites

    Science.gov (United States)

    Frier, Nancy L.; Shiohara, Yuh; Russell, Kenneth C.

    1989-01-01

    Directionally solidified aluminum-indium alloys of the monotectic composition were found to form an in situ rod composite which obeys a lambda exp 2 R = constant relation. The experimental data shows good agreement with previously reported results. A theoretical boundary between cellular and dendritic growth conditions was derived and compared with experiments. The unique wetting characteristics of the monotectic alloys can be utilized to tailor the interface structure in metal matrix composites. Metal matrix composites with monotectic and hypermonotectic Al-In matrices were made by pressure infiltration, remelted and directionally solidified to observe the wetting characteristics of the alloys as well as the effect on structure of solidification in the constrained field of the fiber interstices. Models for monotectic growth are modified to take into account solidification in these constrained fields.

  13. Cement radwaste solidification studies third annual report

    International Nuclear Information System (INIS)

    Brown, D.J.; James, J.M.; Lee, D.J.; Smith, D.L.; Walker, A.T.

    1982-03-01

    This report summarises cement radwaste studies carried out at AEE Winfrith during 1981 on the encapsulation of medium and low active waste in cement. During the year more emphasis has been placed on the work which is directly related to the solidification of SGHWR active sludge. Information has been obtained on the properties of 220 dm 3 drums of cemented waste. The use of cement grouts for the encapsulation of solid items has also been investigated during 1981. (U.K.)

  14. Initial stages of solidification of eutectic alloys

    International Nuclear Information System (INIS)

    Lemaignan, Clement

    1980-01-01

    The study of the various initial stages of eutectic solidification - i.e. primary nucleation, eutectic structure formation and stable growth conditions - was undertaken with various techniques including low angle neutron diffusion, in-situ electron microscopy on solidifying alloys and classical metallography. The results obtained allow to discuss the effect of metastable states during primary nucleation, of surface dendrite during eutectic nucleation and also of the crystallographic anisotropy during growth. (author) [fr

  15. Technical evaluation of the ATI volume reduction and bitumen solidification topical report

    International Nuclear Information System (INIS)

    Henscheid, J.W.; Young, T.E.

    1985-01-01

    This report summarizes EG and G Idaho's review of the Associated Technologies Inorporated (ATI) topical report on a Volume Reduction and Bitumen Solidification System. The review evaluated compliance with pertinent codes, standards and regulations. The initial review was discussed with ATI, and all outstanding issues resolved before this final evaluation was made

  16. Polyethylene solidification of low-level wastes

    International Nuclear Information System (INIS)

    Kalb, P.D.; Colombo, P.

    1985-02-01

    This topical report describes the results of an investigation on the solidification of low-level radioactive waste in polyethylene. Waste streams selected for this study included those which result from advanced volume reduction technologies (dry evaporator concentrate salts and incinerator ash) and those which remain problematic for solidification using contemporary agents (ion exchange resins). Four types of commercially available low-density polyethylenes were employed which encompass a range of processing and property characteristics. Process development studies were conducted to ascertain optimal process control parameters for successful solidification. Maximum waste loadings were determined for each waste and polyethylene type. Property evaluation testing was performed on laboratory-scale specimens to assess the potential behavior of actual waste forms in a disposal environment. Waste form property tests included water immersion, deformation under compressive load, thermal cycling and radionuclide leaching. Recommended waste loadings of 70 wt % sodium sulfate, 50 wt % boric acid, 40 wt % incinerator ash, and 30 wt % ion exchange resins, which are based on process control and waste form performance considerations are reported. 37 refs., 33 figs., 22 tabs

  17. Radwaste volume reduction and solidification by General Electric

    International Nuclear Information System (INIS)

    Green, T.A.; Weech, M.E.; Miller, G.P.; Eberle, J.W.

    1982-01-01

    Since 1978 General Electric has been actively engaged in developing a volume reduction and solidifcation system or treatment of radwaste generated in commercial nuclear power plants. The studies have been aimed at defining an integrated system that would be directly responsive to the rapid evolving needs of the industry for the volume reduction and solidification of low-level radwaste. The resulting General Electric Volume Reduction System (GEVRS) is an integrated system based on two processes: the first uses azeotropic distillation technology and is called AZTECH, and the second is controlled-air incineration...called INCA. The AZTECH process serves to remove water from concentrated salt solutions, ion exchange resins and filter sludge slurries and then encapsulates the dried solids into a dense plastic product. The INCA unit serves to reduce combustible wastes to ashes suitable for encapsulation into the same plastic product produced by AZTECH

  18. Direct numerical simulation of solidification microstructures affected by fluid flow

    International Nuclear Information System (INIS)

    Juric, D.

    1997-12-01

    The effects of fluid flow on the solidification morphology of pure materials and solute microsegregation patterns of binary alloys are studied using a computational methodology based on a front tracking/finite difference method. A general single field formulation is presented for the full coupling of phase change, fluid flow, heat and solute transport. This formulation accounts for interfacial rejection/absorption of latent heat and solute, interfacial anisotropies, discontinuities in material properties between the liquid and solid phases, shrinkage/expansion upon solidification and motion and deformation of the solid. Numerical results are presented for the two dimensional dendritic solidification of pure succinonitrile and the solidification of globulitic grains of a plutonium-gallium alloy. For both problems, comparisons are made between solidification without fluid flow and solidification within a shear flow

  19. Containerless solidification of undercooled oxide and metallic eutectic melts

    International Nuclear Information System (INIS)

    Li Mingjun; Nagashio, Kosuke; Kuribayashi, Kazuhiko

    2004-01-01

    A high-speed video was employed to monitor the in situ recalescence of undercooled oxide Al 2 O 3 -36.8 at.% ZrO 2 and metallic Ni-18.7 at.% Sn eutectics that were processed on an aero-acoustic levitator and an electromagnetic levitator, respectively. For the oxide eutectic, the entire sample becomes brighter and brighter without any clear recalescence front during spontaneous crystallization. When the sample was seeded at desired undercoolings, crystallization started from the seeding point and then spread through the entire sample. Microstructures of the oxide solidified via both the spontaneous crystallization and external seeding consist of many independent eutectic colonies at the sample surface, indicating that copious nucleation takes place regardless of melt undercooling and solidification mode. For the metallic eutectics, two kinds of recalescence are visualized. The surface and cross sectional microstructures reveal that copious nucleation is also responsible for the formation of independent eutectic colonies distributing within the entire sample. It is not possible to measure the growth velocity of a single eutectic colony using optical techniques under the usual magnification. The conventional nucleation concept derived from single-phase alloys may not be applicable to the free solidification of the undercooled double-phase oxide and metallic eutectic systems

  20. Wax solidification of drying agents containing tritiated water

    International Nuclear Information System (INIS)

    Mishikawa, M.; Kido, H.

    1984-01-01

    It is necessary to immobilize the tritium not to give any impact on the environmental biosphere because tritium may give profound effects in the metabolic pathway. One of the most probable methods of immobilizing tritium would be incorporation of tritiated water in solid forms. Any drying or dehydration technique would be effective in a tritium cleanup system for off-gas streams containing tritium or tritiated water. Commonly used drying agents such as activated alumina, silica gel, molecular sieves and calcium sulfate are of value for removal of water vapour from air or other gases. For long term tritium storage, however, these adsorptive materials should be enveloped to prevent contact with water or water vapour because the rate of leaching, evaporation or diffusion of tritium from these porous materials is so large. The beeswax solidification method of the packed bed of drying agents adsorbing tritiated water is developed in this study, where the wax solidification procedure is performed by pouring the melt of wax into the void space of the packed bed of the drying agents and successive gradual cooling. The observed values of diffusivity or permeability of tritium in the wax solidified materials are about one-thousandth of those obtained for the cement block. Effect of coating on the rate of leaching is also discussed

  1. Mechanism of flow reversal during solidification of an anomalous liquid

    Science.gov (United States)

    Kumar, Virkeshwar; Kumawat, Mitesh; Srivastava, Atul; Karagadde, Shyamprasad

    2017-12-01

    In a wide variety of fluidic systems involving thermal and compositional gradients, local density changes lead to the onset of natural convection that influences the process itself, for example, during phase-change phenomena and magmatic flows. Accurate knowledge of the flow characteristics is essential to quantify the impact of the flow of the processes. In this work, the first-ever demonstration of flow reversal during bottom-up solidification of water using full-field thermal and flow measurements and its direct impact on the solidifying interface is presented. Based on prior optical interferometric measurements of full-field temperature distribution in water during solidification, we use the particle image velocimetry technique to quantify and reveal the changing natural convection pattern arising solely due to the density anomaly of water between 0 °C and 4 °C. The independently captured thermal and flow fields show striking similarities and clearly elucidate the plausible mechanism explaining the formation of a curved interface at the stagnation point and the subsequent reversal of flow direction due to a changed interface morphology. A control volume analysis is further presented to estimate the energy invested in the formation of a perturbation and the resulting flip in the flow direction caused by this perturbation.

  2. Solidification process for toxic and hazardous wastes. Second part: Cement solidification matrices

    International Nuclear Information System (INIS)

    Donato, A.; Arcuri, L.; Dotti, M.; Pace, A.; Pietrelli, L.; Ricci, G.; Basta, M.; Cali, V.; Pagliai, V.

    1989-05-01

    This paper reports the second part of a general study carried out at the Nuclear Fuel Division aiming at verifying the possible application of the radioactive waste solidification processes to industrial hazardous wastes (RTN). The cement solidification of several RTN types has been taken into consideration, both from the technical and from the economic point of view. After a short examination of the Italian juridical and economical situation in the field, which demonstrates the need of the RTN solidification, the origin and characteristics of the RTN considered in the study and directly provided by the producing industries are reviewed. The laboratory experimental results of the cementation of RTN produced by gold manufacturing industries and by galvanic industries are reported. The cementation process can be considered a very effective mean for reducing both the RTN management costs and the environmental impact of RTN disposal. (author)

  3. On the Role of Mantle Overturn during Magma Ocean Solidification

    Science.gov (United States)

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

    2017-12-01

    Solidification of potential global magma ocean(s) (MO) early in the history of terrestrial planets may play a key role in the evolution of planetary interiors by setting initial conditions for their long-term evolution. Constraining this initial structure of solid mantles is thus crucial but remains poorly understood. MO fractional crystallization has been proposed to generate gravitationally unstable Fe-Mg chemical stratification capable of driving solid-state mantle overturn. Fractional solidification and overturn hypothesis, while only an ideal limiting case, can explain important geochemical features of both the Moon and Mars. Current overturn models consider generally post-MO overturn where the cumulate pile remains immobile until the end of MO solidification. However, if the cumulate pile overturns during MO solidification, the general picture of early planet evolution might differ significantly from the static crystallization models. We show that the timing of mantle overturn can be characterized with a dimensionless number measuring the ratio of the MO solidification time and the purely compositional overturn timescale. Syn-solidification overturn occurs if this dimensionless parameter, Rc, exceeds a critical value. Rc is mostly affected by the competition between the MO solidification time and mantle viscosity. Overturn that occurs during solidification can result in smaller scales of mantle chemical heterogeneity that could persist for long times thus influencing the whole evolution of a planetary body. We will discuss the effects of compaction/percolation on mantle viscosity. If partially molten cumulate do not have time to compact during MO solidification, viscosity of cumulates would be significantly lower as the interstitcial melt fraction would be large. Both solid mantle remelting during syn-solidification overturn and porous convection of melt retained with the cumulates are expected to reduce the degree of fractional crystallization. Syn-solidification

  4. Containerless solidification of acoustically levitated Ni-Sn eutectic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Geng, D.L.; Xie, W.J.; Wei, B. [Northwestern Polytechnical University, Department of Applied Physics, Xi' an (China)

    2012-10-15

    Containerless solidification of Ni-18.7at%Sn eutectic alloy has been achieved with a single-axis acoustic levitator. The temperature, motion, and oscillation of the sample were monitored by a high speed camera. The temperature of the sample can be determined from its image brightness, although the sample moves vertically and horizontally during levitation. The experimentally observed frequency of vertical motion is in good agreement with theoretical prediction. The sample undergoes shape oscillation before solidification finishes. The solidification microstructure of this alloy consists of a mixture of anomalous eutectic plus regular lamellar eutectic. This indicates the achievement of rapid solidification under acoustic levitation condition. (orig.)

  5. Solidification and vitrification life-cycle economics study

    International Nuclear Information System (INIS)

    Gimpel, R.F.

    1992-01-01

    Solidification (making concrete) and vitrification (making glass) are frequently the treatment methods recommended for treating inorganic or radioactive wastes. Ex-situ solidification and vitrification are the competing methods for treating in excess of 450 000 cm 3 of low-level radioactive and mixed wastes at the Fernald Environmental Management Project (FEMP) located near Cincinnati, Ohio. This paper summarizes a detailed study done to: (1) compare the economics of the solidification and vitrification processes, (2) determine if the stigma assigned to vitrification is warranted and, (3) determine if investing millions of dollars into vitrification development, along with solidification development, at Fernald is warranted

  6. Solidification of Hypereutectic Thin Wall Ductile Cast Iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2006-01-01

    solidification. The first stage, which was relatively short, had none or very little recalescence. Further under cooling, followed by reheating during recalescence, was necessary to initiate the second part of the eutectic solidification. Both the secondary under cooling and recalescence was larger in the 3 mm...... a higher Si content in the ferrite around the larger nodules compared to the ferrite around the rest of the nodules. This indicates that solidification took place along the following path: The solidification starts with nucleation and growth of primary graphite nodules. This probably starts during...

  7. Fluid bed dryer and Aeropep solidification system

    International Nuclear Information System (INIS)

    1975-01-01

    Performance measurements were made on the model of the Fluidized-bed Calciner developed by Aerojet Liquid Rocket Co. The measurements were made over the period August 11-19, 1975, at the Sacramento location of the calciner. The purpose of the tests was to evaluate the performance of the ALRC Fluidized Bed Concentrator for the processing of simulated waste containing realistic concentrations and chemical forms of radioiodine. (auth)

  8. Immobilisation/solidification of hazardous toxic waste in cement matrices

    Directory of Open Access Journals (Sweden)

    Macías, A.

    1999-06-01

    Full Text Available Immobilization and solidification of polluting waste, introduced into the industrial sector more than 20 years ago, and throughout last 10 years is being the object of a growing interest for engineers and environment scientists, has become a remarkable standardized process for treatment and management of toxic and hazardous liquid wastes, with special to those containing toxic metals. Experimental monitorization of the behaviour of immobilized waste by solidification and stabilisation in life time safe deposits is not possible, reason why it is essential to develop models predicting adequately the behaviour of structures that have to undergo a range of conditions simulating the environment where they are to be exposed. Such models can be developed only if the basic physical and chemical properties of the system matrix/solidifying-waste are known. In this work immobilization/solidification systems are analyzed stressing out the formulation systems based on Portland cement. Finally, some examples of the results obtained from the study of interaction of specific species of wastes and fixation systems are presented.

    La inmovilización y solidificación de residuos contaminantes, implantada en el sector comercial desde hace más de 20 años y que desde hace diez es objeto de creciente interés por parte de ingenieros y científicos medioambientales, se ha convertido en un proceso estandarizado único para el tratamiento y gestión de residuos tóxicos y peligrosos líquidos y, en especial, de los que contienen metales pesados. La monitorización experimental del comportamiento de un residuo inmovilizado por solidificación y estabilización en el tiempo de vida de un depósito de seguridad no es posible, por lo que es imprescindible desarrollar modelos que predigan satisfactoriamente el comportamiento del sistema bajo un rango representativo de condiciones del entorno de exposición. Tales modelos sólo pueden ser desarrollados si se

  9. Phase-field simulation of peritectic solidification closely coupled with directional solidification experiments in an Al-36 wt% Ni alloy

    International Nuclear Information System (INIS)

    Siquieri, R; Emmerich, H; Doernberg, E; Schmid-Fetzer, R

    2009-01-01

    In this work we present experimental and theoretical investigations of the directional solidification of Al-36 wt% Ni alloy. A phase-field approach (Folch and Plapp 2005 Phys. Rev. E 72 011602) is coupled with the CALPHAD (calculation of phase diagrams) method to be able to simulate directional solidification of Al-Ni alloy including the peritectic phase Al 3 Ni. The model approach is calibrated by systematic comparison to microstructures grown under controlled conditions in directional solidification experiments. To illustrate the efficiency of the model it is employed to investigate the effect of temperature gradient on the microstructure evolution of Al-36 wt% Ni during solidification.

  10. Solidification of radioactive incinerator ash

    International Nuclear Information System (INIS)

    Schuler, T.F.; Charlesworth, D.L.

    1986-01-01

    The Ashcrete process will solidify ash generated by the Beta Gamma Incinerator (BGI) at the Savannah River Plant (SRP). The system remotely handles, adds material to, and tumbles drums of ash to produce ashcrete, a stabilized wasteform. Full-scale testing of the Ashcrete unit began at Savannah River Laboratory (SRL) in January 1984, using nonradioactive ash. Tests determined product homogeneity, temperature distribution, compressive strength, and final product formulation. Product formulations that yielded good mix homogeneity and final product compressive strength were developed. Drum pressurization and temperature rise (resulting from the cement's heat of hydration) were also studied to verify safe storage and handling characteristics. In addition to these tests, an expert system was developed to assist process troubleshooting

  11. Solidification of ion exchange resin wastes

    International Nuclear Information System (INIS)

    1982-08-01

    Solidification media investigated included portland type I, portland type III and high alumina cements, a proprietary gypsum-based polymer modified cement, and a vinyl ester-styrene thermosetting plastic. Samples formulated with hydraulic cement were analyzed to investigate the effects of resin type, resin loading, waste-to-cement ratio, and water-to-cement ratio. The solidification of cation resin wastes with portland cement was characterized by excessive swelling and cracking of waste forms, both after curing and during immersion testing. Mixed bed resin waste formulations were limited by their cation component. Additives to improve the mechanical properties of portland cement-ion exchange resin waste forms were evaluated. High alumina cement formulations dislayed a resistance to deterioration of mechanical integrity during immersion testing, thus providing a significant advantage over portland cements for the solidification of resin wastes. Properties of cement-ion exchange resin waste forms were examined. An experiment was conducted to study the leachability of 137 Cs, 85 Sr, and 60 Co from resins modified in portland type III and high alumina cements. The cumulative 137 Cs fraction release was at least an order of magnitude greater than that of either 85 Sr or 60 Co. Release rates of 137 Cs in high alumina cement were greater than those in portland III cement by a factor of two.Compressive strength and leach testing were conducted for resin wastes solidified with polymer-modified gypsum based cement. 137 Cs, 85 Sr, and 60 Co fraction releases were about one, two and three orders of magnitude higher, respectively, than in equivalent portland type III cement formulations. As much as 28.6 wt % dry ion exchange resin was successfully solidified using vinyl ester-styrene compared with a maximum of 25 wt % in both portland and gypsum-based cement

  12. Alternative solidification techniques for radioactive ion exchange resins and liquid concentrates

    International Nuclear Information System (INIS)

    Thegerstroem, C.

    1980-01-01

    Methods, that are used or are under development for solidification of radioactive ion exchange resins or liquid concentrates, utilize normally cement, bitumen or some polymere as matrix material. This report contains a review and a description of these solidification processes and their products, especially of relatively new techniques that are under development in different countries. It is possible that solidification in thermosetting resins will be more used in the future, especially when product quality requirements are high (for instance when solidifying medium level resins) or when special waste categories has to be solidified. However it is not probable that thermosetting resins will be extensively used in a broad application as matrix material. In that case the methods are to complicated and expensive compared to, for instance, solidification in concrete. Systems for incorporation in polyesteremulsions (Dow-process) have a potential as they are quite simple and can accept a large variation of liquid wastes. Some methods in an early stage of development (for instance Inert Carrier Radwaste Process) will have to be tested in active application before they can be further evaluated. (author)

  13. [Solidification of volatile oil with graphene oxide].

    Science.gov (United States)

    Yan, Hong-Mei; Jia, Xiao-Bin; Zhang, Zhen-Hai; Sun, E; Xu, Yi-Hao

    2015-02-01

    To evaluate the properties of solidifying volatile oil with graphene oxide, clove oil and zedoary turmeric oil were solidified by graphene oxide. The amount of graphene oxide was optimized with the eugenol yield and curcumol yield as criteria. Curing powder was characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The effects of graphene oxide on dissolution in vitro and thermal stability of active components were studied. The optimum solidification ratio of graphene oxide to volatile oil was 1:1. Dissolution rate of active components had rare influence while their thermal stability improved after volatile oil was solidified. Solidifying herbal volatile oil with graphene oxide deserves further study.

  14. Interface stability during rapid directional solidification

    International Nuclear Information System (INIS)

    Hoglund, D.E.; Aziz, M.J.

    1992-01-01

    This paper reports that at the solidification velocities observed during pulsed laser annealing, the planar interface between solid and liquid is stabilized by capillarity and nonequilibrium effects such as solute trapping. The authors used Rutherford backscattering and electron microscopy to determine the nonequilibrium partition coefficient and critical concentration for breakdown of the planar interface as a function of interface velocity for Sn-implanted silicon. This allows the authors to test the applicability of the Mulliins-Sekerka stability theory to interfaces not in local equilibrium and to test the Coriell-Sekerka and other theories for oscillatory instabilities

  15. Spray solidification of nuclear waste

    International Nuclear Information System (INIS)

    Bonner, W.F.; Blair, H.T.; Romero, L.S.

    1976-08-01

    The spray calciner is a relatively simple machine. Operation is simple and is easily automated. Startup and shutdown can be performed in less than an hour. A wide variety of waste compositions and concentrations can be calcined under easily maintainable conditions. Spray calcination of high-level and mixed high- and intermediate-level liquid wastes has been demonstrated. Waste concentrations of from near infinite dilution to less than 225 liters per tonne of fuel are calcinable. Wastes have been calcined containing over 2M sodium. Feed concentration, composition, and flowrate can vary rapidly by over a factor of two without requiring operator action. Wastes containing mainly sodium cations can be spray calcined by addition of finely divided silica to the feedstock. A remotely replaceable atomizing nozzle has been developed for use in plant-scale equipment. Calciner capacity of over 75 l/h has been demonstrated in pilot-scale equipment. Sintered stainless steel filters are effective in deentraining over 99.9 percent of the solids that result from calcining the feedstock. The volume of recycle required from the effluent treatment system is very small. Vibrator action maintains the calcine holdup in the calciner at less than 1 kg. Successful remote operation and maintenance of a heated-wall spray calciner have been demonstrated while processing high-level waste. Radionuclide volatilization was acceptably low

  16. The solidification of radioactive waste

    International Nuclear Information System (INIS)

    Nagaya, Kiichi; Fujimoto, Yoshio; Hashimoto, Yasuo; Nomura, Ichiro

    1985-01-01

    A previous paper covered the decomposition and vitrification of Na 2 SO 4 (the primary component of the liquid waste from BWR) with silica. Now, in order to establish an integrated treatment system for the radioactive waste from BWR, this paper examines the effects of combining incinerator ash and other incinerator wastes with radioactive waste on the durability of the final vitrified products. A bench scale test plat consisting of a waiped file evaporator/dryer, a Joule-heated glass melter and SO 2 absorber was therefore put into operation and run safety for a period of 3000 hours. The combination of the radioactive waste with incinerator ash and the secondary waste of the incinerator was found to make no difference on the durability of the final vitrified products effecting no increase or decrease. Durability similar to that displayed in the beaker tests was proven, with the final vitrified products exhibiting a leaching rate less than 3 x 10 -4 g/cm 2 /day at 95 deg C. (author)

  17. Solidification with back-diffusion of irregular eutectics

    Directory of Open Access Journals (Sweden)

    M. Trepczyńska-Łent

    2008-10-01

    Full Text Available The definition of the α - parameter back-diffusion has been introduced in the work. The alternative models of solidification were describedtaking into consideration back-diffusion process. The possibility of using those models for eutectic alloys solidification is worthyof interest.

  18. The solidification velocity of nickel and titanium alloys

    Science.gov (United States)

    Altgilbers, Alex Sho

    2002-09-01

    The solidification velocity of several Ni-Ti, Ni-Sn, Ni-Si, Ti-Al and Ti-Ni alloys were measured as a function of undercooling. From these results, a model for alloy solidification was developed that can be used to predict the solidification velocity as a function of undercooling more accurately. During this investigation a phenomenon was observed in the solidification velocity that is a direct result of the addition of the various alloying elements to nickel and titanium. The additions of the alloying elements resulted in an additional solidification velocity plateau at intermediate undercoolings. Past work has shown a solidification velocity plateau at high undercoolings can be attributed to residual oxygen. It is shown that a logistic growth model is a more accurate model for predicting the solidification of alloys. Additionally, a numerical model is developed from simple description of the effect of solute on the solidification velocity, which utilizes a Boltzmann logistic function to predict the plateaus that occur at intermediate undercoolings.

  19. ''New ' technology of solidification of liquid radioactive waste'

    International Nuclear Information System (INIS)

    Sytyl, V.A.; Svistova, L.M.; Spiridonova, V.P.

    1998-01-01

    It is generally accepted that the best method of processing of radioactive waste is its solidification and then storage. At present time, three methods of solidification of radioactive waste are widely used in the world: cementation, bituminous grouting and vitrification. But they do not solve the problem of ecologically processing of waste because of different disadvantages. General disadvantages are: low state of filling, difficulties in solidification of the crystalline hydrated forms of radioactive waste; particular sphere of application and economical difficulties while processing the great volume of waste. In connection with it the urgent necessity is emerging: to develop less expensive and ecologically more reliable technology of solidification of radioactive waste. A new method of solidification is presented with its technical schema. (N.C.)

  20. Solidification of salt solutions on a horizontal surface

    International Nuclear Information System (INIS)

    Braga, S.L.; Viskanta, R.

    1990-01-01

    The freezing of water-salt solutions on a horizontal wall is investigated experimentally and theoretically. The growth of the solid-liquid region is observed for NaCl - H sub(2)O and N H sub(4)Cl - H sub(2)O systems under different temperature and concentration conditions. A unidirectional mathematical model is used to predict the solidification process. The transport of heat is by diffusion, and convection is absent. The mass diffusion is neglected and the growth of crystal is governed by the transport of heat. In all experiments, the solution salt concentration is smaller than the eutectic composition, and the wall temperature is higher than the eutectic temperature. The predicted temperature and salt concentration profiles, as well as the interface position, are compared with experimental data. (author)

  1. The melting and solidification of nanowires

    International Nuclear Information System (INIS)

    Florio, B. J.; Myers, T. G.

    2016-01-01

    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.

  2. The melting and solidification of nanowires

    Science.gov (United States)

    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.

  3. Solidification microstructure of centrifugally cast Inconel 625

    Directory of Open Access Journals (Sweden)

    Silvia Barella

    2017-07-01

    Full Text Available Centrifugal casting is a foundry process allowing the production of near net-shaped axially symmetrical components. The present study focuses on the microstructural characterization of centrifugally cast alloys featuring different chemical compositions for the construction of spheres applied in valves made of alloy IN625 for operation at high pressure. Control of the solidification microstructure is needed to assure the reliability of the castings. Actually, a Ni-base superalloy such as this one should have an outstanding combination of mechanical properties, high temperature stability and corrosion resistance. Alloys such as IN625 are characterised by a large amount of alloying elements and a wide solidification range, so they can be affected by micro-porosity defects, related to the shrinkage difference between the matrix and the secondary reinforcing phases (Nb-rich carbides and Laves phase. In this study, the microstructure characterization was performed as a function of the applied heat treatments and it was coupled with a calorimetric analysis in order to understand the mechanism ruling the formation of micro-porosities that can assure alloy soundness. The obtained results show that the presence of micro-porosities is governed by morphology and by the size of the secondary phases, and the presence of the observed secondary phases is detrimental to corrosion resistance.

  4. The melting and solidification of nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Florio, B. J., E-mail: brendan.florio@ul.ie [University of Limerick, Mathematics Applications Consortium for Science and Industry (MACSI), Department of Mathematics and Statistics (Ireland); Myers, T. G., E-mail: tmyers@crm.cat [Centre de Recerca Matemàtica (Spain)

    2016-06-15

    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.

  5. Two-dimensional time-resolved X-ray diffraction study of directional solidification in steels

    International Nuclear Information System (INIS)

    Yonemura, Mitsuharu

    2009-01-01

    Full text: The high intensity heat source used for fusion welding creates steep thermal gradients of 100 degree C/s from 1800 degree Celsius. Further, the influence of a preferred orientation is serious for observation of a directional solidification that follows the dendrite growth along the direction toward the moving heat source. Therefore, we observed the rapid solidification of weld metal at a time resolution of 0.01∼0.1seconds by the Two-Dimensional Time-Resolved X-ray Diffraction (2DTRXRD) system for real welding. The diffraction ring was dynamically observed by 2DTRXRD during arc-passing over the irradiation area of X-ray with synchrotron energy of 18 KeV. The arc power output was 10 V - 150 A, and a scan speed of the arc was 1.0 mm/s. The temperature rise of instruments was suppressed by the water-cooled copper plate under the sample. Further, the temperature distribution of the weld metal was measured by the thermocouple and related to the diffraction patterns. Consequently, solidification and solid phase transformation of low carbon steels and stainless steels were observed during rapid cooling by 2DTRXRD. In the low-carbon steel, the microstructure is formed in the 2 step process; (i) formation of crystallites and (ii) increase of crystallinity. In the stainless steel, the irregular interface layer of σ/y in the quenched metal after solidification is expected that it is easy for dendrites to move at the lower temperature. In the carbide precipitation stainless steel, it is easy for NbC to grow on σ phase with a little under cooling. Further, a mist-like pattern, which differs from the halo-pattern, in the fusion zone gave some indication of the possibilities to observe the nucleation and the early solidification by 2DTRXRD. (author)

  6. Investigation on the formation of the preferred orientations in a TbDyFe alloy with directional solidification

    International Nuclear Information System (INIS)

    Jiang Chengbao; Xu Huibin

    1999-01-01

    The formation of the preferred orientations in a TbDyFe alloy was studied by transmission electron microscopy (TEM). It was found that there were several different preferred orientations in the experimental TbDyFe alloy with directional solidification. left angle 110 right angle, left angle 112 right angle and left angle 113 right angle preferred orientations were observed in this alloy solidified by our self-made super high gradient temperature directional solidification device. The preferred orientations changed with the variation of the solidification conditions. Two {111} twinning systems resulted in the left angle 110 right angle preferred orientation and a single {111} twinning system resulted in the left angle 112 right angle preferred orientation. The twinning displacement was observed and this formatted the left angle 113 right angle preferred orientation. (orig.)

  7. Droplet solidification and the potential for steam explosions

    International Nuclear Information System (INIS)

    Epstein, M.; Fauske, H.K.; Luangdilok, W.

    2009-01-01

    It is well known that under certain circumstances a mixture of coarse-hot (molten) drops in water formed from pouring a hot melt into water explodes. This so-called 'steam explosion' is generally believed to involve steam-bubble-collapse-induced fine fragmentation of the melt drops and concomitant water vaporization on a timescale that is short compared with the steam pressure relief time. Motivated by the idea put forth by Okkonen and Sehgal that rapid solidification would render UO 2 -containing (Corium) melt drops stiff and resistant to the steam-bubble-collapse-induced fragmentation required to support an explosion, here we combine solidification theory with an available theory of the stability of thin, submerged crusts subject to acceleration to predict the 'cutoff time' beyond which melt-drop fragmentation is suppressed by crust cover rigidity. Illustration calculations show that the cutoff time for Corium melt drops in water is a fraction of a second and probably shorter than the time it takes to form the explosion-prerequisite-coarse-premixture configuration of melt drops in water, while the opposite is true for the molten aluminum oxide/water system for which the window of opportunity for an explosion is predicted to be several seconds. These theoretical findings are consistent with early experiments that revealed molten uranium oxide or Corium pours into water to be non-explosive and that produced steam explosions upon pouring molten aluminum oxide into water. Also in this paper, the recent TROI Corium/water interaction experiments are examined and it is concluded that they do not contravene the earlier experimental observations that the pouring of prototypical Corium mixtures into water does not result in steam explosions with destructive potential. (author)

  8. Relationships Between Solidification Parameters in A319 Aluminum Alloy

    Science.gov (United States)

    Vandersluis, E.; Ravindran, C.

    2018-03-01

    The design of high-performance materials depends on a comprehensive understanding of the alloy-specific relationships between solidification and properties. However, the inconsistent use of a particular solidification parameter for presenting materials characterization in the literature impedes inter-study comparability and the interpretation of findings. Therefore, there is a need for accurate expressions relating the solidification parameters for each alloy. In this study, A319 aluminum alloy castings were produced in a permanent mold with various preheating temperatures in order to control metal cooling. Analysis of the cooling curve for each casting enabled the identification of its liquidus, Al-Si eutectic, and solidus temperatures and times. These values led to the calculation of the primary solidification rate, total solidification rate, primary solidification time, and local solidification time for each casting, which were related to each other as well as to the average casting SDAS and material hardness. Expressions for each of their correlations have been presented with high coefficients of determination, which will aid in microstructural prediction and casting design.

  9. A dendritic solidification experiment under large gravity - implications for the Earth's inner core solidification regime.

    Science.gov (United States)

    Deguen, R.; Alboussière, T.; Brito, D.; La Rizza, P.; Masson, J.

    2009-05-01

    The Earth's inner core solidification regime is usually thought to be dendritic, which should results in the formation of a mushy layer at the inner core boundary, possibly extending deep in the inner core. The release of latent heat and solute associated with crystallization provides an important boyancy source to drive thermo- chemical convection in the core. In the laboratory, two modes of convection associated with the crystallization of mushy layers have been observed. One is a boundary layer mode originating from the destabilisation of the chemical boundary layer present at the mush-liquid interface; the second is the so-called 'mushy layer mode' which involves the whole mushy layer. In the mushy layer mode, convection usually takes the form of narrow plumes rising through crystal free conduits called chimneys. One particularity of inner core crystallization is its extremely small solidification rate compared to typical outer core convective timescales. We have designed and build an experiment devoted to the study of crystallization under a large gravity field, using a centrifuge, of an aqueous solution of ammonium chloride, which is a good analogue to metallic alloys. The large gravity field allows to reach Rayleigh numbers much larger than in typical solidification experiments. Under large gravity fields, we observe the disappearance of chimney convection and show that the large gravity field promotes the boundary layer convection mode at the expent of the mushy layer mode. As the gravitationnal forcing is increased, convective heat and solute transport are significantly enhanced, which results in larger solid fraction directly below the mush-liquid interface. The increase in solid fraction results in a dramatic decrease of the permeability in the mushy layer, which eventually becomes subcritical in respect to the mushy layer mode. Because of the very slow solidification rate of the inner core, convective transport of heat and solute from the ICB is

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

    Science.gov (United States)

    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.

  11. Fluid flow solidification simulation of molten alloys

    International Nuclear Information System (INIS)

    Kaschnitz, E.

    1997-01-01

    In an effort to minimize costs and to obtain optimum designs, computer simulation of shape casting processes is more and more used as a development tool. Accurate predictions are possible by means of three dimensional fluid flow and solidification modelling. The bases of the model are the transient laminar Navier-Stokes-equations for a Newtonian fluid including the tracking of the free surface. They are describing the melt flow pattern during the mold filling sequence. Simultaneously, the temperature development in the alloy and mold is calculated using Fourier's heat transfer equation. At OEGI, a commercial software package (MAGMAsoft) with a finite difference equation solver is used for improvement of casting processes. Different examples of industrial applications will be shown. (author)

  12. Simulation of continuous cast steel product solidification

    Directory of Open Access Journals (Sweden)

    Ardelean, E.

    2007-06-01

    Full Text Available Primary cooling – inside the tundish – has a great impact over the thickness of the solidified steel crust. If on exiting the tundish the crust is too thin, it can punch and break, as a result of the ferrostatic pressure exerted from the inside by the liquid steel as well as because of the weight of the molten steel. The parameters that influence the amount of dissipated heat depend on the cooling water flow of the tundish, on the pressure and temperature of the cooling water but also on the overheating of the continuously cast steel. The secondary cooling takes place at the exit of the semi-finished product from the tundish, when the solidification is supposed to take place all along the cross section of the strand. In order to achieve it, in addition to a correctly managed primary cooling, it is necessary to obtain the proper correlation of the factors that influence the secondary cooling as well: the water flow rate long the three zones of the installation and its pressure in the secondary circuit. All these have in view a proper solidification length; an intense cooling can generate cracks due to the thermal stress, while a too slow cooling can generate a partial solidification of the strand up to the cropping machine area. The paper presents a mathematical simulation of the continuously cast steel solidification.

    El enfriamiento primario del cristalizador tiene una gran importancia sobre el espesor de la costra de acero solidificado. Si al salir del cristalizador, esta costra es demasiado sutil, bajo la acción de la presión ferro estática ejercitada por el acero líquido del interior y gracias el peso propio del hilo, ésta, puede perforar resultando su rompimiento. Los parámetros que influenyen sobre la cantidad de calor cedida dependen del agua de enfriamiento del catalizador, de la presión y de la temperatura de agua de enfriamiento, pero también del sobrecalentamiento del acero fundido continuamente. A la salida del

  13. Evaluation of stabilization-solidification techniques

    International Nuclear Information System (INIS)

    Goubier, R.

    1989-01-01

    This paper reports that among the techniques applied to treat polluting residue in France for the past ten years has been the mixing of pollutants with reactive agents in order to fix the contaminants and to give them a solid consistency. The first applications of these stabilization/solidification processes occurred in 1978 in the treatment of oil residues from the AMOCO CADIZ spill. They have also been used for the treatment of a mayor dump site for petroleum residues, for the disposal of mineral sludges of a detoxication plant, and for the rehabilitation of sites contaminated by various industrial residues, specially acid tars generated by oil refining plants. Although from the beginning these techniques appeared to be able to transform filthy lagoons into solid and apparently safe areas, it was necessary to evaluate their efficiency and to determine the conditions and limits of application

  14. Plastic solidification method for radioactive waste

    International Nuclear Information System (INIS)

    Tomita, Toshihide; Inakuma, Masahiko.

    1992-01-01

    Condensed liquid wastes in radioactive wastes are formed by mixing and condensing several kinds of liquid wastes such as liquid wastes upon regeneration of ion exchange resins, floor draining liquid wastes and equipment draining liquid wastes. Accordingly, various materials are contained, and it is found that polymerization reaction of plastics is inhibited especially when reductive material, such as sodium nitrite is present. Then, in the present invention, upon mixing thermosetting resins to radioactive wastes containing reducing materials, an alkaline material is admixed to an unstaturated polyester resin. This can inactivate the terminal groups of unsaturated polyester chain, to prevent the dissociation of the reducing agent such as sodium nitrite. Further, if an unsaturated polyester resin of low acid value and a polymerization initiator for high temperature are used in addition to the alkaline material, the effect is further enhanced, thereby enabling to obtain a strong plastic solidification products. (T.M.)

  15. Solidification paths in modified Inconel 625 weld overlay material

    DEFF Research Database (Denmark)

    Chandrasekaran, Karthik; Tiedje, Niels Skat; Hald, John

    2009-01-01

    Inconel 625 is commonly used for overlay welding to protect the base metal against high temperature corrosion. The efficiency of corrosion protection depends on effective mixing of the overlay weld with the base metal and the subsequent segregation of alloy elements during solidification....... Metallographic analysis of solidified samples of Inconel 625 with addition of selected elements is compared with thermodynamic modelling of segregation during solidification. The influence of changes in the melt chemistry on the formation of intermetallic phases during solidification is shown. In particular...

  16. Inverse thermal analysis method to study solidification in cast iron

    DEFF Research Database (Denmark)

    Dioszegi, Atilla; Hattel, Jesper

    2004-01-01

    Solidification modelling of cast metals is widely used to predict final properties in cast components. Accurate models necessitate good knowledge of the solidification behaviour. The present study includes a re-examination of the Fourier thermal analysis method. This involves an inverse numerical...... solution of a 1-dimensional heat transfer problem connected to solidification of cast alloys. In the analysis, the relation between the thermal state and the fraction solid of the metal is evaluated by a numerical method. This method contains an iteration algorithm controlled by an under relaxation term...... inverse thermal analysis was tested on both experimental and simulated data....

  17. Solidification of problem wastes: Annual progress report, October 1985-September 1986

    International Nuclear Information System (INIS)

    Franz, E.M.; Heiser, J.H. III; Colombo, P.

    1987-02-01

    This report describes initial work on the development of solidification systems for sodium nitrate waste and compacted waste. Sodium nitrate waste has been solidified in three types of materials: polyethylene, polyester-styrene (PES), and latex cement. Evaluations of the properties of the waste form, such as the ANS 16.1 leaching test, water immersion test and compressive strength measurements were performed on the waste forms containing various amounts of sodium nitrate. 9 refs., 9 figs., 7 tabs

  18. Development of remote handling techniques for the HLLW solidification plant

    International Nuclear Information System (INIS)

    Tosha, Yoshitsugu; Iwata, Toshio; Inada, Eiichi; Nagaki, Hiroshi; Yamamoto, Masao

    1982-01-01

    To develop the techniques for the remote maintenance of the equipment in a HLLW (high-level liquid waste) solidification plant, the mock-up test facility (MTF) has been designed and constructed. Before its construction, the specific mock-up equipment was manufactured and tested. The results of the test and the outline of the MTF are described. As the mock-up equipment, a denitrater-concentrator, a ceramic melter and a canister handling equipment were selected. Remote operation was performed according to the maintenance program, and the evaluation of the component was conducted on the easiness of operation, performance, and the suitability to remote handling equipment. As a result of the test, four important elements were identified; they were guides, lifting fixtures, remote handling bolts, and remote pipe connectors. Many improvements of these elements were achieved, and reflected in the design of the MTF. The MTF is a steel-framed and slate-covered building (25 mL x 20 mW x 27 mH) with five storys of test bases. It contains the following four main systems: pretreatment and off-gas treatment system, glass melting system, canister handling system and secondary waste liquid recovery system. Further development of the remote maintenance techniques is expected through the test in the MTF. (Aoki, K.)

  19. The solidification of aluminum production waste in geopolymer matrix

    Czech Academy of Sciences Publication Activity Database

    Perná, Ivana; Hanzlíček, Tomáš

    2014-01-01

    Roč. 84, DEC 1 (2014), s. 657-662 ISSN 0959-6526 Institutional support: RVO:67985891 Keywords : aluminum waste * solidification * recycling * geopolymer Subject RIV: DM - Solid Waste and Recycling Impact factor: 3.844, year: 2014

  20. Particle Trapping and Banding in Rapid Colloidal Solidification

    KAUST Repository

    Elliott, J. A. W.; Peppin, S. S. L.

    2011-01-01

    We derive an expression for the nonequilibrium segregation coefficient of colloidal particles near a moving solid-liquid interface. The resulting kinetic phase diagram has applications for the rapid solidification of clay soils, gels, and related

  1. Effect Of Natural Convection On Directional Solidification Of Pure Metal

    Directory of Open Access Journals (Sweden)

    Skrzypczak T.

    2015-06-01

    Full Text Available The paper is focused on the modeling of the directional solidification process of pure metal. During the process the solidification front is sharp in the shape of the surface separating liquid from solid in three dimensional space or a curve in 2D. The position and shape of the solid-liquid interface change according to time. The local velocity of the interface depends on the values of heat fluxes on the solid and liquid sides. Sharp interface solidification belongs to the phase transition problems which occur due to temperature changes, pressure, etc. Transition from one state to another is discontinuous from the mathematical point of view. Such process can be identified during water freezing, evaporation, melting and solidification of metals and alloys, etc.

  2. Simulations of rapid pressure-induced solidification in molten metals

    International Nuclear Information System (INIS)

    Patel, Mehul V.; Streitz, Frederick H.

    2004-01-01

    The process of interest in this study is the solidification of a molten metal subjected to rapid pressurization. Most details about solidification occurring when the liquid-solid coexistence line is suddenly transversed along the pressure axis remain unknown. We present preliminary results from an ongoing study of this process for both simple models of metals (Cu) and more sophisticated material models (MGPT potentials for Ta). Atomistic (molecular dynamics) simulations are used to extract details such as the time and length scales that govern these processes. Starting with relatively simple potential models, we demonstrate how molecular dynamics can be used to study solidification. Local and global order parameters that aid in characterizing the phase have been identified, and the dependence of the solidification time on the phase space distance between the final (P,T) state and the coexistence line has been characterized

  3. ENGINEERING BULLETIN: SOLIDIFICATION/STABILIZATION OF ORGANICS AND INORGANICS

    Science.gov (United States)

    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...

  4. A review of the structure and function of vital registration system in Ghana: towards improvement in mortality data quality for health policy analysis

    Directory of Open Access Journals (Sweden)

    Julius N. Fobil

    2011-03-01

    Full Text Available Vital registration systems (VRS are important in the collection of routine data on indicators of development. These are particularly useful if they are properly built to address weaknesses in the system leading to poor data quality. For instance, routine data on health events (e.g. morbidity, mortality etc. are crucial for rapid assessment of disease burden and mortality trends in the population. They are also useful in the identification of vulnerable groups in populations. Despite their usefulness, VRS in many developing countries including Ghana are poorly structured raising questions about the quality of the output data from these systems. The present study aimed at assessing and documenting the structure and function of the VRS in Ghana, as well as at identifying the structural features that potentially compromise the reliability and validity of the output data the system. To perform this study, collection and review of policy and legal documents establishing the VRS, documentation and evaluation of component structures of the system, assessment of procedural protocols guiding data collection processes and in-depth interviews with staff at the Ghana Births and Deaths Registry were performed. The assessment of the structure of the Ghana VRS, policy documents setting it up and the operational procedures reveals important lapses (e.g. presence of outmoded practices, imperfections in Births and Deaths Registry Act, 1965, Act 301 and imperfect system design in the system that could compromise validity and reliability of the data generated from the registration in Ghana.

  5. Multi-scale Modeling of Dendritic Alloy Solidification

    OpenAIRE

    Dagner, Johannes

    2009-01-01

    Solidification of metallic melts is one of the most important processes in material science. The microstructure, which is formed during freezing, determines the mechanical properties of the final product largely. Many physical phenomena influence the solidification process and hence the resulting microstructure. One important parameter is influence of melt flow, which may modify heat and species transport on a large range of length- and time-scales. On the micro-scale, it influences the conce...

  6. Solute redistribution in dendritic solidification with diffusion in the solid

    Science.gov (United States)

    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.

  7. Autonomous Optimization of a Solidification Pattern and Its Effect on Porosity and Segregation in Steel Castings

    DEFF Research Database (Denmark)

    Kotas, Petr; Tutum, Cem Celal; Hattel, Jesper Henri

    2011-01-01

    The present paper considers optimization of a solidification pattern of a gravity sand-cast steel part. That is, the choice of proper riser and chill designs has been investigated using genetic algorithms while simultaneously considering their impact on centerline porosity and macrosegregation...... distribution. This was accomplished by coupling a casting simulation software package with an optimization module. The casting process of the original casting design was simulated using a transient 3D thermal model incorporated in a commercial simulation software package to determine potential flaws...... and inadequacies. After this initial assessment, a new geometrical model was suggested with the redesigned gating system and rearranged chills to obtain better filling and solidification patterns. Based on the improved model, relevant optimization targets and constraints were defined. One multi...

  8. Interfacial wave theory of pattern formation in solidification dendrites, fingers, cells and free boundaries

    CERN Document Server

    Xu, Jian-Jun

    2017-01-01

    This comprehensive work explores interfacial instability and pattern formation in dynamic systems away from the equilibrium state in solidification and crystal growth. Further, this significantly expanded 2nd edition introduces and reviews the progress made during the last two decades. In particular, it describes the most prominent pattern formation phenomena commonly observed in material processing and crystal growth in the framework of the previously established interfacial wave theory, including free dendritic growth from undercooled melt, cellular growth and eutectic growth in directional solidification, as well as viscous fingering in Hele-Shaw flow. It elucidates the key problems, systematically derives their mathematical solutions by pursuing a unified, asymptotic approach, and finally carefully examines these results by comparing them with the available experimental results. The asymptotic approach described here will be useful for the investigation of pattern formation phenomena occurring in a much b...

  9. In situ observations of solidification processes in γ-TiAl alloys by synchrotron radiation

    International Nuclear Information System (INIS)

    Shuleshova, Olga; Holland-Moritz, Dirk; Loeser, Wolfgang; Voss, Andrea; Hartmann, Helena; Hecht, Ulrike; Witusiewicz, Victor T.; Herlach, Dieter M.; Buechner, Bernd

    2010-01-01

    In situ observations of phase transformations involving melts are performed using energy-dispersive diffraction of synchrotron X-rays on electromagnetically levitated γ-TiAl alloys containing Nb. The determined primary solidification modes, confirmed by microstructure analysis, delivered new reliable data about the boundary of the α(Ti) solidification domain, which differs in the various Ti-Al-Nb phase diagram descriptions. These data have been used for a reassessment of the thermodynamic database of the ternary Ti-Al-Nb system. The new description realistically reflects the experimental findings. Liquidus and solidus temperatures determined by the pyrometric method agree fairly well with the calculated values. Direct experimental information on the nature of the reactions along the univariant lines is provided.

  10. Diffusivities of an Al-Fe-Ni melt and their effects on the microstructure during solidification

    International Nuclear Information System (INIS)

    Zhang Lijun; Du Yong; Steinbach, Ingo; Chen Qing; Huang Baiyun

    2010-01-01

    A systematical investigation of the diffusivities in an Al-Fe-Ni melt was presented. Based on the experimental and theoretical data about diffusivities, the temperature- and composition-dependent atomic mobilities were evaluated for the elements in Al-Ni, Al-Fe, Fe-Ni and Al-Fe-Ni melts via an effective approach. Most of the reported diffusivities can be reproduced well by the obtained atomic mobilities. In particular, for the first time the ternary diffusivity of the liquid in a ternary system is described in conjunction with the established atomic mobilities. The effect of the atomic mobilities in a liquid on microstructure and microsegregation during solidification was demonstrated with one Al-Ni binary alloy. The simulation results indicate that accurate databases of mobilities in the liquid phase are much needed for the quantitative simulation of microstructural evolution during solidification by using various approaches, including DICTRA and the phase-field method.

  11. Simulating solidification in metals at high pressure: The drive to petascale computing

    International Nuclear Information System (INIS)

    Streitz, Frederick H; Glosli, James N; Patel, Mehul V; Chan, Bor; Yates, Robert K; Supinski, Bronis R de; Sexton, James; Gunnels, John A

    2006-01-01

    We investigate solidification in metal systems ranging in size from 64,000 to 524,288,000 atoms on the IBM BlueGene/L computer at LLNL. Using the newly developed ddcMD code, we achieve performance rates as high as 103 TFlops, with a performance of 101.7 TFlop sustained over a 7 hour run on 131,072 cpus. We demonstrate superb strong and weak scaling. Our calculations are significant as they represent the first atomic-scale model of metal solidification to proceed, without finite size effects, from spontaneous nucleation and growth of solid out of the liquid, through the coalescence phase, and into the onset of coarsening. Thus, our simulations represent the first step towards an atomistic model of nucleation and growth that can directly link atomistic to mesoscopic length scales

  12. Melting/solidification characteristics of paraffin based nanocomposite for thermal energy storage applications

    Directory of Open Access Journals (Sweden)

    Lokesh Selvam

    2017-01-01

    Full Text Available The present work aimed to investigate the melting and solidification characteristics of nanoparticle enhanced phase change material (NEPCM. The NEPCM were prepared using paraffin as the phase change material and multiwall carbon nanotube (MWCNT as the nanomaterial without using any dispersant. Thermal conductivity of the NEPCM was measured with respect to temperature and the measured data showed higher enhancement than the phase change material both in liquid and solid state, due to inherent high conductive and the continuous networking of the MWCNT. A reduction in solidification and melting time of 42% and 29% was achieved in the case of NEPCM with 0.9% and 0.3%, respectively. It is concluded that enhanced heat transfer characteristics of NEPCM is highly beneficial towards design and development of efficient thermal energy storage system for various applications.

  13. Solidification and vitrification life-cycle economics study

    International Nuclear Information System (INIS)

    Gimpel, R.F.

    1992-01-01

    Solidification (making concrete) and vitrification (making glass) are frequently the treatment methods recommended for treating inorganic or radioactive wastes. Solidification is generally perceived as the most economical treatment method, whereas vitrification is considered (by many) as the most effective of all treatment methods. Unfortunately, vitrification has acquired the stigma that it is too expensive to receive further consideration as an alternative to solidification in high volume treatment applications. Ex situ solidification and vitrification are the competing methods for treating in excess of 450,000 m 3 of low-level radioactive and mixed waste at the Fernald Environmental Management Project (FEMP or simply, Fernald) located near Cincinnati, Ohio. This paper s a detailed study done to: compare the economics of the solidification and vitrification processes; determine if the stigma assigned to vitrification is warranted; determine if investing millions of dollars into vitrification development, along with solidification development, at Fernald is warranted. Common parameters were determined and detailed life-cycle cost estimates were made. Incorporating the unit costs into a computer spreadsheet allowed 'what if' scenarios to be performed. Some scenarios investigated included variation of: remediation times, amount of wastes treated, treatment efficiencies, electrical and material costs and escalation

  14. The solidification of low level radioactive organic fluids with Envirostone Gypsum Cement

    International Nuclear Information System (INIS)

    Rosenstiel, T.L.; Lange, R.G.

    1984-01-01

    The primary method for the management of low level radioactive waste (LLW) has been and continues to be the isolation of the waste in a solid mass. Of the four typical LLW streams, organic fluids pose the most significant waste isolation problem. The organic fluids comprised of lubrication oils, hydraulic fluids, sludges, scintillation fluids, etc., result from the operation and maintenance of nuclear power generating stations, research activities, tooling operations, and diagnostic analyses. The United States Gypsum Company developed the patented Envirostone Gypsum Cement system for the solidification of all types of low level radioactive wastes to facilitate handling and transportation to regulated LLW disposal sites. For the solidification of organic fluids, Envirostone Gypsum Cement is used in conjunction with Envirostone Emulsifier, selected for its ability to emulsify a broad range of organic fluids in aqueous solutions. In the solidification process it is theorized that as the crystalline matrix of the gypsum forms, the micelles of the emulsifier behave as a chemical bridge which draws the organic fluid into the crystalline structure via the hydration water. Initial testing of physical properties of solidified waste forms, including leachability, per the requirements and the procedures specified for 10 CFR Part 61 as outlined in the Branch Technical Position Report from the United States Nuclear Regulatory Commission were in progress as of the writing of this paper. Upon completion of this testing a Topical Report will be submitted to the USNRC for review and approval. The presentation reviews field experience in the use of Envirostone Gypsum Cement for the solidification of low level radioactive organic fluids from nuclear power generating stations and makes an economic comparison between Envirostone Gypsum Cement and portland cement systems

  15. Phase selection and microstructure in directional solidification of glass forming Pd-Si-Cu alloys

    Science.gov (United States)

    Huo, Yang

    Phase selection and microstructure formation during the rapid solidification of alloy melts has been a topic of substantial interest over the last several decades, attributed mainly to the access to novel structures involving metastable crystalline and non-crystalline phases. In this work, Bridgeman type directional solidification was conducted in Pd-Si-Cu glass forming system to study such cooling rate dependent phase transition and microstructure formation. The equilibrium state for Pd-Si-Cu ternary system was investigated through three different works. First of all, phase stabilities for Pd-Si binary system was accessed with respects of first-principles and experiments, showing Pd5Si, Pd9Si2, Pd3Si and Pd 2Si phase are stable all way to zero Kevin while PdSi phase is a high temperature stable phase, and Pd2Si phase with Fe2P is a non-stoichiometry phase. A thermodynamic database was developed for Pd-Si system. Second, crystal structures for compounds with ternary compositions were studied by XRD, SEM and TEM, showing ordered and disordered B2/bcc phases are stable in Pd-rich part. At last, based on many phase equilibria and phase transitions data, a comprehensive thermodynamic discrption for Pd-Si-Cu ternary system was first time to be developed, from which different phase diagrams and driving force for kinetics can be calculated. Phase selection and microstructure formation in directional solidification of the best glass forming composition, Pd 77.5Si16.5Cu6, in this system with growth velocities from 0.005 to 7.5mm/s was systematically studied and the solidification pathways at different conditions were interpreted from thermodynamic simulation. The results show that for growth velocities are smaller than 0.1mm/s Pd 3Si phase is primary phase and Pd9Si2 phase is secondary phase, the difficulty for Pd9Si2 phase nucleation gives rise to the formation of two different eutectic structure. For growth velocities between 0.4 and 1mm/s, instead of Pd3Si phase, Pd9Si2

  16. The effects of solidification on sill propagation dynamics and morphology

    Science.gov (United States)

    Chanceaux, L.; Menand, T.

    2016-05-01

    Sills are an integral part of the formation and development of larger plutons and magma reservoirs. Thus sills are essential for both the transport and the storage of magma in the Earth's crust. However, although cooling and solidification are central to magmatism, their effects on sills have been so far poorly studied. Here, the effects of solidification on sill propagation dynamics and morphology are studied by means of analogue laboratory experiments. Hot fluid vegetable oil (magma analogue), that solidifies during its propagation, is injected as a sill in a colder layered gelatine solid (elastic host rock analogue). The injection flux and temperature are maintained constant during an experiment and systematically varied between each experiment, in order to vary and quantify the amount of solidification between each experiments. The oil is injected directly at the interface between the two gelatine layers. When solidification effects are small (high injection temperatures and fluxes), the propagation is continuous and the sill has a regular and smooth surface. Inversely, when solidification effects are important (low injection temperatures and fluxes), sill propagation is discontinuous and occurs by steps of surface-area creation interspersed with periods of momentary arrest. The morphology of these sills displays folds, ropy structures on their surface, and lobes with imprints of the leading fronts that correspond to each step of area creation. These experiments show that for a given, constant injected volume, as solidification effects increase, the area of the sills decreases, their thickness increases, and the number of propagation steps increases. These results have various geological and geophysical implications. The morphology of sills, such as lobate structures (interpretation of 3D seismic studies in sedimentary basin) and ropy flow structures (field observations) can be related to solidification during emplacement. Moreover, a non-continuous morphology

  17. Electric melting furnace for waste solidification

    International Nuclear Information System (INIS)

    Masaki, Toshio.

    1990-01-01

    To avoid electric troubles or reduction of waste processing performance even when platinum group elements are contained in wastes to be applied with glass solidification. For this purpose, a side electrode is disposed to the side wall of a melting vessel and a central electrode serving as a counter electrode is disposed about at the center inside the melting vessel. With such a constitution, if conductive materials are deposited at the bottom of the furnace or the bottom of the melting vessel, heating currents flow selectively between the side electrode and the central electrode. Accordingly, no electric currents flow through the conductive deposits thereby enabling to prevent abnormal heating in the bottom of the furnace. Further, heat generated by electric supply between the side electrode and the central electrode is supplied efficiently to raw material on the surface of the molten glass liquid to improve the processing performance. Further, disposition of the bottom electrode at the bottom of the furnace enables current supply between the central electrode and the bottom electrode to facilitate the temperature control for the molten glass in the furnace than in the conventional structure. (I.S.)

  18. Glass solidification material confinement test device

    International Nuclear Information System (INIS)

    Namiki, Shigekazu.

    1997-01-01

    In a device for confining glass solidification materials, a pipeline connecting a detection vessel and a detector is formed to have a double walled structure, and air blowing holes are formed on the wall of the inner pipe, and an air supply mechanism is connected to inner and outer pipes for supplying blowing air thereby preventing deposition on the inner pipe wall. The air blowing holes are formed by constituting the pipe by using a porous sintered material and porous portions thereof are defined as the air blowing holes, or holes are formed on the pipe wall made of a metal by machining. A blowing boundary layer is formed by blowing the supplied air along the pipe wall of the inner pipe, by which deposition of the sucked materials to the inner wall of the inner pipe is prevented, and all of the materials sucked from the detection vessel are collected to the detector. In addition, an air exit pipe is formed into a double walled structure so as to be supplied blowing air from the air supply mechanism thereby enabling to prevent deposition of sucked materials more reliably. (N.H.)

  19. Method of manufacturing borosilicate glass solidification products

    International Nuclear Information System (INIS)

    Tanaka, Tsuneya.

    1986-01-01

    Purpose: To obtain glass solidification products efficiently in a dry process from medium and high level radioactive liquid wastes discharged from PWR type reactors. Method: Boric acid-containing radioactive liquid wastes generated from primary coolants of PWR type reactors are evaporated to condensate as the pre-treatment. The concentrated liquid wastes are supplied to a drum type rotary kiln. While on the other hand, usual glass frits are introduced into the kiln. The liquid wastes are dried in the rotary kiln, as well as B 2 O 3 and the glass frits in the liquid wastes are combined into glass particles. In this case, since the kiln is rotated, no glass particles are deposited on the wall of the kiln. Then, the glass particles are introduced for melting into a high frequency melting furnace made of metal. The melting temperature is set to 1100 - 1150 deg C. The molten borosilicate glass is recovered from the bottom of the melting furance, contained in a canister and cooled for several hours, and then a cover is welded to the canister. (Ikeda, J.)

  20. A scaling analysis of alloy solidification in presence of electromagnetic stirring

    International Nuclear Information System (INIS)

    Kumar, Arvind; Dutta, Pradip

    2006-01-01

    Application of electromagnetic stirring (EMS) during continuous casting shears off the dendrites from the solidification front to produce billets with a non-dendritic microstructure. In the present study, a systematic approach to the scaling analysis of momentum, energy and species conservation equations pertaining to the case of the solidification of a binary alloy in the presence of EMS is outlined. With suitable choices of non-dimensionalizing parameters, the governing equations coupled with appropriate boundary conditions are first scaled, and then the relative significance of various terms appearing in them are analysed. In the physical domain two regions are identified, one where the electromagnetic forces play a dominant role in the momentum equations, and the other where the inertia and viscous effects play major roles. Using the scaling predictions, the influence of various processing parameters on the system variables can be utilized for the selection of appropriate electromagnetic forces to shear off the dendrites from the solidification area. For the sake of assessment of the scaling analysis, the predictions are validated against corresponding computational results

  1. Recent advances in cement solidification of radioactive wastes

    International Nuclear Information System (INIS)

    Vigreux, B.; Jaouen, C.

    1987-01-01

    Advanced cement solidification processes and systems have been developed by SGN to meet changing requirements in radioactive waste processing and packaging and to avoid the difficulties often encountered in waste concreting on an industrial scale. SGN applies a strict development methodology to ensure integration of the most recent information on chemical behavior of solidified wastes plus compliance with the precise needs of waste producers and evolving regulatory requirements concerning waste package storage and disposal. Based on a hierarchical definition of objectives, this methodology was implemented following an overall study on radwaste concreting performed in 1983 and 1984 for Electricite de France (EdF), France's national electric power utility. It ensures that industrial and regulatory factors are fully considered from the start of development work. It also constrains development in the direction of true process optimization and guarantees compliance with defined objectives. The methodology has helped SGN develop concreting processes adapted to various types of radioactive waste. The most widely employed processes are first briefly described in this paper. It then presents continuous and batch systems using these processes, focusing on technological features chosen at a very early stage in development

  2. Weld solidification cracking in 304 to 304L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Martinez, Raymond J [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

    2010-01-01

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found. This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GT A W showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  3. Weld solidification cracking in 304 to 204L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

    2010-09-15

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found.This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GTAW showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  4. Solidification effects on sill formation: An experimental approach

    Science.gov (United States)

    Chanceaux, L.; Menand, T.

    2014-10-01

    Sills represent a major mechanism for constructing continental Earth's crust because these intrusions can amalgamate and form magma reservoirs and plutons. As a result, numerous field, laboratory and numerical studies have investigated the conditions that lead to sill emplacement. However, all previous studies have neglected the potential effect magma solidification could have on sill formation. The effects of solidification on the formation of sills are studied and quantified with scaled analogue laboratory experiments. The experiments presented here involved the injection of hot vegetable oil (a magma analogue) which solidified during its propagation as a dyke in a colder and layered solid of gelatine (a host rock analogue). The gelatine solid had two layers of different stiffness, to create a priori favourable conditions to form sills. Several behaviours were observed depending on the injection temperature and the injection rate: no intrusions (extreme solidification effects), dykes stopping at the interface (high solidification effects), sills (moderate solidification effects), and dykes passing through the interface (low solidification effects). All these results can be explained quantitatively as a function of a dimensionless temperature θ, which describes the experimental thermal conditions, and a dimensionless flux ϕ, which describes their dynamical conditions. The experiments reveal that sills can only form within a restricted domain of the (θ , ϕ) parameter space. These experiments demonstrate that contrary to isothermal experiments where cooling could not affect sill formation, the presence of an interface that would be a priori mechanically favourable is not a sufficient condition for sill formation; solidification effects restrict sill formation. The results are consistent with field observations and provide a means to explain why some dykes form sills when others do not under seemingly similar geological conditions.

  5. Rate of solidification of aluminium casting in varying wall thickness of cylindrical metallic moulds

    Directory of Open Access Journals (Sweden)

    Katsina Christopher BALA

    2014-02-01

    Full Text Available The quality of final casting mainly depends on the rate of solidification as rapid solidification produces fine grains structures with better mechanical properties. The analysis of heat transfer during the casting and solidification of aluminium alloy as well as the experimental investigation of the rate of solidification in varying thicknesses of cylindrical metallic mould was carried out. The temperature variation with time of the casting was recorded from which cooling curves were obtained for the determination of solidification time of the cast. The results showed that as the cylindrical mould thickness increases the solidification time decreases due to the chilling effect of the mould.

  6. Real-time X-ray transmission microscopy for fundamental studies solidification: Al-Al2Au eutectic

    International Nuclear Information System (INIS)

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

    1998-01-01

    High resolution real-time X-ray Transmission Microscopy, XTM, has been applied to obtain information fundamental to solidification of optically opaque metallic systems. We have previously reported the measurement of the solute profile in the liquid, phase growth, and detailed solid-liquid interfacial morphology of aluminum based alloys with exposure times less than 2 seconds. Recent advances in XTM furnace design have provided an increase in real-time magnification (during solidification) for the XTM from 40X to 160X. The increased magnification has enabled for the first time the XTM imaging of real-time growth of fibers and particles with diameters of 5 μm. We have previously applied this system to study the kinetics of formation and morphological evolution of secondary fibers and particles in Al-Bi monotectic alloys. In this paper we present the preliminary results of the first real-time observations of fiber morphology evolution in optically opaque bulk metal sample of Aluminum-Gold eutectic alloy. These studies show that the XTM can be applied to study the fundamentals of eutectic and monotectic solidification. We are currently attempting to apply this technology in the fundamentals of solidification in microgravity

  7. Stability Constrained Efficiency Optimization for Droop Controlled DC-DC Conversion System

    DEFF Research Database (Denmark)

    Meng, Lexuan; Dragicevic, Tomislav; Guerrero, Josep M.

    2013-01-01

    implementing tertiary regulation. Moreover, system dynamic is affected when shifting VRs. Therefore, the stability is considered in optimization by constraining the eigenvalues arising from dynamic state space model of the system. Genetic algorithm is used in searching for global efficiency optimum while....... As the efficiency of each converter changes with output power, virtual resistances (VRs) are set as decision variables for adjusting power sharing proportion among converters. It is noteworthy that apart from restoring the voltage deviation, secondary control plays an important role to stabilize dc bus voltage when...

  8. A phenomenological approach of solidification of polymeric phase change materials

    Science.gov (United States)

    Bahrani, Seyed Amir; Royon, Laurent; Abou, Bérengère; Osipian, Rémy; Azzouz, Kamel; Bontemps, André

    2017-01-01

    Phase Change Materials (PCMs) are widely used in thermal energy storage and thermal management systems due to their small volume for a given stored energy and their capability for maintaining nearly constant temperatures. However, their performance is limited by their low thermal conductivity and possible leaks while in the liquid phase. One solution is to imprison the PCM inside a polymer mesh to create a Polymeric Phase Change Material (PPCM). In this work, we have studied the cooling and solidification of five PPCMs with different PCMs and polymer fractions. To understand the heat transfer mechanisms involved, we have carried out micro- and macrorheological measurements in which Brownian motion of tracers embedded in PPCMs has been depicted and viscoelastic moduli have been measured, respectively. Beyond a given polymer concentration, it was shown that the Brownian motion of the tracers is limited by the polymeric chains and that the material exhibits an elastic behavior. This would suggest that heat transfer essentially occurs by conduction, instead of convection. Experiments were conducted to measure temperature variation during cooling of the five samples, and a semi-empirical model based on a phenomenological approach was proposed as a practical tool to choose and size PPCMs.

  9. New insight on glass-forming ability and designing Cu-based bulk metallic glasses: The solidification range perspective

    International Nuclear Information System (INIS)

    Wu, Jili; Pan, Ye; Li, Xingzhou; Wang, Xianfei

    2014-01-01

    Highlights: • The equation, T rg = T g /T l , was rotationally modified to T rg = κ(T m /T l ) + C/T l . • The newly generalized equation suggests a way for describing glass-forming ability. • Several new Cu-based bulk metallic glasses were discovered by solidification range. - Abstract: In this paper, a new equation was rationally generalized from the reduced glass transition temperature. This equation indicates that solidification range can be used for describing glass-forming ability, which can be calculated with the aid of computational thermodynamic approach. Based on this scenario, several new Cu-based bulk metallic glasses in the ternary Cu–Zr–Ti alloy system were discovered. The as-cast samples were characterized by X-ray diffraction and transmission electronic microscopy. The results indicate that as-cast samples have monolithic amorphous nature. Thermal analysis validates that the smaller solidification range is closely related to the higher glass-forming ability, which is contributed to the effect of solidification time on the formation of bulk metallic glasses. This work also suggests that solidus can influence glass formation

  10. Rapid solidification growth mode transitions in Al-Si alloys by dynamic transmission electron microscopy

    International Nuclear Information System (INIS)

    Roehling, John D.; Coughlin, Daniel R.; Gibbs, John W.; Baldwin, J. Kevin; Mertens, James C.E.; Campbell, Geoffrey H.; Clarke, Amy J.; McKeown, Joseph T.

    2017-01-01

    In situ dynamic transmission electron microscope (DTEM) imaging of Al-Si thin-film alloys was performed to investigate rapid solidification behavior. Solidification of alloys with compositions from 1 to 15 atomic percent Si was imaged during pulsed laser melting and subsequent solidification. Solely α-Al solidification was observed in Al-1Si and Al-3Si alloys, and solely kinetically modified eutectic growth was observed in Al-6Si and Al-9Si alloys. A transition in the solidification mode in eutectic and hypereutectic alloys (Al-12Si and Al-15Si) from nucleated α-Al dendrites at lower solidification velocities to planar eutectic growth at higher solidification velocities was observed, departing from trends previously seen in laser-track melting experiments. Comparisons of the growth modes and corresponding velocities are compared with previous solidification models, and implications regarding the models are discussed.

  11. Stabilization/Solidification Remediation Method for Contaminated Soil: A Review

    Science.gov (United States)

    Tajudin, S. A. A.; Azmi, M. A. M.; Nabila, A. T. A.

    2016-07-01

    Stabilization/Solidification (S/S) is typically a process that involves a mixing of waste with binders to reduce the volume of contaminant leachability by means of physical and chemical characteristics to convert waste in the environment that goes to landfill or others possibly channels. Stabilization is attempts to reduce the solubility or chemical reactivity of the waste by changing the physical and chemical properties. While, solidification attempt to convert the waste into easily handled solids with low hazardous level. These two processes are often discussed together since they have a similar purpose of improvement than containment of potential pollutants in treated wastes. The primary objective of this review is to investigate the materials used as a binder in Stabilization/Solidification (S/S) method as well as the ability of these binders to remediate the contaminated soils especially by heavy metals.

  12. Matemathical description of solidification cooling curves of pure metals

    Directory of Open Access Journals (Sweden)

    Arno Müller

    1998-10-01

    Full Text Available The introduction of an "incubation time" to the Schwarz classical mathematical description of metals solidification, resulted in a new model called Modified Schwarz Model. By doing so it was possible to identify and quantify the "delay time" that separates the two heat waves traveling independently in a casting during the solidification: the Supercooled / Superheated Liquid and the Solid / Liquid. The thermal shock produced in the initial stage of the undercooling generation process, can be used as an important parameter in the forecasting of the solidification's behavior of pure metals and alloys, when changing mold's materials, pouring and ambient temperatures. The hypercooling proneness degree of metals and alloys, can also be calculated.

  13. Solidification Mapping of a Nickel Alloy 718 Laboratory VAR Ingot

    Science.gov (United States)

    Watt, Trevor J.; Taleff, Eric M.; Lopez, Felipe; Beaman, Joe; Williamson, Rodney

    The solidification microstructure of a laboratory-scale Nickel alloy 718 vacuum arc remelted (VAR) ingot was analyzed. The cylindrical, 210-mm-diameter ingot was sectioned along a plane bisecting it length-wise, and this mid-plane surface was ground and etched using Canada's reagent to reveal segregation contrast. Over 350 photographs were taken of the etched mid-plane surface and stitched together to form a single mosaic image. Image data in the resulting mosaic were processed using a variety of algorithms to extract quantities such as primary dendrite orientation, primary dendrite arm spacing (PDAS), and secondary dendrite arm spacing (SDAS) as a function of location. These quantities were used to calculate pool shape and solidification rate during solidification using existing empirical relationships for Nickel Alloy 718. The details and outcomes of this approach, along with the resulting comparison to experimental processing conditions and computational models, are presented.

  14. Solidification of low-level wastes by inorganic binder

    International Nuclear Information System (INIS)

    Sasaki, M.T.; Shimojo, M.; Suzuki, K.; Kajikawa, A.; Karasawa, Y.

    1995-01-01

    The use of an alkali activated slag binder has been studied for solidification and stabilization of low-level wastes in nuclear power stations and spent fuel processing facilities. The activated slag effectively formed waste products having good physical properties with high waste loading for sodium sulfate, sodium nitrate, calcium pyrophosphate/phosphate and spent ion-exchange resins. Moreover, the results of the study suggest the slag has the ability to become a common inorganic binder for the solidification of various radioactive wastes. This paper also describes the fixation of radionuclides by the activated slag binder

  15. Solidification of radioactive waste in a cement/lime mixture

    International Nuclear Information System (INIS)

    Zhou, H.; Colombo, P.

    1984-01-01

    The suitability of a cement/lime mixture for use as a solidification agent for different types of wastes was investigated. This work includes studies directed towards determining the wasted/binder compositional field over which successful solidification occurs with various wastes and the measurement of some of the waste from properties relevant to evaluating the potential for the release of radionuclides to the environment. In this study, four types of low-level radioactive wastes were simulated for incorporation into a cement/lime mixture. These were boric acid waste, sodium sulfate wastes, aion exchange resins and incinerator ash. 7 references, 3 figures, 2 tables

  16. Three-dimensional phase-field simulations of directional solidification

    Science.gov (United States)

    Plapp, Mathis

    2007-05-01

    The phase-field method has become the method of choice for simulating microstructural pattern formation during solidification. One of its main advantages is that time-dependent three-dimensional simulations become feasible, which makes it possible to address long-standing questions of pattern stability and pattern selection. Here, a brief introduction to the phase-field model and its implementation is given, and its capabilities are illustrated by examples taken from the directional solidification of binary alloys. In particular, the morphological stability of hexagonal cellular arrays and of eutectic lamellar patterns is investigated.

  17. Solidification processing of intermetallic Nb-Al alloys

    Science.gov (United States)

    Smith, Preston P.; Oliver, Ben F.; Noebe, Ronald D.

    1992-01-01

    Several Nb-Al alloys, including single-phase NbAl3 and the eutectic of Nb2Al and NbAl3, were prepared either by nonconsumable arc melting in Ar or by zone processing in He following initial induction melting and rod casting, and the effect of the solidification route on the microstructure and room-temperature mechanical properties of these alloys was investigated. Automated control procedures and melt conditions for directional solidification of NbAl3 and the Nb2Al/Nb3Al eutectic were developed; high purity and stoichiometry were obtained. The effects of ternary additions of Ti and Ni are described.

  18. Some techniques for the solidification of radioactive wastes in concrete

    International Nuclear Information System (INIS)

    Colombo, P.; Neilson, R. Jr.

    1976-06-01

    Some techniques for the solidification of radioactive wastes in concrete are discussed. The sources, storage, volume reduction, and solidification of liquid wastes at Brookhaven National Laboratory (BNL) using the cement-vermiculite process is described. Solid waste treatment, shipping containers, and off-site shipments of solid wastes at BNL are also considered. The properties of low-heat-generating, high-level wastes, simulating those in storage at the Savannah River Plant (SRP), solidified in concrete were determined. Polymer impregnation was found to further decrease the leachability and improve the durability of these concrete waste forms

  19. Modeling of multiphase flow with solidification and chemical reaction in materials processing

    Science.gov (United States)

    Wei, Jiuan

    Understanding of multiphase flow and related heat transfer and chemical reactions are the keys to increase the productivity and efficiency in industrial processes. The objective of this thesis is to utilize the computational approaches to investigate the multiphase flow and its application in the materials processes, especially in the following two areas: directional solidification, and pyrolysis and synthesis. In this thesis, numerical simulations will be performed for crystal growth of several III-V and II-VI compounds. The effects of Prandtl and Grashof numbers on the axial temperature profile, the solidification interface shape, and melt flow are investigated. For the material with high Prandtl and Grashof numbers, temperature field and growth interface will be significantly influenced by melt flow, resulting in the complicated temperature distribution and curved interface shape, so it will encounter tremendous difficulty using a traditional Bridgman growth system. A new design is proposed to reduce the melt convection. The geometric configuration of top cold and bottom hot in the melt will dramatically reduce the melt convection. The new design has been employed to simulate the melt flow and heat transfer in crystal growth with large Prandtl and Grashof numbers and the design parameters have been adjusted. Over 90% of commercial solar cells are made from silicon and directional solidification system is the one of the most important method to produce multi-crystalline silicon ingots due to its tolerance to feedstock impurities and lower manufacturing cost. A numerical model is developed to simulate the silicon ingot directional solidification process. Temperature distribution and solidification interface location are presented. Heat transfer and solidification analysis are performed to determine the energy efficiency of the silicon production furnace. Possible improvements are identified. The silicon growth process is controlled by adjusting heating power and

  20. Two-dimensional time-resolved x-ray diffraction study of dual phase rapid solidification in steels

    Science.gov (United States)

    Yonemura, Mitsuharu; Osuki, Takahiro; Terasaki, Hidenori; Komizo, Yuichi; Sato, Masugu; Toyokawa, Hidenori; Nozaki, Akiko

    2010-01-01

    The high intensity heat source used for fusion welding creates steep thermal gradients of 100 °C/s from 1800 °C. Further, the influence of preferred orientation is important for the observation of a directional solidification that follows the dendrite growth along the ⟨100⟩ direction toward the moving heat source. In the present study, we observed the rapid solidification of weld metal at a time resolution of 0.01-0.1 s by a two-dimensional time-resolved x-ray diffraction (2DTRXRD) system for real welding. The diffraction rings were dynamically observed by 2DTRXRD with synchrotron energy of 18 keV while the arc passes over the irradiation area of the x-rays. The arc power output was 10 V-150 A, and the scan speed of the arc was 1.0 mm/s. The temperature rise in instruments was suppressed by a water-cooled copper plate under the specimen. Further, the temperature distribution of the weld metal was measured by a thermocouple and correlated with the diffraction patterns. Consequently, solidification and solid phase transformation of low carbon steels and stainless steels were observed during rapid cooling by 2DTRXRD. In the low carbon steel, the microstructure is formed in a two step process, (i) formation of crystallites and (ii) increase of crystallinity. In stainless steel, the irregular interface layer of δ/γ in the quenched metal after solidification is expected to show the easy movement of dendrites at a lower temperature. In carbide precipitation stainless steel, it is easy for NbC to grow on δ phase with a little undercooling. Further, a mistlike pattern, which differs from the halo pattern, in the fusion zone gave some indication of the possibilities to observe the nucleation and the early solidification by 2DTRXRD.

  1. Interfacial free energy and stiffness of aluminum during rapid solidification

    International Nuclear Information System (INIS)

    Brown, Nicholas T.; Martinez, Enrique; Qu, Jianmin

    2017-01-01

    Using molecular dynamics simulations and the capillary fluctuation method, we have calculated the anisotropic crystal-melt interfacial free energy and stiffness of aluminum in a rapid solidification system where a temperature gradient is applied to enforce thermal non-equilibrium. To calculate these material properties, the standard capillary fluctuation method typically used for systems in equilibrium has been modified to incorporate a second-order Taylor expansion of the interfacial free energy term. The result is a robust method for calculating interfacial energy, stiffness and anisotropy as a function of temperature gradient using the fluctuations in the defined interface height. This work includes the calculation of interface characteristics for temperature gradients ranging from 11 to 34 K/nm. The captured results are compared to a thermal equilibrium case using the same model and simulation technique with a zero gradient definition. We define the temperature gradient as the change in temperature over height perpendicular to the crystal-melt interface. The gradients are applied in MD simulations using defined thermostat regions on a stable solid-liquid interface initially in thermal equilibrium. The results of this work show that the interfacial stiffness and free energy for aluminum are dependent on the magnitude of the temperature gradient, however the anisotropic parameters remain independent of the non-equilibrium conditions applied in this analysis. As a result, the relationships of the interfacial free energy/stiffness are determined to be linearly related to the thermal gradient, and can be interpolated to find material characteristics at additional temperature gradients.

  2. Aluminum alloy weldability. Identification of weld solidification cracking mechanisms through novel experimental technique and model development

    Energy Technology Data Exchange (ETDEWEB)

    Coniglio, Nicolas

    2008-07-01

    The objective of the present thesis is to make advancements in understanding solidification crack formation in aluminum welds, by investigating in particular the aluminum 6060/4043 system. Alloy 6060 is typical of a family of Al-Mg-Si extrusion alloys, which are considered weldable only when using an appropriate filler alloy such as 4043 (Al-5Si). The effect of 4043 filler dilution (i.e. weld metal silicon content) on cracking sensitivity and solidification path of Alloy 6060 welds are investigated. Afterwards, cracking models are developed to propose mechanisms for solidification crack initiation and growth. Cracking Sensitivity. Building upon the concept that silicon improves weldability and that weldability can be defined by a critical strain rate, strain rate-composition combinations required for solidification crack formation in the Al- 6060/4043 system were determined using the newly developed Controlled Tensile Weldability (CTW) test utilizing local strain extensometer measurements. Results, presented in a critical strain rate - dilution map, show a crack - no crack boundary which reveals that higher local strain rates require higher 4043 filler dilution to avoid solidification cracking when arc welding Alloy 6060. Using the established crack - no crack boundary as a line of reference, additional parameters were examined and their influence on cracking characterized. These parameter influences have included studies of weld travel speed, weld pool contaminants (Fe, O, and H), and grain refiner additions (TiAl{sub 3} + Boron). Each parameter has been independently varied and its effect on cracking susceptibility quantified in terms of strain rate - composition combinations. Solidification Path. Solidification path of the Al-6060/4043 system was characterized using thermal analysis and phase identification. Increasing 4043 filler dilution from 0 to 16% in Alloy 6060 arc welds resulted in little effect on thermal arrests and microstructure, no effect on

  3. Rapid solidification for preparation of high Tc superconductors

    International Nuclear Information System (INIS)

    Yavari, A.R.

    1988-01-01

    High Tc superconducting oxides are prepared in two different ways using rapid solidification: by oxidation of microcrystalline or amorphous tapes obtained by quenching the liquid alloy and via crystallisation of the amorphous oxide obtained by rapid quenching of the oxide melt. This technique is applied for the first time to the BiCaSrCuO family [fr

  4. Modified sulfur cement solidification of low-level wastes

    Energy Technology Data Exchange (ETDEWEB)

    1985-10-01

    This topical report describes the results of an investigation on the solidification of low-level radioactive wastes in modified sulfur cement. The work was performed as part of the Waste Form Evaluation Program, sponsored by the US Department of Energy's Low-Level Waste Management Program. Modified sulfur cement is a thermoplastic material developed by the US Bureau of Mines. Processing of waste and binder was accomplished by means of both a single-screw extruder and a dual-action mixing vessel. Waste types selected for this study included those resulting from advanced volume reduction technologies (dry evaporator concentrate salts and incinerator ash) and those which remain problematic for solidification using contemporary agents (ion exchange resins). Process development studies were conducted to ascertain optimal process control parameters for successful solidification. Maximum waste loadings were determined for each waste type and method of processing. Property evaluation testing was carried out on laboratory scale specimens in order to compare with waste form performance for other potential matrix materials. Waste form property testing included compressive strength, water immersion, thermal cycling and radionuclide leachability. Recommended waste loadings of 40 wt. % sodium sulfate and boric acid salts and 43 wt. % incinerator ash, which are based on processing and performance considerations, are reported. Solidification efficiencies for these waste types represent significant improvements over those of hydraulic cements. Due to poor waste form performance, incorporation of ion exchange resin waste in modified sulfur cement is not recommended.

  5. Solidification technique of radioactive elements. Research using zirconium phosphates

    International Nuclear Information System (INIS)

    Nakayama, Susumu; Ito, Katsuhiko

    2005-01-01

    Proton type zirconium phosphates HZr 2 (PO 4 ) 3 , NASICON type three-dimensional net work structure, is used for solidification of Cs in the high level radioactive waste. Two kinds of solidification methods such as the dry method and autoclave method are explained. Cs ion entered into 0.6nm space of HZr 2 (PO 4 ) 3 , and formed ionic bonding, which made the difficult situation to remove. When mixture of HZr 2 (PO 4 ) 3 and 23 kinds of M(NO 3 )n (M= Li, Na, K, Pb, Sr, Bi, Y, Mg, Ca, Sc, Mn, Fe, Co, Ni, Cu, Zn, Ag, Cd, Ba, La, Ce, Tl, and Pb; n=1,2 or 3) was treated at 400-700degC by dry method, solidification of the subject metals was succeeded. Amount of solidification of Cs by autoclave at 250degC is almost same as the dry method and its leachability resistance increased 40 times than that of dry method after heat treatment in atmosphere at 700degC. (S.Y.)

  6. Overview of the Tusas Code for Simulation of Dendritic Solidification

    Energy Technology Data Exchange (ETDEWEB)

    Trainer, Amelia J. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Newman, Christopher Kyle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Francois, Marianne M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    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 it 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].

  7. Solidification of Waste Steel Foudry Dust with Portland Cement

    Czech Academy of Sciences Publication Activity Database

    Škvára, F.; Kaštánek, František; Pavelková, I.; Šolcová, Olga; Maléterová, Ywetta; Schneider, Petr

    B89, č. 1 (2001), s. 67-81 ISSN 0304-3894 R&D Projects: GA ČR GA104/99/0440 Institutional research plan: CEZ:AV0Z4072921; CEZ:MSM 223100002 Keywords : solidification, * foundry dust * cement Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.497, year: 2001

  8. Stabilization/solidification of synthetic Nigerian drill cuttings | Opete ...

    African Journals Online (AJOL)

    Stabilization/solidification of synthetic Nigerian drill cuttings. SEO Opete, IA Mangibo, ET Iyagba. Abstract. In the Nigerian oil and gas industry, large quantities of oily and synthetic drill cuttings are produced annually. These drill cuttings are heterogeneous wastes which comprises of hydrocarbons, heavy metals and ...

  9. Modified sulfur cement solidification of low-level wastes

    International Nuclear Information System (INIS)

    1985-10-01

    This topical report describes the results of an investigation on the solidification of low-level radioactive wastes in modified sulfur cement. The work was performed as part of the Waste Form Evaluation Program, sponsored by the US Department of Energy's Low-Level Waste Management Program. Modified sulfur cement is a thermoplastic material developed by the US Bureau of Mines. Processing of waste and binder was accomplished by means of both a single-screw extruder and a dual-action mixing vessel. Waste types selected for this study included those resulting from advanced volume reduction technologies (dry evaporator concentrate salts and incinerator ash) and those which remain problematic for solidification using contemporary agents (ion exchange resins). Process development studies were conducted to ascertain optimal process control parameters for successful solidification. Maximum waste loadings were determined for each waste type and method of processing. Property evaluation testing was carried out on laboratory scale specimens in order to compare with waste form performance for other potential matrix materials. Waste form property testing included compressive strength, water immersion, thermal cycling and radionuclide leachability. Recommended waste loadings of 40 wt. % sodium sulfate and boric acid salts and 43 wt. % incinerator ash, which are based on processing and performance considerations, are reported. Solidification efficiencies for these waste types represent significant improvements over those of hydraulic cements. Due to poor waste form performance, incorporation of ion exchange resin waste in modified sulfur cement is not recommended

  10. Origin of grain orientation during solidification of an aluminum alloy

    International Nuclear Information System (INIS)

    Wei, H.L.; Elmer, J.W.; DebRoy, T.

    2016-01-01

    The evolution of grain morphology during solidification of a moving aluminum alloy pool is simulated by considering heat transfer, flow of liquid metal in the molten pool and solidification parameters. The computationally efficient model consists of a 3D coupled heat transfer and fluid flow simulation to predict the molten pool shape and temperature field, and a 2D model of grain formation in the molten pool. The results demonstrate that columnar grains grow in a curved pattern rather than along straight lines from the fusion boundary towards the center of the molten pool. The calculated results are validated with independent experimental data. The computed ratio of local temperature gradient to solidification rate, G/R, is used to model the columnar to equiaxed transition during solidification. The simulated results show that only curved columnar grains are formed when the scanning speed is low (2.0 mm/s). In contrast, a transition from curved columnar to equiaxed morphologies occurs at the higher scanning speeds of 8.0 mm/s and 11.5 mm/s, with higher equiaxed grain fraction at higher speed. The similarities between the physical processes governing fusion welding and additive manufacturing (AM) make the model capable of predicting grain orientation in both processes.

  11. Purification and solidification of reactor wastes at a Canadian nuclear generating station

    International Nuclear Information System (INIS)

    Buckley, L.P.; Burt, D.A.

    1981-01-01

    The study aimed at development and demonstration of volume reduction and solidification of CANDU reactor wastes has been underway at Chalk River Nuclear Laboratories in the Province of Ontario, Canada. The study comprises membrane separation processes, evaporator appraisal and immobilization of concentrated wastes in bitumen. This paper discusses the development work with a wiped-film evaporator and the successful completion of demonstration tests at Douglas Point Nuclear Generating Station. Heavy water from the moderator system was purified and wastes arising from pump bowl decontamination were immobilized in bitumen with the wiped-film evaporator that was used in the development tests at Chalk River

  12. Improvements to a uranium solidification process by in-plant testing

    International Nuclear Information System (INIS)

    Rindfleisch, J.A.

    1984-01-01

    When a process is having operational or equipment problems, often there is not enough time or money available for an extensive pilot plant program. This is when in-plant testing becomes imperative. One such process at the Idaho Chemical Processing Plant (ICPP) to undergo such an in-plant testing program was the uranium product solidification (denitrator) system. The testing program took approximately six months of in-plant testing that would have required at least two years of pilot plant preparation and operation to obtain the same information. This paper describes the results of the testing program, and the equipment and procedural changes

  13. Analysis of weld solidification cracking in cast nickel aluminide alloys

    International Nuclear Information System (INIS)

    Santella, M.L.; Feng, Z.

    1995-01-01

    A study of the response of several nickel aluminide alloys to SigmaJig testing was done to examine their weld solidification cracking behavior and the effect of Zr concentration. The alloys were based on the Ni-8Al-7.7Cr-1.5Mo-0.003B wt% composition and contained Zr concentrations of 3, 4.5, and 6 wt%. Vacuum induction melted ingots with a diameter of 2.7 in and weight about 18 lb were made of each alloy, and were used to make 2 x 2 x 0.030 in specimens for the Sigmajig test. The gas tungsten arc welds were made at travel speeds of 10, 20, and 30 ipm with heat inputs of 2--2.5 kJ/in. When an arc was established before traveling onto the test specimen centerline cracking was always observed. This problem was overcome by initiating the arc directly on the specimens. Using this approach, the 3 wt% Zr alloy withstood an applied stress of 24 ksi without cracking at a welding speed of 10 ipm. This alloy cracked at 4 ksi applied at 20 ipm, and with no applied load at 30 ipm. Only limited testing was done on the remaining alloys, but the results indicate that resistance to solidification cracking increases with Zr concentration. Zirconium has limited solid solubility and segregates strongly to interdendritic regions during solidification where it forms a Ni solid solution-Ni 5 Zr eutectic. The volume fraction of the eutectic increases with Zr concentration. The solidification cracking behavior of these alloys is consistent with phenomenological theory, and is discussed in this context. The results from SigmaJig testing are analyzed using finite element modeling of the development of mechanical strains during solidification of welds. Experimental data from the test substantially agree with recent analysis results

  14. Finite-element solidification modelling of metals and binary alloys

    International Nuclear Information System (INIS)

    Mathew, P.M.

    1986-12-01

    In the Canadian Nuclear Fuel Waste Management Program, cast metals and alloys are being evaluated for their ability to support a metallic fuel waste container shell under disposal vault conditions and to determine their performance as an additional barrier to radionuclide release. These materials would be cast to fill residual free space inside the container and allowed to solidify without major voids. To model their solidification characteristics following casting, a finite-element model, FAXMOD-3, was adopted. Input parameters were modified to account for the latent heat of fusion of the metals and alloys considered. This report describes the development of the solidification model and its theoretical verification. To model the solidification of pure metals and alloys that melt at a distinct temperature, the latent heat of fusion was incorporated as a double-ramp function in the specific heat-temperature relationship, within an interval of +- 1 K around the solidification temperature. Comparison of calculated results for lead, tin and lead-tin eutectic melts, unidirectionally cooled with and without superheat, showed good agreement with an alternative technique called the integral profile method. To model the solidification of alloys that melt over a temperature interval, the fraction of solid in the solid-liquid region, as calculated from the Scheil equation, was used to determine the fraction of latent heat to be liberated over a temperature interval within the solid-liquid zone. Comparison of calculated results for unidirectionally cooled aluminum-4 wt.% copper melt, with and without superheat, showed good agreement with alternative finite-difference techniques

  15. Evolution of Fe based intermetallic phases in Al–Si hypoeutectic casting alloys: Influence of the Si and Fe concentrations, and solidification rate

    International Nuclear Information System (INIS)

    Gorny, Anton; Manickaraj, Jeyakumar; Cai, Zhonghou; Shankar, Sumanth

    2013-01-01

    Highlights: •Anomalous evolution of Fe based intermetallic phases in Al–Si–Fe alloys. •XRF coupled with nano-diffraction to confirm the nano-size Fe intermetallic phases. •Crystallography of the θ-Al 13 Fe 4 , τ 5 -Al 8 Fe 2 Si and τ 6 -Al 9 Fe 2 Si 2 phases. •Peritectic reactions involving the Fe intermetallic phases in Al–Si–Fe alloys. -- Abstract: Al–Si–Fe hypoeutectic cast alloy system is very complex and reported to produce numerous Fe based intermetallic phases in conjunction with Al and Si. This publication will address the anomalies of phase evolution in the Al–Si–Fe hypoeutectic casting alloy system; the anomaly lies in the peculiarities in the evolution and nature of the intermetallic phases when compared to the thermodynamic phase diagram predictions and past publications of the same. The influence of the following parameters, in various combinations, on the evolution and nature of the intermetallic phases were analyzed and reported: concentration of Si between 2 and 12.6 wt%, Fe between 0.05 and 0.5 wt% and solidification rates of 0.1, 1, 5 and 50 K s −1 . Two intermetallic phases are observed to evolve in these alloys under these solidification conditions: the τ 5 -Al 8 SiFe 2 and τ 6 -Al 9 Fe 2 Si 2 . The τ 5 -Al 8 SiFe 2 phase evolves at all levels of the parameters during solidification and subsequently transforms into the τ 6 -Al 9 Fe 2 Si 2 through a peritectic reaction when promoted by certain combinations of solidification parameters such as higher Fe level, lower Si level and slower solidification rates. Further, it is also hypothesized from experimental evidences that the θ-Al 13 Fe 4 binary phase precludes the evolution of the τ 5 during solidification and subsequently transforms into the τ 6 phase during solidification. These observations are anomalous to the publications as prior art and simulation predictions of thermodynamic phase diagrams of these alloys, wherein, only one intermetallic phases in the

  16. Solidification of ion-exchange resins by hydrothermal hot-pressing

    International Nuclear Information System (INIS)

    Kaneko, M.

    1993-01-01

    The solidification reaction which easily occurs while continuously keeping the mixture of cation and anion exchange resins compressed under hydrothermal conditions has been demonstrated. Dehydration was considered to occur between sulphonic acid (-SO 3 H) from the cation exchange resin and quaternary ammonium [-CH 2 -N(CH 3 ) 3 OH] from anion-exchange resin-on terminal groups. The cation-and anion-exchange resins were mixed in a 1:1 weight ratio, put in a hot-pressing autoclave and compressed between pistons from the top and bottom at 600 kg cm -2 pressure. The material was continuously compressed during hydrothermal treatment at 200 kg cm -2 by a hydraulic jack and heated to a desired temperature with an induction heater. This system could be used for rapid temperature increasing up to 30 o c min -1 . The pressure and temperature were kept constant for 10 min. The autoclave was cooled to room temperature after the hydrothermal treatment. After the specimen was taken out, the ion-exchange radical reactions were estimated and the product structures were examined. The cation- and anion-exchange resin mixture was solidified. The resultant solidified body at a 300 o C reaction condition for 10 min had a 1.0 g cm -3 density and 700 kg cm -2 compressive strength, and the weight loss did not change in distilled water for 2 weeks. On the other hand, a solidification reaction did not occur at below 250 o C when only the cation or anion was solidified, but they were decomposed. These results suggest that a mixture of cation- and anion-exchange resins causes a solidification reaction under hydrothermal hot-pressing conditions at 300 o C. (author)

  17. Strongly nonlinear theory of rapid solidification near absolute stability

    Science.gov (United States)

    Kowal, Katarzyna N.; Altieri, Anthony L.; Davis, Stephen H.

    2017-10-01

    We investigate the nonlinear evolution of the morphological deformation of a solid-liquid interface of a binary melt under rapid solidification conditions near two absolute stability limits. The first of these involves the complete stabilization of the system to cellular instabilities as a result of large enough surface energy. We derive nonlinear evolution equations in several limits in this scenario and investigate the effect of interfacial disequilibrium on the nonlinear deformations that arise. In contrast to the morphological stability problem in equilibrium, in which only cellular instabilities appear and only one absolute stability boundary exists, in disequilibrium the system is prone to oscillatory instabilities and a second absolute stability boundary involving attachment kinetics arises. Large enough attachment kinetics stabilize the oscillatory instabilities. We derive a nonlinear evolution equation to describe the nonlinear development of the solid-liquid interface near this oscillatory absolute stability limit. We find that strong asymmetries develop with time. For uniform oscillations, the evolution equation for the interface reduces to the simple form f''+(βf')2+f =0 , where β is the disequilibrium parameter. Lastly, we investigate a distinguished limit near both absolute stability limits in which the system is prone to both cellular and oscillatory instabilities and derive a nonlinear evolution equation that captures the nonlinear deformations in this limit. Common to all these scenarios is the emergence of larger asymmetries in the resulting shapes of the solid-liquid interface with greater departures from equilibrium and larger morphological numbers. The disturbances additionally sharpen near the oscillatory absolute stability boundary, where the interface becomes deep-rooted. The oscillations are time-periodic only for small-enough initial amplitudes and their frequency depends on a single combination of physical parameters, including the

  18. Effect of thermodiffusion on the fluid flow, heat transfer, and solidification of molten metal alloys

    Directory of Open Access Journals (Sweden)

    E. Jafar-Salehi

    2016-03-01

    Full Text Available In this paper, a transient Finite Element (FE method has been employed to solve the transport equations to investigate the heat transfer and fluid flow and the effect of thermodiffusion on vertical solidification of a binary molten metal alloy, forming a rod. The binary system considered in this study is SnBi composed of 65% Sn and 35% Bi subjected to bottom cooling. It is found that the flow of molten metal at the boundary of the mushy region plays an important role in the shape and geometry of the zone. The presence of thermodiffusion shows considerable difference in the composition of the solidified rod, compared with the one without considering the effect of thermodiffusion. Thermodiffusion also causes a faster solidification and a more uniform concentration distribution. The results of this study may be extended to similar binary and multicomponent systems in which a temperature gradient exists and the Soret coefficient is large enough so as to affect the fluid flow and concentration of the species.

  19. Steady-state and dynamic models for particle engulfment during solidification

    Science.gov (United States)

    Tao, Yutao; Yeckel, Andrew; Derby, Jeffrey J.

    2016-06-01

    Steady-state and dynamic models are developed to study the physical mechanisms that determine the pushing or engulfment of a solid particle at a moving solid-liquid interface. The mathematical model formulation rigorously accounts for energy and momentum conservation, while faithfully representing the interfacial phenomena affecting solidification phase change and particle motion. A numerical solution approach is developed using the Galerkin finite element method and elliptic mesh generation in an arbitrary Lagrangian-Eulerian implementation, thus allowing for a rigorous representation of forces and dynamics previously inaccessible by approaches using analytical approximations. We demonstrate that this model accurately computes the solidification interface shape while simultaneously resolving thin fluid layers around the particle that arise from premelting during particle engulfment. We reinterpret the significance of premelting via the definition an unambiguous critical velocity for engulfment from steady-state analysis and bifurcation theory. We also explore the complicated transient behaviors that underlie the steady states of this system and posit the significance of dynamical behavior on engulfment events for many systems. We critically examine the onset of engulfment by comparing our computational predictions to those obtained using the analytical model of Rempel and Worster [29]. We assert that, while the accurate calculation of van der Waals repulsive forces remains an open issue, the computational model developed here provides a clear benefit over prior models for computing particle drag forces and other phenomena needed for the faithful simulation of particle engulfment.

  20. Liquid low-level waste (LLLW) solidification at Oak Ridge National Laboratory

    International Nuclear Information System (INIS)

    Schultz, R.M.; Monk, T.H.; duMont, S.P.; Helms, R.E.; Keigan, M.V.; Morris, M.I.

    1987-01-01

    In general, the presentation describes the disposal of liquid, low-level (radioactive) waste (LLLW) by the hydrofracture process at Oak Ridge National Laboratory until 1984, when it was shut down due to regulatory concerns and operational anomalies. As a result of this, about 400,000 gallons of concentrated LLLW and 50,000 gallons of transuranic waste-bearing sludges have accumulated in the active, double-contained tank system which is reaching its operational capacity. A major initiative to develop an alternative means of LLLW treatment and disposal was begun about two years ago. This presentation summarizes the implementation strategy of the most likely process options. The strategy is being developed in two phases; a near-term flowsheet and a long-term or reference flowsheet. First, reliable and fully demonstrated commercial, cement solidification systems are being assessed for execution of an initial 50,000 gallon campaign in 1988. Second, development is under way to determine viable sludge separation, LLLW decontamination and solidification alternatives. A flowsheet analysis and cost study is being conducted by a consultant to ensure proper consideration of process developments at other sites. It is estimated that, depending upon funding requirements, it could take up to six years to implement the reference flowsheet

  1. Multiscale modelling of solidification microstructures, including microsegregation and microporosity, in an Al-Si-Cu alloy

    International Nuclear Information System (INIS)

    Lee, P.D.; Chirazi, A.; Atwood, R.C.; Wang, W.

    2004-01-01

    Phase transition phenomena in metallic alloys involve complex physical processes occurring over a wide range of temporal, spatial and energy scales. Multiscale modelling is a powerful methodology for understanding these complex systems. In this paper, a multiscale model of grain and pore formation is presented during solidification. At the microscale, a combined stochastic-deterministic approach based on the cellular automata method is used to solve multicomponent diffusion in a three-phase system (liquid, solid and gas), simulating the nucleation and growth of both grains and pores. The impingement of the growing pores upon the developing solid is also solved to predict the tortuous shape of the porosity, a critical factor for fatigue properties. The micromodel is coupled with a finite element method (FEM) solution of the macroscale heat transfer and fluid flow in industrial castings through the temperature and pressure fields. The result model was used to investigate the influence of local solidification time, hydrogen content, local metallostatic pressure and alloy composition upon the predicted grain structure and pore morphology. Comparison of the model predictions to both laboratory and industrial scale castings are presented

  2. Thermodynamic database of multi-component Mg alloys and its application to solidification and heat treatment

    Directory of Open Access Journals (Sweden)

    Guanglong Xu

    2016-12-01

    Full Text Available An overview about one thermodynamic database of multi-component Mg alloys is given in this work. This thermodynamic database includes thermodynamic descriptions for 145 binary systems and 48 ternary systems in 23-component (Mg–Ag–Al–Ca–Ce–Cu–Fe–Gd–K–La–Li–Mn–Na–Nd–Ni–Pr–Si–Sn–Sr–Th–Y–Zn–Zr system. First, the major computational and experimental tools to establish the thermodynamic database of Mg alloys are briefly described. Subsequently, among the investigated binary and ternary systems, representative binary and ternary systems are shown to demonstrate the major feature of the database. Finally, application of the thermodynamic database to solidification simulation and selection of heat treatment schedule is described.

  3. Industrial wastes solidification and material recovery: prospectives in Italy. Prospettive dell'applicazione delle tecniche di inertizzazione

    Energy Technology Data Exchange (ETDEWEB)

    De Angelis, G; Balzano, S

    1988-12-01

    This paper focuses on state-of-the-art materials recovery techniques employed in the solidification/stabilization of industrial wastes. Particular consideration is given to the Italian situation. After a review, with reference to waste/matrix compatibility inherent problems, of the presently employed main encapsulation techniques (with matrices based on cement, lime, clay, thermoplastic materials, organic polymers, macroencapsulating compounds), attention is addressed to solidification systems which allow a recovery of the waste material as low-technology by-products. Regarding the most important industrial waste streams: thermoplastic refuse, incinerator ashes, chemical sludges, the paper reviews efforts devoted not only to their chemical fixation in order to fulfill the current land disposal requirements, but mainly to their employment for production of manufactured articles.

  4. In Situ Study of Microstructure Evolution in Solidification of Hypereutectic Al-Si Alloys with Application of Thermal Analysis and Neutron Diffraction

    Science.gov (United States)

    Sediako, Dimitry G.; Kasprzak, Wojciech

    2015-09-01

    Understanding of the kinetics of solid-phase evolution in solidification of hypereutectic aluminum alloys is a key to control their as-cast microstructure and resultant mechanical properties, and in turn, to enhance the service characteristics of actual components. This study was performed to evaluate the solidification kinetics for three P-modified hypereutectic Al-19 pct Si alloys: namely, Al-Si binary alloy and with the subsequent addition of 2.8 pct Cu and 2.8 pct Cu + 0.7 pct Mg. Metallurgical evaluation included thermodynamic calculations of the solidification process using the FactSage™ 6.2 software package, as well as experimental thermal analysis, and in situ neutron diffraction. The study revealed kinetics of solid α-Al, solid Si, Al2Cu, and Mg2Si evolution, as well as the individual effects of Cu and Mg alloying additions on the solidification path of the Al-Si system. Various techniques applied in this study resulted in some discrepancies in the results. For example, the FactSage computations, in general, resulted in 281 K to 286 K (8 °C to 13 °C) higher Al-Si eutectic temperatures than the ones recorded in the thermal analysis, which are also ~278 K (~5 °C) higher than those observed in the in situ neutron diffraction. None of the techniques can provide a definite value for the solidus temperature, as this is affected by the chosen calculation path [283 K to 303 K (10 °C to 30 °C) higher for equilibrium solidification vs non-equilibrium] for the FactSage analysis; and further complicated by evolution of secondary Al-Cu and Mg-Si phases that commenced at the end of solidification. An explanation of the discrepancies observed and complications associated with every technique applied is offered in the paper.

  5. Remotely operated facility for in situ solidification of fissile uranium

    International Nuclear Information System (INIS)

    McGinnis, C.P.; Collins, E.D.; Patton, B.D.

    1986-01-01

    A heavily shielded, remotely operated facility, located within the Radiochemical processing Plant at Oak Ridge National Laboratory (ORNL), has been designed and is being operated to convert approx.1000 kg of fissile uranium (containing approx.75% 235 U, approx.10% 233 U, and approx.140 ppM 232 U) from a nitrate solution (130 g of uranium per L) to a solid oxide form. This project, the Consolidated Edison Uranium Solidification Program (CEUSP), is being carried out in order to prepare a stable uranium form for longterm storage. This paper describes the solidification process selected, the equipment and facilities required, the experimental work performed to ensure successful operation, some problems that were solved, and the initial operations

  6. Study of plastic solidification process on solid radioactive waste treatment

    International Nuclear Information System (INIS)

    Jing Weiguan; Zhang Yinsheng; Qian Wenju

    1994-01-01

    Comparisons between the plastic solidification conditions of incinerated ash and waste cation resin by using thermosetting plastic polyvinyl chloride (PVC), polystyrene (PS) and polyethylene (PE), and identified physico-chemical properties and irradiation resistance of solidified products were presented. These solidified products have passed through different tests as compression strength, leachability, durability, stability, permeability and irradiation resistance (10 6 Gy) etc. The result showed that the solidified products possessed stable properties and met the storage requirement. The waste tube of radioimmunoassay, being used as solidification medium to contain incinerated ash, had good mechanical properties and satisfactory volume reduction. This process may develop a new way for disposal solid radioactive waste by means of re-using waste

  7. Continuous Solidification of Immiscible Alloys and Microstructure Control

    Science.gov (United States)

    Jiang, Hongxiang; Zhao, Jiuzhou

    2018-05-01

    Immiscible alloys have aroused considerable interest in last few decades due to their excellent physical and mechanical characteristics as well as potential industrial applications. Up to date, plenty of researches have been carried out to investigate the solidification of immiscible alloys on the ground or in space and great progress has been made. It is demonstrated that the continuous solidification technique have great future in the manufacturing of immiscible alloys, it also indicates that the addition of surface active micro-alloying or inoculants for the nucleation of the minority phase droplets and proper application of external fields, e.g., static magnetic field, electric current, microgravity field, etc. may promote the formation of immiscible alloys with an expected microstructure. The objective of this article is to review the research work in this field.

  8. Fluid mechanics of directional solidification at reduced gravity

    Science.gov (United States)

    Chen, C. F.

    1992-01-01

    The primary objective of the proposed research is to provide additional groundbased support for the flight experiment 'Casting and Solidification Technology' (CAST). This experiment is to be performed in the International Microgravity Laboratory-1 (IML-1) scheduled to be flown on a space shuttle mission scheduled for 1992. In particular, we will provide data on the convective motion and freckle formation during directional solidification of NH4Cl from its aqueous solution at simulated parameter ranges equivalent to reducing the gravity from the sea-level value down to 0.1 g or lower. The secondary objectives of the proposed research are to examine the stability phenomena associated with the onset of freckles and the mechanisms for their subsequent growth and decline (to eventual demise of some) by state-of-the-art imaging techniques and to formulate mathematical models for the prediction of the observed phenomena.

  9. Glass-solidification method for high level radioactive liquid waste

    International Nuclear Information System (INIS)

    Kawamura, Kazuhiro; Kometani, Masayuki; Sasage, Ken-ichi.

    1996-01-01

    High level liquid wastes are removed with precipitates mainly comprising Mo and Zr, thereafter, the high level liquid wastes are mixed with a glass raw material comprising a composition having a B 2 O 3 /SiO 2 ratio of not less than 0.41, a ZnO/Li 2 O ratio of not less than 1.00, and an Al 2 O 3 /Li 2 O ratio of not less than 2.58, and they are melted and solidified into glass-solidification products. The liquid waste content in the glass-solidification products can be increased up to about 45% by using the glass raw material having such a predetermined composition. In addition, deposition of a yellow phase does not occur, and a leaching rate identical with that in a conventional case can be maintained. (T.M.)

  10. Solidification of ion exchange resin wastes in hydraulic cement

    International Nuclear Information System (INIS)

    Neilson, R.M. Jr.; Kalb, P.; Fuhrmann, M.; Colombo, P.

    1982-01-01

    Work has been conducted to investigate the solidification of ion exchange resin wastes with portland cements. These efforts have been directed toward the development of acceptable formulations for the solidification of ion exchange resin wastes and the characterization of the resultant waste forms. This paper describes formulation development work and defines acceptable formulations in terms of ternary phase compositional diagrams. The effects of cement type, resin type, resin loading, waste/cement ratio and water/cement ratio are described. The leachability of unsolidified and solidified resin waste forms and its relationship to full-scale waste form behavior is discussed. Gamma irradiation was found to improve waste form integrity, apparently as a result of increased resin crosslinking. Modifications to improve waste form integrity are described. 3 tables

  11. Method of processing radioactive liquid wastes by solidification with cement

    International Nuclear Information System (INIS)

    Yasumura, Keijiro; Matsuura, Hiroyuki.

    1975-01-01

    Object: To subject radioactive liquid wastes to a cement solidification treatment after heating and drying it by a thin film scrape-off drier to render it into the form of power, and then molding it into pellets for the treatment. Structure: Radioactive liquid wastes discharged from a nuclear power plant or nuclear reactor are supplied through a storage tank into a thin film scrape-off drier. In the drier, the radioactive liquid wastes are heated to separate the liquid, and the residue is taken out as dry powder from the scrape-off apparatus. The powder obtained in this way is molded into pellets of a desired form. These pellets are then packed in a drum can or similar container, into which cement paste is then poured for solidification. (Moriyama, K.)

  12. Solidification and performance of cement doped with phenol

    International Nuclear Information System (INIS)

    Vipulanandan, C.; Krishnan, S.

    1991-01-01

    Treating mixed hazardous wastes using the solidification/stabilization technology is becoming a critical element in waste management planning. The effect of phenol, a primary constituent in many hazardous wastes, on the setting and solidification process of Type I Portland cement was evaluated. The leachability of phenol from solidified cement matrix (TCLP test) and changes in mechanical properties were studied after curing times up to 28 days. The changes in cement hydration products due to phenol were studied using the X-ray diffraction (XRD) powder technique. Results show that phenol interferes with initial cement hydration by reducing the formation of calcium hydroxide and also reduces the compressive strength of cement. A simple model has been proposed to quantify the phenol leached from the cement matrix during the leachate test

  13. Solidification of radioactive wastes with inorganic binders (literature survey)

    International Nuclear Information System (INIS)

    Rudolph, G.; Koester, R.

    A survey is provided on solidification of radioactive waste solutions, sludges and tritium waste water through cement and other inorganic binders. A general survey of the possibilities described in the literature is followed by a somewhat more detailed description of the work carried on at four research establishments in the United States, Oak Ridge National Laboratory, Savannah River Laboratory, Brookhaven National Laboratory, and Atlantic Richfield Hanford Company, supplemented by personal information. Additional sections describe the experiences with various types of cement and the possibilities for improvement of solidification products through preliminary fixation of the toxic nuclides (transformation into insoluble products or absorption); there is a further possibility of post-treatment through polymer impregnation. Finally, definition and determination of leachability are provided and some results compiled. 74 references, 7 figures, 5 tables

  14. Techniques for the solidification of high-level wastes

    International Nuclear Information System (INIS)

    1977-01-01

    The problem of the long-term management of the high-level wastes from the reprocessing of irradiated nuclear fuel is receiving world-wide attention. While the majority of the waste solutions from the reprocessing of commercial fuels are currently being stored in stainless-steel tanks, increasing effort is being devoted to developing technology for the conversion of these wastes into solids. A number of full-scale solidification facilities are expected to come into operation in the next decade. The object of this report is to survey and compare all the work currently in progress on the techniques available for the solidification of high-level wastes. It will examine the high-level liquid wastes arising from the various processes currently under development or in operation, the advantages and disadvantages of each process for different types and quantities of waste solutions, the stages of development, the scale-up potential and flexibility of the processes

  15. Development of high-level waste solidification technology 1

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joon Hyung; Kim, Hwan Young; Kim, In Tae [and others

    1999-02-01

    Spent nuclear fuel contains useful nuclides as valuable resource materials for energy, heat and catalyst. High-level wastes (HLW) are expected to be generated from the R and D activities and reuse processes. It is necessary to develop vitrification or advanced solidification technologies for the safe long-term management of high level wastes. As a first step to establish HLW vitrification technology, characterization of HLWs that would arise at KAERI site, glass melting experiments with a lab-scale high frequency induction melter, and fabrication and property evaluation of base-glass made of used HEPA filter media and additives were performed. Basic study on the fabrication and characterization of candidate ceramic waste form (Synroc) was also carried out. These HLW solidification technologies would be directly useful for carrying out the R and Ds on the nuclear fuel cycle and waste management. (author). 70 refs., 29 tabs., 35 figs.

  16. Dynamics of liquid solidification thermal resistance of contact layer

    CERN Document Server

    Lipnicki, Zygmunt

    2017-01-01

    This monograph comprehensively describes phenomena of heat flow during phase change as well as the dynamics of liquid solidification, i.e. the development of a solidified layer. The book provides the reader with basic knowledge for practical designs, as well as with equations which describe processes of energy transformation. The target audience primarily comprises researchers and experts in the field of heat flow, but the book may also be beneficial for both practicing engineers and graduate students.

  17. Remediation of SRS Basins by In Situ Stabilization/Solidification

    International Nuclear Information System (INIS)

    Ganguly, A.

    1999-01-01

    In the late summer of 1998, the Savannah River Site began remediation of two radiologically contaminated basins using in situ stabilization. These two high-risk, unlined basins contain radiological contaminants, which potentially pose significant risks to human health and the environment. The selected remedy involves in situ stabilization/solidification of the contaminated wastes (basin and pipeline soils, pipelines, vegetation, and other debris) followed by installation of a low permeability soil cover

  18. Formation of Nitrogen Bubbles During Solidification of Duplex Stainless Steels

    Science.gov (United States)

    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.

  19. Non-Equilibrium Solidification of Undercooled Metallic Melts

    Directory of Open Access Journals (Sweden)

    Dieter M. Herlach

    2014-06-01

    Full Text Available If a liquid is undercooled below its equilibrium melting temperature an excess Gibbs free energy is created. This gives access to solidification of metastable solids under non-equilibrium conditions. In the present work, techniques of containerless processing are applied. Electromagnetic and electrostatic levitation enable to freely suspend a liquid drop of a few millimeters in diameter. Heterogeneous nucleation on container walls is completely avoided leading to large undercoolings. The freely suspended drop is accessible for direct observation of rapid solidification under conditions far away from equilibrium by applying proper diagnostic means. Nucleation of metastable crystalline phases is monitored by X-ray diffraction using synchrotron radiation during non-equilibrium solidification. While nucleation preselects the crystallographic phase, subsequent crystal growth controls the microstructure evolution. Metastable microstructures are obtained from deeply undercooled melts as supersaturated solid solutions, disordered superlattice structures of intermetallics. Nucleation and crystal growth take place by heat and mass transport. Comparative experiments in reduced gravity allow for investigations on how forced convection can be used to alter the transport processes and design materials by using undercooling and convection as process parameters.

  20. Solidification behavior of austenitic stainless steel filler metals

    International Nuclear Information System (INIS)

    David, S.A.; Goodwin, G.M.; Braski, D.N.

    1980-02-01

    Thermal analysis and interrupted solidification experiments on selected austenitic stainless steel filler metals provided an understanding of the solidification behavior of austenitic stainless steel welds. The sequences of phase separations found were for type 308 stainless steel filler metal, L + L + delta + L + delta + γ → γ + delta, and for type 310 stainless steel filler metal, L → L + γ → γ. In type 308 stainless steel filler metal, ferrite at room temperature was identified as either the untransformed primary delta-ferrite formed during the initial stages of solidification or the residual ferrite after Widmanstaetten austenite precipitation. Microprobe and scanning transmission electron microscope microanalyses revealed that solute extensively redistributes during the transformation of primary delta-ferrite to austenite, leading to enrichment and stabilization of ferrite by chromium. The type 310 stainless steel filler metal investigated solidifies by the primary crystallization of austenite, with the transformation going to completion at the solidus temperature. In our samples residual ferrite resulting from solute segregation was absent at the intercellular or interdendritic regions

  1. Solidification microstructures and solid-state parallels: Recent developments, future directions

    Energy Technology Data Exchange (ETDEWEB)

    Asta, M. [Department of Chemical Engineering and Materials Science, University of California at Davis, Davis, CA 95616 (United States); Beckermann, C. [Department of Mechanical and Industrial Engineering, University of Iowa, Iowa City, IA 52242 (United States); Karma, A. [Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA 02115 (United States); Kurz, W. [Institute of Materials, Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne (Switzerland)], E-mail: wilfried.kurz@epfl.ch; Napolitano, R. [Department of Materials Science and Engineering, Iowa State University, and Ames Laboratory USDOE, Ames, IA 50011 (United States); Plapp, M. [Physique de la Matiere Condensee, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Purdy, G. [Department of Materials Science and Engineering, McMaster University, Hamilton, Ont., L8S 4L7 (Canada); Rappaz, M. [Institute of Materials, Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne (Switzerland); Trivedi, R. [Department of Materials Science and Engineering, Iowa State University, and Ames Laboratory USDOE, Ames, IA 50011 (United States)

    2009-02-15

    Rapid advances in atomistic and phase-field modeling techniques as well as new experiments have led to major progress in solidification science during the first years of this century. Here we review the most important findings in this technologically important area that impact our quantitative understanding of: (i) key anisotropic properties of the solid-liquid interface that govern solidification pattern evolution, including the solid-liquid interface free energy and the kinetic coefficient; (ii) dendritic solidification at small and large growth rates, with particular emphasis on orientation selection; (iii) regular and irregular eutectic and peritectic microstructures; (iv) effects of convection on microstructure formation; (v) solidification at a high volume fraction of solid and the related formation of pores and hot cracks; and (vi) solid-state transformations as far as they relate to solidification models and techniques. In light of this progress, critical issues that point to directions for future research in both solidification and solid-state transformations are identified.

  2. Microstructure and Corrosion Resistance Property of a Zn-AI-Mg Alloy with Different Solidification Processes

    Directory of Open Access Journals (Sweden)

    Jiang Guang-rui

    2017-01-01

    Full Text Available Zn-Al-Mg alloy coating attracted much attention due to its high corrosion resistance properties, especially high anti-corrosion performance at the cut edge. As the Zn-Al-Mg alloy coating was usually produced by hot-dip galvanizing method, solidification process was considered to influence its microstructure and corrosion properties. In this work, a Zn-Al-Mg cast alloy was melted and cooled to room temperature with different solidification processes, including water quench, air cooling and furnace cooling. Microstructure of the alloy with different solidification processes was characterized by scanning electron microscopy (SEM. Result shows that the microstructure of the Zn-Al-Mg alloy are strongly influenced by solidification process. With increasing solidification rate, more Al is remained in the primary crystal. Electrochemical analysis indicates that with lowering solidification rate, the corrosion current density of the Zn-Al-Mg alloy decreases, which means higher corrosion resistance.

  3. The use of mineral-like matrices for hlw solidification and spent fuel immobilization

    International Nuclear Information System (INIS)

    Pokhitonov, J.A.; Starchenko, V.A.; Strelnikov, A.V.; Sorokin, V.T.; Shvedov, A.A.

    2000-01-01

    The conception of radioactive waste management is based upon the multi-barrier protection principle stating that the long-lived radionuclides safety isolation is ensured by a system of engineering and natural geological barriers. One of the effective ways of the long-lived radionuclides immobilization is the integration of these materials within a mineral-like matrice. This technique may be used both for isolation of separated groups of nuclides (Cs, Sr, TUE, TRE) and for immobilization of spent fuel which for some reason can't be processed at the radiochemical plant. In this paper two variants of flowsheets HLW management are discussed. The following ways of HLW reprocessing are considered: - The first cycle raffinate solidification (without partitioning); - The individual solidification of two separated radionuclide groups (Sr+Cs+FP fraction and TPE+TRE fraction). The calcination of some characteristics (annual and total amounts, specific activity, radiochemical composition and radiogenic heat) of HLW integrated within a mineral-like matrix are performed for both options. The matrix compositions may be also used for spent fuel immobilization by means of the hot isostatic pressing technique. (authors)

  4. A phase-field model for non-equilibrium solidification of intermetallics

    International Nuclear Information System (INIS)

    Assadi, H.

    2007-01-01

    Intermetallics may exhibit unique solidification behaviour-including slow growth kinetics, anomalous partitioning and formation of unusual growth morphologies-because of departure from local equilibrium. A phase-field model is developed and used to illustrate these non-equilibrium effects in solidification of a prototype B2 intermetallic phase. The model takes sublattice compositions as primary field variables, from which chemical long-range order is derived. The diffusive reactions between the two sublattices, and those between each sublattice and the liquid phase are taken as 'internal' kinetic processes, which take place within control volumes of the system. The model can thus capture solute and disorder trapping effects, which are consistent-over a wide range of the solid/liquid interface thickness-with the predictions of the sharp-interface theory of solute and disorder trapping. The present model can also take account of solid-state ordering and thus illustrate the effects of chemical ordering on microstructure formation and crystal growth kinetics

  5. A mesoscale granular model for the mechanical behavior of alloys during solidification

    Energy Technology Data Exchange (ETDEWEB)

    Vernede, Stephane [Computational Materials Laboratory, Ecole Polytechnique Federale de Lausanne, Station 12, Lausanne CH-1015 (Switzerland); Alcan Centre de Recherches de Voreppe, ZI Centr' Alp, 725 rue Aristide Berges, BP 27, Voreppe FR-38341 (France)], E-mail: stephane.vernede@alcan.com; Dantzig, Jonathan A. [Computational Materials Laboratory, Ecole Polytechnique Federale de Lausanne, Station 12, Lausanne CH-1015 (Switzerland); Department of Mechanical Science and Engineering, University of Illinois, 1206 West Green Street Urbana, IL 61801 (United States); Rappaz, Michel [Computational Materials Laboratory, Ecole Polytechnique Federale de Lausanne, Station 12, Lausanne CH-1015 (Switzerland)

    2009-03-15

    We present a two-dimensional granular model for the mechanical behavior of an ensemble of globular grains during solidification. The grain structure is produced by a Voronoi tessellation based on an array of predefined nuclei. We consider the fluid flow caused by grain movement and solidification shrinkage in the network of channels that is formed by the faces of the grains in the tessellation. We develop the governing equations for the flow rate and pressure drop across each channel when the grains are allowed to move, and we then assemble the equations into a global expression that conserves mass and force in the system. We show that the formulation is consistent with dissipative formulations of non-equilibrium thermodynamics. Several example problems are presented to illustrate the effect of tensile strains and the availability of liquid to feed the deforming microstructure. For solid fractions below g{sub s}=0.97, we find that the fluid is able to feed the deformation at low strain, even if external feeding is not permitted. For solid fractions above g{sub s}=0.97, clusters of grains with 'dry' boundaries form and fluid flow becomes highly localized.

  6. Spreading and solidification behavior of molten Si droplets impinging on substrates

    International Nuclear Information System (INIS)

    Nagashio, K.; Murata, H.; Kuribayashi, K.

    2004-01-01

    This paper focuses on an effect of initial undercoolings on the spreading and solidification behavior of Si dropped on a silicon wafer, which was directly observed through it by the infrared imaging system. For an overheated droplet, the melt spreading occurred first and solidified later. The final splat shape was a typical disc. On the other hand, for a droplet with large initial undercooling, the solidification took place at the faster rate than the melt spreading, which resulted in a spherical shape of final splat. It is indicated that the final shape is considerably affected by the initial undercooling in the measurable-scale experiment with large droplets (∼mm size) and low impingement rates (∼m/s order). Moreover, equiaxed grains were found throughout the quenched surface by an electron backscatter pattern analysis. That is, the microstructure formation was nucleation-controlled since the growth parallel to the substrate was suppressed by the time-dependent contact of melt/substrate governed by the melt deformation

  7. Effects of Non-equilibrium Solidification on the Material Properties of Brick Silicon for Photovoltaics

    Science.gov (United States)

    Regnault, W. F.; Yoo, K. C.; Soltani, P. K.; Johnson, S. M.

    1984-01-01

    Silicon ingot growth technologies like the Ubiquitous Crystallization Process (UCP) are solidified within a shaping crucible. The rate at which heat can be lost from this crucible minus the rate at which heat is input from an external source determines the rate at which crystallization will occur. Occasionally, when the process parameters for solidification are exceeded, the normally large multi-centimeter grain size material assocated with the UCP will break down into regions containing extremely small, millimeter or less, grain size material. Accompanying this breakdown in grain growth is the development of so called sinuous grain boundaries. The breakdown in grain growth which results in this type of small grain structure with sinuous boundaries is usually associated with the rapid crystallization that would accompany a system failure. This suggests that there are limits to the growth velocity that one can obtain and still expect to produce material that would possess good photovoltaic properties. It is the purpose to determine the causes behind the breakdown of this material and what parameters will determine the best rates of solidification.

  8. Effect of fill volume on solidification characteristics of DI (deionized) water in a spherical capsule – An experimental study

    International Nuclear Information System (INIS)

    Chandrasekaran, P.; Cheralathan, M.; Velraj, R.

    2015-01-01

    The present study aims to investigate the solidification characteristics of water, as the PCM (phase change material), due to the effect of fill volume of PCM in a spherical capsule. The experiments were conducted with the spherical capsule, filling it with water of 80, 85, 90, 92 and 95 percentage of its full volume and immersing it in a constant temperature bath maintained at various temperatures. It was observed that the increase in fill volume had a significant influence in reducing the degree of supercooling and it was eliminated with 95% fill volume. Further, the increase in fill volume had a considerable effect in advancing the commencement of solidification. Increasing the temperature potential enhanced the heat flux during the solidification of first 50% of PCM mass and its effect was more pronounced at higher fill volumes. The heat flux was increased several fold particularly at 95% fill volume making it highly suitable for applications that demand large cooling load in a short duration. Hence the proper selection of fill volume and temperature driving potential is essential to achieve overall energy efficiency while designing the CTES (cool thermal energy storage) system. - Highlights: • Supercooling was eliminated with 95% fill volume at all surrounding bath temperature. • The effect of higher fill volume is more pronounced with higher temperature potential. • 50% mass is solidified in 10% of solidification duration with 95% fill volume at −12 °C. • Several fold increase in heat flux is achieved with 95% fill volume at −12 °C. • Combination of fill volume and temperature potential is essential for good design.

  9. Validated thermodynamic prediction of AlP and eutectic (Si) solidification sequence in Al-Si cast alloys

    International Nuclear Information System (INIS)

    Liang, S M; Schmid-Fetzer, R

    2016-01-01

    The eutectic microstructure in hypoeutectic Al-Si cast alloys is strongly influenced by AlP particles which are potent nuclei for the eutectic (Si) phase. The solidification sequence of AlP and (Si) phases is, thus, crucial for the nucleation of eutectic silicon with marked impact on its morphology. This study presents this interdependence between Si- and P-compositions, relevant for Al-Si cast alloys, on the solidification sequence of AlP and (Si). These data are predicted from a series of thermodynamic calculations. The predictions are based on a self-consistent thermodynamic description of the Al-Si-P ternary alloy system developed recently. They are validated by independent experimental studies on microstructure and undercooling in hypoeutectic Al-Si alloys. A constrained Scheil solidification simulation technique is applied to predict the undercooling under clean heterogeneous nucleation conditions, validated by dedicated experimental observations on entrained droplets. These specific undercooling values may be very large and their quantitative dependence on Si and P content of the Al alloy is presented. (paper)

  10. A three-dimensional cellular automata model coupled with finite element method and thermodynamic database for alloy solidification

    Science.gov (United States)

    Zhao, Y.; Qin, R. S.; Chen, D. F.

    2013-08-01

    A three-dimensional (3D) cellular automata (CA) model has been developed for the simulation of microstructure evolution in alloy solidification. The governing rule for the CA model is associated with the phase transition driving force which is obtained via a thermodynamic database. This determines the migration rate of the non-equilibrium solid-liquid (SL) interface and is calculated according to the local temperature and chemical composition. The curvature of the interface and the anisotropic property of the surface energy are taken into consideration. A 3D finite element (FE) method is applied for the calculation of transient heat and mass transfer. Numerical calculations for the solidification of Fe-1.5 wt% C alloy have been performed. The morphological evolution of dendrites, carbon segregation and temperature distribution in both isothermal and non-isothermal conditions are studied. The parameters affecting the growth of equiaxed and columnar dendrites are discussed. The calculated results are verified using the analytical model and previous experiments. The method provides a sophisticated approach to the solidification of multi-phase and multi-component systems.

  11. Microstructure and Solidification Crack Susceptibility of Al 6014 Molten Alloy Subjected to a Spatially Oscillated Laser Beam.

    Science.gov (United States)

    Kang, Minjung; Han, Heung Nam; Kim, Cheolhee

    2018-04-23

    Oscillating laser beam welding for Al 6014 alloy was performed using a single mode fiber laser and two-axis scanner system. Its effect on the microstructural evolution of the fusion zone was investigated. To evaluate the influence of oscillation parameters, self-restraint test specimens were fabricated with different beam patterns, widths, and frequencies. The behavior of hot cracking propagation was analyzed by high-speed camera and electron backscatter diffraction. The behavior of crack propagation was observed to be highly correlated with the microstructural evolution of the fusion zone. For most oscillation conditions, the microstructure resembled that of linear welds. A columnar structure was formed near the fusion line and an equiaxed structure was generated at its center. The wide equiaxed zone of oscillation welding increased solidification crack susceptibility. For an oscillation with an infinite-shaped scanning pattern at 100 Hz and 3.5 m/min welding speed, the bead width, solidification microstructure, and the width of the equiaxed zone at the center of fusion fluctuated. Furthermore, the equiaxed and columnar regions alternated periodically, which could reduce solidification cracking susceptibility.

  12. Microstructure and Solidification Crack Susceptibility of Al 6014 Molten Alloy Subjected to a Spatially Oscillated Laser Beam

    Directory of Open Access Journals (Sweden)

    Minjung Kang

    2018-04-01

    Full Text Available Oscillating laser beam welding for Al 6014 alloy was performed using a single mode fiber laser and two-axis scanner system. Its effect on the microstructural evolution of the fusion zone was investigated. To evaluate the influence of oscillation parameters, self-restraint test specimens were fabricated with different beam patterns, widths, and frequencies. The behavior of hot cracking propagation was analyzed by high-speed camera and electron backscatter diffraction. The behavior of crack propagation was observed to be highly correlated with the microstructural evolution of the fusion zone. For most oscillation conditions, the microstructure resembled that of linear welds. A columnar structure was formed near the fusion line and an equiaxed structure was generated at its center. The wide equiaxed zone of oscillation welding increased solidification crack susceptibility. For an oscillation with an infinite-shaped scanning pattern at 100 Hz and 3.5 m/min welding speed, the bead width, solidification microstructure, and the width of the equiaxed zone at the center of fusion fluctuated. Furthermore, the equiaxed and columnar regions alternated periodically, which could reduce solidification cracking susceptibility.

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

    Science.gov (United States)

    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.

  14. Visual Representations of Microcosm in Textbooks of Chemistry: Constructing a Systemic Network for Their Main Conceptual Framework

    Science.gov (United States)

    Papageorgiou, George; Amariotakis, Vasilios; Spiliotopoulou, Vasiliki

    2017-01-01

    The main objective of this work is to analyse the visual representations (VRs) of the microcosm depicted in nine Greek secondary chemistry school textbooks of the last three decades in order to construct a systemic network for their main conceptual framework and to evaluate the contribution of each one of the resulting categories to the network.…

  15. Low-level waste cement solidification design, installation, and start-up

    International Nuclear Information System (INIS)

    Jezek, G.R.

    1988-08-01

    This report describes the design, installation, and start-up activities of the Cement Solidification System (CSS) at the West Valley Demonstration Project (WVDP), West Valley, New York. The CSS, designed to operate within an existing process cell, automatically and remotely solidifies low-level nuclear waste by mixing it with Portland Type I cement. The qualified waste form mixture is placed into square, 270-litre (71-gallon) metal drums. The drums have an integral polyethylene liner to protect the carbon-steel material from potential corrosion. The CSS produces drums at a continuous operation rate of four drums per hour. All system processing data is monitored by a computerized Data Acquisition System (DAS). 6 figs

  16. Stabilization/solidification of lead-contaminated soil using cement and rice husk ash.

    Science.gov (United States)

    Yin, Chun-Yang; Mahmud, Hilmi Bin; Shaaban, Md Ghazaly

    2006-10-11

    This paper presents the findings of a study on solidification/stabilization (S/S) of lead-contaminated soil using ordinary Portland cement (OPC) and rice husk ash (RHA). The effects of varying lead concentrations (in the form of nitrates) in soil samples on the physical properties of their stabilized forms, namely unconfined compressive strength (UCS), setting times of early mixtures and changes in crystalline phases as well as chemical properties such as leachability of lead, pH and alkalinity of leachates are studied. Results have indicated that usage of OPC with RHA as an overall binder system for S/S of lead-contaminated soils is more favorable in reducing the leachability of lead from the treated samples than a binder system with standalone OPC. On the other hand, partial replacement of OPC with RHA in the binder system has reduced the UCS of solidified samples.

  17. Volume reduction and solidification of liquid and solid low-level radioactive waste

    International Nuclear Information System (INIS)

    May, J.R.

    1979-01-01

    This paper presents a brief background of the development of a method of radioactive waste volume reduction using a unique fluidized bed calciner/incinerator. The volume reduction system is capable of processing a variety of liquid chemical wastes, spent ion exchange resin beads, filter treatment sludges, contaminated lubricating oils, and miscellaneous combustible solids such as paper, rags, protective clothing, wood, etc. All of these wastes are processed in one chemical reaction vessel. Detailed process data is presented that shows the system is capable of reducing the total volume of disposable radioactive waste generated by light water reactors by a factor of 10. Equally important to reducing the volume of power reactor radwaste is the final form of the stored or disposable radwaste. This paper also presents process data related to a new radwaste solidification system, presently being developed, that is particularly suited for immobilizing the granular solids and ashes resulting from volume reduction by calcination and/or incineration

  18. Effect of chemical composition and cooling conditions on solidification hot cracking of Ni-based alloys

    International Nuclear Information System (INIS)

    De Vito, Sophie

    2000-01-01

    Ni-based alloys 690 present solidification hot cracks during welding of vapour generators. Hot cracks are qualitatively known to be due to the formation of inter-dendritic liquid films and of secondary phases down to low temperatures. This study aims at establishing the link between thermodynamics, solidification and hot cracking. Experimental solidification paths of high purity alloys (with varying Nb and Si contents) are obtained from quenching during directional solidification and TIG-welding experiments. They are compared to Thermo-Calc computations, assuming no diffusion in the solid. From directional solidification samples, good agreement between computed and experimental solidification paths is shown in the quenched liquid. Secondary arms of dendrites are affected by solid state diffusion of Nb. Combined effect of diffusion and solute build-up in the liquid phase modifies micro-segregation in the solid region. Solidification paths from welding specimens are similar to those of the solid region of quenched samples. Nb solid state diffusion is negligible but undercooling compensates the effect of solid state diffusion in directional solidification. Evolution of liquid fraction at the end of the solidification is in accordance with the hot cracking classification of the alloys. Nb favours formation of inter-dendritic liquid films and eutectic-like phases down to low temperature. (author) [fr

  19. Application of the Method of Direct Solidification for Obtaining New Materials

    International Nuclear Information System (INIS)

    Grankin, S.S.

    2007-01-01

    The influence of the method of direct solidification on the formation of the material structure has been considered. The main methods of single crystal growth have been described. A considerable influence of the crystal growth parameters (temperature gradient at the front of solidification and the speed of moving of the front of solidification) on the type of the structure and morphology of single crystals has been shown. The examples of application of the method of direct solidification in experimental and industrial production are showed: production of directly crystallized blades for turbines of nuclear power plants and gas-turbine engines

  20. Susceptibility of ternary aluminum alloys to cracking during solidification

    International Nuclear Information System (INIS)

    Liu, Jiangwei; Kou, Sindo

    2017-01-01

    The crack susceptibility map of a ternary Al alloy system provides useful information about which alloy compositions are most susceptible to cracking and thus should be avoided by using a filler metal with a significantly different composition. In the present study the crack susceptibility maps of ternary Al alloy systems were calculated based on the maximum |dT/d(f S ) 1/2 | as an index for the crack susceptibility, where T is temperature and f S fraction solid. Due to the complexity associated with ternary alloy solidification, commercial thermodynamic software Pandat and Al database PanAluminum, instead of analytical equations, were used to calculate f S as a function of T and hence the maximum |dT/d(f S ) 1/2 | for ternary Al-Mg-Si, Al-Cu-Mg and Al-Cu-Si alloy systems. A crack susceptibility map covering 121 alloy compositions was constructed for each of the three ternary alloy systems at each of the following three levels of back diffusion: no back diffusion, back diffusion under a 100 °C/s cooling rate, and back diffusion under 20° C/s. The location of the region of high crack susceptibility, which is the most important part of the map, was shown in each of the nine calculated maps. These locations were compared with those observed in crack susceptibility tests by previous investigators. With back diffusion considered, either under 20 or 100 °C/s, the agreement between the calculated and observed maps was good especially for Al-Mg-Si and Al-Cu-Mg. Thus, the maximum |dT/d(f S ) 1/2 | can be used as a crack susceptibility index to construct crack susceptibility maps for ternary Al alloys and to evaluate the effect of back diffusion on their crack susceptibility. - Graphical abstract: The crack susceptibility map of a ternary alloy system indicates the composition range most susceptible to cracking, which should be avoided in welding or casting. The crack susceptibility maps of ternary Al alloy systems Al-Mg-Si, Al-Cu-Mg and Al-Cu-Si were calculated based

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

    Science.gov (United States)

    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

  2. The effects of ultrasonic solidification on aluminum

    OpenAIRE

    Đorđević Slavko 1

    2003-01-01

    The effect of ultrasound on characteristics of solidified aluminum was shown. An ultrasonic head and ultrasonic system for modification was designed and applied to the crystallizing aluminum melt. The ultrasonic generator allows power of 50-500 W, amplitude of oscillations 10-100 um.m and the operating frequency of 25 kHz. Ultrasonic modification was done by ultrasound introduced from above into the melt. Microstructure photographs show decreasing of the grain size more than five times.

  3. The effects of ultrasonic solidification on aluminum

    Directory of Open Access Journals (Sweden)

    Đorđević Slavko 1

    2003-01-01

    Full Text Available The effect of ultrasound on characteristics of solidified aluminum was shown. An ultrasonic head and ultrasonic system for modification was designed and applied to the crystallizing aluminum melt. The ultrasonic generator allows power of 50-500 W, amplitude of oscillations 10-100 um.m and the operating frequency of 25 kHz. Ultrasonic modification was done by ultrasound introduced from above into the melt. Microstructure photographs show decreasing of the grain size more than five times.

  4. Modelling of melting and solidification transport phenomena during hypothetical NPP severe accidents

    International Nuclear Information System (INIS)

    Sarler, B.

    1992-01-01

    A physical and mathematical framework to deal with the transport phenomena occuring during melting and solidification of the hypothetical NPP severe accidents is presented. It concentrates on the transient temperature, velocity, and species concentration distributions during such events. The framework is based on the Mixture Continuum Formulation of the components and phases, cast in the boundary-domain integral shape structured by the fundamental solution of the Laplace equation. The formulation could cope with various solid-liquid sub-systems through the inclusion of the specific closure relations. The deduced system of boundary-domain integral equations for conservation of mass, energy, momentum, and species could be solved by the boundary element discrete approximative method. (author) [sl

  5. Nb-Based Nb-Al-Fe Alloys: Solidification Behavior and High-Temperature Phase Equilibria

    Science.gov (United States)

    Stein, Frank; Philips, Noah

    2018-03-01

    High-melting Nb-based alloys hold significant promise for the development of novel high-temperature materials for structural applications. In order to understand the effect of alloying elements Al and Fe, the Nb-rich part of the ternary Nb-Al-Fe system was investigated. A series of Nb-rich ternary alloys were synthesized from high-purity Nb, Al, and Fe metals by arc melting. Solidification paths were identified and the liquidus surface of the Nb corner of the ternary system was established by analysis of the as-melted microstructures and thermal analysis. Complementary analysis of heat-treated samples yielded isothermal sections at 1723 K and 1873 K (1450 °C and 1600 °C).

  6. Homogeneous nucleation ahead of the solid-liquid interface during rapid solidification of binary alloys

    International Nuclear Information System (INIS)

    Smith, P.M.; Elmer, J.W.

    1996-01-01

    In recent rapid solidification experiments on Al-5%Be alloys, a Liquid Phase Nucleation (LPN) model was developed to explain the formation of periodic arrays of randomly-oriented Be-rich particles in an Al-rich matrix. In the LPN model, Be droplets were assumed to nucleate in the liquid ahead of the solid-liquid interface, but no justification for this was given. Here the authors present a model which considers the geometric constraints (imposed by proximity to the interface) on the number of solute atoms available to form a nucleus. Calculations based on this model predict that nucleation of second-phase particles can be most likely a short distance ahead of the interface in immiscible binary systems such as Al-Be. As part of the nucleation calculations, a semi-empirical method of calculating solid-liquid surface tensions in binary systems was developed, and is presented in the Appendix

  7. Oxycarbonitride glass formation by melt solidification

    Energy Technology Data Exchange (ETDEWEB)

    Imon, M M; Risbud, S H

    1986-04-01

    Experimental results are presented from the synthesis and characterization of multianion oxycarbonitride glasses composed of MgSiAlON glass powders with SiC additions of 5, 10, or 15 wt pct. Nitrogen additions to the oxide MgO-Al2O3-SiO2 glasses increased devitrification resistance, but carbon additions to MgSiAlON glasses promote crystal nucleation. These properties are relevant to the oxycarbonitride glasses use in refractory glass-ceramic and ceramic-ceramic composite systems with good elevated temperature performance. 9 references.

  8. Solidification of low-level radioactive wastes in masonry cement

    International Nuclear Information System (INIS)

    Zhou, H.; Colombo, P.

    1987-03-01

    Portland cements are widely used as solidification agents for low-level radioactive wastes. However, it is known that boric acid wastes, as generated at pressurized water reactors (PWR's) are difficult to solidify using ordinary portland cements. Waste containing as little as 5 wt % boric acid inhibits the curing of the cement. For this purpose, the suitability of masonry cement was investigated. Masonry cement, in the US consists of 50 wt % slaked lime (CaOH 2 ) and 50 wt % of portland type I cement. Addition of boric acid in molar concentrations equal to or less than the molar concentration of the alkali in the cement eliminates any inhibiting effects. Accordingly, 15 wt % boric acid can be satisfactorily incorporated into masonry cement. The suitability of masonry cement for the solidification of sodium sulfate wastes produced at boiling water reactors (BWR's) was also investigated. It was observed that although sodium sulfate - masonry cement waste forms containing as much as 40 wt % Na 2 SO 4 can be prepared, waste forms with more than 7 wt % sodium sulfate undergo catastrophic failure when exposed to an aqueous environment. It was determined by x-ray diffraction that in the presence of water, the sulfate reacts with hydrated calcium aluminate to form calcium aluminum sulfate hydrate (ettringite). This reaction involves a volume increase resulting in failure of the waste form. Formulation data were identified to maximize volumetric efficiency for the solidification of boric acid and sodium sulfate wastes. Measurement of some of the waste form properties relevant to evaluating the potential for the release of radionuclides to the environment included leachability, compression strengths and chemical interactions between the waste components and masonry cement. 15 refs., 19 figs., 9 tabs

  9. Development of Stable Solidification Method for Insoluble Ferrocyanides-13170

    Energy Technology Data Exchange (ETDEWEB)

    Ikarashi, Yuki; Masud, Rana Syed; Mimura, Hitoshi [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba6-6-01-2, Sendai, 980-8579 (Japan); Ishizaki, Eiji; Matsukura, Minoru [UNION SHOWA K.K. 17-20, Mita 2-chome, Minato-ku, Tokyo 108-0073 (Japan)

    2013-07-01

    The development of stable solidification method of insoluble ferrocyanides sludge is an important subject for the safety decontamination in Fukushima NPP-1. By using the excellent immobilizing properties of zeolites such as gas trapping ability and self-sintering properties, the stable solidification of insoluble ferrocyanides was accomplished. The immobilization ratio of Cs for K{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O saturated with Cs{sup +} ions (Cs{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O) was estimated to be less than 0.1% above 1,000 deg. C; the adsorbed Cs{sup +} ions are completely volatilized. In contrast, the novel stable solid form was produced by the press-sintering of the mixture of Cs{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O and zeolites at higher temperature of 1,000 deg. C and 1,100 deg. C; Cs volatilization and cyanide release were completely depressed. The immobilization ratio of Cs, under the mixing conditions of Cs{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O:CP= 1:1 and calcining temperature: 1,000 deg. C, was estimated to be nearly 100%. As for the kinds of zeolites, natural mordenite (NM), clinoptilolite (CP) and Chabazite tended to have higher immobilization ratio compared to zeolite A. This may be due to the difference in the phase transformation between natural zeolites and synthetic zeolite A. In the case of the composites (K{sub 2-X}Ni{sub X/2}[NiFe(CN){sub 6}].nH{sub 2}O loaded natural mordenite), relatively high immobilization ratio of Cs was also obtained. This method using zeolite matrices can be applied to the stable solidification of the solid wastes of insoluble ferrocyanides sludge. (authors)

  10. Divorced Eutectic Solidification of Mg-Al Alloys

    Science.gov (United States)

    Monas, Alexander; Shchyglo, Oleg; Kim, Se-Jong; Yim, Chang Dong; Höche, Daniel; Steinbach, Ingo

    2015-08-01

    We present simulations of the nucleation and equiaxed dendritic growth of the primary hexagonal close-packed -Mg phase followed by the nucleation of the -phase in interdendritic regions. A zoomed-in region of a melt channel under eutectic conditions is investigated and compared with experiments. The presented simulations allow prediction of the final properties of an alloy based on process parameters. The obtained results give insight into the solidification processes governing the microstructure formation of Mg-Al alloys, allowing their targeted design for different applications.

  11. Crystal Growth and Fluid Mechanics Problems in Directional Solidification

    Science.gov (United States)

    Tanveer, Saleh A.; Baker, Gregory R.; Foster, Michael R.

    2001-01-01

    Our work in directional solidification has been in the following areas: (1) Dynamics of dendrites including rigorous mathematical analysis of the resulting equations; (2) Examination of the near-structurally unstable features of the mathematically related Hele-Shaw dynamics; (3) Numerical studies of steady temperature distribution in a vertical Bridgman device; (4) Numerical study of transient effects in a vertical Bridgman device; (5) Asymptotic treatment of quasi-steady operation of a vertical Bridgman furnace for large Rayleigh numbers and small Biot number in 3D; and (6) Understanding of Mullins-Sererka transition in a Bridgman device with fluid dynamics is accounted for.

  12. Solidification process of a tool steel with niobium

    International Nuclear Information System (INIS)

    Makray, E.T.; Bresciani Filho, E.; Martinez Nazar, A.M.

    1984-01-01

    The solidification process of M2 high speed steel where tungsten was totally substituted by niobium was analysed. It occurs through a eutectic type reaction, in four steps. It was verified that one can apply the Coupled Zone Concept to explain the solification mechanism of this alloy: there is a primary phase (NbC), which is envolved by the other phase (ferrite) as a halo in order to send the composition back to the coupled growth region, where the binary eutectic forms. The last step is the formation of other compounds at the grain boundary. (Author) [pt

  13. Isothermal solidification based packaging of biosensors at low temperatures

    International Nuclear Information System (INIS)

    Sharma, R.P.; Khanna, P.K.; Kumar, D.

    2010-01-01

    Thick film Au printed square contact pads are interconnected to Cu substrates at constant pressure and temperature using the isothermal solidification of Bi-In alloy on the joining surfaces. The effect of reaction time on the mechanical strength of the package has been analyzed. Thermal stability of the fabricated specimens have been measured and discussed. The delaminated surfaces examined optically reveal the morphology of the metallization zones on the joining substrates. The scanning electron microscopy of these surfaces is reported in this paper. Tests for thermal shock, pH resistivity and shelf life have been carried out to predict the reliability of the packaging for long term applications.

  14. Rapid Solidification of AB{sub 5} Hydrogen Storage Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gulbrandsen-Dahl, Sverre

    2002-01-01

    This doctoral thesis is concerned with rapid solidification of AB{sub 5} materials suitable for electrochemical hydrogen storage. The primary objective of the work has been to characterise the microstructure and crystal structure of the produced AB{sub 5} materials as a function of the process parameters, e.g. the cooling rate during rapid solidification, the determination of which has been paid special attention to. The thesis is divided into 6 parts, of which Part I is a literature review, starting with a short presentation of energy storage alternatives. Then a general review of metal hydrides and their utilisation as energy carriers is presented. This part also includes more detailed descriptions of the crystal structure, the chemical composition and the hydrogen storage properties of AB{sub 5} materials. Furthermore, a description of the chill-block melt spinning process and the gas atomisation process is given. In Part II of the thesis a digital photo calorimetric technique has been developed and applied for obtaining in situ temperature measurements during chill-block melt spinning of a Mm(NiCoMnA1){sub 5} hydride forming alloy (Mm = Mischmetal of rare earths). Compared with conventional colour transmission temperature measurements, this technique offers a special advantage in terms of a high temperature resolutional and positional accuracy, which under the prevailing experimental conditions were found to be {+-}29 K and {+-} 0.1 mm, respectively. Moreover, it is shown that the cooling rate in solid state is approximately 2.5 times higher than that observed during solidification, indicating that the solid ribbon stayed in intimate contact with the wheel surface down to very low metal temperatures before the bond was broken. During this contact period the cooling regime shifted from near ideal in the melt puddle to near Newtonian towards the end, when the heat transfer from the solid ribbon to the wheel became the rate controlling step. In Part III of the

  15. In-situ solidification cleans up old gas plant site

    International Nuclear Information System (INIS)

    Hatfield, A.D.; Dennis, N.D.

    1995-01-01

    A manufactured gas plant site in Columbus, Georgia, was the location of an environmental cleanup in 1992. Manufactured gas was produced at this site from 1854 to 1931 with the availability of natural gas from a transmission pipeline causing its demise. However, waste products, primarily coal tar from the earlier years of plant operation, remained with the site. In-situ solidification was chosen as the cleanup method. Post monitoring activities show that the project was successful and the site is now a park and a leading part of river front development

  16. Solidification in direct metal deposition by LENS processing

    Science.gov (United States)

    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.

  17. Mixed and chelated waste test programs with bitumen solidification

    International Nuclear Information System (INIS)

    Simpson, S.I.; Morris, M.; Vidal, H.

    1988-01-01

    This paper presents the results of bitumen solidification tests on mixed wastes and chelated wastes. The French Atomic Energy Commission (CEA) performed demonstration tests on radioactive wastes contaminated with chelating agents for Associated Technologies, Inc. (ATI). The chelated wastes were produced and concentrated by Commonwealth Edison Co. as a result of reactor decontamination at Dresden Nuclear Station, Unit 1. Law Engineering in Charlotte, N. C. produced samples and performed tests on simulated heavy metal laden radioactive waste (mixed) to demonstrate the quality of the bituminous product. The simulation is intended to represent waste produced at Oak Ridge National Labs operated by Martin-Marietta

  18. Closed solutions to a differential-difference equation and an associated plate solidification problem.

    Science.gov (United States)

    Layeni, Olawanle P; Akinola, Adegbola P; Johnson, Jesse V

    2016-01-01

    Two distinct and novel formalisms for deriving exact closed solutions of a class of variable-coefficient differential-difference equations arising from a plate solidification problem are introduced. Thereupon, exact closed traveling wave and similarity solutions to the plate solidification problem are obtained for some special cases of time-varying plate surface temperature.

  19. Solidification behaviors of a single-crystal superalloy under lateral constraints

    International Nuclear Information System (INIS)

    Zhuangqi Hu; Huaming Wang

    1993-01-01

    The effect of lateral constraints ahead of solidification interface on the solidification behaviors of a newly developed hot corrosion resistant single-crystal nickel-base superalloy was investigated under commercial single-crystal production conditions. The lateral constraints or section variations ahead of solidification front were found to have drastic influences both on the modes of solidification and the profiles of solute segregation. As lateral constraints were imposed ahead of the directionally solidifying interface, the solidification microstructure of the single-crystal superalloy changed suddenly, through a γ/γ' eutectic-free zone which is characterized by an extremely-fine and highly-developed dendrite network, from the original well-branched dendritic structure to a fine cellular-dendrite or regular cell structure, accompanying which the primary arm spacing, the severity of segregation and the amount of microporosity decreased remarkably. The newly formed cellular dendrite or cell structure transforms always gradually to the initial coarse dendrite structure as the lateral constraint is finally released whether gradually or sharply. Moreover, an abnormal porosity zone was readily observed in the initial section beneath and away from the eutectic-free zone. The solidification microstructural changes were attributed to the drastic dynamical changes in local solidification cooling conditions and in momentum transport during solidification due to the presence of lateral constraint

  20. Nucleation and solidification of thin walled ductile iron - Experiments and numerical simulation

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2005-01-01

    Investigation of solidification of thin walled ductile cast iron has been performed based on experiments and numerical simulation. The experiments were based on temperature and microstructure examination. Results of the experiments have been compared with a 1-D numerical solidification model...

  1. Effects Disposal Condition and Ground Water to Leaching Rate of Radionuclides from Solidification Products

    International Nuclear Information System (INIS)

    Herlan Martono; Wati

    2008-01-01

    Effects disposal condition and ground water to leaching rate of radionuclides from solidification products have been studied. The aims of leaching test at laboratory to get the best composition of solidified products for continuous process or handling. The leaching rate of radionuclides from the many kinds of matrix from smallest to bigger are glass, thermosetting plastic, urea formaldehyde, asphalt, and cement. Glass for solidification of high level waste, thermosetting plastic and urea formaldehyde for solidification of low and intermediate waste, asphalt and cement for solidification of low and intermediate level waste. In shallow land burial, ground water rate is fast, debit is high, and high permeability, so the probability contact between solidification products and ground water is occur. The pH of ground water increasing leaching rate, but cation in the ground water retard leaching rate. Effects temperature radiation and radiolysis to solidification products is not occur. In the deep repository, ground water rate is slow, debit is small, and low permeability, so the probability contact between solidification products and ground water is very small. There are effect cooling time and distance between pits to rock temperature. Alfa radiation effects can be occur, but there is no contact between solidification products and ground water, so that there is not radiolysis. (author)

  2. Heat transfer and solidification processes of alloy melt with undercooling: I. Experimental results

    International Nuclear Information System (INIS)

    Yoshioka, Hideaki; Tada, Yukio; Kunimine, Kanji; Furuichi, Taira; Hayashi, Yujiro

    2006-01-01

    The solidification process of Pb-Sn and Bi-Sn alloy melts is discussed to obtain a basic understanding of the essential phenomena of solidification with undercooling. First, from macroscopic observations, it is shown that the solidification process consists of the following three stages: (1) free growth with recalescence dissipation of thermal undercooling (2) expansion of crystals with the relaxation of constitutional undercooling or with the recovering process of interrupted quasi-steady heat conduction, and (3) equilibrium solidification. The specific features of free growth under non-uniform undercooling are also shown by comparison with the Lipton, Glicksman, and Kurz model. Next, from microscopic observations, the distribution of the solute concentration and the change of crystal morphology in the solidified materials were investigated quantitatively using scanning electron microscopy and energy-dispersive spectroscopy. Finally, the solidification path during the above three fundamental processes is dynamically represented on phase diagrams

  3. Microstructural evolution in Mg-Zn alloys during solidification: An experimental and simulation study

    Science.gov (United States)

    Paliwal, Manas; Jung, In-Ho

    2014-05-01

    A comprehensive microstructural evolution of Mg-1.5, 4.0 and 5.5 wt% Zn alloys with respect to the solidification parameters such as thermal gradient (G), solidification velocity (V), cooling rate (GV) and solute (Zn) content were investigated in the present study. Solidification techniques such as directional solidification and wedge casting were employed in order to obtain cooling rates between 0.05 and 250 K/s. Microstructural features such as secondary dendrite arm spacing (SDAS), primary dendrite arm spacing (PDAS), microsegregration along the secondary dendrites and secondary phase fractions were experimentally determined. A solidification model that incorporates solute back diffusion, secondary arm coarsening, dendrite tip undercooling and dynamically linked with accurate thermodynamic databases is used to explain the experimental results.

  4. Solidification analysis of a centrifugal atomizer using the Al-32.7wt.% Cu alloy

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, Matthew G. [Iowa State Univ., Ames, IA (United States)

    1998-02-23

    A centrifugal atomizer (spinning disk variety) was designed and constructed for the production of spherical metal powders, 100-1,000 microns in diameter in an inert atmosphere. Initial atomization experiments revealed the need for a better understanding of how the liquid metal was atomized and how the liquid droplets solidified. To investigate particle atomization, Ag was atomized in air and the process recorded on high-speed film. To investigate particle solidification, Al-32.7 wt.% Cu was atomized under inert atmosphere and the subsequent particles were examined microscopically to determine solidification structure and rate. This dissertation details the experimental procedures used in producing the Al-Cu eutectic alloy particles, examination of the particle microstructures, and determination of the solidification characteristics (e.g., solidification rate) of various phases. Finally, correlations are proposed between the operation of the centrifugal atomizer and the observed solidification spacings.

  5. Choosing solidification or vitrification for low-level radioactive and mixed waste treatment

    International Nuclear Information System (INIS)

    Gimpel, R.F.

    1992-01-01

    Solidification (making concrete) and vitrification (making glass) are frequently the treatment methods recommended for treating inorganic or radioactive wastes. Solidification is generally perceived as the most economical treatment method. Whereas, vitrification is considered (by many) as the most effective of all treatment methods. Unfortunately, vitrification has acquired the stigma that it is too expensive to receive further consideration as an alternative to solidification in high volume treatment applications. Ironically, economic studies, as presented in this paper, show that vitrification may be more competitive in some high volume applications. Ex-situ solidification and vitrification are the competing methods for treating in excess of 450 000m 3 of low-level radioactive and mixed waste at the Fernald Environmental Management Project (FEMP or simply, Fernald) located near Cincinnati, Ohio. This paper summarizes how Fernald is choosing between solidification and vitrification as the primary waste treatment method

  6. Choosing solidification or vitrification for low-level radioactive and mixed waste treatment

    International Nuclear Information System (INIS)

    Gimpel, R.F.

    1992-01-01

    Solidification (making concrete) and vitrification (making glass) are frequently the treatment methods recommended for treating inorganic or radioactive wastes. Solidification is generally perceived as the most economical treatment method. Whereas, vitrification is considered (by many) as the most effective of all treatment methods. Unfortunately, vitrification has acquired the stigma that it is too expensive to receive further consideration as an alternative to solidification in high volume treatment applications. Ironically, economic studies, as presented in this paper, show that vitrification may be more competitive in some high volume applications. Ex-situ solidification and vitrification are the competing methods for treating in excess of 450,000 m 3 of low-level radioactive and mixed waste at the Fernald Environmental Management Project (FEMP or simply, Fernald) located near Cincinnati, Ohio. This paper summarized how Fernald is choosing between solidification and vitrification as the primary waste treatment method

  7. Research and Development of the Solidification of Slab Ingots from Special Tool Steels

    Directory of Open Access Journals (Sweden)

    Tkadlečková M.

    2017-09-01

    Full Text Available The paper describes the research and development of casting and solidification of slab ingots from special tool steels by means of numerical modelling using the finite element method. The pre-processing, processing and post-processing phases of numerical modelling are outlined. Also, problems with determining the thermophysical properties of materials and heat transfer between the individual parts of the casting system are discussed. Based on the type of grade of tool steel, the risk of final porosity is predicted. The results allowed to improve the production technology of slab ingots, and also to verify the ratio, the chamfer and the external/ internal shape of the wall of the new designed slab ingots.

  8. Development and evaluation of polyethylene as solidification agent for low-level waste

    International Nuclear Information System (INIS)

    Franz, E.M.; Colombo, P.

    1986-09-01

    A polyethylene solidification process, using an extrusion system, has been developed for the immobilization of dry wastes resulting from volume reduction technologies. Ease of processibility and high packing efficiencies were obtained through the use of low-density polyethylene (0.917 to 0.924 g/cm 3 ) with melt indices from 2.0 to 55.0 g/10 min. Maximum waste loadings of 70 wt % sodium sulfate, 50 wt % boric acid, 40 wt % incinerator ash and 65 wt % ion exchnge were obtained. A series of tsts were conducted to assess the acceptability of polyethylene waste forms to meet the requirements of 10 CFR 61. Based on test results and process control considerations, optimal waste loadings of 70 wt % sodium sulfate, 50 wt % boric acid, 40 wt % incinerator ash and 30 wt % ion exchange resins are recommended

  9. Superconducting properties of single-crystal Nb sphere formed by large-undercooling solidification process

    Energy Technology Data Exchange (ETDEWEB)

    Takeya, H.; Sung, Y.S.; Hirata, K.; Togano, K

    2003-10-15

    An electrostatic levitation (ESL) system has been used for investigating undercooling effects on superconducting materials. In this report, preliminary experiments on Nb (melting temperature: T{sub m}=2477 deg. C) have been performed by melting Nb in levitation using 150 and 250 W Nd-YAG lasers. Since molten Nb is solidified without any contact in a high vacuum condition, a significantly undercooled state up to 400 deg. C is maintained before recalescence followed by solidification. Spherical single crystals of Nb are formed by the ESL process due to the suppression of heterogeneous nucleation. The field dependence of magnetization of Nb shows a reversible behavior as an ideal type II superconductor, implying that it contains almost no flux-pinning centers.

  10. Study of the thermal and kinetic parameters during directional solidification of zinc-aluminum eutectic alloys

    International Nuclear Information System (INIS)

    Gueijman, Sergio Fabian; Ares, Alicia Esther; Schvezov, Carlos Enrique

    2008-01-01

    Much work has been done recently on investigating zinc-based binary alloys, with different aluminum content, and modified or not with small amounts of other alloying elements. Some of these alloys have interesting properties, such as, the ZA alloys that have properties similar to some bronzes that are used in applications that require pieces with enough resistance to mechanical stresses. The longitudinal thermal gradients, the minimal gradients, the velocities of the liquid interphases, the velocities of the solid interphases and the accelerations of both interphases as a function of time and position were determined for each diluted alloy of the eutectic concentration considered (Zn-5%Al, % in weight), solidified horizontally with caloric extraction from both ends of the test pieces. The values obtained from the horizontal solidification with two directions of predominant caloric extraction are compared to previous values obtained for the same vertically solidified alloy system with a predominantly caloric extraction direction

  11. Phase-field simulation of solidification in multicomponent alloys coupled with thermodynamic and diffusion mobility databases

    International Nuclear Information System (INIS)

    Zhang Ruijie; Jing Tao; Jie Wanqi; Liu Baicheng

    2006-01-01

    To simulate quantitatively the microstructural evolution in the solidification process of multicomponent alloys, we extend the phase-field model for binary alloys to multicomponent alloys with consideration of the solute interactions between different species. These interactions have a great influence not only on the phase equilibria but also on the solute diffusion behaviors. In the model, the interface region is assumed to be a mixture of solid and liquid with the same chemical potential, but with different compositions. The simulation presented is coupled with thermodynamic and diffusion mobility databases, which can accurately predict the phase equilibria and the solute diffusion transportation in the whole system. The phase equilibria in the interface and other thermodynamic quantities are obtained using Thermo-Calc through the TQ interface. As an example, two-dimensional computations for the dendritic growth in Al-Cu-Mg ternary alloy are performed. The quantitative solute distributions and diffusion matrix are obtained in both solid and liquid phases

  12. Solidification of low-level radioactive liquid waste using a cement-silicate process

    International Nuclear Information System (INIS)

    Grandlund, R.W.; Hayes, J.F.

    1979-01-01

    Extensive use has been made of silicate and Portland cement for the solidification of industrial waste and recently this method has been successfully used to solidify a variety of low level radioactive wastes. The types of wastes processed to date include fuel fabrication sludges, power reactor waste, decontamination solution, and university laboratory waste. The cement-silicate process produces a stable solid with a minimal increase in volume and the chemicals are relatively inexpensive and readily available. The method is adaptable to either batch or continuous processing and the equipment is simple. The solid has leaching characteristics similar to or better than plain Portland cement mixtures and the leaching can be further reduced by the use of ion-exchange additives. The cement-silicate process has been used to solidify waste containing high levels of boric acid, oils, and organic solvents. The experience of handling the various types of liquid waste with a cement-silicate system is described

  13. A Review of Permanent Magnet Stirring During Metal Solidification

    Science.gov (United States)

    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.

  14. Solidification treatment of thiophene and BTEX contaminated soils

    International Nuclear Information System (INIS)

    Zarlinski, S.J.; Kingham, N.W.; Blevins, J.

    1995-01-01

    Contamination at the McColl Superfund Site, located in Fullerton, California, is due to the disposal, in pits, of spent sulfuric acid sludge from the production of aviation fuel. A treatability study was performed to evaluate the electiveness of in situ solidification treatment of materials contaminated with high concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX), as well as thiophene and other organic compounds. The contaminated materials were extremely acidic (pH<1) and had high organic and sulfur contents of greater than 70 percent and 10 percent, respectively. A total of 150 mixtures were screened to evaluate the effectiveness of 15 reagents. Based on the preliminary screening results, six mixtures were selected as being the most effective at treating the contaminated materials. Comprehensive evaluations of the candidate mixtures included (1) quantitative glovebag volatilization studies, (2) chemical characterization of the treated materials, (3) strength characterizations at multiple cure times of up to 60 days, (4) emissions monitoring of the treated materials at cure times of 7 and 14 days, and (5) the evaluation of oxidation reagents for treatment of the thiophene contamination. The treatability study demonstrated that solidification treatment is an effective alternative for remediation of the thiophene and BTEX contaminated materials

  15. Numerical Model for Solidification Zones Selection in the Large Ingots

    Directory of Open Access Journals (Sweden)

    Wołczyński W.

    2015-12-01

    Full Text Available A vertical cut at the mid-depth of the 15-ton forging steel ingot has been performed by curtesy of the CELSA - Huta Ostrowiec plant. Some metallographic studies were able to reveal not only the chilled undersized grains under the ingot surface but columnar grains and large equiaxed grains as well. Additionally, the structural zone within which the competition between columnar and equiaxed structure formation was confirmed by metallography study, was also revealed. Therefore, it seemed justified to reproduce some of the observed structural zones by means of numerical calculation of the temperature field. The formation of the chilled grains zone is the result of unconstrained rapid solidification and was not subject of simulation. Contrary to the equiaxed structure formation, the columnar structure or columnar branched structure formation occurs under steep thermal gradient. Thus, the performed simulation is able to separate both discussed structural zones and indicate their localization along the ingot radius as well as their appearance in term of solidification time.

  16. Search for a solute-drag effect in dendritic solidification

    International Nuclear Information System (INIS)

    Eckler, K.; Herlach, D.M.; Aziz, M.J.

    1994-01-01

    The authors report the results of an indirect experimental test for the solute-drag effect in alloy solidification by fitting the data of Eckler et.al. for Ni-B dendrite tip velocities vs undercooling to models in several ways. The unknown equilibrium partition coefficient, k e , was varied as a fitting parameter. When they combine the dendrite growth model of Boettinger et al. with the Continuous Growth Model (CGM) of Aziz and Kaplan with solute drag, they cannot fit the data for any value of k e . When they combine dendrite growth theory with the CGM without solute drag, they obtain a reasonable fit to the data for k e = 4 x 10 -6 . When they combine dendrite growth theory with a new partial-solute-drag interpolation between the with-solute-drag and the without-solute-drag versions of the CGM, they obtain a still better fit to the data for k e = 2.8 x 10 - 4. This result points out the possibility of partial solute-drag during solidification and the importance of an independent determination of k e in order to distinguish between models

  17. Simulation of spreading with solidification: assessment synthesis of Thema code

    Energy Technology Data Exchange (ETDEWEB)

    Spindler, B.; Veteau, J.M. [CEA Grenoble, Direction de l' Energie Nucleaire, Dept. de Technologie Nucleaire, Service d' Etudes Thermohydrauliques et Technologiques, 38 (France)

    2004-07-01

    After a presentation of the models included in THEMA code, which simulates the spreading of a fluid with solidification, the whole assessment calculations are presented. The first series concerns the comparison with analytical or numerical solutions: dam break, conduction for the heat transfer in the substrate, crust growth. The second series concerns the comparison with the CORINE isothermal tests (simulating fluid at low temperature). The third series concerns the CORINE tests with heat transfer. The fourth series concerns the tests with simulating materials at medium or high temperature (RIT, KATS). The fifth series concerns the tests with prototypical materials (COMAS, FARO, VULCANO). Finally the blind simulations of the ECOKATS tests are presented. All the calculations are performed with the same physical models (THEMA version 2.5), without any variable tuning parameter according to the test under consideration. Sensitivity studies concern the influence of the viscosity model in the solidification interval, and for the tests with prototypical materials the inlet temperature and the solid fraction. The relative difference between the calculated and measured spreading areas is generally less than 20 % except for the test with prototypical materials, for which the assessment is not easy due to the large experimental uncertainties. The level of validation of THEMA is considered as satisfactory, taking into account the required accuracy. (authors)

  18. Crystallographic investigation of grain selection during initial solidification

    International Nuclear Information System (INIS)

    Esaka, H; Shinozuka, K; Kataoka, Y

    2016-01-01

    Normally, macroscopic solidified structure consists of chill, columnar and equiaxed zones. In a chill zone, many fine grains nucleate on the mold surface and grow their own preferred growth direction. Only a few of them continue to grow because of grain selection. In order to understand the grain selection process, crystallographic investigation has been carried out in the zone of initial solidification in this study. 10 g of Al-6 wt%Si alloy was melted at 850 °C and poured on the thick copper plate. Longitudinal cross section of the solidified shell was observed by a SEM and analyzed by EBSD. The result of EBSD mapping reveals that crystallographic orientation was random in the range of initial solidification. Further, some grains are elongated along their <100> direction. Columnar grains, whose growth directions are almost parallel to the heat flow direction, develop via grain selection. Here, a dendrite whose growth direction is close to the heat flow direction overgrows the other dendrite whose growth direction is far from the heat flow direction. However, sometimes we observed that dendrite, whose zenith angle is large, overgrew the other dendrite. It can be deduced that the time of nucleation on the mold surface is not constant. (paper)

  19. The solidification behavior of dilute aluminium-scandium alloys

    International Nuclear Information System (INIS)

    Norman, A.F.; Prangnell, P.B.; McEwen, R.S.

    1998-01-01

    The solidification behavior of dilute Sc containing Al alloys has been investigated. In binary Al-Sc alloys, Sc additions greater than the eutectic composition (0.55 wt%) were found to produce a remarkable refinement in the grain size of aluminum castings, of two orders of magnitude, due to the formation of the primary Al 3 Sc intermetallic phase during solidification. The refinement in grain size only occurred in hypereutectic compositions and was shown to be far greater than can be achieved by conventional Al grain refiners. Grain refinement by the addition of Sc is accompanied by a change in growth morphology from dendritic, in the large unrefined grains, to fine spherical grains with a divorced eutectic appearing on the grain boundaries in the refined castings. Similar levels of refinement were observed in Al-Sc-Zr and Al-Cu-Sc alloys. In the latter, a change in the segregation behavior of Cu was observed, from a strongly interdendritic segregation pattern to a more homogeneous distribution. The supersaturated Al-Sc solid solution can decompose via a discontinuous precipitation reaction to form coherent rod-like precipitates of the L1 2 Al 3 Sc phase

  20. Modeling of columnar and equiaxed solidification of binary mixtures

    International Nuclear Information System (INIS)

    Roux, P.

    2005-12-01

    This work deals with the modelling of dendritic solidification in binary mixtures. Large scale phenomena are represented by volume averaging of the local conservation equations. This method allows to rigorously derive the partial differential equations of averaged fields and the closure problems associated to the deviations. Such problems can be resolved numerically on periodic cells, representative of dendritic structures, in order to give a precise evaluation of macroscopic transfer coefficients (Drag coefficients, exchange coefficients, diffusion-dispersion tensors...). The method had already been applied for a model of columnar dendritic mushy zone and it is extended to the case of equiaxed dendritic solidification, where solid grains can move. The two-phase flow is modelled with an Eulerian-Eulerian approach and the novelty is to account for the dispersion of solid velocity through the kinetic agitation of the particles. A coupling of the two models is proposed thanks to an original adaptation of the columnar model, allowing for undercooling calculation: a solid-liquid interfacial area density is introduced and calculated. At last, direct numerical simulations of crystal growth are proposed with a diffuse interface method for a representation of local phenomena. (author)

  1. Simulation of spreading with solidification: assessment synthesis of Thema code

    International Nuclear Information System (INIS)

    Spindler, B.; Veteau, J.M.

    2004-01-01

    After a presentation of the models included in THEMA code, which simulates the spreading of a fluid with solidification, the whole assessment calculations are presented. The first series concerns the comparison with analytical or numerical solutions: dam break, conduction for the heat transfer in the substrate, crust growth. The second series concerns the comparison with the CORINE isothermal tests (simulating fluid at low temperature). The third series concerns the CORINE tests with heat transfer. The fourth series concerns the tests with simulating materials at medium or high temperature (RIT, KATS). The fifth series concerns the tests with prototypical materials (COMAS, FARO, VULCANO). Finally the blind simulations of the ECOKATS tests are presented. All the calculations are performed with the same physical models (THEMA version 2.5), without any variable tuning parameter according to the test under consideration. Sensitivity studies concern the influence of the viscosity model in the solidification interval, and for the tests with prototypical materials the inlet temperature and the solid fraction. The relative difference between the calculated and measured spreading areas is generally less than 20 % except for the test with prototypical materials, for which the assessment is not easy due to the large experimental uncertainties. The level of validation of THEMA is considered as satisfactory, taking into account the required accuracy. (authors)

  2. Modeling of columnar and equiaxed solidification of binary mixtures; Modelisation de la solidification colonnaire et equiaxe de melanges binaires

    Energy Technology Data Exchange (ETDEWEB)

    Roux, P

    2005-12-15

    This work deals with the modelling of dendritic solidification in binary mixtures. Large scale phenomena are represented by volume averaging of the local conservation equations. This method allows to rigorously derive the partial differential equations of averaged fields and the closure problems associated to the deviations. Such problems can be resolved numerically on periodic cells, representative of dendritic structures, in order to give a precise evaluation of macroscopic transfer coefficients (Drag coefficients, exchange coefficients, diffusion-dispersion tensors...). The method had already been applied for a model of columnar dendritic mushy zone and it is extended to the case of equiaxed dendritic solidification, where solid grains can move. The two-phase flow is modelled with an Eulerian-Eulerian approach and the novelty is to account for the dispersion of solid velocity through the kinetic agitation of the particles. A coupling of the two models is proposed thanks to an original adaptation of the columnar model, allowing for undercooling calculation: a solid-liquid interfacial area density is introduced and calculated. At last, direct numerical simulations of crystal growth are proposed with a diffuse interface method for a representation of local phenomena. (author)

  3. Theoretical modeling of cellular and dendritic solidification microstructures

    Science.gov (United States)

    Song, Younggil

    In this dissertation, we use three-dimensional (3D) phase-field (PF) modeling to investigate (i) 3D solid-liquid interface dynamics observed in microgravity experiments, and (ii) array patterns in a thin-sample geometry. In addition, using the two-dimensional (2D) dendritic-needle-network (DNN) model, we explore (iii) secondary sidebranching dynamics. Recently, solidification experiments are carried out in the DSI (Directional Solidification Insert) of the DECLIC (Device for the study of Critical LIquids and Crystallization) facility aboard the International Space Station (ISS). Thus, the directional solidification experiments are achieved under limited convective currents, and the experimental observations reveal unique dynamics of 3D microstructure in a purely diffusive growth regime. In this directional solidification setup, a temperature field between heat sources could evolve due to two main factors: (i) heat transfer within an adiabatic zone and (ii) latent heat rejection at the interface. These two thermal effects are phenomenologically characterized using a time-dependent thermal shift. In addition, we could quantitatively account for these thermal factors using a numerical calculation of the evolution of temperature field. We introduce these phenomenological and quantitative thermal representations into the PF model. The performed simulations using different thermal descriptions are compared to the experimental measurements from the initial planar interface dynamics to the final spacing selection. The DECLIC-DSI experimental observations exhibit complex grain boundary (GB) dynamics between large grains with a small misorientation. In the observations, several large grains with a small misorientation with respect to the temperature gradient are formed during solidification. Specifically, at a convergent GB, a localized group of misoriented cells penetrates into a nearby grain, which yields the morphological instability of grain boundaries. Remarkably, while

  4. Solidified structure and leaching properties of metallurgical wastewater treatment sludge after solidification/stabilization process.

    Science.gov (United States)

    Radovanović, Dragana Đ; Kamberović, Željko J; Korać, Marija S; Rogan, Jelena R

    2016-01-01

    The presented study investigates solidification/stabilization process of hazardous heavy metals/arsenic sludge, generated after the treatment of the wastewater from a primary copper smelter. Fly ash and fly ash with addition of hydrated lime and Portland composite cement were studied as potential binders. The effectiveness of the process was evaluated by unconfined compressive strength (UCS) testing, leaching tests (EN 12457-4 and TCLP) and acid neutralization capacity (ANC) test. It was found that introduction of cement into the systems increased the UCS, led to reduced leaching of Cu, Ni and Zn, but had a negative effect on the ANC. Gradual addition of lime resulted in decreased UCS, significant reduction of metals leaching and high ANC, due to the excess of lime that remained unreacted in pozzolanic reaction. Stabilization of more than 99% of heavy metals and 90% of arsenic has been achieved. All the samples had UCS above required value for safe disposal. In addition to standard leaching tests, solidificates were exposed to atmospheric conditions during one year in order to determine the actual leaching level of metals in real environment. It can be concluded that the EN 12457-4 test is more similar to the real environmental conditions, while the TCLP test highly exaggerates the leaching of metals. The paper also presents results of differential acid neutralization (d-AN) analysis compared with mineralogical study done by scanning electron microscopy and X-ray diffraction analysis. The d-AN coupled with Eh-pH (Pourbaix) diagrams were proven to be a new effective method for analysis of amorphous solidified structure.

  5. Emergence of two types of terrestrial planet on solidification of magma ocean.

    Science.gov (United States)

    Hamano, Keiko; Abe, Yutaka; Genda, Hidenori

    2013-05-30

    Understanding the origins of the diversity in terrestrial planets is a fundamental goal in Earth and planetary sciences. In the Solar System, Venus has a similar size and bulk composition to those of Earth, but it lacks water. Because a richer variety of exoplanets is expected to be discovered, prediction of their atmospheres and surface environments requires a general framework for planetary evolution. Here we show that terrestrial planets can be divided into two distinct types on the basis of their evolutionary history during solidification from the initially hot molten state expected from the standard formation model. Even if, apart from their orbits, they were identical just after formation, the solidified planets can have different characteristics. A type I planet, which is formed beyond a certain critical distance from the host star, solidifies within several million years. If the planet acquires water during formation, most of this water is retained and forms the earliest oceans. In contrast, on a type II planet, which is formed inside the critical distance, a magma ocean can be sustained for longer, even with a larger initial amount of water. Its duration could be as long as 100 million years if the planet is formed together with a mass of water comparable to the total inventory of the modern Earth. Hydrodynamic escape desiccates type II planets during the slow solidification process. Although Earth is categorized as type I, it is not clear which type Venus is because its orbital distance is close to the critical distance. However, because the dryness of the surface and mantle predicted for type II planets is consistent with the characteristics of Venus, it may be representative of type II planets. Also, future observations may have a chance to detect not only terrestrial exoplanets covered with water ocean but also those covered with magma ocean around a young star.

  6. Immobilisation of heavy metal in cement-based solidification/stabilisation: A review

    International Nuclear Information System (INIS)

    Chen, Q.Y.; Tyrer, M.; Hills, C.D.; Yang, X.M.; Carey, P.

    2009-01-01

    Heavy metal-bearing waste usually needs solidification/stabilization (s/s) prior to landfill to lower the leaching rate. Cement is the most adaptable binder currently available for the immobilisation of heavy metals. The selection of cements and operating parameters depends upon an understanding of chemistry of the system. This paper discusses interactions of heavy metals and cement phases in the solidification/stabilisation process. It provides a clarification of heavy metal effects on cement hydration. According to the decomposition rate of minerals, heavy metals accelerate the hydration of tricalcium silicate (C 3 S) and Portland cement, although they retard the precipitation of portlandite due to the reduction of pH resulted from hydrolyses of heavy metal ions. The chemical mechanism relevant to the accelerating effect of heavy metals is considered to be H + attacks on cement phases and the precipitation of calcium heavy metal double hydroxides, which consumes calcium ions and then promotes the decomposition of C 3 S. In this work, molecular models of calcium silicate hydrate gel are presented based on the examination of 29 Si solid-state magic angle spinning/nuclear magnetic resonance (MAS/NMR). This paper also reviews immobilisation mechanisms of heavy metals in hydrated cement matrices, focusing on the sorption, precipitation and chemical incorporation of cement hydration products. It is concluded that further research on the phase development during cement hydration in the presence of heavy metals and thermodynamic modelling is needed to improve effectiveness of cement-based s/s and extend this waste management technique

  7. Measuring device for weight of glass of glass solidification product to be charged

    International Nuclear Information System (INIS)

    Yasutake, Nobuhiro; Arai, Masaki; Akashi, Ken-ichi

    1998-01-01

    The present invention provides a device for accurately calculating the weight of molten glass to be charged during manufacturing glass solidification products of radioactive liquid wastes. Namely, a discharge nozzle at the lower end of a glass melting furnace and an upper end of a vessel for glass solidification materials are connected by a connecting device extensible vertically in a cylindrical shape. Molten glasses are flown down by way of the connecting device and filled into the vessel for solidification products. A first scale is constituted so as to measure the weight of load, and the vessel for solidification products are loaded. A second scale is constituted so as to measure the own weight and a weight of load, and is interposed between a flange at the circumference of a charging port and the lower end of the connecting device, and has an opening for flowing down the molten glass at the central portion. With such a constitution, the first scale can weigh the total of the weight of molten glass charged to the vessel for solidification products, the weight of the vessel for solidification products, the counterforce from the connecting device and the weight of the second scale. If the measured value of the secondary scale and the weight of the vessel for solidification products are subtracted from the former value, the weight of the charged molten glass can be determined. (I.S.)

  8. Melting and solidification behavior of Cu/Al and Ti/Al bimetallic core/shell nanoparticles during additive manufacturing by molecular dynamics simulation

    Science.gov (United States)

    Rahmani, Farzin; Jeon, Jungmin; Jiang, Shan; Nouranian, Sasan

    2018-05-01

    Molecular dynamics (MD) simulations were performed to investigate the role of core volume fraction and number of fusing nanoparticles (NPs) on the melting and solidification of Cu/Al and Ti/Al bimetallic core/shell NPs during a superfast heating and slow cooling process, roughly mimicking the conditions of selective laser melting (SLM). One recent trend in the SLM process is the rapid prototyping of nanoscopically heterogeneous alloys, wherein the precious core metal maintains its particulate nature in the final manufactured part. With this potential application in focus, the current work reveals the fundamental role of the interface in the two-stage melting of the core/shell alloy NPs. For a two-NP system, the melting zone gets broader as the core volume fraction increases. This effect is more pronounced for the Ti/Al system than the Cu/Al system because of a larger difference between the melting temperatures of the shell and core metals in the former than the latter. In a larger six-NP system (more nanoscopically heterogeneous), the melting and solidification temperatures of the shell Al roughly coincide, irrespective of the heating or cooling rate, implying that in the SLM process, the part manufacturing time can be reduced due to solidification taking place at higher temperatures. The nanostructure evolution during the cooling of six-NP systems is further investigated. [Figure not available: see fulltext.

  9. Polymer solidification of mixed wastes at the Rocky Flats Plant

    International Nuclear Information System (INIS)

    Faucette, A.M.; Logsdon, B.W.; Lucerna, J.J.; Yudnich, R.J.

    1994-01-01

    The Rocky Flats Plant is pursuing polymer solidification as a viable treatment option for several mixed waste streams that are subject to land disposal restrictions within the Resource Conservation and Recovery Act provisions. Tests completed to date using both surrogate and actual wastes indicate that polyethylene microencapsulation is a viable treatment option for several mixed wastes at the Rocky Flats Plant, including nitrate salts, sludges, and secondary wastes such as ash. Treatability studies conducted on actual salt waste demonstrated that the process is capable of producing waste forms that comply with all applicable regulatory criteria, including the Toxicity Characteristic Leaching Procedure. Tests have also been conducted to evaluate the feasibility of macroencapsulating certain debris wastes in polymers. Several methods and plastics have been tested for macroencapsulation, including post-consumer recycle and regrind polyethylene

  10. Solidification/stabilization of dredged marine sediments for road construction.

    Science.gov (United States)

    Wang, Dong Xing; Abriak, Nor Edine; Zentar, Rachid; Xu, WeiYa

    2012-01-01

    Cement/lime-based solidification is an environmentally sound solution for the management of dredged marine sediments, instead of traditional solutions such as immersion. Based on the mineralogical composition and physical characteristics of Dunkirk sediments, the effects of cement and lime are assessed through Atterberg limits, modified Proctor compaction, unconfined compressive strength and indirect tensile strength tests. The variation of Atterberg limits and the improvement in strength are discussed at different binder contents. The potential of sediments solidified with cement or lime for road construction is evaluated through a proposed methodology from two aspects: I-CBR value and material classification. The test results show the feasibility of solidified dredged sediments for beneficial use as a material in road construction. Cement is superior to lime in terms of strength improvement, and adding 6% cement is an economic and reasonable method to stabilize fine sediments.

  11. Solidification/stabilization of technetium in cement-based grouts

    International Nuclear Information System (INIS)

    Gilliam, T.M.; Bostick, W.D.; Spence, R.D.; Shoemaker, J.L.

    1990-01-01

    Mixed low-level radioactive and chemically hazardous process treatment wastes from the Portsmouth Gaseous Diffusion Plant are stabilized by solidification in cement-based grouts. Conventional portland cement and fly ash grouts have been shown to be effective for retention of hydrolyzable metals (e.g., lead, cadmium, uranium and nickel) but are marginally acceptable for retention of radioactive Tc-99, which is present in the waste as the highly mobile pertechnate anion. Addition of ground blast furnace slag to the grout is shown to reduce the leachability of technetium by several orders of magnitude. The selective effect of slag is believed to be due to its ability to reduce Tc(VII) to the less soluble Tc(IV) species. 12 refs., 4 tabs

  12. Solidification structure and abrasion resistance of high chromium white irons

    Science.gov (United States)

    Doğan, Ö. N.; Hawk, J. A.; Laird, G.

    1997-06-01

    Superior abrasive wear resistance, combined with relatively low production costs, makes high Cr white cast irons (WCIs) particularly attractive for applications in the grinding, milling, and pumping apparatus used to process hard materials. Hypoeutectic, eutectic, and hypereutectic cast iron compositions, containing either 15 or 26 wt pct chromium, were studied with respect to the macrostructural transitions of the castings, solidification paths, and resulting microstructures when poured with varying superheats. Completely equiaxed macrostructures were produced in thick section castings with slightly hypereutectic compositions. High-stress abrasive wear tests were then performed on the various alloys to examine the influence of both macrostructure and microstructure on wear resistance. Results indicated that the alloys with a primarily austenitic matrix had a higher abrasion resistance than similar alloys with a pearlitic/bainitic matrix. Improvement in abrasion resistance was partially attributed to the ability of the austenite to transform to martensite at the wear surface during the abrasion process.

  13. Solidification of metal oxide from electrokinetic-electrodialytic decontamination

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Daeseo; Park, Uk-Ryang; Kim, Gye-Nam; Kim, Seung-Soo; Moon, Jei-Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Electrokinectic-electrodialytic decontamination technology reduced 80% of the concentration of the uranium soil waste to below the concentration of self-disposal. After conducting electrokinectic-electrodialytic decontamination, more than 10% of the remainder of radioactive waste from the cathodes of electrokinectic-electrodialytic equipment were produced. To dispose of such waste, it is necessary to solidify second radioactive waste owing to the requirements of radioactive waste from public corporations. In this study, a solidification experiment was carried out using a polymer. At first, a sampling of second radioactive waste was conducted. Then, second radioactive waste and a polymer were mixed. Third, the solidified state between the second radioactive waste and polymer was checked. In our next study, an experiment for the requirements of a public radioactive waste corporation will be conducted.

  14. UJV line for research into radioactive wastes solidification

    International Nuclear Information System (INIS)

    Neumann, L.; Feist, I.; Kepak, F.; Nachmilner, L.; Napravnik, J.; Novak, M.; Pecak, V.; Vojtech, O.

    1985-01-01

    An experimental line with a capacity of 0.01 m 3 /h was developed and built for research of the solidification of liquid radioactive wastes at the Nuclear Research Institute. The line allows the research and pilot plant testing of processes based on vitrification but also on other procedures including calcination. It consists of a horizontal calciner, a resistance melting unit, a homogenization device for research into cementation of the calcinate, and equipment for the disposal of gaseous emissions. The facility is provided with a control console which allows remote control and the control of all basic operating parameters. The design of the line allows its eventual completion with other equipment. (Z.M.)

  15. Solidification, processing and properties of ductile cast iron

    DEFF Research Database (Denmark)

    Tiedje, Niels Skat

    2010-01-01

    Ductile cast iron has been an important engineering material in the past 50 years. In that time, it has evolved from a complicated material that required the foundry metallurgist's highest skill and strict process control to being a commonly used material that can easily be produced with modern...... of the latest years of research indicate that ductile cast iron in the future will become a highly engineered material in which strict control of a range of alloy elements combined with intelligent design and highly advanced processing allows us to target properties to specific applications to a much higher...... degree than we have seen previously. It is the aim of the present paper to present ductile iron as a modern engineering material and present the many different possibilities that the material hides. Focus will be on the latest research in solidification and melt treatment. But for completeness...

  16. Advanced powder metallurgy aluminum alloys via rapid solidification technology

    Science.gov (United States)

    Ray, R.

    1984-01-01

    Aluminum alloys containing 10 to 11.5 wt. pct. of iron and 1.5 to 3 wt. pct. of chromium using the technique of rapid solidification powder metallurgy were studied. Alloys were prepared as thin ribbons (.002 inch thick) rapidly solidified at uniform rate of 10(6) C/second by the melt spinning process. The melt spun ribbons were pulverized into powders (-60 to 400 mesh) by a rotating hammer mill. The powders were consolidated by hot extrusion at a high reduction ratio of 50:1. The powder extrusion temperature was varied to determine the range of desirable processing conditions necessary to yield useful properties. Powders and consolidated alloys were characterized by SEM and optical metallography. The consolidated alloys were evaluated for (1) thermal stability, (2) tensile properties in the range, room temperature to 450 F, and (3) notch toughness in the range, room temperature to 450 F.

  17. Microprestress - solidification theory for aging and drying creep of concrete

    DEFF Research Database (Denmark)

    Bazant, Zdenek P.; Hauggaard-Nielsen, Anders Boe; Baweja, Sandeep

    1996-01-01

    A new physical theory for the effects of long-term aging and drying on concrete creep is proposed. The previously proposed solidification theory, in which aging is explained and modeled by the volume growth (into the pores of hardened Portland cement paste) of a nonaging viscoelastic constituent...... external load or the macroscopic continuum deformation of concrete can cause only very small changes of the microprestress, such that the response to load is determined by tangential linearization. Relaxation of the microprestress causes the tangential viscosity to increase, which reduces long-term creep....... A decrease of relative humidity in the pores causes (due to changes of capillary tension, surface tension and disjoining pressure) a large increase in the microprestress, which in turn reduces tangential viscosity and thus increases the creep rate. This explains the drying effect (Pickett effect...

  18. Integral solution of equiaxed solidification with an interface kinetics model for nuclear waste management

    International Nuclear Information System (INIS)

    Naterer, G.F.

    1996-01-01

    In this paper, a one-dimensional analysis of energy and species transport during binary dendritic solidification is presented and compared to experimental results. The paper's objective is a continuation of previous studies of solidification control for the waste management of nuclear materials in the underground disposal concept. In the present analysis, interface kinetics at the solid - liquid interface accounts for recalescent thermal behaviour during solidification. The theoretical results were compared to available experimental results and the agreement appears fair although some discrepancies have been attributed to uncertainties with thermophysical properties. (author)

  19. Numerical simulation of freckle formation in directional solidification of binary alloys

    Science.gov (United States)

    Felicelli, Sergio D.; Heinrich, Juan C.; Poirier, David R.

    1992-01-01

    A mathematical model of solidification is presented which simulates the formation of segregation models known as 'freckles' during directional solidification of binary alloys. The growth of the two-phase or dendritic zone is calculated by solving the coupled equations of momentum, energy, and solute transport, as well as maintaining the thermodynamic constraints dictated by the phase diagram of the alloy. Calculations for lead-tin alloys show that the thermosolutal convection in the dendritic zone during solidification can produce heavily localized inhomogeneities in the composition of the final alloy.

  20. Multiscale modeling of alloy solidification using a database approach

    Science.gov (United States)

    Tan, Lijian; Zabaras, Nicholas

    2007-11-01

    A two-scale model based on a database approach is presented to investigate alloy solidification. Appropriate assumptions are introduced to describe the behavior of macroscopic temperature, macroscopic concentration, liquid volume fraction and microstructure features. These assumptions lead to a macroscale model with two unknown functions: liquid volume fraction and microstructure features. These functions are computed using information from microscale solutions of selected problems. This work addresses the selection of sample problems relevant to the interested problem and the utilization of data from the microscale solution of the selected sample problems. A computationally efficient model, which is different from the microscale and macroscale models, is utilized to find relevant sample problems. In this work, the computationally efficient model is a sharp interface solidification model of a pure material. Similarities between the sample problems and the problem of interest are explored by assuming that the liquid volume fraction and microstructure features are functions of solution features extracted from the solution of the computationally efficient model. The solution features of the computationally efficient model are selected as the interface velocity and thermal gradient in the liquid at the time the sharp solid-liquid interface passes through. An analytical solution of the computationally efficient model is utilized to select sample problems relevant to solution features obtained at any location of the domain of the problem of interest. The microscale solution of selected sample problems is then utilized to evaluate the two unknown functions (liquid volume fraction and microstructure features) in the macroscale model. The temperature solution of the macroscale model is further used to improve the estimation of the liquid volume fraction and microstructure features. Interpolation is utilized in the feature space to greatly reduce the number of required

  1. Propagative selection of tilted array patterns in directional solidification

    Science.gov (United States)

    Song, Younggil; Akamatsu, Silvère; Bottin-Rousseau, Sabine; Karma, Alain

    2018-05-01

    We investigate the dynamics of tilted cellular/dendritic array patterns that form during directional solidification of a binary alloy when a preferred-growth crystal axis is misoriented with respect to the temperature gradient. In situ experimental observations and phase-field simulations in thin samples reveal the existence of a propagative source-sink mechanism of array spacing selection that operates on larger space and time scales than the competitive growth at play during the initial solidification transient. For tilted arrays, tertiary branching at the diverging edge of the sample acts as a source of new cells with a spacing that can be significantly larger than the initial average spacing. A spatial domain of large spacing then invades the sample propagatively. It thus yields a uniform spacing everywhere, selected independently of the initial conditions, except in a small region near the converging edge of the sample, which acts as a sink of cells. We propose a discrete geometrical model that describes the large-scale evolution of the spatial spacing profile based on the local dependence of the cell drift velocity on the spacing. We also derive a nonlinear advection equation that predicts the invasion velocity of the large-spacing domain, and sheds light on the fundamental nature of this process. The models also account for more complex spacing modulations produced by an irregular dynamics at the source, in good quantitative agreement with both phase-field simulations and experiments. This basic knowledge provides a theoretical basis to improve the processing of single crystals or textured polycrystals for advanced materials.

  2. Evolution of Fe based intermetallic phases in Al–Si hypoeutectic casting alloys: Influence of the Si and Fe concentrations, and solidification rate

    Energy Technology Data Exchange (ETDEWEB)

    Gorny, Anton; Manickaraj, Jeyakumar [Light Metal Casting Research Centre (LMCRC), Department of Mechanical Engineering, McMaster University, 1280 Main Street W, Hamilton, ON, Canada L8S 4L7 (Canada); Cai, Zhonghou [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Shankar, Sumanth, E-mail: shankar@mcmaster.ca [Light Metal Casting Research Centre (LMCRC), Department of Mechanical Engineering, McMaster University, 1280 Main Street W, Hamilton, ON, Canada L8S 4L7 (Canada)

    2013-11-15

    Highlights: •Anomalous evolution of Fe based intermetallic phases in Al–Si–Fe alloys. •XRF coupled with nano-diffraction to confirm the nano-size Fe intermetallic phases. •Crystallography of the θ-Al{sub 13}Fe{sub 4}, τ{sub 5}-Al{sub 8}Fe{sub 2}Si and τ{sub 6}-Al{sub 9}Fe{sub 2}Si{sub 2} phases. •Peritectic reactions involving the Fe intermetallic phases in Al–Si–Fe alloys. -- Abstract: Al–Si–Fe hypoeutectic cast alloy system is very complex and reported to produce numerous Fe based intermetallic phases in conjunction with Al and Si. This publication will address the anomalies of phase evolution in the Al–Si–Fe hypoeutectic casting alloy system; the anomaly lies in the peculiarities in the evolution and nature of the intermetallic phases when compared to the thermodynamic phase diagram predictions and past publications of the same. The influence of the following parameters, in various combinations, on the evolution and nature of the intermetallic phases were analyzed and reported: concentration of Si between 2 and 12.6 wt%, Fe between 0.05 and 0.5 wt% and solidification rates of 0.1, 1, 5 and 50 K s{sup −1}. Two intermetallic phases are observed to evolve in these alloys under these solidification conditions: the τ{sub 5}-Al{sub 8}SiFe{sub 2} and τ{sub 6}-Al{sub 9}Fe{sub 2}Si{sub 2}. The τ{sub 5}-Al{sub 8}SiFe{sub 2} phase evolves at all levels of the parameters during solidification and subsequently transforms into the τ{sub 6}-Al{sub 9}Fe{sub 2}Si{sub 2} through a peritectic reaction when promoted by certain combinations of solidification parameters such as higher Fe level, lower Si level and slower solidification rates. Further, it is also hypothesized from experimental evidences that the θ-Al{sub 13}Fe{sub 4} binary phase precludes the evolution of the τ{sub 5} during solidification and subsequently transforms into the τ{sub 6} phase during solidification. These observations are anomalous to the publications as prior art and

  3. Transport processes in directional solidification and their effects on microstructure development

    Science.gov (United States)

    Mazumder, Prantik

    The processing of materials with unique electronic, mechanical, optical and thermal properties plays a crucial role in modern technology. The quality of these materials depend strongly on the microstructures and the solute/dopant fields in the solid product, that are strongly influenced by the intricate coupling of heat and mass transfer and melt flow in the growth systems. An integrated research program is developed that include precisely characterized experiments and detailed physical and numerical modeling of the complex transport and dynamical processes. Direct numerical simulation of the solidification process is carried out that takes into account the unsteady thermo-solutal convection in the vertical Bridgman crystal growth system, and accurately models the thermal interaction between the furnace and the ampoule by appropriately using experimentally measured thermal profiles. The flow instabilities and transitions and the nonlinear evolution following the transitions are investigated by time series and flow pattern analysis. A range of complex dynamical behavior is predicted with increasing thermal Rayleigh number. The route to chaos appears as: steady convection --> transient mono-periodic --> transient bi-periodic --> transient quasiperiodic --> transient intermittent oscillation- relaxation --> stable intermittent oscillation-relaxation attractor. The spatio-temporal dynamics of the melt flow is found to be directly related to the spatial patterns observed experimentally in the solidified crystals. The application of the model to two phase Sn-Cd peritectic alloys showed that a new class of tree-like oscillating microstructure develops in the solid phase due to unsteady thermo-solutal convection in the liquid melt. These oscillating layered structures can give the illusion of band structures on a plane of polish. The model is applied to single phase solidification in the Al-Cu and Pb-Sn systems to characterize the effect of convection on the macroscopic

  4. Thermodynamic assessment of liquid composition change during solidification and its effect on freckle formation in superalloys

    International Nuclear Information System (INIS)

    Long Zhengdong; Liu Xingbo; Yang Wanhong; Chang, K.-M.; Barbero, Ever

    2004-01-01

    The solidification macrosegregation, i.e. freckle, becomes more and more concerned with ever increasing demand for the large ingot size of superalloys. The evaluation of freckle formation is very difficult because of the less understanding of freckle formation mechanism and complex solidification behaviors of multi-component superalloys. The macrostructure of typical Nb-bearing and Ti-bearing superalloys in horizontally directional solidification and vacuum arc remelting (VAR) ingots were investigated to clarify the freckle formation mechanism. The thermodynamic approach was proposed to simulate the solidification behaviors. The relative Ra numbers, a reliable criterion, of freckle formation for some alloys were obtained based on the results of thermodynamic calculations. This thermodynamic approach was evaluated through comparison of the calculations from semi-experimental results. The Ra numbers obtained by thermodynamic approach are in good agreement with the ingot size capability of the industry melting shops, which is limited mainly by freckle defects

  5. Toxic and hazardous waste disposal. Volume 1. Processes for stabilization/solidification

    International Nuclear Information System (INIS)

    Pojasek, R.B.

    1979-01-01

    Processes for the stabilization and/or solidification of toxic, hazardous, and radioactive wastes are reviewed. The types of wastes classified as hazardous are defined. The following processes for the solidification of hazardous wastes are described: lime-based techniques; thermoplastic techniques; organic polymer techniques; and encapsulation. The following processes for the solidification of high-level radioactive wastes are described: calcination; glassification; and ceramics. The solidification of low-level radioactive wastes with asphalt, cement, and polymeric materials is also discussed. Other topics covered include: the use of an extruder/evaporator to stabilize and solidify hazardous wastes; effect disposal of fine coal refuse and flue gas desulfurization slurries using Calcilox additive stabilization; the Terra-Tite Process; the Petrifix Process; the SFT Terra-Crete Process; Sealosafe Process; Chemfix Process; and options for disposal of sulfur oxide wastes

  6. Variations of Microsegregation and Second Phase Fraction of Binary Mg-Al Alloys with Solidification Parameters

    Science.gov (United States)

    Paliwal, Manas; Kang, Dae Hoon; Essadiqi, Elhachmi; Jung, In-Ho

    2014-07-01

    A systematic experimental investigation on microsegregation and second phase fraction of Mg-Al binary alloys (3, 6, and 9 wt pct Al) has been carried out over a wide range of cooling rates (0.05 to 700 K/s) by employing various casting techniques. In order to explain the experimental results, a solidification model that takes into account dendrite tip undercooling, eutectic undercooling, solute back diffusion, and secondary dendrite arm coarsening was also developed in dynamic linkage with an accurate thermodynamic database. From the experimental data and solidification model, it was found that the second phase fraction in the solidified microstructure is not determined only by cooling rate but varied independently with thermal gradient and solidification velocity. Lastly, the second phase fraction maps for Mg-Al alloys were calculated from the solidification model.

  7. Recent Advances in Study of Solid-Liquid Interfaces and Solidification of Metals

    Directory of Open Access Journals (Sweden)

    Mohsen Asle Zaeem

    2018-02-01

    Full Text Available Solidification occurs in several material processing methods, such as in casting, welding, and laser additive manufacturing of metals, and it controls the nano- and microstructures, as well as the overall properties of the products[...

  8. THE SITE DEMONSTRATION OF CHEMFIX SOLIDIFICATION/ STABILIZATION PROCESS AT THE PORTABLE EQUIPMENT SALVAGE COMPANY SITE

    Science.gov (United States)

    A demonstration of the GHEMFIX solidification/stabilization process was conducted under the United States Environmental Protection Agency`s (EPA) Superfund Innovative Technology Evaluation (SITE) program. The demonstration was conducted in March 1989, at the Portable Equipment Sa...

  9. Microstructural characterization of TiAl3 intermetallic obtained by the Fast solidification technique

    International Nuclear Information System (INIS)

    Angeles C, C.; Rosas, G.; Perez C, R.

    1997-01-01

    In this work preliminary studies about the TiAl 3 characterization are reported which is obtained starting from the Fast solidification technique in an arc furnace using Scanning electron microscopy, X-ray diffraction and Transmission electron microscopy. (Author)

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

    Science.gov (United States)

    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...

  11. SUPERFUND TREATABILITY CLEARINGHOUSE: BDAT FOR SOLIDIFICATION/STABILIZATION TECHNOLOGY FOR SUPERFUND SOILS (DRAFT FINAL REPORT)

    Science.gov (United States)

    This report evaluates the performance of solidification as a method for treating solids from Superfund sites. Tests were conducted on four different artificially contaminated soils which are representative of soils found at the sites. Contaminated soils were solidified us...

  12. EVALUATION OF SOLIDIFICATION/STABILIZATION AS A BEST DEMONSTRATED AVAILABLE TECHNOLOGY FOR CONTAMINATED SOILS

    Science.gov (United States)

    This project involved the evaluation of solidification/stabilization technology as a BDAT for contaminated soil. Three binding agents were used on four different synthetically contaminated soils. Performance evaluation data included unconfined compressive strength (UCS) and the T...

  13. LOW COST SOLIDIFICATION/STABILIZATION TREATMENT FOR SOILS CONTAMINATED WITH DIOXIN, PCP AND CREOSOTE

    Science.gov (United States)

    The USEPA's NRMRL conducted successful treatability tests of innovative solidification/stabilization (S/S) formulations to treat soils contaminated with dioxins, pentachlorophenol (PCP), and creosote from four wood preserving sites. Formulations developed during these studies wer...

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

    Science.gov (United States)

    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.

  15. Elemental analysis of the Al-Fe intermetallic prepared by fast solidification

    International Nuclear Information System (INIS)

    Sandoval J, R.A.; Lopez M, J.; Ramirez T, J.J.; Aspiazu F, J.; Villasenor S, P.

    2003-01-01

    Applying the PIXE technique samples of the Al-Fe intermetallic prepared by fast solidification, obtained starting from Al recycled were analyzed. The concentrations of the found elements are given. (Author)

  16. Solidification process for toxic and hazardous wastes. Second part: Cement solidification matrices; Inertizzazione di rifiuti tossici e nocivi (RTN). Parte seconda: Inertizzazione in matrici cementizie

    Energy Technology Data Exchange (ETDEWEB)

    Donato, A; Arcuri, L; Dotti, M; Pace, A; Pietrelli, L; Ricci, G [ENEA - Dipartimento Ciclo del Combustibile, Centro Ricerche Energia, Casaccia (Italy); Basta, M; Cali, V; Pagliai, V [ENEA - Dipartimento Ciclo del Combustibile, Centro Ricerche Energia, Saluggia (Italy)

    1989-05-15

    This paper reports the second part of a general study carried out at the Nuclear Fuel Division aiming at verifying the possible application of the radioactive waste solidification processes to industrial hazardous wastes (RTN). The cement solidification of several RTN types has been taken into consideration, both from the technical and from the economic point of view. After a short examination of the Italian juridical and economical situation in the field, which demonstrates the need of the RTN solidification, the origin and characteristics of the RTN considered in the study and directly provided by the producing industries are reviewed. The laboratory experimental results of the cementation of RTN produced by gold manufacturing industries and by galvanic industries are reported. The cementation process can be considered a very effective mean for reducing both the RTN management costs and the environmental impact of RTN disposal. (author)

  17. Laboratory micro- and nanoscale X-ray tomographic investigation of Al–7 at.%Cu solidification structures

    International Nuclear Information System (INIS)

    Patterson, B.M.; Henderson, K.C.; Gibbs, P.J.; Imhoff, S.D.; Clarke, A.J.

    2014-01-01

    X-ray computed tomography across multiple length scales provides an opportunity to non-destructively visualize and quantify the micro- to nano-scale microstructural features of solidification structures in three dimensions. Aluminum–7 at.%copper samples were directionally solidified at three cooling rates (0.44, 0.67, and 1.33 °C/s), resulting in systematic changes in the as-solidified microstructure, which are difficult to quantify using traditional microscopic techniques. The cooling rate of a material affects its ultimate microstructure, and characterizing that microstructure is key to predicting and understanding its bulk properties. Here, two different laboratory X-ray computed tomography instruments were used to characterize as-solidified microstructures, including micro-scale computed tomography with approximately 1 mm field-of-view, ∼ 1.7 μm resolution, and nano-scale X-ray computed tomography ∼ 65 μm FOV, 150 nm resolution. Micro-scale X-ray radiography and computed tomography enabled a quantitative investigation of changes in the primary dendritic solidification structure with increasing cooling rate. Nano-scale absorption contrast X-ray computed tomography resolved the distinct phases of the lamellar eutectic structure and three dimensional measurements of the ∼ 1 μm interlamellar spacing. It is found that the lamella eutectic structure thickness is inversely proportional to the cooling rate. Nano-scale Zernike phase contrast was also used to image voids at eutectic colony boundaries. The application and resolution of these two instruments are discussed with respect to the resolvable features of the solidification structures. - Highlights: • Al–Cu eutectic is a model system for studying solidification microstructure. • X-ray computed tomography provides a 3D picture of these complex structures. • Micro-scale tomography images the primary and secondary dendritic structures. • Nano-scale tomography images the eutectic lamella and

  18. Laboratory micro- and nanoscale X-ray tomographic investigation of Al–7 at.%Cu solidification structures

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, B.M., E-mail: bpatterson@lanl.gov; Henderson, K.C.; Gibbs, P.J.; Imhoff, S.D.; Clarke, A.J.

    2014-09-15

    X-ray computed tomography across multiple length scales provides an opportunity to non-destructively visualize and quantify the micro- to nano-scale microstructural features of solidification structures in three dimensions. Aluminum–7 at.%copper samples were directionally solidified at three cooling rates (0.44, 0.67, and 1.33 °C/s), resulting in systematic changes in the as-solidified microstructure, which are difficult to quantify using traditional microscopic techniques. The cooling rate of a material affects its ultimate microstructure, and characterizing that microstructure is key to predicting and understanding its bulk properties. Here, two different laboratory X-ray computed tomography instruments were used to characterize as-solidified microstructures, including micro-scale computed tomography with approximately 1 mm field-of-view, ∼ 1.7 μm resolution, and nano-scale X-ray computed tomography ∼ 65 μm FOV, 150 nm resolution. Micro-scale X-ray radiography and computed tomography enabled a quantitative investigation of changes in the primary dendritic solidification structure with increasing cooling rate. Nano-scale absorption contrast X-ray computed tomography resolved the distinct phases of the lamellar eutectic structure and three dimensional measurements of the ∼ 1 μm interlamellar spacing. It is found that the lamella eutectic structure thickness is inversely proportional to the cooling rate. Nano-scale Zernike phase contrast was also used to image voids at eutectic colony boundaries. The application and resolution of these two instruments are discussed with respect to the resolvable features of the solidification structures. - Highlights: • Al–Cu eutectic is a model system for studying solidification microstructure. • X-ray computed tomography provides a 3D picture of these complex structures. • Micro-scale tomography images the primary and secondary dendritic structures. • Nano-scale tomography images the eutectic lamella and

  19. A study of aluminum-lithium alloy solidification using acoustic emission techniques. Ph.D. Thesis, 1991

    Science.gov (United States)

    Henkel, Daniel P.

    1992-01-01

    Physical phenomena associated with the solidification of an aluminum lithium alloy was characterized using acoustic emission (AE) techniques. It is shown that repeatable patterns of AE activity may be correlated to microstructural changes that occur during solidification. The influence of the experimental system on generated signals was examined in the time and frequency domains. The analysis was used to show how an AE signal from solidifying aluminum is changed by each component in the detection system to produce a complex waveform. Conventional AE analysis has shown that a period of high AE activity occurs in pure aluminum, an Al-Cu alloy, and the Al-Li alloy, as the last fraction of solid forms. A model attributes this to the internal stresses of grain boundary formation. An additional period of activity occurs as the last fraction of solid forms, but only in the two alloys. A model attributes this to the formation of interdendritic porosity which was not present in the pure aluminum. The AE waveforms were dominated by resonant effects of the waveguide and the transducer.

  20. Investigation of solidification behavior of the Sn-rich ternary Sn–Bi–Zn alloys

    Directory of Open Access Journals (Sweden)

    S Mladenović

    2017-03-01

    Full Text Available Solidification properties and microstructure of six as-cast Sn–Bi–Zn alloys with 80 at.% of Sn and variable contents of Bi and Zn were experimentally investigated using the scanning electron microscopy (SEM with energy-dispersive X-ray spectroscopy (EDS and differential scanning calorimetry (DSC. The experimentally obtained results were compared with predicted phase equilibria according to the calculation of phase diagram (CALPHAD method and by the Scheil solidification simulation.

  1. Premature melt solidification during mold filling and its influence on the as-cast structure

    Science.gov (United States)

    Wu, M.; Ahmadein, M.; Ludwig, A.

    2018-03-01

    Premature melt solidification is the solidification of a melt during mold filling. In this study, a numerical model is used to analyze the influence of the pouring process on the premature solidification. The numerical model considers three phases, namely, air, melt, and equiaxed crystals. The crystals are assumed to have originated from the heterogeneous nucleation in the undercooled melt resulting from the first contact of the melt with the cold mold during pouring. The transport of the crystals by the melt flow, in accordance with the socalled "big bang" theory, is considered. The crystals are assumed globular in morphology and capable of growing according to the local constitutional undercooling. These crystals can also be remelted by mixing with the superheated melt. As the modeling results, the evolutionary trends of the number density of the crystals and the volume fraction of the solid crystals in the melt during pouring are presented. The calculated number density of the crystals and the volume fraction of the solid crystals in the melt at the end of pouring are used as the initial conditions for the subsequent solidification simulation of the evolution of the as-cast structure. A five-phase volume-average model for mixed columnar-equiaxed solidification is used for the solidification simulation. An improved agreement between the simulation and experimental results is achieved by considering the effect of premature melt solidification during mold filling. Finally, the influences of pouring parameters, namely, pouring temperature, initial mold temperature, and pouring rate, on the premature melt solidification are discussed.

  2. Effect of blended materials on U(VI) retention characteristics for portland cement solidification product

    International Nuclear Information System (INIS)

    Tan Hongbin; Ma Xiaoling; Li Yuxiang

    2006-01-01

    Using the simulated groundwater as leaching liquid, the retention capability of U(VI) in solidification products with Portland cement, the Portland cement containing silica fume, the Portland cement containing metakaolin and the Portland cement containing fly ash was researched by leaching experiments at 25 degree C for 42 d. The results indicate silica fume and metakaolin as blended materials can improve the U(VI) retention capability of Portland cement solidification product, but fly ash can not. (authors)

  3. Application of the dual reciprocity boundary element method for numerical modelling of solidification process

    Directory of Open Access Journals (Sweden)

    E. Majchrzak

    2008-12-01

    Full Text Available The dual reciprocity boundary element method is applied for numerical modelling of solidification process. This variant of the BEM is connected with the transformation of the domain integral to the boundary integrals. In the paper the details of the dual reciprocity boundary element method are presented and the usefulness of this approach to solidification process modelling is demonstrated. In the final part of the paper the examples of computations are shown.

  4. Analysis of capital and operating costs associated with high level waste solidification processes

    International Nuclear Information System (INIS)

    Heckman, R.A.; Kniazewycz, B.G.

    1978-03-01

    An analysis was performed to evaluate the sensitivity of annual operating costs and capital costs of waste solidification processes to various parameters defined by the requirements of a proposed Federal waste repository. Five process methods and waste forms examined were: salt cake, spray calcine, fluidized bed calcine, borosilicate glass, and supercalcine multibarrier. Differential cost estimates of the annual operating and maintenance costs and the capital costs for the five HLW solidification alternates were developed

  5. Bridging the gap between molecular dynamics simulations and phase-field modelling: dynamics of a [NixZr1-x]liquid-Zrcrystal solidification front

    International Nuclear Information System (INIS)

    Danilov, Denis; Nestler, Britta; Guerdane, Mohammed; Teichler, Helmar

    2009-01-01

    Results are presented from phase-field modelling and molecular dynamics simulations concerning the relaxation dynamics in a finite-temperature two-phase crystal-liquid sample subjected to an abrupt temperature drop. Relaxation takes place by propagation of the solidification front under formation of a spatially varying concentration profile in the melt. The molecular dynamics simulations are carried out with an interatomic model appropriate for the NiZr alloy system and provide the thermophysical data required for setting up the phase-field simulations. Regarding the concentration profile and velocity of the solidification front, best agreement between the phase-field model and molecular dynamics simulation is obtained when increasing the apparent diffusion coefficients in the phase-field treatment by a factor of four against their molecular dynamics estimates.

  6. Utilization of coal fly ash in solidification of liquid radioactive waste from research reactor.

    Science.gov (United States)

    Osmanlioglu, Ahmet Erdal

    2014-05-01

    In this study, the potential utilization of fly ash was investigated as an additive in solidification process of radioactive waste sludge from research reactor. Coal formations include various percentages of natural radioactive elements; therefore, coal fly ash includes various levels of radioactivity. For this reason, fly ashes have to be evaluated for potential environmental implications in case of further usage in any construction material. But for use in solidification of radioactive sludge, the radiological effects of fly ash are in the range of radioactive waste management limits. The results show that fly ash has a strong fixing capacity for radioactive isotopes. Specimens with addition of 5-15% fly ash to concrete was observed to be sufficient to achieve the target compressive strength of 20 MPa required for near-surface disposal. An optimum mixture comprising 15% fly ash, 35% cement, and 50% radioactive waste sludge could provide the solidification required for long-term storage and disposal. The codisposal of radioactive fly ash with radioactive sludge by solidification decreases the usage of cement in solidification process. By this method, radioactive fly ash can become a valuable additive instead of industrial waste. This study supports the utilization of fly ash in industry and the solidification of radioactive waste in the nuclear industry.

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

    Science.gov (United States)

    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.

  8. Geometrical modulus of a casting and its influence on solidification process

    Directory of Open Access Journals (Sweden)

    F. Havlicek

    2011-10-01

    Full Text Available Object: The work analyses the importance of the known criterion for evaluating the controlled solidification of castings, so called geometrical modulus defined by N. Chvorinov as the first one. Geometrical modulus influences the solidification process. The modulus has such specificity that during the process of casting formation it is not a constant but its initial value decreases with the solidification progress because the remaining melt volume can decrease faster than its cooling surface.Methodology: The modulus is determined by a simple calculation from the ratio of the casting volume after pouring the metal in the mould to the cooled mould surface. The solidified metal volume and the cooled surface too are changed during solidification. That calculation is much more complicated. Results were checked up experimentally by measuring the temperatures in the cross-section of heavy steel castings during cooling them.Results: The given experimental results have completed the original theoretical calculations by Chvorinov and recent researches done with use of numerical calculations. The contribution explains how the geometrical modulus together with the thermal process in the casting causes the higher solidification rate in the axial part of the casting cross-section and shortening of solidification time. Practical implications: Change of the geometrical modulus negatively affects the casting internal quality. Melt feeding by capillary filtration in the dendritic network in the casting central part decreases and in such a way the shrinkage porosity volume increases. State of stress character in the casting is changed too and it increases.

  9. On the relation between primary and eutectic solidification structures in gray iron

    International Nuclear Information System (INIS)

    Elmquist, L; Sonawane, P A

    2012-01-01

    The solidification of hypoeutectic gray cast iron starts with the nucleation of primary austenite crystals. Before graphite is nucleated, and the eutectic structure is formed, these crystals start to grow as columnar or equiaxed dendrites. However, very little is known about these dendrites, and especially how they influence the subsequent eutectic structure. Besides, it has previously been shown that the primary solidification structure influences the formation of defects. Shrinkage porosity was found between the dendrites, in the grain boundaries, and the formation of the primary solidification structure was found to influence problems related to metal expansion penetration. Therefore a better understanding about the formation of this structure is of importance. In this work, different inoculants and their influence on the formation of the micro- and macrostructures has been investigated. The inoculants considered are commercially used inoculants, i.e. inoculants used in the foundries, as well as different iron powders. The addition of iron powder is used to promote the primary solidification structure. It is shown that the nucleation of the dendrites is influenced by the amount of iron powder. Secondary dendrite arm spacing is a quantitative measurement in the microstructure related to these dendrites, which in turn depends on the solidification time. Eutectic cell size, on the other hand, is found to depend on secondary dendrite arm spacing. It is shown how the addition of inoculants influences both primary and eutectic solidification structures, and how they are related to each other.

  10. PD and I works to improve the waste solidification performance of Angra 1

    International Nuclear Information System (INIS)

    Tello, Cledola C.O. de; Gomes, Nelson J.P.O.

    2009-01-01

    Angra 1 Power Plant is the first Brazilian NPP, and started its commercial operation in 1985. The wastes from its operation are spent ion exchange resins, expended filter cartridges, boric acid evaporator concentrates; and solid wastes such as gloves, cleaning tools, plastics and protective clothing. Liquid waste streams are treated by evaporation to reduce the volume, and the concentrate is solidified in cement. The original cementation unit was designed to meet the US product acceptance criteria of the early seventies, when environmental and safety requirements were less restrictive than now. This system had a very low efficiency, and the waste product quality was very poor. A new solidification plant was bought, and R and D project was carried out to study and develop a suitable cementation process and the PCP - process control program - to guarantee the licensing of the plant and maximize its efficiency using Brazilian materials. To accomplish these objectives, a huge amount of experiments were carried on. Tests were performed to determine the main properties of the process and the product, e.g. the workability, set time, compressive strength (stress resistance) and leachability. After reaching the established parameters, the mixture system was optimized. The paddle and container designs were modified and also the motor specifications, so that the process efficiency could be improved. The performance of this new system is increased allowing solidifying from 56 till 69% in volume of waste, much better in comparison of the old one, whose maximum value was about 20%. (author)

  11. Determination for the Entrapment Criterion of Non-metallic Inclusions by the Solidification Front During Steel Centrifugal Continuous Casting

    Science.gov (United States)

    Wang, Qiangqiang; Zhang, Lifeng

    2016-06-01

    In the current study, the three-dimensional fluid flow, heat transfer, and solidification in steel centrifugal continuous casting strands were simulated. The volume of fluid model was used to solve the multiphase phenomena between the molten steel and the air. The entrapment and final distribution of inclusions in the solidified shell were studied with the discussion on the effect of rotation behavior of the caster system. Main results indicate that after applying the rotation of the shell, the fluid flow transformed from a recirculation flow to a rotation flow in the mold region and was driven to flow around in the casting direction. As the distance below the meniscus increased, the distribution of the tangential speed of the flow and the centrifugal force along one diameter of the strand became symmetrical gradually. The jet flow from the nozzle hardly impinged on the same location on the shell due to the rotation of the shell during solidification. Thus, the shell thickness on the same height was uniform around, and the thinning shell and a hot spot on the surface of shell were avoided. Both of the measurement and the calculation about the distribution of oxide inclusions along the radial direction indicated the number of inclusions at the side and the center was more than that at the quarter on the cross section of billet. With a larger diameter, inclusions tended to be entrapped toward the center area of the billet.

  12. Superior metallic alloys through rapid solidification processing (RSP) by design

    Energy Technology Data Exchange (ETDEWEB)

    Flinn, J.E. [Idaho National Engineering Laboratory, Idaho Falls, ID (United States)

    1995-05-01

    Rapid solidification processing using powder atomization methods and the control of minor elements such as oxygen, nitrogen, and carbon can provide metallic alloys with superior properties and performance compared to conventionally processing alloys. Previous studies on nickel- and iron-base superalloys have provided the baseline information to properly couple RSP with alloy composition, and, therefore, enable alloys to be designed for performance improvements. The RSP approach produces powders, which need to be consolidated into suitable monolithic forms. This normally involves canning, consolidation, and decanning of the powders. Canning/decanning is expensive and raises the fabrication cost significantly above that of conventional, ingot metallurgy production methods. The cost differential can be offset by the superior performance of the RSP metallic alloys. However, without the performance database, it is difficult to convince potential users to adopt the RSP approach. Spray casting of the atomized molten droplets into suitable preforms for subsequent fabrication can be cost competitive with conventional processing. If the fine and stable microstructural features observed for the RSP approach are preserved during spray casing, a cost competitive product can be obtained that has superior properties and performance that cannot be obtained by conventional methods.

  13. Solidification of liquid radioactive concentrates by fixation with cement

    International Nuclear Information System (INIS)

    Pekar, A.; Breza, M.; Timulak, J.; Krajc, T.

    1985-01-01

    In testing the technology of liquid radioactive wastes cementation, the effect was mainly studied of the content of boric acid and its salts on cement solidification, the effect of additives on radionuclide leachability and the effect of the salt content on the cementation product. On the basis of experimental work carried out on laboratory scale with model samples and samples of radioactive concentrate from the V-1 nuclear power plant, the following suitable composition of the cementation mixture was determined: 40% Portland cement, 40% zeolite containing material and 20% power plant ash. The most suitable ratio of liquid radioactive wastes and the cementation mixture is 0.5. As long as in such case the salt content of the concentrate ranges between 20 and 25%, the cementation product will have a maximum salt content of 10% and a leachability of the order of 10 -3 to 10 -4 g/cm 2 per day with a mechanical strength allowing safe handling. It was also found that the quality processing of the cement paste with degassing, e.g., by vibration, is more effective for the production of a pore-free cementation product than the application of various additives which are supposed to eliminate pore formation. (Z.M.)

  14. Instabilities in rapid directional solidification under weak flow

    Science.gov (United States)

    Kowal, Katarzyna N.; Davis, Stephen H.; Voorhees, Peter W.

    2017-12-01

    We examine a rapidly solidifying binary alloy under directional solidification with nonequilibrium interfacial thermodynamics viz. the segregation coefficient and the liquidus slope are speed dependent and attachment-kinetic effects are present. Both of these effects alone give rise to (steady) cellular instabilities, mode S , and a pulsatile instability, mode P . We examine how weak imposed boundary-layer flow of magnitude |V | affects these instabilities. For small |V | , mode S becomes a traveling and the flow stabilizes (destabilizes) the interface for small (large) surface energies. For small |V | , mode P has a critical wave number that shifts from zero to nonzero giving spatial structure. The flow promotes this instability and the frequencies of the complex conjugate pairs each increase (decrease) with flow for large (small) wave numbers. These results are obtained by regular perturbation theory in powers of V far from the point where the neutral curves cross, but requires a modified expansion in powers of V1 /3 near the crossing. A uniform composite expansion is then obtained valid for all small |V | .

  15. Determination of melting and solidification enthalpy of hypereutectic silumins

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2008-04-01

    Full Text Available The study was related with determination of the values of enthalpy of melting and solidification of hypereutectic AlSi18, AlSi21 and AlSi24 silumins modified with phosphorus in the form of Cu-P. The calorimetry, preceded by thermal analysis and derivative thermal analysis (TA and DTA, respectively was carried out on a high-temperature scanning calorimeter, model MHTC-96, made by SETARAM, applying the method of direct determination of parameters of the high-temperature process, and in particular of the enthalpy of phase transformations. Modern control and measuring instruments coupled with PC computer provide a very precise tool for determination of these transformations. An additional advantage was development of appropriate software called „SETSOFT”, owing to which it was possible to determine in an easy way the enthalpy of the investigated phase transformations. Moreover, an additional thermal effect, related most probably with pre-eutectic crystallization of primary silicon, was observed and confirmed by calorimetric examinations.

  16. Stabilization and solidification of chromium-contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Cherne, C.A.; Thomson, B.M. [Univ. of New Mexico, Albuquerque, NM (United States). Civil Engineering Dept.; Conway, R. [Sandia National Labs., Albuquerque, NM (United States)

    1997-11-01

    Chromium-contaminated soil is a common environmental problem in the United States as a result of numerous industrial processes involving chromium. Hexavalent chromium [Cr(VI)] is the species of most concern because of its toxicity and mobility in groundwater. One method of diminishing the environmental impact of chromium is to reduce it to a trivalent oxidation state [Cr(III)], in which it is relatively insoluble and nontoxic. This study investigated a stabilization and solidification process to minimize the chromium concentration in the Toxicity Characteristic Leaching Procedure (TCLP) extract and to produce a solidified waste form with a compressive strength in the range of 150 to 300 pounds per square inch (psi). To minimize the chromium in the TCLP extract, the chromium had to be reduced to the trivalent oxidation state. The average used in this study was an alluvium contaminated with chromic and sulfuric acid solutions. The chromium concentration in the in the in situ soil was 1212 milligrams per kilogram (mg/kg) total chromium and 275 mg/kg Cr(VI). The effectiveness of iron, ferrous sulfate to reduce Cr(VI) was tested in batch experiments.

  17. Numerical simulation of controlled directional solidification under microgravity conditions

    Science.gov (United States)

    Holl, S.; Roos, D.; Wein, J.

    The computer-assisted simulation of solidification processes influenced by gravity has gained increased importance during the previous years regarding ground-based as well as microgravity research. Depending on the specific needs of the investigator, the simulation model ideally covers a broad spectrum of applications. These primarily include the optimization of furnace design in interaction with selected process parameters to meet the desired crystallization conditions. Different approaches concerning the complexity of the simulation models as well as their dedicated applications will be discussed in this paper. Special emphasis will be put on the potential of software tools to increase the scientific quality and cost-efficiency of microgravity experimentation. The results gained so far in the context of TEXUS, FSLP, D-1 and D-2 (preparatory program) experiments, highlighting their simulation-supported preparation and evaluation will be discussed. An outlook will then be given on the possibilities to enhance the efficiency of pre-industrial research in the Columbus era through the incorporation of suitable simulation methods and tools.

  18. Solidifications/stabilization treatability study of a mixed waste sludge

    International Nuclear Information System (INIS)

    Spence, R.D.; Stine, E.F.

    1996-01-01

    The Department of Energy Oak Ridge Operations Office signed a Federal Facility Compliance Agreement with the US Environmental Protection Agency Region IV regarding mixed wastes from the Oak Ridge Reservation (ORR) subject to the land disposal restriction provisions of the Resource Conservation and Recovery Act (RCRA). This agreement required treatability studies of solidification/stabilization (S/S) on mixed wastes from the ORR. This paper reports the results of the cementitious S/S studies conducted on a waste water treatment sludge generated from biodenitrification and heavy metals precipitation. For the cementitious waste forms, the additives tested were Portland cement, ground granulated blast furnace slag, Class F fly ash, and perlite. The properties measured on the treated waste were density, free-standing liquid, unconfined compressive strength, and TCLP performance. Spiking up to 10,000, 10,000, and 4,400 mg/kg of nickel, lead, and cadmium, respectively, was conducted to test waste composition variability and the stabilization limitations of the binding agents. The results indicated that nickel, lead and cadmium were stabilized fairly well in the high pH hydroxide-carbonate- ''bug bones'' sludge, but also clearly confirmed the established stabilization potential of cementitious S/S for these RCRA metals

  19. Stabilization and solidification of chromium-contaminated soil

    International Nuclear Information System (INIS)

    Cherne, C.A.; Thomson, B.M.

    1997-11-01

    Chromium-contaminated soil is a common environmental problem in the United States as a result of numerous industrial processes involving chromium. Hexavalent chromium [Cr(VI)] is the species of most concern because of its toxicity and mobility in groundwater. One method of diminishing the environmental impact of chromium is to reduce it to a trivalent oxidation state [Cr(III)], in which it is relatively insoluble and nontoxic. This study investigated a stabilization and solidification process to minimize the chromium concentration in the Toxicity Characteristic Leaching Procedure (TCLP) extract and to produce a solidified waste form with a compressive strength in the range of 150 to 300 pounds per square inch (psi). To minimize the chromium in the TCLP extract, the chromium had to be reduced to the trivalent oxidation state. The average used in this study was an alluvium contaminated with chromic and sulfuric acid solutions. The chromium concentration in the in the in situ soil was 1212 milligrams per kilogram (mg/kg) total chromium and 275 mg/kg Cr(VI). The effectiveness of iron, ferrous sulfate to reduce Cr(VI) was tested in batch experiments

  20. Interface Shape and Convection During Solidification and Melting of Succinonitrile

    Science.gov (United States)

    Degroh, Henry C., III; Lindstrom, Tiffany

    1994-01-01

    An experimental study was conducted of the crystal growth of succinonitrile during solidification, melting, and no-growth conditions using a horizontal Bridgman furnace and square glass ampoule. For use as input boundary conditions to numerical codes, thermal profiles on the outside of the ampoule at five locations around its periphery were measured along the ampoule's length. Temperatures inside the ampoule were also measured. The shapes of the s/l interface in various two dimensional planes were quantitatively determined. Though interfaces were nondendritic and noncellular, they were not flat, but were highly curved and symmetric in only one unique longitudinal y-z plane (at x=O). The shapes of the interface were dominated by the primary longitudinal flow cell characteristic of shallow cavity flow in horizontal Bridgman; this flow cell was driven by the imposed furnace temperature gradient and caused a 'radical' thermal gradient such that the upper half of the ampoule was hotter than the bottom half. We believe that due to the strong convection, the release of latent heat does not significantly influence the thermal conditions near the interface. We hope that the interface shape and thermal data presented in this paper can be used to optimize crystal growth processes and validate numerical models.

  1. Solidification of radioactive waste solutions by pelletization technique

    International Nuclear Information System (INIS)

    Akbar, A.H.; Koester, R.; Rudolph, G.

    1980-04-01

    A possible way of performing the cement fixation of radioactive wastes is the incorporation into cement pellets on a pan pelletizer, followed by embedding the pellets into an inactive cement matrix. This procedure is suitable for various types of waste, particularly for medium level liquid wastes, and can be used both at drum disposal and at in-situ solidification. This report describes some initial studies on the pelletization technique using a laboratory pelletizer. Formation and size of the pellets have been found to be determined by speed, angle, and load of the pan, ratio and mode of addition of the liquid and solid components, ect. Pellets in various compositions have been produced from cement and water or simulated waste solution, in some cases with the addition of bentonite for improving cesium retention. Some mechanical properties of the pellets such as fall height of fresh pellets, development of hardness (crush test), impact and abrasion resistance, have been determined. Some preliminary experiments were done on backfilling the void space between the pellets - about 40 per cent of the bulk volume - with cement grouts of appropriate compositions. (orig.) [de

  2. Solidification of acidic liquid waste from 99Mo isotope production

    International Nuclear Information System (INIS)

    Parsons, G.J.

    2001-01-01

    results in the solidification of the deammoniated product in stainless steel vessels designed for long term storage. The process was developed and commissioned through sequential steps. Initial testing was conducted on natural uranium nitrate based solutions followed by similar solutions with increasing levels of trace activity derived from the stored waste. The process was commissioned on stored liquid waste in 1999 and is now a routine operation. Initial processing through the concentration phase has been successful in removing 82-95% of the original liquor volume at a throughput rate of generally 4-4.5 L/h. The ammonia content in the acid waste had arisen principally from the addition of ammonia bearing condensate from the molybdenum extraction and initial purification process. This practice of combining these two liquid wastes is no longer continued but has resulted in an inventory of historical acid waste containing small concentrations of ammonia. A deammoniation process was developed to treat batches of concentrate before solidification. This processing step has been successful in reducing NH 3 -N to less than 10ppm under controlled conditions. Nitrogen oxides (NOx gasses) are a product of this chemical process and off gas is treated through a catalytic converter. Solidification to date has resulted in a product of 0.6-2.3% of the original liquor volume (or 1.7- 5.7% of the original solution weight). The solidification takes place in thick- walled once-use stainless steel vessels. The vessel is heated in a thermic oil bath with slow continuous feed of deammoniated concentrate and withdrawal of condensate. This phase is slower with throughput rates of around 1L/h decreasing to less than 0.5L/h as processing continues. When the required amount has been added to the vessel it is further heated, resulting in a product which solidifies on cooling. When this process is complete the connections to the vessel are removed and the vessel ports plugged. The vessel is then

  3. Effects of additives on solidification of API separator sludge.

    Science.gov (United States)

    Faschan, A; Tittlebaum, M; Cartledge, F; Eaton, H

    1991-08-01

    API separator sludge was solidified with various combinations of binders and absorbent soil additives. The binders utilized were Type I Portland Cement, Type C Flyash, and a 1:1 combination of the two. The soil additives used were bentonite, diatomite, Fuller's earth, and two brands of chemically altered bentonites, or organoclays. The effectiveness of the solidification materials was based on their effect on the physical and leaching characteristics of the sludge.It was determined the Portland cement and combination binders provided the sludge with adequate physical and strength characteristics. It was also determined the affinity of each additive for water had an important influence on the physical characteristics of the solidified sludge. The results of the leaching procedure indicated the binders alone reduced the leachability of organic constituents from the sludge by 1/5 to 1/10. It appeared the use of the additives with the binders may have further reduced the leachability of constituents from sludge, with the incorporation of the organoclay additives further reducing leachability by up to 1/2. Also, it appeared the absorbing capacity of the additives was directly related to their ability to reduce the leachability of organic constituents from the sludge.

  4. Sandia solidification process: consolidation and characterization. Part I. Consolidation studies

    International Nuclear Information System (INIS)

    Johnstone, J.K.

    1978-05-01

    The consolidation behavior of a complex polycrystalline ceramic nuclear waste form composed of titanates, zeolite, and metallic silicon was studied. Initial solidification takes place by an ion exchange process. The resulting powder exhibits a large surface area, approximately 350 m 2 /g, and several decomposition, crystallization and phase change reactions from room temperature to 1100 0 C. In spite of the large surface area, consolidation by cold pressing and atmospheric sintering to 1100 0 C was not satisfactory. Vacuum hot pressing was found to produce fully dense pellets (less than 1% residual porosity) under very mild conditions, 6.9 MPa (1100 psi) and 1100 0 C. The dominant densification mechanism was viscous flow. Under less than optimum hot pressing conditions, three stages of densification were observed. Initial densification took place by particle rearrangement which was described with a viscous flow model. Second stage densification occurred by a solution-precipitation process controlled by a phase boundary dissolution reaction. In several cases, a third, final densification stage was observed. Detailed studies describe the effects of heating rate, processing temperature, pressure, residence time, atmosphere, composition, heat treatment, and the addition of consolidation aids on the densification behavior. In addition, fully radioactive high level mixed fission product titanate/waste pellets (1.27 cm diameter) were hot pressed at Oak Ridge National Laboratory to demonstrate the feasibility of such a process in a remotely operated hot cell. High density uniform pellets were obtained

  5. Feasibility study of solidification for low-level liquid waste generated by sulfuric acid elution treatment of spent ion exchange resin

    International Nuclear Information System (INIS)

    Asano, Takashi; Kawasaki, Tooru; Higuchi, Natsuko; Horikawa, Yoshihiko

    2007-01-01

    Low-level liquid waste with relatively high levels of radioactivity is generated by the sulfuric acid elution treatment of spent ion exchange resin used in water purification systems of nuclear power plants. We studied cement-like solidification process for this type waste that contains a high concentration of sodium sulfate. For this type waste, it is important that the sulfate ion should not dissolve from the solid waste because it forms ettringite on reaction with minerals in the concrete, and this leads to cracking during repository storage. It is also preferable that the pH of pore water of the solid waste be low, because the bentonite of the repository changes in quality on exposure to alkaline solution. Our solidification process has two procedures: conversion into insoluble sulfate from sodium sulfate (CIS) and formation of low pH cement-like solid (FLS). In the CIS procedure, BaSO 4 precipitation occurs with addition of Ba(OH) 2 ·8H 2 O to the liquid waste when the Ba/SO 4 molar ratio > 1. In the FLS procedure, silica fume and blast furnace slag are added to the liquid wastes containing Ba S O 4 precipitate. The CIS reaction yield is over 98% and the pH of pore water of the solid waste is 11.5 or less. Therefore, we think that our solidification process is one of the best methods for treating liquid waste that contains a high concentration of sodium sulfate. (author)

  6. Formation and magic number characteristics of clusters formed during solidification processes

    International Nuclear Information System (INIS)

    Liu Rangsu; Dong Kejun; Tian Zean; Liu Hairong; Peng Ping; Yu Aibing

    2007-01-01

    A molecular dynamics simulation study has been performed for a large-sized system consisting of 10 6 liquid metal Al atoms to investigate the formation and magic number characteristics of various clusters formed during solidification processes. The cluster-type index method (CTIM) is adopted to describe various types of cluster by basic clusters. It is demonstrated that the icosahedral cluster (12 0 12 0) is the most important basic cluster, and that it plays a critical role in the microstructure transition. A new statistical method has been proposed to classify the clusters as some group levels according to the numbers of basic clusters contained in each cluster. The magic numbers can be determined by the respective peak value positions of different group levels of clusters, and the magic number sequence in the system is 13, 19, 25(27), 31(33), 38(40), 42(45), 48(51), 55(59), 61(65), 67,... the numbers in the brackets are the second magic number of the corresponding group levels of clusters. This magic number sequence is in good agreement with the experimental results obtained by Schriver and Harris et al, and the experimental results can be reasonably well explained

  7. Modelling of melting and solidification transport phenomena during hypothetical NPP severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Sarler, B [Inst. Jozef Stefan, Ljubljana (Slovenia)

    1992-07-01

    A physical and mathematical framework to deal with the transport phenomena occuring during melting and solidification of the hypothetical NPP severe accidents is presented. It concentrates on the transient temperature, velocity, and species concentration distributions during such events. The framework is based on the Mixture Continuum Formulation of the components and phases, cast in the boundary-domain integral shape structured by the fundamental solution of the Laplace equation. The formulation could cope with various solid-liquid sub-systems through the inclusion of the specific closure relations. The deduced system of boundary-domain integral equations for conservation of mass, energy, momentum, and species could be solved by the boundary element discrete approximative method. (author) [Slovenian] Predstavljeno je fizikalno in matematicno ogrodje za obravnavo prenosnih pojavov taljenja in strjevanja med hipoteticnimi tezkimi nezgodami v jedrskih elektrarnah. Osredotoceno je na popis neustaljene porazdelitve temperatur, hitrosti in koncentracij sestavin med taksnimi dogodki. Ogrodje temelji na formulaciji kontinuuma mesanice komponent in faz, v obliki robno obmocnih integralskih enacb, ki so sestavljena na podlagi fundamentalne resitve Laplace-ove enacbe. Formulacija lahko popisuje stevilne trdno-tekoce pod-sisteme na podlagi specificnih sklopitvenih relacij. Izpeljan sistem robno-obmocnih integralskih enacb za popis ohranitve mase, energije, gibalne kolicine in sestavin lahko resimo na podlagi diskretne aproksimativne metode robnih elementov. (author)

  8. Development of sodium disposal technology. Experiment of sodium compound solidification process

    International Nuclear Information System (INIS)

    Matsumoto, Toshiyuki; Ohura, Masato; Yatoh, Yasuo

    2007-07-01

    A large amount of sodium containing radioactive waste will come up at the time of final shutdown/decommission of FBR plant. The radioactive waste is managed as solid state material in a closed can in Japan. As for the sodium, there is no established method to convert the radioactive sodium to solid waste. Further, the sodium is highly reactive. Thus, it is recommended to convert the sodium to a stable substance before the solidification process. One of the stabilizing methods is conversion of sodium into sodium hydroxide solution. These stabilization and solidification processes should be safe, economical, and efficient. In order to develop such sodium disposal technology, nonradioactive sodium was used and a basic experiment was performed. Waste-fluid Slag Solidification method was employed as the solidification process of sodium hydroxide solution. Experimental parameters were mixing ratio of the sodium hydroxide and the slag solidification material, temperature and concentration of the sodium hydroxide. The best parameters were obtained to achieve the maximum filling ratio of the sodium hydroxide under a condition of enough high compressive strength of the solidified waste. In a beaker level test, the solidified waste was kept in a long term and it was shown that there was no change of appearance, density, and also the compressive strength was kept at a target value. In a real scale test, homogeneous profiles of the density and the compressive strength were obtained. The compressive strength was higher than the target value. It was shown that the Waste-fluid Slag Solidification method can be applied to the solidification process of the sodium hydroxide solution, which was produced by the stabilization process. (author)

  9. PREFACE: Third International Conference on Advances in Solidification Processes (ICASP - 3)

    Science.gov (United States)

    Zimmermann, Gerhard; Ratke, Lorenz

    2012-01-01

    The 3rd International Conference on Advances in Solidification Processes was held in the Rolduc Abbey in the Netherlands a few kilometres away from Aachen. Around 200 scientists from 24 countries come in for the four day meeting. They found a stimulating but also relaxing environment and atmosphere, with beautiful weather and the medieval abbey inviting for walks, discussions, sitting outside and drinking a beer or wine. The contributions given at the conference reflected recent advances in various topics of solidification processes, ranging from fundamental aspects to applied casting technologies. In 20 oral sessions and a large poster session innovative results of segregation phenomena, microstructure evolution, nucleation and growth, phase formation, polyphase solidification, rapid solidification and welding, casting technology, thermophysics of molten alloys, solidification with forced melt flow and growth of single crystals and superalloys together with innovative diagnostic techniques were presented. Thereby, findings from experiments as well as from numerical modeling on different lengths scales were jointly discussed and contribute to new insight in solidification behaviour. The papers presented in this open access proceedings cover about half the oral and poster presentations given. They were carefully reviewed as in classical peer reviewed journals by two independent referees and most of them were revised and thus improved according to the reviewers comments. We think that this collection of papers presented at ICASP-3 gives an impression of the excellent contributions made. The papers embrace both the basic and applied aspects of solidification. We especially wish to express our appreciation for the team around Georg Schmitz and Margret Nienhaus organising this event and giving us their valued advice and support at every stage in preparing the conference. We also thank Lokasenna Lektorat for taking the task of checking all language-associated issues and

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

    Science.gov (United States)

    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.

  11. Solidification of radioactive liquid wastes. A comparison of treatment options for spent resins and concentrates

    International Nuclear Information System (INIS)

    Roth, A.; Willmann, F.; Ebata, M.; Wendt, S.

    2008-01-01

    Ion exchange is one of the most common and effective treatment methods for liquid radioactive waste. However, spent ion exchange resins are considered to be problematic waste that in many cases require special approaches and pre-conditioning during its immobilization to meet the acceptance criteria for disposal. Because of the function that they fulfill, spent ion exchange resins often contain high concentrations of radioactivity and pose special handling and treatment problems. Another very common method of liquid radioactive waste treatment and water cleaning is the evaporation or diaphragm filtration. Both treatment options offer a high volume reduction of the total volume of liquids treated but generate concentrates which contain high concentrations of radioactivity. Both mentioned waste streams, spent resins as well as concentrates, resulting from first step liquid radioactive waste treatment systems have to be conditioned in a suitable manner to achieve stable waste products for final disposal. The most common method of treatment of such waste streams is the solidification in a solid matrix with additional inactive material like cement, polymer etc. In the past good results have been achieved and the high concentration of radioactivity can be reduced by adding the inactive material. On the other hand, under the environment of limited space for interim storage and the absence of a final repository site, the built-up of additional volume has to be considered as very critical. Moreover, corrosive effects on cemented drums during long-term interim storage at the surface have raised doubts about the long-term stability of such waste products. In order to avoid such disadvantages solidification methods have been improved in order to get a well-defined product with a better load factor of wastes in the matrix. In a complete different approach, other technologies solidify the liquid radioactive wastes without adding of any inactive material by means of drying

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

    Science.gov (United States)

    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

  13. MODELING SOLIDIFICATION-INDUCED STRESSES IN CERAMIC WASTE FORMS CONTAINING NUCLEAR WASTES

    International Nuclear Information System (INIS)

    Solbrig, Charles W.; Bateman, Kenneth J.

    2010-01-01

    The goal of this work is to produce a ceramic waste form (CWF) that permanently occludes radioactive waste. This is accomplished by absorbing radioactive salts into zeolite, mixing with glass frit, heating to a molten state 915 C to form a sodalite glass matrix, and solidifying for long-term storage. Less long term leaching is expected if the solidifying cooling rate doesn't cause cracking. In addition to thermal stress, this paper proposes that a stress is formed during solidification which is very large for fast cooling rates during solidification and can cause severe cracking. A solidifying glass or ceramic cylinder forms a dome on the cylinder top end. The temperature distribution at the time of solidification causes the stress and the dome. The dome height, ''the length deficit,'' produces an axial stress when the solid returns to room temperature with the inherent outer region in compression, the inner in tension. Large tensions will cause cracking of the specimen. The temperature deficit, derived by dividing the length deficit by the coefficient of thermal expansion, allows solidification stress theory to be extended to the circumferential stress. This paper derives the solidification stress theory, gives examples, explains how to induce beneficial stresses, and compares theory to experimental data.

  14. Containerless solidification of BiFeO3 oxide under microgravity

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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%.

  16. Effect of Chemical Composition on Susceptibility to Weld Solidification Cracking in Austenitic Weld Metal

    Science.gov (United States)

    Kadoi, Kota; Shinozaki, Kenji

    2017-12-01

    The influence of the chemical composition, especially the niobium content, chromium equivalent Creq, and nickel equivalent Nieq, on the weld solidification cracking susceptibility in the austenite single-phase region in the Schaeffler diagram was investigated. Specimens were fabricated using the hot-wire laser welding process with widely different compositions of Creq, Nieq, and niobium in the region. The distributions of the susceptibility, such as the crack length and brittle temperature range (BTR), in the Schaeffler diagram revealed a region with high susceptibility to solidification cracking. Addition of niobium enhanced the susceptibility and changed the distribution of the susceptibility in the diagram. The BTR distribution was in good agreement with the distribution of the temperature range of solidification (Δ T) calculated by solidification simulation based on Scheil model. Δ T increased with increasing content of alloying elements such as niobium. The distribution of Δ T was dependent on the type of alloying element owing to the change of the partitioning behavior. Thus, the solidification cracking susceptibility in the austenite single-phase region depends on whether the alloy contains elements. The distribution of the susceptibility in the region is controlled by the change in Δ T and the segregation behavior of niobium with the chemical composition.

  17. Evaluation of process alternatives for solidification of the West Valley high-level liquid wastes

    International Nuclear Information System (INIS)

    Holton, L.K.; Larson, D.E.

    1982-01-01

    The Department of Energy (DOE) established the West Valley Solidification Project (WVSP) in 1980. The project purpose is to demonstrate removal and solidification of the high-level liquid wastes (HLLW) presently stored in tanks at the Western New York Nuclear Service Center (WNYNSC), West Valley, New York. As part of this effort, the Pacific Northwest Laboratory (PNL) conducted a study to evaluate process alternatives for solidifcation of the WNYNSC wastes. Two process approaches for waste handling before solidification, together with solidification processes for four terminal and four interim waste forms, were considered. The first waste-handling approach, designated the salt/sludge separation process, involves separating the bulk of the nonradioactive nuclear waste constituents from the radioactive waste constituents, and the second waste-handling approach, designated the combined-waste process, involves no waste segregation prior to solidification. The processes were evaluated on the bases of their (1) readiness for plant startup by 1987, (2) relative technical merits, and (3) process cost. The study has shown that, based on these criteria, the salt/sludge separation process with a borosilicate glass waste form is preferred when producing a terminal waste form. It was also concluded that if an interim waste form is to be used, the preferred approach would be the combined waste process with a fused-salt waste form

  18. Nuclear waste disposal: alternatives to solidification in glass proposed

    International Nuclear Information System (INIS)

    Kerr, R.A.

    1979-01-01

    More than a quarter-million cubic meters of liquid radioactive wastes are now being held at government installations awaiting final disposal. During the past 20 years, the disposal plan of choice has been to incorporate the 40 to 50 radioactive elements dissolved in liquid wastes into blocks of glass, seal the glass in metal canisters, and insert the canisters into deep, geologically stable salt beds. Over the last few years, some geologists and materials scientists have become concerned that perhaps not enough is known yet about the interaction of waste, container, and salt (or any rock) to have a reasonable assurance that the hazardous wastes will be contained successfully. The biggest advantage of glass at present is the demonstrated practicality of producing large, highly radioactive blocks of it. The frontrunner as a successor to glass is ceramics, which are nonmetallic crystalline materials formed at high temperature, such as chinaware or natural minerals. An apparent advantage of ceramics is that they already have an ordered atomic structure, whose properties can be tailored to a particular waste element and to conditions of a specific disposal site. A ceramic tailored for waste disposal called supercalcine-ceramic has been developed. It was emphasized that the best minerals for waste solidification may be those that have proved most stable under natural conditions over geologic time. Disadvantage to ceramics are radiation damage and transmutation. However, it is now obvious that some ceramics are more stable than glass under certain conditions. Metal-encapsulated ceramic, called cermet, is being developed as a waste form. Cermets are considerably more resistant at 100 0 C than a borosilicate waste glass. Researchers are now testing prospective waste forms under the most extreme conditions that might prevail in a waste disposal site

  19. Design and construction of solidification and dewatering facility at Alabama Power Company's Farley Nuclear Plant

    International Nuclear Information System (INIS)

    Farnsworth, P.

    1988-01-01

    The approximate total cost of the structure and supporting piping systems is estimated to be 4.1 million dollars. Total dose savings per year could be as high as 70 man Rem for resin processing alone. The ability to store refueling equipment, process contaminated oils, load and unload trucks and containers regardless of weather conditions and support repair work on equipment greatly enhances the cost effectiveness of the project. It will take at least one year of operation of the facility to accurately assess the true cost savings to Alabama Power Company. The morale factor for the Waste and Decon Group has escalated measurably due to the dose reduction to our personnel. Plant and company management are well pleased due to the possibility of a spill or release to the environment has been eliminated which was on intangible cost. Facility construction has been completed as of this date and resin transfer anticipated within the next few days. Some of the problems encountered in planning and constructing this solidification and dewatering facility are presented. A safety evaluation for the facility is included in the appendix

  20. The correlation between composition, structure and properties of high-level waste solidification products

    International Nuclear Information System (INIS)

    Neumann, L.; Vojtech, O.; Santarova, M.; Stejskal, I.; Gulinskij, V.

    1977-01-01

    The final product of a high-level liquid waste solidification process must meet a number of quantitative criteria. The necessary data can be obtained by direct measurement of certain parameters of the product (leachability of important radionuclides from the basic matrix, total solubility of the final product, thermal conductivity, mechanical properties, the temperature dependence of viscosity, etc.). Some insight can also be obtained on the basis of a profound analysis of micro- and macrostructure of the solid product. Detailed knowledge of the structure makes it easier to evaluate the final product. In this paper an effort is made to find a relationship between composition and structure of the system and the properties of the product obtained under the specific conditions of the process. The results are demonstrated using a phosphate matrix in which fission products and corrosion products are included in a wide range of concentrations. For analysis of the structure properties, X-ray diffraction, microscopic and electron probe microanalysis (back-scattered electrons and characteristic X-radiation detection) have been used. Using standard methods, the hydrolytical resistance of the product and the selective leachability of caesium, strontium and rare-earth ions have been measured. The results obtained so far have confirmed the usefulness of structure analysis as a parallel method for product evaluation in the development of the process and probably also for large-scale application. (author)

  1. A unified momentum equation approach for computing thermal residual stresses during melting and solidification

    Science.gov (United States)

    Yeo, Haram; Ki, Hyungson

    2018-03-01

    In this article, we present a novel numerical method for computing thermal residual stresses from a viewpoint of fluid-structure interaction (FSI). In a thermal processing of a material, residual stresses are developed as the material undergoes melting and solidification, and liquid, solid, and a mixture of liquid and solid (or mushy state) coexist and interact with each other during the process. In order to accurately account for the stress development during phase changes, we derived a unified momentum equation from the momentum equations of incompressible fluids and elastoplastic solids. In this approach, the whole fluid-structure system is treated as a single continuum, and the interaction between fluid and solid phases across the mushy zone is naturally taken into account in a monolithic way. For thermal analysis, an enthalpy-based method was employed. As a numerical example, a two-dimensional laser heating problem was considered, where a carbon steel sheet was heated by a Gaussian laser beam. Momentum and energy equations were discretized on a uniform Cartesian grid in a finite volume framework, and temperature-dependent material properties were used. The austenite-martensite phase transformation of carbon steel was also considered. In this study, the effects of solid strains, fluid flow, mushy zone size, and laser heating time on residual stress formation were investigated.

  2. Grout and glass performance in support of stabilization/solidification of ORNL tank sludges

    International Nuclear Information System (INIS)

    Spence, R.D.; Mattus, C.H.; Mattus, A.J.

    1998-09-01

    Wastewater at Oak Ridge National Laboratory (ORNL) is collected, evaporated, and stored in the Melton Valley Storage Tanks (MVST) and Bethel Valley Evaporator Storage Tanks (BVEST) pending treatment for disposal. In addition, some sludges and supernatants also requiring treatment remain in two inactive tank systems: the gunite and associated tanks (GAAT) and the old hydrofracture (OHF) tank. The waste consists of two phases: sludge and supernatant. The sludges contain a high amount of radioactivity, and some are classified as TRU sludges. Some Resource Conservation and Recovery Act (RCRA) metal concentrations are high enough to be defined as RCRA hazardous; therefore, these sludges are presumed to be mixed TRU waste. Grouting and vitrification are currently two likely stabilization/solidification alternatives for mixed wastes. Grouting has been used to stabilize/solidify hazardous and low-level radioactive waste for decades. Vitrification has been developed as a high-level radioactive alternative for decades and has been under development recently as an alternative disposal technology for mixed waste. The objective of this project is to define an envelope, or operating window, for grout and glass formulations for ORNL tank sludges. Formulations will be defined for the average composition of each of the major tank farms (BVEST/MVST, GAAT, and OHF) and for an overall average composition of all tank farms. This objective is to be accomplished using surrogates of the tank sludges with hot testing of actual tank sludges to check the efficacy of the surrogates

  3. Volume reduction/solidification of liquid radioactive waste using bitumen at Ontario Hydro's Bruce Nuclear Generating Station 'A'

    International Nuclear Information System (INIS)

    Day, J.E.; Baker, R.L.

    1995-01-01

    Ontario Hydro at the Bruce Nuclear Generating Station 'A' has undertaken a program to render the station's liquid radioactive waste suitable for discharge to Lake Huron by removing sufficient radiological and chemical contaminants to satisfy regulatory requirements for emissions. The system will remove radionuclide and chemical contaminants from five different plant waste streams. The contaminants will be immobilized and stored at on-site radioactive waste storage facilities and the purified streams will be discharged. The discharge targets established by Ontario Hydro are set well below the limits established by the Ontario Ministry of Environment (MOE) and are based on the Best Available Technology Economically Achievable Approach (B.A.T.E.A.). ADTECHS Corporation has been selected by Ontario Hydro to provide volume reduction/solidification technology for one of the five waste streams. The system will dry and immobilize the contaminants from a liquid waste stream in emulsified asphalt using thin film evaporation technology

  4. On the stable eutectic solidification of iron–carbon–silicon alloys

    International Nuclear Information System (INIS)

    Stefanescu, Doru M.; Alonso, Gorka; Larrañaga, Pello; Suarez, Ramon

    2016-01-01

    Extensive effort was expanded to elucidate the growth and morphology of the stable eutectic grains during early solidification of continuous cooled Fe–C–Si alloys. To this purpose, quenching experiments at successive stages during solidification have been carried out on five cast irons with various magnesium and titanium levels designed to produce graphite morphologies ranging from lamellar to mixed compacted–spheroidal. The graphite shape factors were measured on the metallographic samples, and their evolution as a function of the chemical composition and the solid fraction was analyzed. Extensive scanning electron microscopy was carried on to evaluate the change in graphite shape during early solidification, to establish the fraction of solid at which the transition from spheroidal-to-compacted-to-lamellar graphite occurs, and to outline the early morphology of the eutectic grains. It was confirmed that solidification of Mg containing irons started with the development of spheroidal graphite even at Mg levels as low as 0.013 mass%. Then, as solidification proceeds, when some spheroids developed one or more tails (tadpole graphite), the spheroidal-to-compacted graphite transition occurs. The new findings were then integrated in previous knowledge to produce an understanding of the eutectic solidification of these materials. It was concluded that in hypoeutectic lamellar graphite iron austenite/graphite eutectic grains can nucleate at the austenite/liquid interface or in the bulk of the liquid, depending on the sulfur content and on the cooling rate. When graphite nucleation occurs on the primary austenite, several eutectic grains can nucleate and grow on the same dendrite. The primary austenite continues growing as eutectic austenite and therefore the two have the same crystallographic orientation. Thus, a final austenite grain may include several eutectic grains. In eutectic irons the eutectic grains nucleate and grow mostly in the liquid. The eutectic

  5. Effect and kinetic mechanism of ultrasonic vibration on solidification of 7050 aluminum alloy

    Directory of Open Access Journals (Sweden)

    Ripeng Jiang

    2014-07-01

    Full Text Available The work described in this paper dealt with the effect of ultrasonic vibration on the solidification of 7050 aluminum alloy. Two experiments were carried out through introducing ultrasound into the semi-continuous direct-chill (DC casting of aluminum alloy and into alloy solidifying in a crucible, respectively. Results show that ultrasonic vibration can refine grains in the whole cross-section of a billet in the first experiment and is able to increase the cooling rate within the temperature range from 625 °C to 590 °C in the other one. The mechanism of particle resonance caused by ultrasonic vibration was illustrated on the basis of theoretical analysis of the kinetics and energy conversion during the solidification. It is demonstrated that the kinetic energy of resonant particles are mainly from the latent heat energy of solidification, which can shorten the cooling time, inhibit the crystal growth and then lead to the grain refinement.

  6. Solidification of low-level waste - a dilemma for the small user

    International Nuclear Information System (INIS)

    Harris, S.; Gilmore, A.

    1980-01-01

    The requirement that radioactive waste for sea disposal must be solidified by the originator is discussed. Attempts to solidify small quantities of radioactive waste such as contaminated oils and labelled benzyopyrene with other solvents are described. Encapsulation media tested were concrete and interior and exterior grade Polyfilla (a plaster and cellulose based filler). Problems were presented by the difficulty of mixing the materials and by the maximum uptake of solvents while still allowing solidification. In all cases a soft crumbling material resulted. It is concluded that solidification processing on a small scale does not make economic or scientific sense and that if solidification is necessary it would be better carried out as a national operation by collecting liquids from users. (U.K.)

  7. Elimination of Hot Tears in Steel Castings by Means of Solidification Pattern Optimization

    DEFF Research Database (Denmark)

    Kotas, Petr; Tutum, Cem Celal; Thorborg, Jesper

    2012-01-01

    A methodology of how to exploit the Niyama criterion for the elimination of various defects such as centerline porosity, macrosegregation, and hot tearing in steel castings is presented. The tendency of forming centerline porosity is governed by the temperature distribution close to the end...... of the solidification interval, specifically by thermal gradients and cooling rates. The physics behind macrosegregation and hot tears indicate that these two defects also are dependent heavily on thermal gradients and pressure drop in the mushy zone. The objective of this work is to show that by optimizing...... the solidification pattern, i.e., establishing directional and progressive solidification with the help of the Niyama criterion, macrosegregation and hot tearing issues can be both minimized or eliminated entirely. An original casting layout was simulated using a transient three-dimensional (3-D) thermal fluid model...

  8. Cement solidification of spent ion exchange resins produced by the nuclear industry

    International Nuclear Information System (INIS)

    Jaouen, C.; Vigreux, B.

    1988-01-01

    Cement solidification technology has been applied to spent ion exchange resins for many years in countries throughout the world (at reactors, research centers and spent fuel reprocessing plants). Changing specifications for storage of radioactive waste have, however, confronted the operators of such facilities with a number of problems. Problems related both to the cement solidification process (water/cement/resin interactions and chemical interactions) and to its utilization (mixing, process control, variable feed composition, etc.) have often led waste producers to prefer other, polymer-based processes, which are very expensive and virtually incompatible with water. This paper discusses research on cement solidification of ion exchange resins since 1983 and the development of application technologies adapted to nuclear service conditions and stringent finished product quality requirements

  9. In situ observations of graphite formation during solidification of cast iron

    DEFF Research Database (Denmark)

    Bjerre, Mathias Karsten

    solidification and growth continues throughout solid state cooling and the eutectoid transformation. Years of research have greatly improved the understanding of the basic mechanisms that control graphite growth as well as the ability to control graphite morphology during industrial production of cast components......, the solidification of cast iron is studied with focus on formation and growth of spheroidal graphite. To this end, an experiment is conducted at the Diamond Light Source synchrotron facility in Harwell, UK: Employing an environmental cell devel-oped at the Manchester X-ray Imaging Facility at the University...... state growth presented in the present thesis. From the analysis it is clear that the presented data is of an unprecedented quality and that it represents a solid basis for validation of future models. Solidification simulations of a ductile cast iron component highlights the importance of the nucleation...

  10. Numerical simulation of convection and inclusion distribution during solidification in a heavy steel ingot

    International Nuclear Information System (INIS)

    Lin, Rui; Shen, Houfa

    2015-01-01

    Inclusions content in the steel ingot is an important index for homogeneity, and it becomes more serious for heavy steel ingots which are used for major equipment. However, knowledge about the formation of inclusion in steel ingot is limited, and modeling of inclusion distribution is still challenging, so it is of great significance to research the behavior of inclusion. In this paper, fluid flow during solidification is numerically simulated based on the equilibrium equations of mass, momentum and energy, and then inclusion distribution is modeled according to the Lagrangian Stokes trajectory method. The Results show that the inclusion distribution in the steel ingot is influenced by the flow pattern which is affected by the solidification pattern. Therefore, inclusion distribution could be controlled by the solidification front with the optimization of heat transfer condition such as the hot top design of steel ingot for the high quality steel production. (paper)

  11. External field effects on diffusion and solidification derived from the free-volume model

    Science.gov (United States)

    Miller, R. I.; Ruff, R. C.

    1975-01-01

    Expressions for the diffusion coefficient and the solidification rate from the free-volume model of liquids developed by Turnbull and Cohen have been used to estimate the effects which microgravity and magnetic fields will have on these quantities. The mathematical formalism describing changes of the diffusion coefficient and the solidification rate is the same for both the microgravity and magnetic field cases, but the difference between the magnitudes of the two effects is quite large. The change in the two parameters is found to be less than .0001% for the microgravity case and on the order of 0.1 to 1.1% for the magnetic field case for four representative materials. The diffusion coefficient and the solidification rate are found to increase under the influence of an applied magnetic field, and this is in agreement with experimental observations.

  12. Numerical investigation on natural convection and solidification of molten pool with OpenFOAM

    International Nuclear Information System (INIS)

    Wang Xi; Meng Zhaocan; Cheng Xu

    2015-01-01

    The in-vessel retention is adopted by the third generation nuclear power technology as an important severe accident mitigation strategy. The integrity of reactor pressure vessel depends on the heat flux distribution of molten pool. In present study, the solidification model in open source CFD software OpenFOAM was applied to simulate solidification and natural convection which was driven by internal heat source or temperature difference. The stratified molten pool heat transfer experiment carried out by Royal Institute of Technology was analyzed in the paper, and the solidified crust, temperature and heat flux distributions were obtained. The simulation results were compared with experimental data. It is shown that this numerical method can be used in the simulation of natural convection and solidification of molten pool, and it will probably be used in the analysis of molten corium behavior in reactor lower head. (authors)

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

    International Nuclear Information System (INIS)

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

    2008-01-01

    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.

  14. Study and modeling of heat transfer during the solidification of semi-crystalline polymers

    Energy Technology Data Exchange (ETDEWEB)

    Le Goff, R.; Poutot, G.; Delaunay, D. [Laboratoire de Thermocinetique de l' ecole polytechnique de l' universite de Nantes, UMR CNRS 6607, rue Christian Pauc, BP 50609 44306 Nantes cedex 3 (France); Fulchiron, R.; Koscher, E. [Laboratoire des Materiaux Polymeres et des Biomateriaux, IMP/UMR CNRS 5627, Universite Claude Bernard, Lyon 1, 69622 Villeurbanne Cedex (France)

    2005-12-01

    Semi-crystalline polymers are materials whose behavior during their cooling is difficult to model because of the strong coupling between the crystallization, heat transfer, pressure and shear. Thanks to two original apparatus we study solidification of such a polymer without shear. Firstly the comparison between experimental results and a numerical model will permit to validate crystallization kinetic for cooling rate reachable by DSC. The second experiment makes it possible to analyze solidification for high cooling rate, corresponding to some manufacturing processes. It appears that crystallization has an influence on the thermal contact resistance. (author)

  15. Literature review of stabilization/solidification of volatile organic compounds and the implications for Hanford grouts

    International Nuclear Information System (INIS)

    Spence, R.D.; Osborne, S.C.

    1993-09-01

    A literature review was conducted on the stabilization/solidification of volatile organic compounds (VOCs). Based on this literature, it is likely that the limestone-containing grout will not permanently immobilize VOCs and that no presently available additives can guarantee permanent immobilization. The Westinghouse hanford company grout may be fairly effective at retarding aqueous leaching of VOCs, and commercial additives can improve this performance. Significant VOC losses do occur during stabilization/solidification, and the high temperatures of the Westinghouse Hanford Company waste and grout should exacerbate this problem. In fact, these high temperatures raise doubts about the presence of VOCs in the double-shell tanks supernates

  16. Processing and solidification of Savannah River Plant high-level waste

    International Nuclear Information System (INIS)

    Kelley, J.A.

    1981-01-01

    The entire flowsheet for processing and solidification of Savannah River Plant (SRP) high-level wastes has been demonstrated. A new small-scale integrated pilot plant is operating with actual radioactive wastes, and large-scale equipment is being demonstrated with nonradioactive simulated wastes. Design of a full-scale waste solidification plant is in progress. Plant construction is expected to begin in 1983, and startup is anticipated in 1988. The plant will poduce about 500 cans of glass per year with each can containing about 1.5 tons of glass

  17. Solidification of hazardous and mixed radioactive waste at the Idaho National Engineering Laboratory

    International Nuclear Information System (INIS)

    Boehmer, A.M.; Larsen, M.M.

    1986-01-01

    EG and G Idaho has initiated a program to develop treatment options for the hazardous and mixed wastes generated at the Idaho National Engineering Laboratory (INEL). This program includes development of solidification methods for some of these wastes. Testing has shown that toxic wastes can be successfully solidified using cement, cement-silicate, or ENVIROSTONE binders to produce nontoxic stable waste forms for safe, long term disposal. This paper presents the results of the solidification development program conducted at the INEL by EG and G Idaho

  18. Solidification method for organic solution and processing method of aqueous solution

    International Nuclear Information System (INIS)

    Kamoshida, Mamoru; Fukazawa, Tetsuo; Yazawa, Noriko; Hasegawa, Toshihiko

    1998-01-01

    The relative dielectric constant of an organic solution containing polar ingredients is controlled to 13 or less to enable its solidification. The polarity of the organic solution can be evaluated quantitatively by using the relative dielectric constant. If the relative dielectric constant is high, it can be controlled by dilution using a non-polar organic solvent of low relative dielectric constant. With such procedures, solidification can be conducted by using an economical 12-hydroxy stearic acid, process of liquid wastes can be facilitated and the safety can be ensured. (T.M.)

  19. Solidification structure and dispersoids in rapidly solidified Ti-Al-Sn-Zr-Er-B alloys

    International Nuclear Information System (INIS)

    Rowe, R.G.; Broderick, T.F.; Koch, E.F.; Froes, F.H.

    1986-01-01

    The microstructure of melt extracted and melt spun titanium alloys containing erbium and boron revealed a duplex solidification structure of columnar grains leading to equiaxed and dendritic structures near the free surface of melt extracted and melt spun alloys. The solidification structure was revealed by apparent boride segregation to cellular, interdendritic and grain boundaries. Precipitation of needle or lath-like TiB particles occurred adjacent to Er/sub 2/O/sub 3/ dispesoid particles in as-rapidly solidified ribbon

  20. Phase transformation and liquid density redistribution during solidification of Ni-based superalloy Inconel 718

    Directory of Open Access Journals (Sweden)

    Wang Ling

    2012-08-01

    Full Text Available The influences of chemical segregation and phase transformation on liquid density variation during solidification of Ni-based supperalloy Inconel 718 were investigated using SEM and EDS. It was found that significant segregation in liquid prompts high Nb phase to precipitate directly from liquid, which results in the redistribution of alloy elements and liquid density in their vicinity. The term “inter-precipitate liquid density” is therefore proposed and this concept should be applied to determine the solidification behavior of superalloy Inconel 718.

  1. Solidification of hazardous and mixed radioactive waste at the Idaho National Engineering Laboratory

    International Nuclear Information System (INIS)

    Boehmer, A.M.; Larsen, M.M.

    1986-03-01

    EG and G Idaho has initiated a program to develop treatment options for the hazardous and mixed wastes generated at the Idaho National Engineering Laboratory (INEL). This program includes development of solidification methods for some of these wastes. Testing has shown that toxic wastes can be successfully solidified using cement, cement-silicate, or ENVIROSTONE binders to produce nontoxic stable waste forms for safe, long term disposal. This paper presents the results of the solidification development program conducted at the INEL by EG and G Idaho

  2. Hazardous and mixed waste solidification development conducted at the Idaho National Engineering Laboratory

    International Nuclear Information System (INIS)

    Boehmer, A.M.; Larsen, M.M.

    1986-04-01

    EG and G Idaho, Inc., has initiated a program to develop safe, efficient, cost-effective solidification treatment methods for the disposal of some of the hazardous and mixed wastes generated at the Idaho National Engineering Laboratory (INEL). Testing has shown that Extraction Procedure (EP) toxic wastes can be successfully solidified using cement, cement-silicate, or ENVIROSTONE binders to produce nontoxic stable waste forms for safe, long-term disposal as general or low-level waste, depending upon the radioactivity. The results of the solidification development program are presented in this report

  3. Physicochemical characterization of solidification agents used and products formed with radioactive wastes at LWR nuclear power plants

    International Nuclear Information System (INIS)

    Kibbey, A.H.; Godbee, H.W.

    1978-01-01

    Solidification of evaporator concentrates, filter sludges, and spent ion exchange resins used in LWR streams is discussed. The introduction of solidification agents to immobilize these sludges and resins can increase the volume of these wastes by a factor of slightly over 1 to greater than 2, depending on the binder chosen. The agents and methods used or proposed for use in solidification of LWR power plant wastes are generally suitable for treating most of the other-than-high-level wastes generated throughout the entire fuel cycle. Among the solidification agents most commonly used or suggested for use are the inorganic cements and organic plastics, which are listed and compared. A summary of considerations important in choosing a solidification agent is presented tabularly

  4. In situ solidification/stabilization pilot study for the treatment of coal tar contaminated soils and river sediments

    International Nuclear Information System (INIS)

    Lawson, M.A.; Venn, J.G.; Pugh, L.B.; Vallis, T.

    1996-01-01

    Coal tar contamination was encountered at a former coal gasification site in soils below the groundwater table, and in the sediments of the adjacent river. Ex situ remediation techniques at this site would be costly because of the need to dewater the impacted media. In situ solidification/stabilization was tested to evaluate its effectiveness. Treatability testing was performed to evaluate a Portland cement/fly ash binder system with added stabilizing agents. Results were sufficiently promising to warrant pilot testing. Grout containing Portland cement, fly ash, organically modified clay, and granular activated carbon was pilot tested at the site. Test specimens were collected and tested to evaluate durability, compressive strength, and permeability. The samples were extracted by several methods and analyzed to measure the leachable concentrations of organic compounds and metals. Results indicated acceptable physical characteristics. Leachable concentrations of most polynuclear aromatic compounds were decreased

  5. Solidification of metallic aluminum on magnesium phosphate cements

    International Nuclear Information System (INIS)

    Lahalle, Hugo

    2016-01-01

    This work deals with the stabilization/solidification of radioactive waste using cement. More particularly, it aims at assessing the chemical compatibility between metallic aluminum and mortars based on magnesium phosphate cement. The physical and chemical processes leading to setting and hardening of the cement are first investigated. X-ray diffraction (XRD), thermogravimetry (TGA) and nuclear magnetic resonance spectroscopy ("3"1P and "1"1B MAS-NMR) are first used to characterize the solid phases formed during hydration, while inductively coupled plasma atomic emission spectroscopy analysis (ICP-AES), electrical conductometry and pH measurements provide information on the pore solution composition. Then, the corrosion of metallic aluminum in magnesium phosphate mortars is studied by monitoring the equilibrium potential and by electrochemical impedance spectroscopy (EIS). Magnesium phosphate cement is prepared from a mix of magnesium oxide (MgO) and potassium dihydrogen orthophosphate (KH_2PO_4). In the presence of water, hydration occurs according to a dissolution - precipitation process. The main hydrate is K-struvite (MgKPO_4.6H_2O). Its precipitation is preceded by that of two transient phases: phosphorrosslerite (MgHPO_4.7H_2O) and Mg_2KH(PO_4)_2.15H_2O. Boric acid retards cement hydration by delaying the formation of cement hydrates. Two processes may be involved in this retardation: the initial precipitation of amorphous or poorly crystallized minerals containing boron and phosphorus atoms, and/or the stabilization of cations (Mg"2"+, K"+) in solution. As compared with a Portland cement-based matrix, corrosion of aluminum is strongly limited in magnesium phosphate mortar. The pore solution pH is close to neutrality and falls within the passivation domain of aluminum. Corrosion depends on several parameters: it is promoted by a water-to-cement ratio (w/c) significantly higher than the chemical water demand of cement (w/c = 0.51), and by the addition of boric

  6. Al-Si-Re Alloys Cast by the Rapid Solidification Process / Stopy Al-Si-Re Odlewane Metodą Rapid Solidification

    Directory of Open Access Journals (Sweden)

    Szymanek M.

    2015-12-01

    Full Text Available The aim of the studies described in this article was to present the effect of rare earth elements on aluminium alloys produced by an unconventional casting technique. The article gives characteristics of the thin strip of Al-Si-RE alloy produced by Rapid Solidification (RS. The effect of rare earth elements on structure refinement, i.e. on the size of near-eutectic crystallites in an aluminium-silicon alloy, was discussed. To determine the size of crystallites, the Scherrer X-ray diffraction method was used. The results presented capture relationships showing the effect of variable casting parameters and chemical composition on microstructure of the examined alloys. Rapid Solidification applied to Al-Si alloys with the addition of mischmetal (Ce, La, Ne, Pr refines their structure.

  7. The role of the Staphylococcal VraTSR regulatory system on vancomycin resistance and vanA operon expression in vancomycin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Qureshi, Nadia K; Yin, Shaohui; Boyle-Vavra, Susan

    2014-01-01

    Vancomycin is often the preferred treatment for invasive methicillin-resistant Staphylococcus aureus (MRSA) infection. With the increase in incidence of MRSA infections, the use of vancomycin has increased and, as feared, isolates of vancomycin-resistant Staphylococcus aureus (VRSA) have emerged. VRSA isolates have acquired the entercoccal vanA operon contained on transposon (Tn) 1546 residing on a conjugal plasmid. VraTSR is a vancomycin and β-lactam-inducible three-component regulatory system encoded on the S. aureus chromosome that modulates the cell-wall stress response to cell-wall acting antibiotics. Mutation in vraTSR has shown to increase susceptibility to β-lactams and vancomycin in clinical VISA strains and in recombinant strain COLVA-200 which expresses a plasmid borne vanA operon. To date, the role of VraTSR in vanA operon expression in VRSA has not been demonstrated. In this study, the vraTSR operon was deleted from the first clinical VRSA strain (VRS1) by transduction with phage harvested from a USA300 vraTSR operon deletion strain. The absence of the vraTSR operon and presence of the vanA operon were confirmed in the transductant (VRS1Δvra) by PCR. Broth MIC determinations, demonstrated that the vancomycin MIC of VRS1Δvra (64 µg/ml) decreased by 16-fold compared with VRS1 (1024 µg/ml). The effect of the vraTSR operon deletion on expression of the van gene cluster (vanA, vanX and vanR) was examined by quantitative RT-PCR using relative quantification. A 2-5-fold decreased expression of the vanA operon genes occured in strain VRS1Δvra at stationary growth phase compared with the parent strain, VRS1. Both vancomycin resistance and vancomycin-induced expression of vanA and vanR were restored by complementation with a plasmid harboring the vraTSR operon. These findings demonstrate that expression in S. aureus of the horizontally acquired enterococcal vanA gene cluster is enhanced by the staphylococcal three-component cell wall stress regulatory

  8. Simulation of Microstructure during Laser Rapid Forming Solidification Based on Cellular Automaton

    Directory of Open Access Journals (Sweden)

    Zhi-jian Wang

    2014-01-01

    Full Text Available The grain microstructure of molten pool during the solidification of TC4 titanium alloy in the single point laser cladding was investigated based on the CAFE model which is the cellular automaton (CA coupled with the finite element (FE method. The correct temperature field is the prerequisite for simulating the grain microstructure during the solidification of the molten pool. The model solves the energy equation by the FE method to simulate the temperature distribution in the molten pool of the single point laser cladding. Based on the temperature field, the solidification microstructure of the molten pool is also simulated with the CAFE method. The results show that the maximum temperature in the molten pool increases with the laser power and the scanning rate. The laser power has a larger influence on the temperature distribution of the molten pool than the scanning rate. During the solidification of the molten pool, the heat at the bottom of the molten pool transfers faster than that at the top of the molten pool. The grains rapidly grow into the molten pool, and then the columnar crystals are formed. This study has a very important significance for improving the quality of the structure parts manufactured through the laser cladding forming.

  9. A coupled model on fluid flow, heat transfer and solidification in continuous casting mold

    Directory of Open Access Journals (Sweden)

    Xu-bin Zhang

    2017-11-01

    Full Text Available Fluid flow, heat transfer and solidification of steel in the mold are so complex but crucial, determining the surface quality of the continuous casting slab. In the current study, a 2D numerical model was established by Fluent software to simulate the fluid flow, heat transfer and solidification of the steel in the mold. The VOF model and k-ε model were applied to simulate the flow field of the three phases (steel, slag and air, and solidification model was used to simulate the solidification process. The phenomena at the meniscus were also explored through interfacial tension between the liquid steel and slag as well as the mold oscillation. The model included a 20 mm thick mold to clarify the heat transfer and the temperature distribution of the mold. The simulation results show that the liquid steel flows as upper backflow and lower backflow in the mold, and that a small circulation forms at the meniscus. The liquid slag flows away from the corner at the meniscus or infiltrates into the gap between the mold and the shell with the mold oscillating at the negative strip stage or at the positive strip stage. The simulated pitch and the depth of oscillation marks approximate to the theoretical pitch and measured depth on the slab.

  10. Oxygen and carbon transfer during solidification of semiconductor grade silicon in different processes

    Science.gov (United States)

    Ribeyron, P. J.; Durand, F.

    2000-03-01

    A model is established for comparing the solute distribution resulting from four solidification processes currently applied to semiconductor grade silicon: Czochralski pulling (CZ), floating zone (FZ), 1D solidification and electromagnetic continuous pulling (EMCP). This model takes into account solid-liquid interface exchange, evaporation to or contamination by the gas phase, container dissolution, during steady-state solidification, and in the preliminary preparation of the melt. For simplicity, the transfers are treated in the crude approximation of perfectly mixed liquid and boundary layers. As a consequence, only the axial ( z) distribution can be represented. Published data on oxygen and carbon transfer give a set of acceptable values for the thickness of the boundary layers. In the FZ and EMCP processes, oxygen evaporation can change the asymptotic behaviour of the reference Pfann law. In CZ and in 1D-solidification, a large variety of solute profile curves can be obtained, because they are very sensitive to the balance between crucible dissolution and evaporation. The CZ process clearly brings supplementary degrees of freedom via the geometry of the crucible, important for the dissolution phenomena, and via the rotation rate of the crystal and of the crucible, important for acting on transfer kinetics.

  11. Numerical Simulation on the Origin of Solidification Cracking in Laser Welded Thick-Walled Structures

    Directory of Open Access Journals (Sweden)

    Nasim Bakir

    2018-06-01

    Full Text Available One of the main factors affecting the use of lasers in the industry for welding thick structures is the process accompanying solidification cracks. These cracks mostly occurring along the welding direction in the welding center, and strongly affect the safety of the welded components. In the present study, to obtain a better understanding of the relation between the weld pool geometry, the stress distribution and the solidification cracking, a three-dimensional computational fluid dynamic (CFD model was combined with a thermo-mechanical model. The CFD model was employed to analyze the flow of the molten metal in the weld pool during the laser beam welding process. The weld pool geometry estimated from the CFD model was used as a heat source in the thermal model to calculate the temperature field and the stress development and distributions. The CFD results showed a bulging region in the middle depth of the weld and two narrowing areas separating the bulging region from the top and bottom surface. The thermo-mechanical simulations showed a concentration of tension stresses, transversally and vertically, directly after the solidification during cooling in the region of the solidification cracking.

  12. Ductile failure in upsetting of a rapid-solidification-processed aluminium alloy

    NARCIS (Netherlands)

    Habraken, F.A.C.M.; Dautzenberg, J.H.

    1993-01-01

    Cold upset-tests have been performed on a Rapid Solidification Processed (RSP) aluminium-alloy, produced by the ‘melt-spun ribbons’-process out of 70% car-scrap and 30% primary scrap. The ribbons are hot extruded, resulting in 29 mm diameter bar. Its properties regarding plastic flow and fracture

  13. Comparison of solidification temperatures of different rare earth sesquioxides; effect of atmosphere

    International Nuclear Information System (INIS)

    Coutures, J.-P.; Verges, R.; Foex, M.

    1975-01-01

    The measurement of the solidification point of the rare earth sesquioxides shows anomalies for La 2 O 3 , Gd 2 O 3 , Lu 2 O 3 and allows to find the well known ceric group and yttric group. The effects of the atmosphere on the refractory character are generally low. An interpretation in order to explain the observed changes, is proposed [fr

  14. Solidification microstructures in a short fiber reinforced alloy composite containing different fiber fractions

    Directory of Open Access Journals (Sweden)

    JING Qing-xiu

    2006-02-01

    Full Text Available The solidification microstructures and micro-segregation of a fiber reinforced Al-9 Cu alloy, containing different volume fractions of Al2O3 short fibers about 6 μm diameter and made by squeeze casting have been studied. The results indicate that as volume fraction of fiber Vf increases, the size of final grains becomes finer in the matrix. If λf /λ>1, the fibers have almost no influence on the solidification behavior of the matrix, so the final grains grow coarse, where λf is the average inter-fiber spacing and λ is the secondary dendrite arm spacing. While if λf /λ<1, the growth of crystals in the matrix is affected significantly by the fibers and the grain size is reduced to the value of the inter-fiber spacing. The fibers influence the average length of a solidification volume element L of the matrix and also influence the solidification time θt of the matrix. As a result of fibers influencing L and θt, the micro-segregation in the matrix is improved when the composite contains more fibers, although the level of the improvement is slight. The Clyne-Kurz model can be used to semi-quantitatively analyze the relationship between Vf and the volume fraction fe of the micro-segregation eutectic structure.

  15. Numerical modeling of coupled heat transfer and phase transformation for solidification of the gray cast iron

    DEFF Research Database (Denmark)

    Jabbari, Masoud; Hosseinzadeh, Azin

    2013-01-01

    In the present study the numerical model in 2D is used to study the solidification bahavior of the gray cast iron. The conventional heat transfer is coupled with the proposed micro-model to predict the amount of different phases, i.e. total austenite (c) phase, graphite (G) and cementite (C...

  16. Solidification of low and medium level wastes in bitumen at Barsebaeck nuclear power station

    International Nuclear Information System (INIS)

    Harfors, C.

    1979-01-01

    Operating experience is presented from 4 years of bitumen solidification of wastes coming from two boiling water reactors. Methods used to sample, analyse and document the wastes are described. Transport and storage methods without remote handling have been adopted. The risk of fire is discussed and a description is given of the measures taken for fire protection. (author)

  17. Validation of a 3D multi-physics model for unidirectional silicon solidification

    NARCIS (Netherlands)

    Simons, P.; Lankhorst, A.M.; Habraken, A.; Faber, A.J.; Tiuleanu, D.; Pingel, R.

    2012-01-01

    A model for transient movements of solidification fronts has been added to X-stream, an existing multi-physics simulation program for high temperature processes with flow and chemical reactions. The implementation uses an enthalpy formulation and works on fixed grids. First we show the results of a

  18. Influence of solidification parameters on the cellular sub-structure of tin and some tin alloys

    International Nuclear Information System (INIS)

    Milosavljevic, Dj.

    1965-01-01

    This paper describes an attempt to obtain qualitative data on sub-structure of samples solidified in contact with the cooler. The objective of experiments was to study micro segregation phenomena by investigating the substructure in the solidified sample obtained under experimental conditions which are similar to real solidification conditions

  19. Joining of superalloy Inconel 600 by diffusion induced isothermal solidification of a liquated insert metal

    International Nuclear Information System (INIS)

    Egbewande, A.T.; Chukwukaeme, C.; Ojo, O.A.

    2008-01-01

    The effect of process variables on the microstructure of transient liquid phase bonded IN 600 using a commercial filler alloy was studied. Microstructural examination of bonded specimens showed that isothermal solidification of the liquated insert occurred during holding at the joining temperatures. In cases where the holding time was insufficient for complete isothermal solidification, the residual liquid transformed on cooling into a centerline eutectic product. The width of the eutectic decreased with increased holding time and an increase in initial gap width resulted in thicker eutectic width in specimens bonded at the same temperature and for equivalent holding times. In addition to the centerline eutectic microconstituent, precipitation of boron-rich particles was observed within the base metal region adjacent to the substrate-joint interface. Formation of these particles appeared to have influenced the rate of solidification of the liquated interlayer during bonding. In contrast to the conventional expectation of an increase in the rate of isothermal solidification with an increase in temperature, a decrease in the rate was observed with an increase in temperatures above 1160 deg. C. This could be related to a decrease in solubility of boron in nickel above the Ni-B eutectic temperature

  20. Numerical simulation of solute trapping phenomena using phase-field solidification model for dilute binary alloys

    Directory of Open Access Journals (Sweden)

    Henrique Silva Furtado

    2009-09-01

    Full Text Available Numerical simulation of solute trapping during solidification, using two phase-field model for dilute binary alloys developed by Kim et al. [Phys. Rev. E, 60, 7186 (1999] and Ramirez et al. [Phys. Rev. E, 69, 05167 (2004] is presented here. The simulations on dilute Cu-Ni alloy are in good agreement with one dimensional analytic solution of sharp interface model. Simulation conducted under small solidification velocity using solid-liquid interface thickness (2λ of 8 nanometers reproduced the solute (Cu equilibrium partition coefficient. The spurious numerical solute trapping in solid phase, due to the interface thickness was negligible. A parameter used in analytical solute trapping model was determined by isothermal phase-field simulation of Ni-Cu alloy. Its application to Si-As and Si-Bi alloys reproduced results that agree reasonably well with experimental data. A comparison between the three models of solute trapping (Aziz, Sobolev and Galenko [Phys. Rev. E, 76, 031606 (2007] was performed. It resulted in large differences in predicting the solidification velocity for partition-less solidification, indicating the necessity for new and more acute experimental data.

  1. Effect of alloying elements on solidification of primary austenite in Ni-Mn-Cu cast iron

    Directory of Open Access Journals (Sweden)

    A. Janus

    2011-04-01

    Full Text Available Within the research, determined were direction and intensity of alloying elements influence on solidification way (directional orvolumetric of primary austenite dendrites in hypoeutectic austenitic cast iron Ni-Mn-Cu. 50 cast shafts dia. 20 mm were analysed.Chemical composition of the alloy was as follows: 1.7 to 3.3 % C, 1.4 to 3.1 % Si, 2.8 to 9.9 % Ni, 0.4 to 7.7 % Mn, 0 to 4.6 % Cu, 0.14 to0.16 % P and 0.03 to 0.04 % S. The discriminant analysis revealed that carbon influences solidification of primary austenite dendrites most intensively. It clearly increases the tendency to volumetric solidification. Influence of the other elements is much weaker. This means that the solidification way of primary austenite dendrites in hypoeutectic austenitic cast iron Ni-Mn-Cu does not differ from that in an unalloyed cast iron.

  2. Process control of Low and Intermediate-level radioactive wastes solidification

    International Nuclear Information System (INIS)

    1993-01-01

    Safety guidelines issued by the Spanish Council of Nuclear Safety (CSN) with basic criteria which must be adopted for the control of the Process for wastes solidification, establishing, in addition, a series of protocols and basic contents to assist the elaboration of Process Control Programs

  3. Temperature measurement during solidification of thin wall ductile cast iron. Part 2: Numerical simulations

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2008-01-01

    Temperature measurements in castings are carried out with thermocouples (TC’s), which are inserted in the melt. The TC influence solidification of the casting, especially in thin wall castings where the heat content of the melt is small compared to the cooling power of the TC. A numerical analysi...

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

    Science.gov (United States)

    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.

  5. The Refining Mechanism of Super Gravity on the Solidification Structure of Al-Cu Alloys

    Directory of Open Access Journals (Sweden)

    Yuhou Yang

    2016-12-01

    Full Text Available There is far less study of the refining effect of super gravity fields on solidification structures of metals than of the effects of electrical currents, magnetic and ultrasonic fields. Moreover, the refining mechanisms of super gravity are far from clear. This study applied a super gravity field to Al-Cu alloys to investigate its effect on refining their structures and the mechanism of interaction. The experimental results showed that the solidification structure of Al-Cu alloys can be greatly refined by a super gravity field. The major refining effect was mainly achieved when super gravity was applied at the initial solidification stage; only slight refinement could be obtained towards the end of solidification. No refinement was obtained by the super gravity treatment on pure liquid or solid stages. The effectiveness of super gravity results from its promoting the multiplication of crystal nuclei, which we call “Heavy Crystal Rain”, thereby greatly strengthening the migration of crystal nuclei within the alloy. Increasing the solute Cu content can increase nucleation density and restrict the growth of crystals, which further increases the refining effect of super gravity. Within this paper, we also discuss the motile behavior of crystals in a field of super gravity.

  6. Defense waste solidification studies. Volume 2. Drawing supplement. Savannah River Plant, Project S-1780

    International Nuclear Information System (INIS)

    1977-01-01

    Volume 2 contains the drawings prepared and used in scoping and estimating the Glass-Form Waste Solidification facilities and the alternative studies cited in the report, the Off-Site Shipping Case, the Decontaminated Salt Storage Case, and a revised Reference Plant (Concrete-Form Waste) Case

  7. Solidification of ash from incineration of low-level radioactive waste

    International Nuclear Information System (INIS)

    Roberson, W.A.; Albenesius, E.L.; Becker, G.W.

    1983-01-01

    The safe disposal of both high-level and low-level radioactive waste is a problem of increasing national attention. A full-scale incineration and solidification process to dispose of suspect-level and low-level beta-gamma contaminated combustible waste is being demonstrated at the Savannah River Plant (SRP) and Savannah River Laboratory (SRL). The stabilized wasteform generated by the process will meet or exceed all future anticipated requirements for improved disposal of low-level waste. The incineration process has been evaluated at SRL using nonradioactive wastes, and is presently being started up in SRP to process suspect-level radioactive wastes. A cement solidification process for incineration products is currently being evaluated by SRL, and will be included with the incineration process in SRP during the winter of 1984. The GEM alumnus author conducted research in a related disposal solidification program during the GEM-sponsored summer internship, and upon completion of the Masters program, received full-time responsibility for developing the incineration products solidification process

  8. Micromechanical modeling of stress-induced strain in polycrystalline Ni–Mn–Ga by directional solidification

    International Nuclear Information System (INIS)

    Zhu, Yuping; Shi, Tao; Teng, Yao

    2015-01-01

    Highlights: • A micromechanical model of directional solidification Ni–Mn–Ga is developed. • The stress–strain curves in different directions are tested. • The martensite Young’s moduli in different directions are predicted. • The macro reorientation strains in different directions are investigated. - Abstract: Polycrystalline ferromagnetic shape memory alloy Ni–Mn–Ga produced by directional solidification possess unique properties. Its compressive stress–strain behaviors in loading–unloading cycle show nonlinear and anisotropic. Based on the self-consistent theory and thermodynamics principle, a micromechanical constitutive model of polycrystalline Ni–Mn–Ga by directional solidification is developed considering the generating mechanism of the macroscopic strain and anisotropy. Then, the stress induced strains at different angles to solidification direction are calculated, and the results agree well with the experimental data. The predictive curves of martensite Young’s modulus and macro reorientation strain in different directions are investigated. It may provide theoretical guidance for the design and use of ferromagnetic shape memory alloy

  9. Elimination of Hot Tears in Steel Castings by Means of Solidification Pattern Optimization

    Science.gov (United States)

    Kotas, Petr; Tutum, Cem Celal; Thorborg, Jesper; Hattel, Jesper Henri

    2012-06-01

    A methodology of how to exploit the Niyama criterion for the elimination of various defects such as centerline porosity, macrosegregation, and hot tearing in steel castings is presented. The tendency of forming centerline porosity is governed by the temperature distribution close to the end of the solidification interval, specifically by thermal gradients and cooling rates. The physics behind macrosegregation and hot tears indicate that these two defects also are dependent heavily on thermal gradients and pressure drop in the mushy zone. The objective of this work is to show that by optimizing the solidification pattern, i.e., establishing directional and progressive solidification with the help of the Niyama criterion, macrosegregation and hot tearing issues can be both minimized or eliminated entirely. An original casting layout was simulated using a transient three-dimensional (3-D) thermal fluid model incorporated in a commercial simulation software package to determine potential flaws and inadequacies. Based on the initial casting process assessment, multiobjective optimization of the solidification pattern of the considered steel part followed. That is, the multiobjective optimization problem of choosing the proper riser and chill designs has been investigated using genetic algorithms while simultaneously considering their impact on centerline porosity, the macrosegregation pattern, and primarily on hot tear formation.

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

    Science.gov (United States)

    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.

  11. Application of sulfur concrete for solidification of radioactive wastes and building of repositories

    International Nuclear Information System (INIS)

    Cholerzynski, A.; Tomczak, W.; Switalski, J.

    2000-01-01

    The application of sulfur concrete as solidification material for radioactive wastes and as building material used in repositories have been presented. Their high shear strength, low level of leaching, and high radiation resistance decide of positive recommendation of such material for wide use in radioactive waste treatment processes and repositories building

  12. Solidification, growth mechanisms, and associated properties of Al-Si and magnesium lightweight casting alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hosch, Timothy [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Continually rising energy prices have inspired increased interest in weight reduction in the automotive and aerospace industries, opening the door for the widespread use and development of lightweight structural materials. Chief among these materials are cast Al-Si and magnesium-based alloys. Utilization of Al-Si alloys depends on obtaining a modified fibrous microstructure in lieu of the intrinsic flake structure, a process which is incompletely understood. The local solidification conditions, mechanisms, and tensile properties associated with the flake to fiber growth mode transition in Al-Si eutectic alloys are investigated here using bridgman type gradient-zone directional solidification. Resulting microstructures are examined through quantitative image analysis of two-dimensional sections and observation of deep-etched sections showing three-dimensional microstructural features. The transition was found to occur in two stages: an initial stage dominated by in-plane plate breakup and rod formation within the plane of the plate, and a second stage where the onset of out-of-plane silicon rod growth leads to the formation of an irregular fibrous structure. Several microstructural parameters were investigated in an attempt to quantify this transition, and it was found that the particle aspect ratio is effective in objectively identifying the onset and completion velocity of the flake to fiber transition. The appearance of intricate out-of-plane silicon instability formations was investigated by adapting a perturbed-interface stability analysis to the Al-Si system. Measurements of silicon equilibrium shape particles provided an estimate of the anisotropy of the solid Si/liquid Al-Si system and incorporation of this silicon anisotropy into the model was found to improve prediction of the instability length scale. Magnesium alloys share many of the benefits of Al-Si alloys, with the added benefit of a 1/3 lower density and increased machinability. Magnesium castings

  13. Effect of Manganese on Microstructures and Solidification Modes of Cast Fe-Mn-Si-Cr-Ni Shape Memory Alloys

    Science.gov (United States)

    Peng, Huabei; Wen, Yuhua; Du, Yangyang; Yu, Qinxu; Yang, Qin

    2013-10-01

    We investigated microstructures and solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys to clarify whether Mn was an austenite former during solidification. Furthermore, we examined whether the Creq/Nieq equations (Delong, Hull, Hammer and WRC-1992 equations) and Thermo-Calc software® together with database TCFE6 were valid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys. The results have shown that the solidification modes of Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni alloys changed from the F mode to the FA mode with increasing the Mn concentration. Mn is an austenite former during the solidification for the cast Fe-Mn-Si-Cr-Ni shape memory alloys. The Delong, Hull, Hammer, and WRC-1992 equations as well as Thermo-Calc software® together with database TCFE6 are invalid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni SMAs. To predict the solidification modes of cast Fe-Mn-Si-Cr-Ni alloys, a new Creq/Nieq equation should be developed or the thermodynamic database of Thermo-Calc software® should be corrected.

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

    International Nuclear Information System (INIS)

    Rajani, H R Zareie; Phillion, A B

    2015-01-01

    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. (paper)

  15. Thermodynamic pathways to melting, ablation, and solidification in absorbing solids under pulsed laser irradiation

    International Nuclear Information System (INIS)

    Lorazo, Patrick; Lewis, Laurent J.; Meunier, Michel

    2006-01-01

    The thermodynamic pathways involved in laser irradiation of absorbing solids are investigated in silicon for pulse durations of 500 fs and 100 ps. This is achieved by accounting for carrier and atom dynamics within a combined Monte Carlo and molecular-dynamics scheme and simultaneously tracking the time evolution of the irradiated material in ρ-T-P space. Our simulations reveal thermal changes in long-range order and state of aggregation driven, in most cases, by nonequilibrium states of rapidly heated or promptly cooled matter. Under femtosecond irradiation near the ablation threshold, the system is originally pulled to a near-critical state following rapid ( -12 s) disordering of the mechanically unstable crystal and isochoric heating of the resulting metallic liquid. The latter is then adiabatically cooled to the liquid-vapor regime where phase explosion of the subcritical, superheated melt is initiated by a direct conversion of translational, mechanical energy into surface energy on a ∼10 -12 -10 -11 s time scale. At higher fluences, matter removal involves, instead, the fragmentation of an initially homogeneous fluid subjected to large strain rates upon rapid, supercritical expansion in vacuum. Under picosecond irradiation, homogeneous and, at later times, heterogeneous melting of the superheated solid are followed by nonisochoric heating of the molten metal. In this case, the subcritical liquid material is subsequently cooled onto the binodal by thermal conduction and explosive boiling does not take place; as a result, ablation is associated with a ''trivial'' fragmentation process, i.e., the relatively slow expansion and dissociation into liquid droplets of supercritical matter near thermodynamic equilibrium. This implies a liquid-vapor equilibration time of ∼10 -11 -10 -10 s and heating along the binodal under nanosecond irradiation. Solidification of the nonablated, supercooled molten material is eventually observed on a ∼10 -11 -10 -9 s time scale

  16. The influence of Ta on the solidification microstructure and segregation behavior of γ(Ni)/γ′(Ni3Al)–δ(Ni3Nb) eutectic Ni-base superalloys

    International Nuclear Information System (INIS)

    Xie, M.; Helmink, R.; Tin, S.

    2013-01-01

    Highlights: ► Ta and Nb have a nominally identical influence on equilibrium δ volume fraction. ► Ta and Nb impact the sequence and segregation differently during solidification. ► Microstructure varies with both overall Ta + Nb level and Ta/Nb ratio. ► Pandat (PanNi7) is unable to predict trends quantitatively in this system. -- Abstract: Polycrystalline γ/γ′–δ eutectic Ni-base superalloys based on the Ni–Al–Nb alloy system were recently demonstrated to possess excellent high temperature strength and creep resistance. Investigations aimed to establish the fundamental relationships between alloy chemistry, solidification behavior and cast microstructure in these novel Ni–Al–Nb γ/γ′–δ alloy systems are currently underway. This particular study is focused on understanding the influence of Ta additions on the solidification sequence, phase volume fraction, distribution coefficient and solid state partitioning parameter of this eutectic alloy system by systematically investigating a series of experimental alloys with nominally constant overall levels of Ta + Nb content but varying Ta/Nb ratios. Although many of the tendencies observed in these multi-component γ/γ′–δ eutectic alloys are in agreement with trends observed in lower order model alloy systems, Ta additions were found to significantly modify solidification characteristics of the alloys. The experimental observations were also used to critically assess the predictive capability of thermodynamic database calculations. Despite the qualitative agreement observed between the experimental results and predictions for relatively simple quaternary and quinary model alloys, comparison of the results for higher order, multi-component γ/γ′–δ eutectic alloys reveals notable differences

  17. Solidification of radioactive liquid wastes, Treatment options for spent resins and concentrates - 16405

    International Nuclear Information System (INIS)

    Roth, Andreas

    2009-01-01

    Ion exchange is one of the most common and effective treatment methods for liquid radioactive waste. However, spent ion exchange resins are considered to be problematic waste that in many cases require special approaches and pre-conditioning during its immobilization to meet the acceptance criteria for disposal. Because of the function that they fulfill, spent ion exchange resins often contain high concentrations of radioactivity and pose special handling and treatment problems. Another very common method of liquid radioactive waste treatment and water cleaning is the evaporation or diaphragm filtration. Both treatment options offer a high volume reduction of the total volume of liquids treated but generate concentrates which contain high concentrations of radioactivity. Both mentioned waste streams, spent resins as well as concentrates, resulting from first step liquid radioactive waste treatment systems have to be conditioned in a suitable manner to achieve stable waste products for final disposal. Spent resin and concentrate treatment often appear as a specific task in decommissioning projects, because in the past those waste streams typically had been stored in tanks for the lifetime of the plant and needs to be retrieved, conditioned and packed prior to dismantling activities. Additionally a large amount of contaminated liquids will be generated by utilizing decontamination processes and needs to be processed further on. Such treatment options need to achieve waste products acceptable for final disposal, because due to the closure of the site no interim storage can be envisaged. The most common method of treatment of such waste streams is the solidification in a solid matrix with additional inactive material like cement, polymer etc. In the past good results have been achieved and the high concentration of radioactivity can be reduced by adding the inactive material. On the other hand, under the environment of limited space for interim storage and the absence

  18. Competencia destructiva hacia adentro vrs competencia constructiva hacia afuera

    Directory of Open Access Journals (Sweden)

    Mario Davide Parrilli

    1998-12-01

    Full Text Available En este artículo, se señalan el potencial de la rama madera/muebles como generadora de valor agregado, ingresos, empleo, etc., y el débil aprovechamiento de los recursos forestales y humanos. Buscamos una solución radical para romper el enraizado conformismo ante el subdesarrollo de nuestra pequeña industria. Se identifican dos problemas fundamentales: la organización todavía artesanal de la pequeña industria, que sólo produce pequeñas cantidades de baja calidad/precio para el mercado local; y el mercado interno, aún muy cerrado. La solución parece ser la conversión de la actual competencia hacia adentro, en la cual los productores se por para el mismo pequeño mercado local, en una competencia hacia fuera, en la cual los empresarios se unen y buscan nuevos mercados en el exterior, donde hay mayores precios y una demanda potencial.

  19. Cadarache LOR (liquides organiques radioactifs) treatment by a solidification process using NOCHAR polymers

    International Nuclear Information System (INIS)

    Vaudey, Claire-Emilie; Renou, Sebastien; Kelley, Dennis; Cochaud, Chantal; Serrano, Roger

    2013-01-01

    In France, two options can be considered to handle the Very Low Level Waste (VLLW) and the Low Level Waste (LLW). The first one is the incineration at CENTRACO facility and the second one is the disposal at ANDRA sites. The waste acceptance in these two channels is dependent upon the adequacy between the waste characteristics (physical chemistry and radiological) and the channel specifications. If the waste characteristics and the channel specifications (presence of significant quantities of halogens, complexing agents, organic components... or/and high activity limits) are incompatible, an alternative solution have to be identify. It consists of a waste pre-treatment process. For Cadarache LOR (Liquides Organiques Radioactifs) waste streams, two radioactive scintillation cocktails have to be treated. They are composed of a mix of organic liquids and water: for the first one, 19 % of organic compounds (xylene, mesitylene, diphenyloxazole, TBP...) and 86.9 % of water, and for the second one, 23 % of organic compounds (TBP...) and 77 % of water. They contain halogens (chlorine and fluorine), complexants agents (nitrate, sulphate, oxalate and formate) and have got αβγ spectra with mass activities equal to some 100 Bq/g. Therefore, tritium is also present. As a consequence, in order for storage acceptance at the ANDRA site, it is necessary to pre-treat the waste. An adequate solution seems to be a solidification process using NOCHAR polymers. Indeed, NOCHAR polymers correspond to an important variety of products applied to the treatment of radioactive aqueous and organic liquids (solvent, oil, solvent/oil mixing ...) and sludge through a mechanical and chemical solidification process. For Cadarache LOR, N910 and N960 respectively dedicated to the organic and aqueous liquids solidification are considered. With the N910, the organic waste solidification occurs in two steps. As the organic liquid travels moves through the polymer strands, the strands swell and

  20. NOCHAR Polymers: An Aqueous and Organic Liquid Solidification Process for Cadarache LOR (Liquides Organiques Radioactifs) - 13195

    International Nuclear Information System (INIS)

    Vaudey, Claire-Emilie; Renou, Sebastien; Porco, Julien; Kelley, Dennis; Cochaud, Chantal; Serrano, Roger

    2013-01-01

    To handle the Very Low Level Waste (VLLW) and the Low Level Waste (LLW) in France, two options can be considered: the incineration at CENTRACO facility and the disposal facility on ANDRA sites. The waste acceptance in these radwaste routes is dependent upon the adequacy between the waste characteristics (physical chemistry and radiological) and the radwaste route specifications. If the waste characteristics are incompatible with the radwaste route specifications (presence of significant quantities of chlorine, fluorine, organic component etc or/and high activity limits), it is necessary to find an alternative solution that consists of a waste pre-treatment process. In the context of the problematic Cadarache LOR (Liquides Organiques Radioactifs) waste streams, two radioactive scintillation cocktails have to be treated. The first one is composed of organic liquids at 13.1 % (diphenyloxazol, mesitylene, TBP, xylene) and water at 86.9 %. The second one is composed of TBP at 8.6 % and water at 91.4 %. They contain chlorine, fluorine and sulphate and have got alpha/beta/gamma spectra with mass activities equal to some kBq.g -1 . Therefore, tritium is present and creates the second problematic waste stream. As a consequence, in order for disposal acceptance at the ANDRA site, it is necessary to pre-treat the waste. The NOCHAR polymers as an aqueous and organic liquid solidification process seem to be an adequate solution. Indeed, these polymers constitute an important variety of products applied to the treatment of radioactive aqueous and organic liquids (solvent, oil, solvent/oil mixing etc) and sludge through a mechanical and chemical solidification process. For Cadarache LOR, N910 and N960 respectively dedicated to the organic and aqueous liquids solidification are considered. With the N910, the organic waste solidification occurs in two steps. As the organic liquid travels moves through the polymer strands, the strands swell and immobilise the liquid. Then as the

  1. Functional promiscuity in a mammalian chemosensory system: extensive expression of vomeronasal receptors in the main olfactory epithelium of mouse lemurs

    Directory of Open Access Journals (Sweden)

    Philipp eHohenbrink

    2014-09-01

    Full Text Available The vomeronasal organ (VNO is functional in most terrestrial mammals, though progressively reduced in the primate lineage, and is used for intraspecific communication and predator recognition. Vomeronasal receptor (VR genes comprise two families of chemosensory genes (V1R and V2R that have been considered to be specific for the VNO. However, recently a large number of VRs were reported to be expressed in the main olfactory epithelium (MOE of mice, but there is little knowledge of the expression of these genes outside of rodents. To explore the function of VR genes in mammalian evolution, we analyzed and compared the expression of 64 V1R and 2 V2R genes in the VNO and the MOE of the grey mouse lemur (Microcebus murinus, the primate with the largest known VR repertoire. We furthermore compared expression patterns in adults of both sexes and seasons, and in an infant. A large proportion (83% – 97% of the VR loci was expressed in the VNO of all individuals. The repertoire in the infant was as rich as in adults, indicating reliance on olfactory communication from early postnatal development onwards. In concordance with mice, we also detected extensive expression of VRs in the MOE, with proportions of expressed loci in individuals ranging from 29% to 45%. TRPC2, which encodes a channel protein crucial for signal transduction via VRs, was co-expressed in the MOE in all individuals indicating likely functionality of expressed VR genes in the MOE. In summary, the large VR repertoire in mouse lemurs seems to be highly functional. Given the differences in the neural pathways of MOE and VNO signals, which project to higher cortical brain centers or the limbic system, respectively, this raises the intriguing possibility that the evolution of MOE-expression of VRs enabled mouse lemurs to adaptively diversify the processing of VR-encoded olfactory information.

  2. Effect of process parameters on hardness, temperature profile and solidification of different layers processed by direct metal laser sintering (DMLS)

    International Nuclear Information System (INIS)

    Ahmed, Sazzad Hossain; Mian, Ahsan; Srinivasan, Raghavan

    2016-01-01

    In DMLS process objects are fabricated layer by layer from powdered material by melting induced by a controlled laser beam. Metallic powder melts and solidifies to form a single layer. Solidification map during layer formation is an important route to characterize micro-structure and grain morphology of sintered layer. Generally, solidification leads to columnar, equiaxed or mixture of these two types grain morphology depending on solidification rate and thermal gradient. Eutectic or dendritic structure can be formed in fully equiaxed zone. This dendritic growth has a large effect on material properties. Smaller dendrites generally increase ductility of the layer. Thus, materials can be designed by creating desired grain morphology in certain regions using DMLS process. To accomplish this, hardness, temperature distribution, thermal gradient and solidification cooling rate in processed layers will be studied under change of process variables by using finite element analysis, with specific application to Ti-6Al-4V.

  3. Effect of process parameters on hardness, temperature profile and solidification of different layers processed by direct metal laser sintering (DMLS)

    Science.gov (United States)

    Ahmed, Sazzad Hossain; Mian, Ahsan; Srinivasan, Raghavan

    2016-07-01

    In DMLS process objects are fabricated layer by layer from powdered material by melting induced by a controlled laser beam. Metallic powder melts and solidifies to form a single layer. Solidification map during layer formation is an important route to characterize micro-structure and grain morphology of sintered layer. Generally, solidification leads to columnar, equiaxed or mixture of these two types grain morphology depending on solidification rate and thermal gradient. Eutectic or dendritic structure can be formed in fully equiaxed zone. This dendritic growth has a large effect on material properties. Smaller dendrites generally increase ductility of the layer. Thus, materials can be designed by creating desired grain morphology in certain regions using DMLS process. To accomplish this, hardness, temperature distribution, thermal gradient and solidification cooling rate in processed layers will be studied under change of process variables by using finite element analysis, with specific application to Ti-6Al-4V.

  4. Influences on Distribution of Solute Atoms in Cu-8Fe Alloy Solidification Process Under Rotating Magnetic Field

    Science.gov (United States)

    Zou, Jin; Zhai, Qi-Jie; Liu, Fang-Yu; Liu, Ke-Ming; Lu, De-Ping

    2018-05-01

    A rotating magnetic field (RMF) was applied in the solidification process of Cu-8Fe alloy. Focus on the mechanism of RMF on the solid solution Fe(Cu) atoms in Cu-8Fe alloy, the influences of RMF on solidification structure, solute distribution, and material properties were discussed. Results show that the solidification behavior of Cu-Fe alloy have influenced through the change of temperature and solute fields in the presence of an applied RMF. The Fe dendrites were refined and transformed to rosettes or spherical grains under forced convection. The solute distribution in Cu-rich phase and Fe-rich phase were changed because of the variation of the supercooling degree and the solidification rate. Further, the variation in solute distribution was impacted the strengthening mechanism and conductive mechanism of the material.

  5. Microstructure and fractal characteristics of the solid-liquid interface forming during directional solidification of Inconel 718

    Directory of Open Access Journals (Sweden)

    WANG Ling

    2007-08-01

    Full Text Available The solidification microstructure and fractal characteristics of the solid-liquid interfaces of Inconel 718, under different cooling rates during directional solidification, were investigated by using SEM. Results showed that 5 μm/s was the cellular-dendrite transient rate. The prime dendrite arm spacing (PDAS was measured by Image Tool and it decreased with the cooling rate increased. The fractal dimension of the interfaces was calculated and it changes from 1.204310 to 1.517265 with the withdrawal rate ranging from 10 to 100 μm/s. The physical significance of the fractal dimension was analyzed by using fractal theory. It was found that the fractal dimension of the dendrites can be used to describe the solidification microstructure and parameters at low cooling rate, but both the fractal dimension and the dendrite arm spacing are needed in order to integrally describe the evaluation of the solidification microstructure completely.

  6. X-Ray Radiographic Observation of Directional Solidification Under Microgravity: XRMON-GF Experiments on MASER12 Sounding Rocket Mission

    Science.gov (United States)

    Reinhart, G.; NguyenThi, H.; Bogno, A.; Billia, B.; Houltz, Y.; Loth, K.; Voss, D.; Verga, A.; dePascale, F.; Mathiesen, R. H.; hide

    2012-01-01

    The European Space Agency (ESA) - Microgravity Application Promotion (MAP) programme entitled XRMON (In situ X-Ray MONitoring of advanced metallurgical processes under microgravity and terrestrial conditions) aims to develop and perform in situ X-ray radiography observations of metallurgical processes in microgravity and terrestrial environments. The use of X-ray imaging methods makes it possible to study alloy solidification processes with spatio-temporal resolutions at the scales of relevance for microstructure formation. XRMON has been selected for MASER 12 sounding rocket experiment, scheduled in autumn 2011. Although the microgravity duration is typically six minutes, this short time is sufficient to investigate a solidification experiment with X-ray radiography. This communication will report on the preliminary results obtained with the experimental set-up developed by SSC (Swedish Space Corporation). Presented results dealing with directional solidification of Al-Cu confirm the great interest of performing in situ characterization to analyse dynamical phenomena during solidification processes.

  7. TECHNOLOGY EVALUATION REPORT: SILICATE TECHNOLOGY CORPORATION - SOLIDIFICATION/STABILIZATION OF PCP AND INORGANIC CONTAMINANTS IN SOILS - SELMA, CA

    Science.gov (United States)

    This Technolgy Evaluation Report evaluates the solidification/stabilization process of Silicate Technology Corporation (STC) for the on-site treatment of contaminated soil The STC immobilization technology uses a proprietary product (FMS Silicate) to chemically stabilize and ...

  8. Effect of process parameters on hardness, temperature profile and solidification of different layers processed by direct metal laser sintering (DMLS)

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Sazzad Hossain; Mian, Ahsan, E-mail: ahsan.mian@wright.edu; Srinivasan, Raghavan [Department of Mechanical and Materials Engineering, Wright State University, Dayton, Ohio 45435 (United States)

    2016-07-12

    In DMLS process objects are fabricated layer by layer from powdered material by melting induced by a controlled laser beam. Metallic powder melts and solidifies to form a single layer. Solidification map during layer formation is an important route to characterize micro-structure and grain morphology of sintered layer. Generally, solidification leads to columnar, equiaxed or mixture of these two types grain morphology depending on solidification rate and thermal gradient. Eutectic or dendritic structure can be formed in fully equiaxed zone. This dendritic growth has a large effect on material properties. Smaller dendrites generally increase ductility of the layer. Thus, materials can be designed by creating desired grain morphology in certain regions using DMLS process. To accomplish this, hardness, temperature distribution, thermal gradient and solidification cooling rate in processed layers will be studied under change of process variables by using finite element analysis, with specific application to Ti-6Al-4V.

  9. Effect of the hypo and hyperstoichiometry of niobium about the solidification of steel with medium carbon content

    International Nuclear Information System (INIS)

    Kestenbach, H.-J.; Rodrigues, J.A.; Makray, E.T.

    1984-01-01

    The solidification sequency and the microstructure from carbon steel with 0.4%C and several content of Nb were investigated. Additions between 1 and 5% in Nb weight to obtain compositions hypo and hyperstoichiometric in relation to the niobium carbide formation were used. The metallographic observations were interpreted based in several solidifications reactions that could be occur in the iron rich region of the ternary diagram Fe-Nb-C. (E.G.) [pt

  10. Influence of non-technical policies on choices of waste solidification technologies

    International Nuclear Information System (INIS)

    Trubatch, S.L.

    1987-01-01

    This paper describes and discusses non-technical policy considerations which may improperly influence decisions on the solidification of low-level radioactive wastes (''LLW''). These policy considerations are contained principally in several State and Federal statutes which regulate various aspects of LLW disposal. One policy consideration in particular, the unqualified bias in favor of volume reduction, is shown to present a substantial potential for leading to technically suboptimal decisions on the appropriate processes for solidifying LLW. To avoid the unintended skewing of technical decisions by non-technical policy considerations, certain current policies may need to be revised to ensure that the choices of waste treatment, including decisions on solidification, are based primarily on reasonable assurance of adequate protection of public health and safety. This goal may be realized in part by basing any disposal fee structure on more than just LLW volume to include consideration of the waste's activity and its difficulty of confinement

  11. Cellular interface morphologies in directional solidification. III - The effects of heat transfer and solid diffusivity

    Science.gov (United States)

    Ungar, Lyle H.; Bennett, Mark J.; Brown, Robert A.

    1985-01-01

    The shape and stability of two-dimensional finite-amplitude cellular interfaces arising during directional solidification are compared for several solidification models that account differently for latent heat released at the interface, unequal thermal conductivities of melt and solid, and solute diffusivity in the solid. Finite-element analysis and computer-implemented perturbation methods are used to analyze the families of steadily growing cellular forms that evolve from the planar state. In all models a secondary bifurcation between different families of finite-amplitude cells exists that halves the spatial wavelength of the stable interface. The quantitative location of this transition is very dependent on the details of the model. Large amounts of solute diffusion in the solid retard the growth of large-amplitude cells.

  12. Solidification of cast iron - A study on the effect of microalloy elements on cast iron

    DEFF Research Database (Denmark)

    Moumeni, Elham

    The present thesis deals with the heat transfer and solidification of ductile and microalloyed grey cast iron. Heterogeneous nucleation of nodular graphite at inclusions in ductile iron during eutectic solidification has been investigated. A series of ductile iron samples with two different...... of the austenite, in the last region to solidify. The superfine graphite which forms in this type of irons is short (10-20µm) and stubby. The microstructure of this kind of graphite flakes in titanium alloyed cast iron is studied using electron microscopy techniques. The methods to prepare samples of cast iron...... for comprehensive transmission electron microscopy of graphite and the surrounding iron matrix have been developed and explained. Dual beam microscopes are used for sample preparation. A TEM study has been carried out on graphite flakes in grey cast iron using selected area electron diffraction (SAED). Based...

  13. Temperature and Pressure Evolution during Al Alloy Solidification at Different Squeeze Pressures

    International Nuclear Information System (INIS)

    Li, Junwen; Zhao, Haidong; Chen, Zhenming

    2015-01-01

    Squeeze casting is an advanced and near net-shape casting process, in which external high pressure is applied to solidifying castings. The castings are characterized with fine grains and good mechanical properties. In this study, a series of experiments were carried out to measure the temperature and pressure histories in cavity of Al-Si-Mg direct squeeze castings with different applied solidification pressures of 0.1, 50, 75, and 100 MPa. The evolution of the measured temperatures and pressures was compared and discussed. The effect of pressure change on formation of shrinkage defects was analyzed. Further the friction between the castings and dies during solidification was calculated. It is shown that the applied squeeze pressure has significant influence on the friction at die and casting interfaces, which affects the pressure evolution and transmission. The results could provide some benchmark data for future thermal-mechanics coupled modeling of squeeze castings. (paper)

  14. Sodalite-type radioactive waste solidification product and method of synthesizing the same

    International Nuclear Information System (INIS)

    Koyama, Masashi; Yoshida, Takumasa.

    1995-01-01

    Radioactive waste solidification products formed by solidifying radioactive wastes comprising halides such as chlorides of alkali metal elements, alkaline earth metal elements, rare earth elements, noble metal elements generated upon dry-type reprocessing of nuclear fuels and separation of dry-type high level liquid wastes, are solidified to stable products by incorporating radioactive wastes in the form of halides into a cavity of sodalite condensation cage of aluminosilicates having three dimensional skeleton structure. Alternatively, NaOH, Al 2 O 3 , SiO 2 are mixed and heated to 600 to 900degC to form an intermediate reaction products, and then the reaction products are mixed with the halides and heated to form sodalite-type radioactive water solidification products. Thus, the halides in fission products can be held by the three dimensional skeleton structure similar with that of sodalite which is a sort of natural minerals containing chlorides, thereby enabling to solidify them stably. (N.H.)

  15. Simulation of the solidification in a channel of a water-cooled glass flow

    Directory of Open Access Journals (Sweden)

    G. E. Ovando Chacon

    2014-12-01

    Full Text Available A computer simulation study of a laminar steady-state glass flow that exits from a channel cooled with water is reported. The simulations are carried out in a two-dimensional, Cartesian channel with a backward-facing step for three different angles of the step and different glass outflow velocities. We studied the interaction of the fluid dynamics, phase change and thermal behavior of the glass flow due to the heat that transfers to the cooling water through the wall of the channel. The temperature, streamline, phase change and pressure fields are obtained and analyzed for the glass flow. Moreover, the temperature increments of the cooling water are characterized. It is shown that, by reducing the glass outflow velocity, the solidification is enhanced; meanwhile, an increase of the step angle also improves the solidification of the glass flow.

  16. Modélisation de la solidification par la méthode d’enthalpie

    OpenAIRE

    BENAMEUR, Benamar

    2014-01-01

    La modélisation numérique du phénomène de solidification à l’échelle macroscopique a une importance considérable dans la conception virtuelle des procédés d’élaboration des matériaux. Ce phénomène de solidification est caractérisé par la formation d’une frontière mobile qui sépare les deux phases liquide et solide au cours de changement de phase, ce qui nécessite des techniques appropriées pour suivre le mouvement de front et localiser sa position. Dans ce mémoire et afin de...

  17. Modélisation de la solidification par la méthode d’enthalpie

    OpenAIRE

    BENAMEUR, Benamar

    2013-01-01

    La modélisation numérique du phénomène de solidification à l’échelle macroscopique a une importance considérable dans la conception virtuelle des procédés d’élaboration des matériaux. Ce phénomène de solidification est caractérisé par la formation d’une frontière mobile qui sépare les deux phases liquide et solide au cours de changement de phase, ce qui nécessite des techniques appropriées pour suivre le mouvement de front et localiser sa position. Dans ce mémoire et afin de...

  18. Alternative method of solidification for low-level class a radioactive waste

    International Nuclear Information System (INIS)

    Mayo, K.S.

    1988-01-01

    New solidification media have been developed that exhibit excellent spatial efficiency over the entire range of virtually all Class A liquid wastes. These new media are being used to incorporate from 41 to 48 gallons of liquid radioactive waste in a 55-gallon drum. To date, wastes processing at nuclear power plants and facilities include oils, evaporator bottoms, sludges, and ion-exchanges resins as well as combinations of these waste streams. This paper comparatively discusses the performance of solidification agents known as AQUASET TM and PETROSET TM with other currently available agents. It presents key advantages of using the AQUASET and PETROSET media over other media. These advantages include improvements in packaging efficiency, leachability, and repeatability

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

    Science.gov (United States)

    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

  20. Effect of the delta ferrite solidification morphology of austenitic steels weld metal on the joint properties

    International Nuclear Information System (INIS)

    Bilmes, P.; Gonzalez, A.; Llorente, C.; Solari, M.

    1996-01-01

    The properties of austenitic stainless steel weld metals are largely influenced by the appearance in the microstructure of delta ferrite of a given morphology. The susceptibility to hot cracks and low temperature toughness are deeply conditioned by the mixed complex austenitic-ferritic structures which depending on the steel chemical composition and on the cooling rate may be developed. The latest research on this issue points out the importance of the sodification mode as regards to the influence in the appearance of delta ferrite of a certain morphology. In fact, it is very important to understand the solidification sequences, the primary solidification modes which are possible and the subsequent solid state transformations to correlate the structural elements of the weld metal with the parameters of the welding process on the one had, and the weld joint properties on the other. (Author) 19 refs

  1. SPECIFIC FEATURES OF OLIGOMERIC PRODUCT SOLIDIFICATION FROM POLYURETHANE WASTES AND THEIR PRACTICAL APPLICATION

    OpenAIRE

    V. Belyatsky; Yu. Kryvogus

    2012-01-01

    The paper considers a possibility to use secondary polyurethane obtained by  thermal depolymerization of wastes on the basis of cross-linked polyurethane (polyurethane adduct) and isocyanate. An effect of density dependence of the obtained polyurethane samples on nature and quantity of solvent has been revealed and it is significantly observed while using low-boiling solvents. The influence of adduct/solidification agent ratio on mechanical hardness of the obtained samples has been studied in...

  2. Rapid Solidification of a New Generation Aluminum-Lithium Alloy via Electrospark Deposition

    Science.gov (United States)

    Heard, David W.; Boselli, Julien; Gauvin, Raynald; Brochu, Mathieu

    Electrospark deposition (ESD) is a rapid solidification processing technique capable of depositing a metal onto a conductive substrate. The short pulse duration and high pulse frequency, combined with the small amount of material transferred during each pulse, results in high cooling rates being realized, on the order of 105-106 C/sec. This study investigates the ability to induce solute trapping behavior, for a new generation aluminum-lithium alloy, AA2199, using ESD.

  3. Simultaneous effects of mechanical vibration and inoculation with niobium on the solidification structure of aluminium

    International Nuclear Information System (INIS)

    Mello, J.D.B. de; Arruda, A.C.F. de

    1980-01-01

    This study concerns the effect of mechanical vibration applied simultaneously with inoculation (0,05% Nb) on the solidification structure of aluminium, with a view to refining the grain size. The results shows that the method used is an efficient way to control the final structure of the aluminium. The best results were found for low values of the frequencies of vibration and for the small amplitudes. (Author) [pt

  4. Bitumen and cement solidifications of LL and ML liquid radwaste. The SGN experience

    International Nuclear Information System (INIS)

    Tchemitcheff, E.; Roux, P.

    1993-01-01

    The presentation is focused on the thin-film evaporator technology and the experience gained in the field of the NPPs and research centers on radwaste conditioning. As early as 1970, SGN was licensed by the CEA for the bituminization of LL and ML radwaste. With the support of EDF and COGEMA, SGN has been performing in depth research on cement solidification of borated concentrates and ion exchange resins generated by reactors or reprocessing plant since 1983

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

    Science.gov (United States)

    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.

  6. Large-grain polycrystalline silicon film by sequential lateral solidification on a plastic substrate

    International Nuclear Information System (INIS)

    Kim, Yong-Hae; Chung, Choong-Heui; Yun, Sun Jin; Moon, Jaehyun; Park, Dong-Jin; Kim, Dae-Won; Lim, Jung Wook; Song, Yoon-Ho; Lee, Jin Ho

    2005-01-01

    A large-grain polycrystalline silicon film was obtained on a plastic substrate by sequential lateral solidification. With various combinations of sputtering powers and Ar working gas pressures, the conditions for producing dense amorphous silicon (a-Si) and SiO 2 films were optimized. The successful crystallization of the a-Si film is attributed to the production of a dense a-Si film that has low argon content and can endure high-intensity laser irradiation

  7. Solidification Technologies for Radioactive and Chemical Liquid Waste Treatment - Final CRADA Report

    International Nuclear Information System (INIS)

    Castiglioni, Andrew J.; Gelis, Artem V.

    2016-01-01

    This project, organized under DOE/NNSA's Global Initiatives for Proliferation Prevention program, joined Russian and DOE scientists in developing more effective solidification and storage technologies for liquid radioactive waste. Several patent applications were filed by the Russian scientists (Russia only) and in 2012, the technology developed was approved by Russia's Federal State Unitary Enterprise RADON for application throughout Russia in cleaning up and disposing of radioactive waste.

  8. The effect of the solidification mode on eutectic structure in Fe-C-V alloys

    International Nuclear Information System (INIS)

    Fras, E.; Guzik, E.

    1980-01-01

    The aim of the study was to determine such a chemical composition of Fe-C-V alloys which would ensure the formation of perfectly eutectic structures as well as to investigate the eutectic morphology of these alloys when undergoing bulk and directional solidification. Attempts have been done to get in situ composites from Fe-C-V alloys. The adopted testing methods as well as obtained results are described in detail. (H.M.)

  9. Leaching of Contamination from Stabilization/Solidification Remediated Soils of Different Texture

    OpenAIRE

    Burlakovs, J; Kasparinskis, R; Klavins, M

    2012-01-01

    Development of soil and groundwater remediation technologies is a matter of great importance to eliminate historically and currently contaminated sites. Stabilization/solidification (S/S) refers to binding of waste contaminants to a more chemically stable form and thus diminishing leaching of contamination. It can be performed using cement with or without additives in order to stabilize and solidify soil with the contamination in matrix. A series of experiments were done to determine leaching...

  10. Statement of research in the field of solidification of high level radioactive wastes in France

    International Nuclear Information System (INIS)

    Bonniaud, R.; Sombret, C.

    1975-01-01

    Researches undertaken in France on the solidification of fission products are presented. Examples of glass compositions suitable for several types of fuels are given. The irradiation effects, crystallization, leaching and effects of α emitters have been studied. Two processes, one discontinuous, the other continuous have been studied and developed. In Marcoule, a continuous vitrification plant is under building and an experimental air-cooling storage is carried out [fr

  11. Nuclear criticality safety assessment of the Consolidated Edison Uranium-Solidification Program Facility

    International Nuclear Information System (INIS)

    Thomas, J.T.

    1984-01-01

    A nuclear criticality assessment of the Consolidated Edison Uranium-Solidification Program facility confirms that all operations involved in the process may be conducted with an acceptable margin of subcriticality. Normal operation presents no concern since subcriticality is maintained by design. Several recommendations are presented to prevent, or mitigate the consequences of, any abnormal events that might occur in the various portions of the process. These measures would also serve to reduce to a minimum the administrative controls required to prevent criticality

  12. Optimization of Magnetically Driven Directional Solidification of Silicon Using Artificial Neural Networks and Gaussian Process Models

    Czech Academy of Sciences Publication Activity Database

    Dropka, N.; Holeňa, Martin

    2017-01-01

    Roč. 471, 1 August (2017), s. 53-61 ISSN 0022-0248 R&D Projects: GA ČR GA17-01251S Institutional support: RVO:67985807 Keywords : computer simulation * fluid flows * magnetic fields * directional solidification * semiconducting silicon Subject RIV: IN - Informatics, Computer Science OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.751, year: 2016

  13. Utilization of air pollution control residues for the stabilization/solidification of trace element contaminated soil.

    Science.gov (United States)

    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.

  14. Optimization of heat transfer during the directional solidification process of 1600 kg silicon feedstock

    Science.gov (United States)

    Hu, Chieh; Chen, Jyh Chen; Nguyen, Thi Hoai Thu; Hou, Zhi Zhong; Chen, Chun Hung; Huang, Yen Hao; Yang, Michael

    2018-02-01

    In this study, the power ratio between the top and side heaters and the moving velocity of the side insulation are designed to control the shape of the crystal-melt interface during the growth process of a 1600 kg multi-crystalline silicon ingot. The power ratio and insulation gap are adjusted to ensure solidification of the melt. To ensure that the crystal-melt interface is slightly convex in relation to the melt during the entire solidification process, the power ratio should be augmented gradually in the initial stages while being held to a constant value in the middle stages. Initially the gap between the side and the bottom insulation is kept small to reduce thermal stress inside the seed crystals. However, the growth rate will be slow in the early stages of the solidification process. Therefore, the movement of the side insulation is fast in the initial stages but slower in the middle stages. In the later stages, the side insulation gap is fixed. With these modifications, the convexity of the crystal-melt interface in relation to the melt can be maintained during the growth process with an approximately 41% reduction in the thermal stress inside the growing ingot and an 80% reduction in dislocation density along the center line of the ingot compared with the original case.

  15. The microstructure and composition of equilibrium phases formed in hypoeutectic Te-In alloy during solidification

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Baoguang [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Hu, Jinwu [Center of Failure Analysis, Central Iron and Steel Research Institute, Beijing 100081 (China); Wang, Chongyun; Yang, Wenhui [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Tian, Wenhuai, E-mail: wenhuaitian@ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

    2017-03-15

    As a key tellurium atoms evaporation source for ultraviolet detection photocathode, the hypoeutectic Te{sub 75}In{sub 25} alloy was prepared by employing a slow solidification speed of about 10{sup −2} K/s. The microstructure and chemical composition of the equilibrium phases formed in the as-prepared alloy were studied in this research work. The experimental results show that the as-prepared Te-In alloy was constituted by primary In{sub 2}Te{sub 5} phase and eutectic In{sub 2}Te{sub 5}/Te phases. The eutectic In{sub 2}Te{sub 5}/Te phases are distributed in the grain boundaries of primary In{sub 2}Te{sub 5} phase. With the slow solidification speed, a pure eutectic Te phase without any excessive indium solute was obtained, where Te content of eutectic Te phase is 100 mass%. Moreover, it can be considered that the stress between the In{sub 2}Te{sub 5} and Te phases plays an important role in reducing the tellurium vapor pressure in Te{sub 75}In{sub 25} alloy. - Highlights: • The microstructure of Te-In alloy as an evaporation source was analyzed. • A pure eutectic Te phase was obtained by using a slow solidification speed method. • The relation between vapor pressure and inner-stress in the alloy was discussed.

  16. Diffusion-stress coupling in liquid phase during rapid solidification of binary mixtures

    International Nuclear Information System (INIS)

    Sobolev, S.L.

    2014-01-01

    An analytical model has been developed to describe the diffusion-viscous stress coupling in the liquid phase during rapid solidification of binary mixtures. The model starts with a set of evolution equations for diffusion flux and viscous pressure tensor, based on extended irreversible thermodynamics. It has been demonstrated that the diffusion-stress coupling leads to non-Fickian diffusion effects in the liquid phase. With only diffusive dynamics, the model results in the nonlocal diffusion equations of parabolic type, which imply the transition to complete solute trapping only asymptotically at an infinite interface velocity. With the wavelike dynamics, the model leads to the nonlocal diffusion equations of hyperbolic type and describes the transition to complete solute trapping and diffusionless solidification at a finite interface velocity in accordance with experimental data and molecular dynamic simulation. -- Highlights: •We propose the diffusion-stress coupling model for binary solidification. •The coupling arises at deep undercooling. •With diffusive dynamics, the models result in parabolic transfer equations. •With the wavelike dynamics, the models lead to hyperbolic transfer equations. •The coupling strongly affects the solute partition coefficient

  17. Development of a geopolymer solidification method for radioactive wastes by compression molding and heat curing

    International Nuclear Information System (INIS)

    Shimoda, Chiaki; Matsuyama, Kanae; Okabe, Hirofumi; Kaneko, Masaaki; Miyamoto, Shinya

    2017-01-01

    Geopolymer solidification is a good method for managing waste because of it is inexpensive as compared with vitrification and has a reduced risk of hydrogen generation. In general, when geopolymers are made, water is added to the geopolymer raw materials, and then the slurry is mixed, poured into a mold, and cured. However, it is difficult to control the reaction because, depending on the types of materials, the viscosity can immediately increase after mixing. Slurries of geopolymers easily attach to the agitating wing of the mixer and easily clog the plumbing during transportation. Moreover, during long-term storage of solidified wastes containing concentrated radionuclides in a sealed container without vents, the hydrogen concentration in the container increases over time. Therefore, a simple method using as little water as possible is needed. In this work, geopolymer solidification by compression molding was studied. As compared with the usual methods, it provides a simple and stable method for preparing waste for long-term storage. From investigations performed before and after solidification by compression molding, it was shown that the crystal structure changed. From this result, it was concluded that the geopolymer reaction proceeded during compression molding. This method (1) reduces the energy needed for drying, (2) has good workability, (3) reduces the overall volume, and (4) reduces hydrogen generation. (author)

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

    Science.gov (United States)

    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.

  19. Solidification/stabilization of fly and bottom ash from medical waste incineration facility.

    Science.gov (United States)

    Anastasiadou, Kalliopi; Christopoulos, Konstantinos; Mousios, Epameinontas; Gidarakos, Evangelos

    2012-03-15

    In the present work, the stabilization/solidification of fly and bottom ash generated from incinerated hospital waste was studied. The objectives of the solidification/stabilization treatment were therefore to reduce the leachability of the heavy metals present in these materials so as to permit their disposal in a sanitary landfill requiring only a lower degree of environmental protection. Another objective of the applied treatment was to increase the mechanical characteristics of the bottom ash using different amounts of Ordinary Portland Cement (OPC) as a binder. The solidified matrix showed that the cement is able to immobilize the heavy metals found in fly and bottom ash. The TCLP leachates of the untreated fly ash contain high concentrations of Zn (13.2 mg/l) and Pb (5.21 mg/l), and lesser amounts of Cr, Fe, Ni, Cu, Cd and Ba. Cement-based solidification exhibited a compressive strength of 0.55-16.12 MPa. The strength decreased as the percentage of cement loading was reduced; the compressive strength was 2.52-12.7 MPa for 60% cement mixed with 40% fly ash and 6.62-16.12 MPa for a mixture of 60% cement and 40% bottom ash. The compressive strength reduced to 0.55-1.30 MPa when 30% cement was mixed with 70% fly ash, and to 0.90-7.95 MPa when 30% cement was mixed with 70% bottom ash, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Solidification of saturated radioactive organic ion exchangers and of ash from incineration plant

    International Nuclear Information System (INIS)

    Timulak, J.; Krejci, F.; Pekar, A.; Gulis, G.; Breza, M.

    1985-01-01

    The study of bituminization of saturated radioactive organic ion exchangers was centred on finding the effect of the water content of ion exchangers on the process of solidification and on the water content of bituminization products, the optimization of temperature conditions in the process of bituminization, on seeking a suitable bitumen, on testing the radiation and thermal stability of the bituminization product, on finding its properties as well as the effects of nuclear radiation on these properties. Ion exchangers of Czechoslovak and Soviet make were used in all experiments. It was found that solidified ion exchangers must have a maximum moisture of 10%, and the temperature during solidification must not exceed 130 degC. The negative effect of boric acid on cement solidification may be removed by neutralization of esterification of this acid following its release from the ion exchangers by hydrochloric acid. Some other results of the experiments are tabulated. The obtained results describe the behaviour of the product only during a brief period of time as compared with the long time of long-term disposal. It will therefore be necessary to devote attention to finding the characteristics of long-term behaviour of products during disposal. (Z.M.)