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Sample records for investment casting process

  1. Prediction of ALLOY SHRINKAGE FACTORS FOR THE INVESTMENT CASTING PROCESS

    SciTech Connect

    Sabau, Adrian S

    2006-01-01

    This study deals with the experimental measurements and numerical predictions of alloy shrinkage factors (SFs) related to the investment casting process. The dimensions of the A356 aluminum alloy casting were determined from the numerical simulation results of solidification, heat transfer, fluid dynamics, and deformation phenomena. The investment casting process was carried out using wax patterns of unfilled wax and shell molds that were made of fused silica with a zircon prime coat. The dimensions of the die tooling, wax pattern, and casting were measured, in order to determine the actual tooling allowances. Several numerical simulations were carried out, to assess the level of accuracy for the casting shrinkage. The solid fraction threshold, at which the transition from the fluid dynamics to the solid dynamics occurs, was found to be important in predicting shrinkage factors (SFs). It was found that accurate predictions were obtained for all measued dimensions when the shell mold was considered a deformable material.

  2. Mineral processing techniques for recycling investment casting shell

    SciTech Connect

    Dahlin, Cheryl L.; Nilsen, David N.; Dahlin, David C.; Hunt, Alton H.; Collins, W. Keith

    2002-01-01

    The Albany Research Center of the U.S. Department of Energy used materials characterization and minerals beneficiation methods to separate and beneficially modify spent investment-mold components to identify recycling opportunities and minimize environmentally sensitive wastes. The physical and chemical characteristics of the shell materials were determined and used to guide bench-scale research to separate reusable components by mineral-beneficiation techniques. Successfully concentrated shell materials were evaluated for possible use in new markets.

  3. Friction Stir Processing of Investment-Cast Ti-6Al-4V: Microstructure and Properties

    NASA Astrophysics Data System (ADS)

    Pilchak, A. L.; Norfleet, D. M.; Juhas, M. C.; Williams, J. C.

    2008-07-01

    Investment-cast titanium components are becoming increasingly common in the aerospace industry due to the ability to produce large, complex, one-piece components that were previously fabricated by mechanically fastening multiple pieces together. The fabricated components are labor-intensive and the fastener holes are stress concentrators and prime sites for fatigue crack initiation. The castings are typically hot-isostatically-pressed (HIP) to close internal porosity, but have a coarse, fully lamellar structure that has low resistance to fatigue crack initiation. The as-cast + HIP material exhibited 1- to 1.5-mm prior β grains containing a fully lamellar α + β microstructure consistent with slow cooling from above the β transus. Friction stir processing (FSP) was used to locally modify the microstructure on the surface of an investment-cast Ti-6Al-4V plate. Friction stir processing converted the as-cast microstructure to fine (1- to 2-μm) equiaxed α grains. Using micropillars created with a dual-beam focused ion beam device, it was found that the fine-grained equiaxed structure has about a 12 pct higher compressive yield stress. In wrought products, higher strength conditions are more resistant to fatigue crack initiation, while the coarse lamellar microstructure in the base material has better fatigue crack growth resistance. In combination, these two microstructures can increase the fatigue life of titanium alloy castings by increasing the number of cycles prior to crack initiation while retaining the same low-crack growth rates of the colony microstructure in the remainder of the component. In the current study, high-cycle fatigue testing of investment-cast Ti-6Al-4V was performed on four-point bend specimens. Early results show that FSP can increase fatigue strength dramatically.

  4. Investment casting design of experiment. Final report

    SciTech Connect

    Owens, R.

    1997-10-01

    Specific steps in the investment casting process were analyzed in a designed experiment. The casting`s sensitivity to changes in these process steps was experimentally determined Dimensional and radiographic inspection were used to judge the sensitivity of the casting. Thirty-six castings of different pedigrees were poured and measured. Some of the dimensional inspection was conducted during the processing. It was confirmed that wax fixturing, number of gates, gate location, pour and mold temperature, pour speed, and cooling profile all affected the radiographic quality of the casting. Gate and runner assembly techniques, number of gates, and mold temperature affect the dimensional quality of the casting.

  5. Effects of process variables on the properties of YBa2Cu3O(7-x) ceramics formed by investment casting

    NASA Technical Reports Server (NTRS)

    Hooker, M. W.; Taylor, T. D.; Leigh, H. D.; Wise, S. A.; Buckley, J. D.; Vasquez, P.; Buck, G. M.; Hicks, L. P.

    1993-01-01

    An investment casting process has been developed to produce net-shape, superconducting ceramics. In this work, a factorial experiment was performed to determine the critical process parameters for producing cast YBa2Cu3O7 ceramics with optimum properties. An analysis of variance procedure indicated that the key variables in casting superconductive ceramics are the particle size distribution and sintering temperature. Additionally, the interactions between the sintering temperature and the other process parameters (e.g., particle size distribution and the use of silver dopants) were also found to influence the density, porosity, and critical current density of the fired ceramics.

  6. Combination Of Investment And Centrifugal Casting

    NASA Technical Reports Server (NTRS)

    Creeger, Gordon A.

    1994-01-01

    Modifications, including incorporation of centrifugal casting, made in investment-casting process reducing scrap rate. Used to make first- and second-stage high-pressure-fuel-turbopump nozzles, containing vanes with thin trailing edges and other thin sections. Investment mold spun for short time while being filled, and stopped before solidification occurs. Centrifugal force drives molten metal into thin trailing edges, ensuring they are filled. With improved filling, preheat and pour temperatures reduced and solidification hastened so less hot tearing.

  7. Effect of Friction Stir Processing on Fatigue Behavior of an Investment Cast Al-7Si-0.6 Mg Alloy

    SciTech Connect

    Jana, Saumyadeep; Mishra, Rajiv S.; Baumann, John B.; Grant, Glenn J.

    2010-02-01

    Cast aluminum alloys in general show poor fatigue performance due to presence of defects. Friction stir processing (FSP) can be used as a tool for enhancing mechanical properties of cast alloys by eliminating such defects. In the present study FSP led to a five times improvement in fatigue life of an investment cast Al-7Si-0.6Mg hypoeutectic alloy. The reason for such enhancement was linked to closure of casting porosity which acted as crack nucleation sites in the as-cast condition. Porosity acted as notches in the as-cast alloy and led to an order of magnitude higher crack growth rate. As FSP eliminated the porosity and refined Si particles, crack growth rate dropped due to the elimination of the notch effect together with increased crack path tortuosity. Finally, short crack behavior was noted in both cast and FSP specimens. The critical crack length where transition from short crack to long crack behavior took place is related to respective microstructural characteristic dimensions.

  8. Advanced Pattern Material for Investment Casting Applications

    SciTech Connect

    F. Douglas Neece Neil Chaudhry

    2006-02-08

    Cleveland Tool and Machine (CTM) of Cleveland, Ohio in conjunction with Harrington Product Development Center (HPDC) of Cincinnati, Ohio have developed an advanced, dimensionally accurate, temperature-stable, energy-efficient and cost-effective material and process to manufacture patterns for the investment casting industry. In the proposed technology, FOPAT (aFOam PATtern material) has been developed which is especially compatible with the investment casting process and offers the following advantages: increased dimensional accuracy; increased temperature stability; lower cost per pattern; less energy consumption per pattern; decreased cost of pattern making equipment; decreased tooling cost; increased casting yield. The present method for investment casting is "the lost wax" process, which is exactly that, the use of wax as a pattern material, which is then melted out or "lost" from the ceramic shell. The molten metal is then poured into the ceramic shell to produce a metal casting. This process goes back thousands of years and while there have been improvements in the wax and processing technology, the material is basically the same, wax. The proposed technology is based upon an established industrial process of "Reaction Injection Molding" (RIM) where two components react when mixed and then "molded" to form a part. The proposed technology has been modified and improved with the needs of investment casting in mind. A proprietary mix of components has been formulated which react and expand to form a foam-like product. The result is an investment casting pattern with smooth surface finish and excellent dimensional predictability along with the other key benefits listed above.

  9. The effect of friction stir processing on the microstructure, mechanical properties and fracture behavior of investment cast titanium aluminum vanadium

    NASA Astrophysics Data System (ADS)

    Pilchak, Adam L.

    The use of investment cast titanium components is becoming increasingly common in the aerospace industry due to the ability to produce large, one-piece components with complex geometries that were previously fabricated by mechanically fastening or welding multiple smaller parts together. However, the coarse, fully lamellar microstructure typical of investment cast alpha + beta titanium alloys results in relatively poor fatigue strength compared to forged titanium products. As a result, investment castings are not considered for use in fatigue limited structures. In recent years, friction stir processing has emerged as a solid state metalworking technique capable of substantial microstructure refinement in aluminum and nickel-aluminum-bronze alloys. The purpose of the present study is to determine the feasibility of friction stir processing and assess its effect on the microstructure and mechanical properties of the most widely used alpha + beta titanium alloy, Ti-6Al-4V. Depending on processing parameters, including tool travel speed, rotation rate and geometry, the peak temperature in the stir zone was either above or below the beta transus. The resulting microstructures consisted of either ˜1 mum equiaxed a grains, ˜25 mum prior beta grains containing a colony alpha + beta microstructure or a combination of 1 mum equiaxed alpha and fine, acicular alpha + beta. The changes in microstructure were characterized with scanning and transmission electron microscopy and electron backscatter diffraction. The texture in the stir zone was nearly random for all processing conditions, however, several components of ideal simple shear textures were observed in both the hexagonal close packed alpha and the body centered cubic beta phases which provided insight into the operative grain refinement mechanisms. Due to the relatively small volume of material affected by friction stir processing, conventionally sized test specimens were unable to be machined from the stir zone

  10. A future vision for the investment casting industry

    SciTech Connect

    Zanner, F.J.; Maguire, M.C.

    1993-11-01

    All of American industry is being subjected to increased competitive pressures due to customer needs for shorter cycle times and better quality. The investment casting industry could be in a unique position to satisfy these needs by incorporating several emerging technologies into production processes. The inherent versatility and flexibility of casting make it a truly agile manufacturing process. Because of its compatibility with new rapid prototyping technologies, investment casting could be one of the key vehicles in the new ``art to part`` paradigm. Recently, dramatic advances have been made in the quality of wax and plastic patterns, parts, and tooling by investment casting on time scales unheard of today. Because design and acquisition of tooling contributes heavily to the lead time for any market, these advances will strengthen the position of investment casting manufacturers and customers, and create opportunities in traditional and non-tradition markets. Key to achieving this goal is to use the technology to remove uncertainties from investment casting process. To do this, we must collectively build the infrastructure to enable investment casting companies to make parts right the first time, every time. Integration of mature and on-the-horizon technologies will make this revolution possible and create large growth in markets for investment castings.

  11. WinMod: An expert advisor for investment casting

    SciTech Connect

    Bivens, H.P.; Williamson, G.A. Jr.; Luger, G.F.; Erdmann, R.G.; Maguire, M.C.; Baldwin, M.D.; Anderson, D.J.

    1998-04-01

    Investment casting is an important method for fabricating a variety of high quality components in mechanical systems. Cast components, unfortunately, have a large design and gate/runner build time associated with their fabrication. In addition, casting engineers often require many years of actual experience in order to consistently pour high quality castings. Since 1989, Sandia National Laboratories has been investigating casting technology and software that will reduce the time overhead involved in producing quality casts. Several companies in the casting industry have teamed up with Sandia to form the FASTCAST Consortium. One result of this research and the formation of the FASTCAST consortium is the creation of the WinMod software, an expert casting advisor that supports the decision making process of the casting engineer through visualization and advice to help eliminate possible casting defects.

  12. Physical Simulation of Investment Casting of Complex Shape Parts

    NASA Astrophysics Data System (ADS)

    Rahimian, Mehdi; Milenkovic, Srdjan; Maestro, Laura; De Azua, Aitor Eguidazu Ruiz; Sabirov, Ilchat

    2015-05-01

    Development of investment casting process has been a challenge for manufacturers of complex shape parts. Numerous experimental casting trials are typically carried out to determine the optimum casting parameters for fabrication of high-quality products. In this work, it is demonstrated that physical simulation of investment casting can successfully predict microstructure and hardness in as-cast complex shape parts. The physical simulation tool consists of a thermal model and melting/solidification experiments in thermo-mechanical simulator. The thermal model is employed to predict local cooling rate during solidification at each point of a casting. Melting/solidification experiments are carried out under controlled cooling rates estimated by the thermal model. Microstructural and mechanical characterization of the solidified specimens is performed; the obtained results predict the local microstructure and mechanical properties of the casting. This concept is applied to investment casting of complex shape nozzle guide vanes from Mar-M247 Ni-based superalloy. Experimental casting trials are performed and the outcomes of physical simulation tool are validated against experimental results. It is shown that phase composition, secondary dendrite arm spacing, grain size, γ/ γ' eutectic size and volume fraction, size and shape of carbide particles, and local microhardness can be predicted at each point of the casting via physical simulation.

  13. Some Investigations on Hardness of Investment Casting Process After Advancements in Shell Moulding for Reduction in Cycle Time

    NASA Astrophysics Data System (ADS)

    Singh, R.; Mahajan, V.

    2014-07-01

    In the present work surface hardness investigations have been made on acrylonitrile butadiene styrene (ABS) pattern based investment castings after advancements in shell moulding for replication of biomedical implants. For the present study, a hip joint, made of ABS material, was fabricated as a master pattern by fused deposition modelling (FDM). After preparation of master pattern, mold was prepared by deposition of primary (1°), secondary (2°) and tertiary (3°) coatings with the addition of nylon fibre (1-2 cm in length of 1.5D). This study outlines the surface hardness mechanism for cast component prepared from ABS master pattern after advancement in shell moulding. The results of study highlight that during shell production, fibre modified shells have a much reduced drain time. Further the results are supported by cooling rate and micro structure analysis of casting.

  14. Shrinkage Prediction for the Investment Casting of Stainless Steels

    SciTech Connect

    Sabau, Adrian S

    2007-01-01

    In this study, the alloy shrinkage factors were obtained for the investment casting of 17-4PH stainless steel parts. For the investment casting process, unfilled wax and fused silica with a zircon prime coat were used for patterns and shell molds, respectively. Dimensions of the die tooling, wax pattern, and casting were measured using a Coordinate Measurement Machine in order to obtain the actual tooling allowances. The alloy dimensions were obtained from numerical simulation results of solidification, heat transfer, and deformation phenomena. The numerical simulation results for the shrinkage factors were compared with experimental results.

  15. Investment cast AISI H13 tooling for automotive applications

    SciTech Connect

    Maguire, M.C.; Baldwin, M.D.; Hochanadel, P.W.; Edwards, G.R.

    1995-07-01

    While many techniques exist for production of soft tooling, for die casting there is limited recent experience with cast tooling. The most common US alloy used for manufacture of die casting tooling is wrought AISI H13. If the performance of the cast material is comparable to the wrought counterpart, the use of investment cast HI 3 tooling directly from patterns made via rapid prototyping is of considerable interest. A metallurgical study of investment cast H13 was conducted to evaluate the mechanical behavior in simulated die casting applications. Variable thickness plate investment castings of AISI H13 hot work die steel were produced and characterized in the as-cast and heat-treated conditions. The characterization included light microscopy and mechanical testing. Wrought samples of standard and premium grade H13 were heat-treated and characterized similarly for comparison. Microstructural differences were observed in as-cast samples produced in different section thicknesses. Dendrite cell size and carbide morphology constituted the most prominent microstructural differences observed. After a full heat-treatment, microstructural differences between the wrought material and cast materials were slight regardless of section thickness.The mechanical properties of the cast and heat-treated material proved similar to the properties of the standard heat-treated wrought material. A thermal fatigue testing unit was to con-elate the heat checking susceptibility of H13 steel to its processing and consequent microstructural condition. Surface hardness decreased significantly with thermal cycling, and heat checking was observed in as few as 50 cycles. Thermal softening and thermal fatigue susceptibility were quantified and discussed relative to the microstructural conditions created by processing and heat-treatment. It was found that the premium grade wrought H13 steel provided the best overall resistance to heat checking.

  16. Rapid Tooling via Investment Casting and Rapid Prototype Patterns

    SciTech Connect

    Baldwin, Michael D.

    1999-06-01

    The objective of this work to develop the materials processing and design technologies required to reduce the die development time for metal mold processes from 12 months to 3 months, using die casting of Al and Mg as the example process. Sandia demonstrated that investment casting, using rapid prototype patterns produced from Stereo lithography or Selective laser Sintering, was a viable alternative/supplement to the current technology of machining form wrought stock. A demonstration die insert (ejector halt) was investment cast and subsequently tested in the die casting environment. The stationary half of the die insert was machined from wrought material to benchmark the cast half. The two inserts were run in a die casting machine for 3,100 shots of aluminum and at the end of the run no visible difference could be detected between the cast and machined inserts. Inspection concluded that the cast insert performed identically to the machined insert. Both inserts had no indications of heat checking or degradation.

  17. Predicting Pattern Tooling and Casting Dimensions for Investment Casting - Phase II

    SciTech Connect

    Sabau, Adrian S

    2005-09-01

    The investment casting process allows the production of complex-shape parts and close dimensional tolerances. One of the most important phases in the investment casting process is the design of the pattern die. Pattern dies are used to create wax patterns by injecting wax into dies. The wax patterns are used to create a ceramic shell by the application of a series of ceramic coatings, and the alloy is cast into the dewaxed shell mold (Fig. 1.1). However, the complexity of shape and the close dimensional tolerances required in the final casting make it difficult to determine tooling dimensions. The final linear dimension of the casting depends on the cumulative effects of the linear expansions or contractions in each step of the investment casting process (Fig. 1.2). In most cases, the mold geometry or cores restrict the shrinkage of the pattern or the cast part, and the final casting dimensions may be affected by time-dependent processes such as viscoelastic deformation of the wax, and viscoplastic creep and plastic deformations of the shell and alloy. The pattern die is often reworked several times to produce castings whose dimensions are within acceptable tolerances. To date, investment casting technology has been based on hands-on training and experience. Technical literature is limited to experimental, phenomenological studies aimed at obtaining empirical correlations for quick and easy application in industry. The goal of this project was to predict casting dimensions for investment castings in order to meet blueprint nominal during the first casting run. Several interactions have to be considered in a coupled manner to determine the shrinkage factors: these are the die-wax, wax-shell, and shell-alloy interactions (as illustrated in Fig. 1.3). In this work, the deformations of the die-wax and shell-alloy systems were considered in a coupled manner, while the coupled deformation of the wax-shell system was not considered. Future work is needed in order to

  18. Rapid prototyping: A paradigm shift in investment casting

    SciTech Connect

    Atwood, C.L.; Maguire, M.C.; Baldwin, M.D.; Pardo, B.T.

    1996-09-01

    The quest for fabricating complex metal parts rapidly and with minimal cost has brought rapid prototyping (RP) processes to the forefront of the investment casting industry. Relatively recent advances in DTM Corporation`s selective laser sintering (SLS) and 3D Systems stereolithography (SL) processes have had a significant impact on the overall quality of patterns produced using these rapid prototyping processes. Sandia National Laboratories uses patterns generated from rapid prototyping processes to reduce the cycle time and cost of fabricating prototype and small lot production parts in support of a program called FASTCAST. The SLS process is used to fabricate patterns from materials such as investment casting wax, polycarbonate, and a new material called TrueForm PM{trademark}. With the timely introduction of each of these materials, the quality of patterns fabricated has improved. The development and implementation of SL QuickCast{trademark} software has enabled this process to produce highly accurate patterns for use in investment casting. This paper focuses on the successes with these new pattern materials and the infrastructure required to cast rapid prototyping patterns successfully. In addition, a brief overview of other applications of rapid prototyping at Sandia will be discussed.

  19. Effect of Friction Stir Processing on Microstructure and Tensile Properties of an Investment Cast Al-7Si-0.6Mg Alloy

    SciTech Connect

    Jana, Saumyadeep; Mishra, Rajiv S.; Baumann, John B.; Grant, Glenn J.

    2010-10-01

    Friction stir processing (FSP) is emerging as a promising tool for microstructural modification. The present study assesses the effects of FSP on the microstructure and mechanical properties of an investment cast Al-7Si-Mg alloy. FSP eliminates porosity and significantly refines eutectic Si particles. The extent of particle refinement varied with changes in processing conditions. High tool rotation rate and low to intermediate tool traverse speed generated a higher volume fraction of finer particles. Tensile ductility changed significantly as a result of FSP, whereas UTS improved only marginally. Yield strength was similar in both cast and FSPed samples under various heat treated conditions, with the highest value obtained after a T6 heat treatment. Further, FSP caused significant grain refinement in the stir zone, subsequently transforming into very coarse grains as abnormal grain growth (AGG) occurred during solution treatment at high temperature.

  20. Efficient Runner Networks for Investment Castings

    SciTech Connect

    GIVLER,RICHARD C.; SAYLORS,DAVID B.

    2000-07-18

    We present a computational method that finds an efficient runner network for an investment casting, once the gate locations have been established. The method seeks to minimize a cost function that is based on total network volume. The runner segments are restricted to lie in the space not occupied by the part itself. The collection of algorithms has been coded in C and runner designs have been computed for several real parts, demonstrating substantial reductions in rigging volume.

  1. Cast Process Simulation for the Rapid Tooling.

    NASA Astrophysics Data System (ADS)

    Zhang, Renji; Jiang, Rui; Liu, Yuan; Yan, Yongnian

    1997-03-01

    A major use for RP (Rapid Prototyping) now is in the foundry industry. It is so called RT (Rapid Tooling). Models are used as patterns for sand and plaster casting or used as sacrificial models in investment casting in the RT. In order to improve casting quality, a cast process simulation program for the RT has been made. This simulation depends on analysis of size accuracy parameters. The result could be came back into the CAD forming program. After that a new CAD data have been adopted in RT process. Then the RT technology could have sufficient accuracy in fabrication. Work supported by the Natural Science Foundation of China (NSFC).

  2. FInal Report - Investment Casting Shell Cracking

    SciTech Connect

    Von Richards

    2003-12-01

    This project made a significant contribution to the understanding of the investment casting shell cracking problem. The effects of wax properties on the occurrence of shell cracking were demonstrated and can be measured. The properties measured include coefficient of thermal expansion, heating rate and crystallinity of the structure. The important features of production molds and materials properties have been indicated by case study analysis and fractography of low strength test bars. It was found that stress risers in shell cavity design were important and that typical critical flaws were either oversize particles or large pores just behind the prime coat. It was also found that the true effect of fugitive polymer fibers was not permeability increase, but rather a toughening mechanism due to crack deflection.

  3. Analysis of Different Inhibitors for Magnesium Investment Casting

    NASA Astrophysics Data System (ADS)

    Herrero-Dorca, N.; Sarriegi Etxeberria, H.; Hurtado, I.; Andres, U.; Rodriguez, P.; Arruebarrena, G.

    2012-01-01

    Investment casting of magnesium is a well suited process for the production of aeronautic and automotive components. But still, this process has not been properly developed. One reason for that are the reactions between the Mg melt and the ceramics of the mould that produce a non-desired oxide layer on the part surface. These reactions can be inhibited by the use of silica-free slurries with a higher stability than conventional ones. Another way is using inhibitors, chemical compounds based in fluorides that react with the melt, creating a protective surface layer in the casting. With the aim of developing a reaction-free process, alumina moulds with a stepped geometry have been constructed. These provide different interface conditions. Conventional SF6, non-conventional KBF4 and NaBF4 and environmentally friendly FK inhibitors have been tested on. As a result, KBF4 has been identified as the most suitable inhibitor for magnesium investment casting. Furthermore, the analysis of the cooling curve of different interfaces has provided essential information about the reaction mechanism of the inhibitors.

  4. Energy Saving Melting andRevert Reduction Technology (E0SMARRT): Predicting Pattern Tooling and Casting Dimension for Investment Casting

    SciTech Connect

    Nick Cannell; Dr. Mark Samonds; Adi Sholapurwalla; Sam Scott

    2008-11-21

    The investment casting process is an expendable mold process where wax patterns of the part and rigging are molded, assembled, shelled and melted to produce a ceramic mold matching the shape of the component to be cast. Investment casting is an important manufacturing method for critical parts because of the ability to maintain dimensional shape and tolerances. However, these tolerances can be easily exceeded if the molding components do not maintain their individual shapes well. In the investment casting process there are several opportunities for the final casting shape to not maintain the intended size and shape, such as shrinkage of the wax in the injection tool, the modification of the shape during shell heating, and with the thermal shrink and distortion in the casting process. Studies have been completed to look at the casting and shell distortions through the process in earlier phases of this project. Dr. Adrian Sabau at Oak Ridge National Labs performed characterizations and validations of 17-4 PH stainless steel in primarily fused silica shell systems with good agreement between analysis results and experimental data. Further tasks provided material property measurements of wax and methodology for employing a viscoelastic definition of wax materials into software. The final set of tasks involved the implementation of the findings into the commercial casting analysis software ProCAST, owned and maintained by ESI Group. This included: o the transfer of the wax material property data from its raw form into separate temperature-dependent thermophysical and mechanical property datasets o adding this wax material property data into an easily viewable and modifiable user interface within the pre-processing application of the ProCAST suite, namely PreCAST o and validating the data and viscoelastic wax model with respect to experimental results

  5. Processing of IN-718 Lattice Block Castings

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.

    2002-01-01

    Recently a low cost casting method known as lattice block casting has been developed by JAM Corporation, Wilmington, Massachusetts for engineering materials such as aluminum and stainless steels that has shown to provide very high stiffness and strength with only a fraction of density of the alloy. NASA Glenn Research Center has initiated research to investigate lattice block castings of high temperature Ni-base superalloys such as the model system Inconel-718 (IN-718) for lightweight nozzle applications. Although difficulties were encountered throughout the manufacturing process , a successful investment casting procedure was eventually developed. Wax formulation and pattern assembly, shell mold processing, and counter gravity casting techniques were developed. Ten IN-718 lattice block castings (each measuring 15-cm wide by 30-cm long by 1.2-cm thick) have been successfully produced by Hitchiner Gas Turbine Division, Milford, New Hampshire, using their patented counter gravity casting techniques. Details of the processing and resulting microstructures are discussed in this paper. Post casting processing and evaluation of system specific mechanical properties of these specimens are in progress.

  6. Integrally cored ceramic investment casting mold fabricated by ceramic stereolithography

    NASA Astrophysics Data System (ADS)

    Bae, Chang-Jun

    Superalloy airfoils are produced by investment casting (IC), which uses ceramic cores and wax patterns with ceramic shell molds. Hollow cored superalloy airfoils in a gas turbine engine are an example of complex IC parts. The complex internal hollow cavities of the airfoil are designed to conduct cooling air through one or more passageways. These complex internal passageways have been fabricated by a lost wax process requiring several processing steps; core preparation, injection molding for wax pattern, and dipping process for ceramic shell molds. Several steps generate problems such as high cost and decreased accuracy of the ceramic mold. For example, costly tooling and production delay are required to produce mold dies for complex cores and wax patterns used in injection molding, resulting in a big obstacle for prototypes and smaller production runs. Rather than using separate cores, patterns, and shell molds, it would be advantageous to directly produce a mold that has the casting cavity and the ceramic core by one process. Ceramic stereolithography (CerSLA) can be used to directly fabricate the integrally cored ceramic casting mold (ICCM). CerSLA builds ceramic green objects from CAD files from many thin liquid layers of powder in monomer, which are solidified by polymerization with a UV laser, thereby "writing" the design for each slice. This dissertation addresses the integrally cored casting ceramic mold (ICCM), the ceramic core with a ceramic mold shell in a single patternless construction, fabricated by ceramic stereolithography (CerSLA). CerSLA is considered as an alternative method to replace lost wax processes, for small production runs or designs too complex for conventional cores and patterns. The main topic is the development of methods to successfully fabricate an ICCM by CerSLA from refractory silica, as well as related issues. The related issues are the segregation of coarse fused silica powders in a layer, the degree of segregation parameter to

  7. Predicting Pattern Tooling and Casting Dimensions for Investment Casting, Phase III

    SciTech Connect

    Sabau, Adrian S

    2008-04-01

    Efforts during Phase III focused mainly on the shell-alloy systems. A high melting point alloy, 17-4PH stainless steel, was considered. The experimental part of the program was conducted at ORNL and commercial foundries, where wax patterns were injected, molds were invested, and alloys were poured. Shell molds made of fused-silica and alumino-silicates were considered. A literature review was conducted on thermophysical and thermomechanical properties alumino-silicates. Material property data, which were not available from material suppliers, was obtained. For all the properties of 17-4PH stainless steel, the experimental data available in the literature did not cover the entire temperature range necessary for process simulation. Thus, some material properties were evaluated using ProCAST, based on CompuTherm database. A comparison between the predicted material property data and measured property data was made. It was found that most material properties were accurately predicted only over several temperature ranges. No experimental data for plastic modulus were found. Thus, several assumptions were made and ProCAST recommendations were followed in order to obtain a complete set of mechanical property data at high temperatures. Thermal expansion measurements for the 17-4PH alloy were conducted during heating and cooling. As a function of temperature, the thermal expansion for both the alloy and shell mold materials showed different evolution on heating and cooling. Numerical simulations were performed using ProCAST for the investment casting of 17-4PH stainless steel parts in fused silica molds using the thermal expansion obtained on heating and another one with thermal expansion obtained on cooling. Since the fused silica shells had the lowest thermal expansion properties in the industry, the dewaxing phase, including the coupling between wax-shell systems, was neglected. The shell mold was considered to be a pure elastic material. The alloy dimensions were

  8. Fastcast: Integration and application of rapid prototyping and computational simulation to investment casting

    SciTech Connect

    Maguire, M.C.; Baldwin, M.D.; Atwood, C.L.

    1996-09-01

    The emergence of several rapid prototyping and manufacturing (RP and M) technologies is having a dramatic impact on investment casting. While the most successful of the rapid prototyping technologies are almost a decade old, relatively recent process advances in their application have produced some remarkable success in utilizing their products as patterns for investment castings. Sandia National Laboratories has been developed highly coupled experimental and computational capabilities to examine the investment casting process with the intention of reducing the amount of time required to manufacture castings, and to increase the quality of the finished product. This presentation will begin with process aspects of RP and M pattern production and handling, shell fabrication, burnout, and casting. The emphasis will be on how the use of Stereolithography (SL) or Selective Laser Sintered (SLS) patterns differs from more traditional wax pattern processes. Aspects of computational simulation to couple design, thermal analysis, and mold filling will be discussed. Integration of these topics is probably the greatest challenge to the use of concurrent engineering principles with investment casting. Sandia has conducted several experiments aimed at calibrating computer codes and providing data for input into these simulations. Studies involving materials as diverse as stainless steel and gold have been conducted to determine liquid metal behavior in molds via real time radiography. The application of these experiments to predictive simulations will be described.

  9. Comparative analysis of constraints and caste differences in brain investment among social paper wasps

    PubMed Central

    O'Donnell, Sean; Clifford, Marie; Molina, Yamile

    2011-01-01

    We compared species mean data on the size of functionally distinct brain regions to test the relative rates at which investment in higher-order cognitive processing (mushroom body calyces) versus peripheral sensory processing (optic and antennal lobes) increased with increasing brain size. Subjects were eusocial paper wasps from queen and worker castes of 10 species from different genera. Relative investment in central processing tissue increased with brain size at a higher rate than peripheral structure investment, demonstrating that tissue devoted to higher-order cognitive processing is more constrained by brain size. This pattern held for raw data and for phylogenetically independent contrasts. These findings suggest that there is a minimum necessary investment in peripheral sensory processing brain tissue, with little to gain from additional investment. In contrast, increased brain size provides opportunities to invest in additional higher-order cognitive processing tissue. Reproductive castes differed within species in brain tissue investment, with higher central-to-peripheral brain tissue ratios in queens than in workers. Coupled with previous findings that paper wasp queen, but not worker, brain architecture corresponds to ecological and social variation, queen brain evolution appears to be most strongly shaped by cognitive demands, such as social interactions. These evolutionary patterns of neural investment echo findings in other animal lineages and have important implications, given that a greater investment in higher-order processing has been shown to increase the prevalence of complex and flexible behaviors across the animal kingdom. PMID:21482775

  10. Predicting Pattern Tooling and Casting Dimensions for Investment Casting, Phase II

    SciTech Connect

    Nick Cannell; Adrian S. Sabau

    2005-09-30

    The investment casting process allows the production of complex-shape parts and close dimensional tolerances. One of the most important phases in the investment casting process is the design of the pattern die. Pattern dies are used to create wax patterns by injecting wax into dies. The first part of the project involved preparation of reports on the state of the art at that time for all the areas under consideration (die-wax, wax-shell, and shell-alloy). The primary R&D focus during Phase I was on the wax material since the least was known about it. The main R&D accomplishments during this phase were determination of procedures for obtaining the thermal conductivity and viscoelastic properties of an unfilled wax and validating those procedures. Phase II focused on die-wax and shell-alloy systems. A wax material model was developed based on results obtained during the previous R&D phase, and a die-wax model was successfully incorporated into and used in commercial computer programs. Current computer simulation programs have complementary features. A viscoelastic module was available in ABAQUS but unavailable in ProCAST, while the mold-filling module was available in ProCAST but unavailable in ABAQUS. Thus, the numerical simulation results were only in good qualitative agreement with experimental results, the predicted shrinkage factors being approximately 2.5 times larger than those measured. Significant progress was made, and results showed that the testing and modeling of wax material had great potential for industrial applications. Additional R&D focus was placed on one shell-alloy system. The fused-silica shell mold and A356 aluminum alloy were considered. The experimental part of the program was conducted at ORNL and commercial foundries, where wax patterns were injected, molds were invested, and alloys were poured. It was very important to obtain accurate temperature data from actual castings, and significant effort was made to obtain temperature profiles in

  11. 3-Dimensional simulation of the grain formation in investment castings

    SciTech Connect

    Gandin, C.A.; Rappaz, M. ); Tintillier, R. . Dept. Materiaux et Procedes-Direction Technique)

    1994-03-01

    A 3-dimensional (3-D) probabilistic model which has been developed previously for the prediction of grain structure formation during solidification is applied to thin superalloy plates produced using the investment-casting process. This model considers the random nucleation and orientation of nuclei formed at the mold surface and in the bulk of the liquid, the growth kinetics of the dendrite tips, and the preferential growth directions of the dendrite trunks and arms. In the present study, the grains are assumed to nucleate at the surface of the mold only. The computed grain structures, as observed in 2-dimensional (2-D) sections made parallel to the mold surface, are compared with experimental micrographs. The grain densities are then deduced as a function of the distance from the mold surface for both the experiment and the simulation. It is shown that these values are in good agreement, thus, providing validation of the grain formation mechanisms built into the 3-D probabilistic model. Finally, this model is further extended to more complex geometries and the 3-D computed grain structure of an equiaxed turbine-blade airfoil is compared with the experimental transverse section micrograph.

  12. Development of a New Ferrous Aluminosilicate Refractory Material for Investment Casting of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Yuan, Chen; Jones, Sam; Blackburn, Stuart

    2012-12-01

    Investment casting is a time-consuming, labour intensive process, which produces complex, high value-added components for a variety of specialised industries. Current environmental and economic pressures have resulted in a need for the industry to improve current casting quality, reduce manufacturing costs and explore new markets for the process. Alumino-silicate based refractories are commonly used as both filler and stucco materials for ceramic shell production. A new ceramic material, norite, is now being produced based on ferrous aluminosilicate chemistry, having many potential advantages when used for the production of shell molds for casting aluminum alloy. This paper details the results of a direct comparison made between the properties of a ceramic shell system produced with norite refractories and a typical standard refractory shell system commonly used in casting industry. A range of mechanical and physical properties of the systems was measured, and a full-scale industrial casting trial was also carried out. The unique properties of the norite shell system make it a promising alternative for casting aluminum based alloys in the investment foundry.

  13. Investigation of Oxide Bifilms in Investment Cast Superalloy IN100: Part II. Characterization

    NASA Astrophysics Data System (ADS)

    Kaplan, Max A.; Fuchs, Gerhard E.

    2016-05-01

    Oxide bifilms are a proposed casting inclusion reported to have been observed in vacuum investment cast polycrystalline Ni-based superalloys. Ongoing research seeks to determine if current superalloy casting practices can result in the formation of oxide bifilms, and subsequently if it is possible to observe and characterize this phenomenon. The effect of casting atmosphere, turbulence, filtering, hot isostatic pressing, and heat treatment has been investigated to identify the critical parameters that have been reported to result in bifilm formation in Ni-based superalloy IN100. Scanning Auger microscopy (SAM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) were utilized to characterize samples from each casting condition. In situ ultrahigh vacuum Auger fractography did not indicate the presence of bifilms on the fracture behavior of IN100 in any processing condition. SAM analysis identified a sulfur-enriched monolayer on the surface of dendritic casting porosity, and identified heterogeneous Ti oxycarbide inclusions in air cast IN100. SEM analysis also indicated the presence of Ti oxycarbide inclusions in air cast IN100, and determined that these inclusion structures consist of fine blocky external M(Ti, Mo)C carbide enveloping an internal core of alumina. HR-TEM analysis indicated that none of the oxycarbide inclusion interfaces exist as discontinuous unbound interfaces, and that the internal alumina core is an ultra-fine polycrystalline structure.

  14. Investigation of Oxide Bifilms in Investment Cast Superalloy IN100: Part I. Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Fuchs, Gerhard E.; Kaplan, Max A.

    2016-05-01

    Oxide bifilms are a proposed casting inclusion reported to have been observed in vacuum investment cast polycrystalline Ni-based superalloys. Ongoing research seeks to determine if current superalloy casting practices can result in the formation of oxide bifilms, and subsequently if it is possible to observe and characterize this phenomenon. The effects of casting atmosphere, turbulence, filtering, hot isostatic pressing (HIP), and heat treatment have been investigated to identify the critical parameters that have been reported to result in bifilm formation in Ni-based superalloys. Room temperature tensile and room temperature fatigue testing are used to identify the effects of each casting and processing parameter on casting defect formation and the resultant effects on mechanical properties. Characterization of mechanical test specimens seeks to identify the role of casting defects and microstructural features on the fracture mechanisms of the specimen conditions analyzed, and in particular, evidence of bifilm formation and the chemical composition(s) of oxide bifilms. Analyzed tensile and fatigue data did not indicate an influence of bifilms on the tensile or fatigue strength of vacuum processed IN100. Bifilms were not observed, via the characterization methods utilized, to be an active mechanism in tensile or fatigue fracture.

  15. Surface modification of investment cast-316L implants: microstructure effects.

    PubMed

    El-Hadad, Shimaa; Khalifa, Waleed; Nofal, Adel

    2015-03-01

    Artificial femur stem of 316L stainless steel was fabricated by investment casting using vacuum induction melting. Different surface treatments: mechanical polishing, thermal oxidation and immersion in alkaline solution were applied. Thicker hydroxyapatite (HAP) layer was formed in the furnace-oxidized samples as compared to the mechanically polished ones. The alkaline treatment enhanced the precipitation of HAP on the samples. It was also observed that the HAP precipitation responded differently to the different phases of the microstructure. The austenite phase was observed to have more homogeneous and smoother layer of HAP. In addition, the growth of HAP was sometimes favored on the austenite phase rather than on ferrite phase.

  16. Investigation of an investment casting method combined with additive manufacturing methods for manufacturing lattice structures

    NASA Astrophysics Data System (ADS)

    Kodira, Ganapathy D.

    Cellular metals exhibit combinations of mechanical, thermal and acoustic properties that provide opportunities for various implementations and applications; light weight aerospace and automobile structures, impact and noise absorption, heat dissipation, and heat exchange. Engineered cell topologies enable one to control mechanical, thermal, and acoustic properties of the gross cell structures. A possible way to manufacture complex 3D metallic cellular solids for mass production with a relatively low cost, the investment casting (IC) method may be used by combining the rapid prototyping (RP) of wax or injection molding. In spite of its potential to produce mass products of various 3D cellular metals, the method is known to have significant casting porosity as a consequence of the complex cellular topology which makes continuous fluid's access to the solidification interface difficult. The effects of temperature on the viscosity of the fluids were studied. A comparative cost analysis between AM-IC and additive manufacturing methods is carried out. In order to manufacture 3D cellular metals with various topologies for multi-functional applications, the casting porosity should be resolved. In this study, the relations between casting porosity and processing conditions of molten metals while interconnecting with complex cellular geometries are investigated. Temperature and pressure conditions on the rapid prototyping -- investment casting (RP-IC) method are reported, thermal stresses induced are also studied. The manufactured samples are compared with those made by additive manufacturing methods.

  17. Process development of thin strip steel casting

    SciTech Connect

    Sussman, R.C.; Williams, R.S.

    1990-12-01

    An important new frontier is being opened in steel processing with the emergence of thin strip casting. Casting steel directly to thin strip has enormous benefits in energy savings by potentially eliminating the need for hot reduction in a hot strip mill. This has been the driving force for numerous current research efforts into the direct strip casting of steel. The US Department of Energy initiated a program to evaluate the development of thin strip casting in the steel industry. In earlier phases of this program, planar flow casting on an experimental caster was studied by a team of engineers from Westinghouse Electric corporation and Armco Inc. A subsequent research program was designed as a fundamental and developmental study of both planar and melt overflow casting processes. This study was arranged as several separate and distinct tasks which were often completed by different teams of researchers. An early task was to design and build a water model to study fluid flow through different designs of planar flow casting nozzles. Another important task was mathematically modeling of melt overflow casting process. A mathematical solidification model for the formation of the strip in the melt overflow process was written. A study of the material and conditioning of casting substrates was made on the small wheel caster using the melt overflow casting process. This report discusses work on the development of thin steel casting.

  18. Alloy Shrinkage factors for the investment casting of 17-4PH stainless steel parts

    SciTech Connect

    Sabau, Adrian S; Porter, Wallace D

    2008-01-01

    In this study, the alloy shrinkage factors were obtained for the investment casting of 17-4PH stainless steel parts. For the investment casting process, unfilled wax and fused silica with a zircon prime coat were used for patterns and shell molds, respectively. Dimensions of the die tooling, wax pattern, and casting were measured using a Coordinate Measurement Machine. For all the properties, the experimental data available in the literature did not cover the entire temperature range necessary for process simulation. A comparison between the predicted material property data measured property data is made. It was found that most material properties were accurately predicted over the most of the temperature range of the process. Several assumptions were made in order to obtain a complete set of mechanical property data at high temperatures. Thermal expansion measurements for the 17-4PH alloy were conducted at heating and cooling. As a function of temperature, the thermal expansion for both the alloy and shell mold materials showed different evolution at heating and cooling. Thus, one generic simulation were performed with thermal expansion obtained at heating and another one with thermal expansion obtained at cooling. The alloy dimensions were obtained from numerical simulation results of solidification, heat transfer, and deformation phenomena. As compared with experimental results, the numerical simulation results for the shrinkage factors were slightly over-predicted.

  19. Vacuum investment cast PH13-8Mo corrosion resistant steel. (SAE standard)

    SciTech Connect

    1991-07-01

    An industry-wide interest has arisen with regards to the properties and capabilities of investment cast PH 13-8Mo corrosion resistant steel. Specifically of interest are the structural applications in the aerospace industry for this product heat treated to the H1000 condition. The objective of this AMEC cooperative test program was to generate and compile useful data for aerospace structural evaluation of investment cast PH 13-8Mo heat treated to H1000. The determination was made of overall mechanical properties, fatigue, fracture toughness, and crack growth data along with basic microstructural evaluation of the investment cast material. The evaluation of mechanical property variations between cast and machined tensile specimens and evaluation of microstructural constituents. PH 13-8Mo, H1000 investment castings for use in the aerospace industry is included.

  20. Characterization of oxide bifilms and nonmetallic inclusions in investment cast superalloy IN100

    NASA Astrophysics Data System (ADS)

    Kaplan, Max A.

    Oxide bifilms are a proposed casting inclusion reported to have been observed in vacuum investment cast polycrystalline Ni-base superalloys. This investigation seeks to determine if current superalloy casting methods can result in the formation of oxide bifilms, and subsequently if it is possible to observe and characterize this phenomenon. The effect of casting atmosphere, turbulence, filtering, HIP, and heat treatment have been investigated to identify the critical parameters that may result in bifilm formation in Ni-based superalloy IN100. Bifilms have been reported to impact mechanical behavior and fracture characteristics of cast superalloys, therefore tensile and fatigue testing was used in an effort to identify the effects of each casting and processing parameter on bifilm formation. Characterization of mechanical test specimens sought to identify the role of bifilms in the fracture mechanics of the conditions utilized, as well as the prevalence of bifilm formation and the chemical composition(s) of oxide bifilms. The characterization methods used were SEM, EDS, SAM, AES, STEM, BF-TEM, and HR-TEM. Tensile and fatigue test data did not indicate an influence of bifilms on the mechanical behavior of IN100, however there was a considerable impact due to the formation of Ti oxycarbide inclusions. Statistical analysis confirmed that vacuum and argon cast material under conditions expected to cause abundant bifilm formation exhibit no measurable debit to mechanical properties as compared to conditions anticipated to prevent/remediate bifilms. Bifilms were not identified during metallographic characterization or fractographic analysis of mechanical test specimens. In-situ ultrahigh vacuum Auger fractography also did not indicate the presence of bifilms in the fracture behavior of IN100 in any processing condition. However, a sulfur-enriched monolayer has been identified on the surface of dendritic casting porosity, as characterized by Auger analysis. Metallographic

  1. Microscopy analysis of dental titanium casting investment materials

    SciTech Connect

    Mueller, H.J. )

    1989-09-01

    Scanning electron microscopy (SEM) analysis and qualitative energy dispersive x-ray microanalysis (EDS) of investment materials for dental titanium casting were performed. Two commercial investment materials, Ohara and Castmatic, and an experimental zirconia material were analyzed. The microstructural constituents and the unfired and fired structures were included. Larger refractory particles and matrix embedding smaller particles were observed with each material. Detection of aluminum, silicon, magnesium, zirconium and oxygen provided a basis to reason the presence of alumina (Al2O3), silica (SiO2), magnesia (MgO), and zirconia (ZrO2). Hence, Ohara contained quartz and an alumino-silicate, Castmatic contained magnesia and quartz and experimental zirconia contained zirconia and an alumino-silicate, taken to be kyanite, as components providing refractoriness and expansion. Even though unequivocal detection of phosphorous in the spectra for Ohara was not obtained (P K alpha = 2.013 keV; Zr L alpha = 2.042 keV), an emission peak at 2.0 keV was taken to be due to P and related, along with MgO, to bonding by magnesium phosphate. For Castmatic, unfired strength was thought to be due to calcium chloride and calcium silicate and fired strength to forsterite, (2MgO.SiO2). Detection of calcium and chlorine also suggested bonding of experimental zirconia via calcium chloride. Extensive microcracking occurred around refractory particles and through matrix in experimental zirconia which is likely to have resulted from the firing of kyanite to 1400 degrees C, to the monoclinic to tetragonal transformation of any unstabilized ZrO2, or to the thermal expansion mismatch between kyanite and matrix.

  2. Rapid tooling for functional prototyping of metal mold processes: Literature review on cast tooling

    SciTech Connect

    Baldwin, M.D.; Hochanadel, P.W.

    1995-11-01

    This report is a literature review on cast tooling with the general focus on AISI H13 tool steel. The review includes processing of both wrought and cast H13 steel along with the accompanying microstructures. Also included is the incorporation of new rapid prototyping technologies, such as Stereolithography and Selective Laser Sintering, into the investment casting of tool steel. The limiting property of using wrought or cast tool steel for die casting is heat checking. Heat checking is addressed in terms of testing procedures, theories regarding the mechanism, and microstructural aspects related to the cracking.

  3. [Thermoanalytical studies on gypsum- and phosphate-bonded casting investments].

    PubMed

    Fuchs, P; Henning, G; Springer, O

    1975-09-01

    The two test series were carried out with the dilatometer TMA 500 (of Haereus company). The measurements for thermic expansion are easily reproducible, not so for setting expansion. The recorded setting expansion values are identical with the manufacturers' data given for Luster Cast, Aurovest, and Deguvest HFG, among the thermic expansion values only those for Luster Cast are in line with the data given; the values given for Bayer DC are most different from those we found.

  4. The improvement of aluminium casting process control by application of the new CRIMSON process

    NASA Astrophysics Data System (ADS)

    Dai, X.; Jolly, M.; Zeng, B.

    2012-07-01

    All The traditional foundry usually not only uses batch melting where the aluminium alloys are melted and held in a furnace for long time, but also uses the gravity filling method in both Sand Casting Process (SCP) and Investment Casting Process (ICP). In the gravity filling operation, the turbulent behaviour of the liquid metal causes substantial entrainment of the surface oxide films which are subsequently trapped into the liquid and generate micro cracks and casting defects. In this paper a new CRIMSON process is introduced which features instead of gravity filling method, using the single shot up-casting method to realize the rapid melting and rapid filling mould operations which reduce the contact time between the melt and environment thus reducing the possibility of defect generation. Another advantage of the new process is the drastic reduction of energy consumption due to shortened melting and filling time. Two types of casting samples from SCP and ICP were compared with the new process. The commercial software was used to simulate the filling and solidification processes of the casting samples. The results show that the new process has a more improved behaviour during filling a mould and solidification than the two conventional casting processes.

  5. Computational mechanics applied to the design and analysis of investment casting

    SciTech Connect

    Gartling, D.K.; Givler, R.C.; Glass, M.W.; Hogan, R.E.; Rashid, M.M.

    1992-11-01

    Computational mechanics simulation capability via the finite element method is being integrated into the FASTCAST project to allow realistic analyses of investment casting problems. Commercial and in-house software is being coupled to new, solid model based mesh generation capabilities to provide improved access to fluid, thermal and structural simulations. These simulations are being used for the validation of complex gating designs and the study of fundamental problems in casting.

  6. Effect of impression material on surface reactive layer when casting pure titanium in phosphate investment.

    PubMed

    Komasa, Y; Moriguchi, A; Asai, M; Nezumi, M; Kakimoto, K; Gonda, Y

    1998-10-01

    We evaluated the effect of impression materials used in preparation of pure titanium castings on the surface reactive layer. Surface roughness of the refractory models before and after firing was smaller when silicone rather than agar impression material was used. The surface roughness of castings prepared with T-invest varied little with the impression material. However, the surface roughness of the castings prepared with CD Titaninvest was less when silicone impression material was used. Surface hardness of the castings was slightly greater when agar impression material was used, and metallic texture analysis of the surface of the castings showed a chill layer and a columnar crystal layer extending from the surface toward the interior. A relatively non-corroded white layer and a markedly corroded black layer were observed in the chill layer, and their thickness was smaller when silicone impression material was used. Use of the Electron Probe Micro Analyzer (EPMA) to determine distribution of various elements in the superficial layer of the casting plates showed that the reactive layer contained less P and Si when silicone impression material was used rather than agar. NH4H2 PO4, which is a component of the bonding material in the investment, was present at a high concentration in the superficial layer of the agar impression material. This shows the importance of preparing refractory models with a non-water-absorbing impression material to obtain pure titanium casting plates with a smaller reactive layer.

  7. Investigation of rapid freeze prototyping and investment casting with ice patterns

    NASA Astrophysics Data System (ADS)

    Liu, Qingbin

    Rapid Freeze Prototyping (RFP) can generate three-dimensional ice patterns from CAD models by depositing and solidifying water droplets layer by layer. The waiting time between two successive layers is a critical factor. Finite Element Analysis (FEA) is employed to predict the solidification time of a newly deposited water layer in order to develop a better understanding of heat transfer during the RFP process. The result is used to investigate the effects of various process parameters on the solidification time of an ice column and a vertical ice wall. Experiments are conducted and the measured results are shown to agree well with simulation results. Investment casting with ice patterns is similar to that with wax patterns but with significant process differences. An interface agent can be coated around the ice pattern to protect it from damage during the process. To compensate for the thickness of the interface agent, analytical models have been constructed to predict the thickness of the interface agent for a large ice cylinder and for a small ice part. The dimensional accuracy of the generated metal castings for small parts can be much improved by compensating the interface layer thickness. Due to the use of ice, canned models must be made at sub-freezing temperatures. Success of this process depends significantly on curing kinetics of the slurries and the fracture toughness of mold materials. The curing kinetics of the slurries and mold material fracture toughness from different compositions are examined and the effects of various processing parameters on the results are examined and discussed.

  8. Gating geometry studies of thin-walled 17-4PH investment castings

    SciTech Connect

    Maguire, M.C.; Zanner, F.J.

    1992-01-01

    The ability to design gating systems that reliably feed and support investment castings is often the result of cut-and-try'' methodology. Factors such as hot tearing, porosity, cold shuts, misruns, and shrink are defects often corrected by several empirical gating design iterations. Sandia National Laboratories is developing rules that aid in removing the uncertainty involved in the design of gating systems for investment castings. In this work, gating geometries used for filling of thin walled investment cast 17-4PH stainless steel flat plates were investigated. A full factorial experiment evaluating the influence of metal pour temperature, mold preheat temperature, and mold channel thickness were conducted for orientations that filled a horizontal flat plate from the edge. A single wedge gate geometry was used for the edge-gated configuration. Thermocouples placed along the top of the mold recorded metal front temperatures, and a real-time x-ray imaging system tracked the fluid flow behavior during filling of the casting. Data from these experiments were used to determine the terminal fill volumes and terminal fill times for each gate design.

  9. Gating geometry studies of thin-walled 17-4PH investment castings

    SciTech Connect

    Maguire, M.C.; Zanner, F.J.

    1992-11-01

    The ability to design gating systems that reliably feed and support investment castings is often the result of ``cut-and-try`` methodology. Factors such as hot tearing, porosity, cold shuts, misruns, and shrink are defects often corrected by several empirical gating design iterations. Sandia National Laboratories is developing rules that aid in removing the uncertainty involved in the design of gating systems for investment castings. In this work, gating geometries used for filling of thin walled investment cast 17-4PH stainless steel flat plates were investigated. A full factorial experiment evaluating the influence of metal pour temperature, mold preheat temperature, and mold channel thickness were conducted for orientations that filled a horizontal flat plate from the edge. A single wedge gate geometry was used for the edge-gated configuration. Thermocouples placed along the top of the mold recorded metal front temperatures, and a real-time x-ray imaging system tracked the fluid flow behavior during filling of the casting. Data from these experiments were used to determine the terminal fill volumes and terminal fill times for each gate design.

  10. Mould design and casting process improvement on vibrator shell

    NASA Astrophysics Data System (ADS)

    Zhang, Lipan; Fang, Ligao; Chen, Zhong; Song, Kai

    2011-12-01

    Vibrator shell is a part with complex structure. While the vibrator shell is designed and manufactured by traditional sand casting process, more than 80% castings are found the defects of porosity, shrinkage and pouring-shortage at the top. Aiming to the problems in traditional sand casting, this paper focused on the improvement of castings structure and the optimization of casting process. Designing process bar in the gate-channel region which is connected with the gate in castings is used to improve the castings structure, and low speed filling and solidification under high pressure are adopted to optimize the casting process which is finished by self-made four-column type hydraulic machine equipped. It can be seen that the castings quality can be greatly improved by process improvement.

  11. The Impact of Ceramic Shell Strength on Hot Tearing during Investment Casting

    SciTech Connect

    Norouzi, Saeid; Farhangi, Hassan

    2011-01-17

    The effect of ceramic shell strength on hot tearing susceptibility during solidification was inspected practicing investment casting of the cobalt-base superalloy samples with the same casting conditions, but different ceramic shell systems. Results showed that the lower the ceramic shell strength upon using polymer additives, the lower the hindered contraction rate, and the lower the hindered contraction rate, the smaller the hot tearing tendency. Optical microscopy and electron microscopy scanning revealed that the hot tear propagated along the last solidified interdendritic phase, and that the hot tear surface had two major modes: (1) the ductile region in the outer layer; and (2) the inner region of liquid embrittlement.

  12. Process for slip casting textured tubular structures

    DOEpatents

    Steinlage, Greg A.; Trumble, Kevin P.; Bowman, Keith J.

    2002-01-01

    A process for centrifugal slip casting a textured hollow tube. A slip made up of a carrier fluid and a suspended powder is introduced into a porous mold which is rotated at a speed sufficient to create a centrifugal force that forces the slip radially outward toward the inner surface of the mold. The suspended powder, which is formed of particles having large dimensional aspect ratios such as particles of superconductive BSCCO, settles in a textured fashion radially outward toward the mold surface. The carrier fluid of the slip passes by capillary action radially outward around the settled particles and into the absorbent mold. A layer of mold release material is preferably centrifugally slip cast to cover the mold inner surface prior to the introduction of the BSCCO slip, and the mold release layer facilitates removal of the BSCCO greenbody from the mold without fracturing.

  13. Application of Rapid Prototyping to the Investment Casting of Test Hardware (MSFC Center Director's Discretionary Fund Final Report, Project No. 98-08)

    NASA Technical Reports Server (NTRS)

    Cooper, K. G.; Wells, D.

    2000-01-01

    Investment casting masters of a selected propulsion hardware component, a fuel pump housing, were rapid prototyped on the several processes in-house, along with the new Z-Corp process acquired through this project. Also, tensile samples were prototyped and cast using the same significant parameters. The models were then shelled in-house using a commercial grade zircon-based slurry and stucco technique. Next, the shelled models were fired and cast by our in-house foundry contractor (IITRI), with NASA-23, a commonly used test hardware metal. The cast models are compared by their surface finish and overall appearance (i.e., the occurrence of pitting, warping, etc.), as well as dimensional accuracy.

  14. The effect of microstructure on the thermal fatigue resistance of investment cast and wrought AISI H13 hot work die steel

    SciTech Connect

    Hochanadel, P.W.; Edwards, G.R.; Maguire, M.C.; Baldwin, M.D.

    1995-07-01

    Variable thickness plate investment castings of AISI H13 hot work die steel were pour and characterized in the as-cast and heat treated conditions. The characterization included light microscopy and mechanical testing. Wrought samples of standard and premium grade H13 steel were heat treated and characterized similarly for comparison. Microstructural differences were observed in as-cast samples poured to different section thicknesses. Dendrite cell size and carbide morphology constituted the most prominent microstructural differences observed. After a full heat treatment, however, Microstructural differences between the wrought material and cast materials were slight regardless of section thickness. The mechanical properties of the cast and heat treated material proved similar to the properties of the standard heat treated wrought material. A thermal fatigue testing unit was designed and built to correlate the heat checking susceptibility of AISI H13 steel to its processing and consequent microstructural condition. Surface hardness decreased significantly with thermal cycling, and heat checking was noticed in as few as 50 cycles. Thermal softening and thermal fatigue susceptibility were quantified and discussed relative to the microstructural conditions created by processing and heat treatment. It was found that the premium grade wrought H13 steel provided the best overall resistance to heat checking; however, the heat-treat cast and as-cast H13 tool steel (made from standard grade wrought H13 tool steel) provided comparable resistance to heat checking in terms Of area fraction of heat checking and maximum crack length.

  15. Soda-lime glass as a binder in reusable experimental investment for dental castings.

    PubMed

    Yagi, Satoshi; Zhang, Zutai; Aida, Yoshiteru; Hotta, Yasuhiro; Tamaki, Yukimichi; Miyazaki, Takashi

    2011-01-01

    In this study, different glasses were investigated to improve reusable investments. Borosilicate glass (BSG) powder and soda-lime glass (SLG) powder were prepared by milling broken beakers and microscope slides, respectively, and used in experimental investments (I-BSG, I-SLG) by blending glass powder (10 wt%) with cristobalite (90 wt%). Some properties and casting fits were evaluated with commercial gypsum-bonded investment as the control. Both BSG and SLG were mainly composed of Si, but SLG had a large Ca content. The glass transition temperatures were approximately 800°C (BSG) and 700°C (SLG). Experimental investments with heating showed the significantly (p<0.05) higher expansion than that of the control. The compressive strength of I-SLG was higher than that of I-BSG, and increased with temperature. The MOD inlay obtained from I-SLG had a significantly smaller gap than that from I-BSG, and was comparable to the control. These results suggest SLG could be applied clinically as a reusable dental investment.

  16. Casting process modeling using ProCAST and CAST2D

    SciTech Connect

    Shapiro, A.; Stein, W.; Raboin, P.

    1990-12-01

    Correctly modeling the fluid flow and heat transfer during the filling of a mold with a molten metal, and the thermal-mechanical physics of solidification and cooldown is important in predicting the quality of a cast part. Determining the dynamics of the flow and the free surface shape during filling are essential in establishing the temperature gradients in the melt and in the mold. Correctly modeling the physics of volume change on solidification, shrinkage on cooling, and contact resistance across the part-mold interface directly affects the cooling rate and ultimately the final cast shape and stress state of the cast part. In this paper we describe our current research efforts on modeling fluid fill using the commercial code ProCAST by UES, and thermal-mechanical solidification modeling using the code CAST2D by LLNL.

  17. Casting process modeling using CAST2D: The part mold interface

    SciTech Connect

    Shapiro, A.B.

    1991-10-01

    Correctly modeling the physics across the part-mold interface is crucial in predicting the quality of a cast part. Most metals undergo a volume change on solidification (e.g., aluminum -6.6%) and shrinkage on cooling. As the cast metal shrinks, it pulls away from the mol wall creating a gap. This gap effects the thermal contact resistance between the part and mold. The thermal contact resistance increase as the gap widens. This directly effects the cooling rate and ultimately the final cast shape, stress state, and quality of the cast part. CAST2D is a coupled thermal-stress finite element computer code for casting process modeling. This code can be used to predict the final shape and stress state of cast parts. CAST2D couples the heat transfer code TOPAZ2D and solid mechanics code NIKE2D. CAST2D is a code in development. This report presents the status of a general purpose thermal-mechanical interface algorithm. 3 refs., 3 figs.

  18. Cryogenic Fracture Toughness Evaluation of an Investment Cast Al-Be Alloy for Structural Applications

    NASA Technical Reports Server (NTRS)

    Gamwell, W. R.; McGill, P. B.

    2006-01-01

    Aluminum-Beryllium metal matrix composite materials are useful due to their desirable performance characteristics for aerospace applications. Desirable characteristics of this material includes light-weight, dimensional stability, stiffness, good vibration damping characteristics, low coefficient of thermal expansion, and workability, This material is 3.5 times stiffer and 22% lighter than conventional aluminum alloys. electro-optical systems, advanced sensor and guidance components for flight and satellite systems, components for light-weight high-performance aircraft engines, and structural components for helicopters. Aluminum-beryllium materials are now available in the form of near net shape investment castings. In this materials properties characterization study, the cryogenic tensile and fracture properties of an investment casting alloy, Beralcast 363, were determined. Tensile testing was performed at 21 C (70 F), -73.3 C (-100 F), -195.5 C (-320 F) and -252.8 C (-423 F), and fracture (K(sub lc) and da/dN) testing was performed at -73.3 C (-100 F), -195.5 C (-320 F) and -252.8 C (-423 F). Their use is attractive for weight critical structural applications such as advanced

  19. Marginal accuracy of nickel chromium copings fabricated by conventional and accelerated casting procedures, produced with ringless and metal ring investment procedures: A comparative in vitro study

    PubMed Central

    Alex, Deepa; Shetty, Y. Bharath; Miranda, Glynis Anita; Prabhu, M. Bharath; Karkera, Reshma

    2015-01-01

    Background: Conventional investing and casting techniques are time-consuming and usually requires 2–4 h for completion. Accelerated nonstandard, casting techniques have been reported to achieve similar quality results in significantly less time, namely, in 30–40 min. During casting, it is essential to achieve compensation for the shrinkage of solidifying alloy by investment expansion. The metal casting ring restricts the thermal expansion of investment because the thermal expansion of the ring is lesser than that of the investment. The use of casting ring was challenged with the introduction of the ringless technique. Materials and Methods: A total of 40 test samples of nickel chromium (Ni-Cr) cast copings were obtained from the patterns fabricated using inlay casting wax. The 20 wax patterns were invested using metal ring and 20 wax patterns were invested using the ringless investment system. Of both the groups, 10 samples underwent conventional casting, and the other 10 underwent accelerated casting. The patterns were casted using the induction casting technique. All the test samples of cast copings were evaluated for vertical marginal gaps at four points on the die employing a stereo optical microscope. Results: The vertical marginal discrepancy data obtained were tabulated. Mean and standard deviations were obtained. Vertical discrepancies were analyzed using analysis of variance and Tukey honestly significantly different. The data obtained were found to be very highly significant (P < 0.001). Mean vertical gap was the maximum for Group II (53.64 μm) followed by Group IV (47.62 μm), Group I (44.83 μm) and Group III (35.35 μm). Conclusion: The Ni-Cr cast copings fabricated with the conventional casting using ringless investment system showed significantly better marginal fit than that of cast copings fabricated from conventional and accelerated casting with metal ring investment and accelerated casting using ringless investment since those copings had

  20. CAST2D: A finite element computer code for casting process modeling

    SciTech Connect

    Shapiro, A.B.; Hallquist, J.O.

    1991-10-01

    CAST2D is a coupled thermal-stress finite element computer code for casting process modeling. This code can be used to predict the final shape and stress state of cast parts. CAST2D couples the heat transfer code TOPAZ2D and solid mechanics code NIKE2D. CAST2D has the following features in addition to all the features contained in the TOPAZ2D and NIKE2D codes: (1) a general purpose thermal-mechanical interface algorithm (i.e., slide line) that calculates the thermal contact resistance across the part-mold interface as a function of interface pressure and gap opening; (2) a new phase change algorithm, the delta function method, that is a robust method for materials undergoing isothermal phase change; (3) a constitutive model that transitions between fluid behavior and solid behavior, and accounts for material volume change on phase change; and (4) a modified plot file data base that allows plotting of thermal variables (e.g., temperature, heat flux) on the deformed geometry. Although the code is specialized for casting modeling, it can be used for other thermal stress problems (e.g., metal forming).

  1. Phosphate-bonded ZrSiO4 investments added with ZrC and ZrN for casting titanium.

    PubMed

    Takahashi, Junzo; Kitahara, Kazuyoshi; Kubo, Fuminobu

    2004-09-01

    In this study, new investments for titanium were developed by adding ZrC or ZrN as chemical additive for thermal expansion to a phosphate-bonded zircon (ZrSiO4) investment. The following effects were then examined: setting expansion, residual thermal expansion, and compressive strength of these experimental investments; surface roughness of cast plate; and casting accuracy of titanium crown. For residual thermal expansion, it occurred even while investments were cooled to room temperature after firing in air atmosphere. This was due to the additives' oxidation to ZrO2--suggesting that residual thermal expansion increased with increased amount of these additives. As for casting accuracy of full-crown cast into molds at room temperature, it correlated with the ZrN content. Hence by adding the right amount of ZrN, cast titanium crowns with low surface roughness and good adaptability could be obtained. PMID:15510859

  2. Hanford's Simulated Low Activity Waste Cast Stone Processing

    SciTech Connect

    Kim, Young

    2013-08-20

    Cast Stone is undergoing evaluation as the supplemental treatment technology for Hanford’s (Washington) high activity waste (HAW) and low activity waste (LAW). This report will only cover the LAW Cast Stone. The programs used for this simulated Cast Stone were gradient density change, compressive strength, and salt waste form phase identification. Gradient density changes show a favorable outcome by showing uniformity even though it was hypothesized differently. Compressive strength exceeded the minimum strength required by Hanford and greater compressive strength increase seen between the uses of different salt solution The salt waste form phase is still an ongoing process as this time and could not be concluded.

  3. Development of a thin steel strip casting process. Final report

    SciTech Connect

    Williams, R.S.

    1994-04-01

    This is a comprehensive effort to develop direct strip casting to the point where a pilot scale program for casting carbon steel strip could be initiated. All important aspects of the technology were being investigated, however the program was terminated early due to a change in the business strategy of the primary contractor, Armco Inc. (focus to be directed at specialty steels, not low carbon steel). At termination, the project was on target on all milestones and under budget. Major part was casting of strip at the experiment casting facility. A new caster, capable of producing direct cast strip of up to 12 in. wide in heats of 1000 and 3000 lb, was used. A total of 81 1000-1200 lb heats were cast as well as one test heat of 3000 lb. Most produced strip of from 0.016 to 0.085 in. thick. Process reliability was excellent for short casting times; quality was generally poor from modern hot strip mill standards, but the practices necessary for good surface quality were identified.

  4. Molten metal processing of advanced cast aluminum alloys

    NASA Astrophysics Data System (ADS)

    Shivkumar, S.; Wang, L.; Apelian, D.

    1991-01-01

    Premium quality aluminum alloy castings are used extensively in various applications requiring a high strength-to-weight ratio, such as aerospace, automotive and other structural components. The mechanical properties in these structure-sensitive alloys are determined primarily by the secondary dendrite arm spacing and the morphology of interdendritic phases. In addition, the amount of porosity in the casting and the inclusion concentration have a strong influence on fracture, fatigue and impact properties. During the production of the casting, various molten metal processing techniques can be implemented to control these microstructural parameters. These melt treatments include grain refinement with Ti-B, eutectic modification with strontium or sodium, degassing with purge gases and filtration of inclusions. The efficiency of these treatments determines the quality of the cast component.

  5. [Application of gypsum-bonded investment containing niobium carbide on casting of alloy for metal-ceramic restoration].

    PubMed

    Tsuruta, S; Ban, S; Hasegawa, J; Hayashi, S; Iiyama, K; Yamamura, Y

    1990-07-01

    Experimental gypsum-bonded investments containing 0.5-5.0 wt% NbC were prepared by mechanical mixing of each powder. Setting and thermal expansion measurement, compressive strength and casting accuracy for Ni-Cr alloy for metal-ceramic restoration were investigated. Analysis of NbC during heating was carried out by X-ray diffraction, TG-DTA and SEM. NbC was oxidized to Nb2O5 with a volume change between 300-600 degrees C, as in the following equation: 2NbC + 4 1/2O2----Nb2O5 + 2CO2 The theoretical volume of 1/2Nb2O5 calculated from the lattice constants according to JCPDS file was approximately 4 times larger than that of NbC. The experimental investments of 70 wt% cristobalite and 30 wt% gypsum containing 2.0, 3.0 and 5.0 wt% NbC showed large thermal expansion of 7.0, 10.0 and 13.0% respectively. The investment containing 2.0 wt% NbC showed nearly the same casting accuracy for Ni-Cr alloys for metal-ceramic restoration as the commercial phosphate-bonded investment.

  6. Process to Continuously Melt, Refine and Cast High Quality Steel

    SciTech Connect

    2005-09-01

    The purpose of this project is to conduct research and development targeted at designing a revolutionary steelmaking process. This process will deliver high quality steel from scrap to the casting mold in one continuous process and will be safer, more productive, and less capital intensive to build and operate than conventional steelmaking. The new process will produce higher quality steel faster than traditional batch processes while consuming less energy and other resources.

  7. Process improvement as an investment: Measuring its worth

    NASA Technical Reports Server (NTRS)

    Mcgarry, Frank; Jeletic, Kellyann

    1993-01-01

    This paper discusses return on investment (ROI) generated from software process improvement programs. It details the steps needed to compute ROI and compares these steps from the perspective of two process improvement approaches: the widely known Software Engineering Institute's capability maturity model and the approach employed by NASA's Software Engineering Laboratory (SEL). The paper then describes the specific investments made in the SEL over the past 18 years and discusses the improvements gained from this investment by the production organization in the SEL.

  8. Prototype casting fabrication by stereolithography

    SciTech Connect

    Cromwell, W.E.

    1992-03-01

    The evolution of the new technology of producing CAD models by ultraviolet solidification of resin materials (``STEREOLITHOGRAPHY``) continues to progress. The potential application area of rigid fabrication of prototype investment castings is becoming more feasible as we continue to successfully yield experimental castings by the ``SHELL`` processing method. This supplemental (to 11/90 publication) report briefly reviews the original project objectives, activities related to these objectives since November 1990, and progress made through December 1991. We discuss several new case studies involving new resin materials (and other materials) tested along with investment casting processing results. The most recent success, the processing of the highly complex ``C`` HOUSING design by the ``shell`` mold process in both aluminum and steel, will be discussed. This is considered a major breakthrough toward establishing this new technology as a viable approach to the rapid development of prototype investment castings, employing the most common aerospace (precision) cast process. Our future planning calls for expanding the study to help the investment casting industry in refining related processing techniques and to continue our evaluation of new resins suitable for the casting process. Present project planning calls for the completion of this study by the third quarter FY93 or sooner. We believe that with the continued excellent cooperation of our casting supplier study team and an accelerated effort by resin materials producers to further refine related materials, we can achieve all objectives during the planned time frame.

  9. Prototype casting fabrication by stereolithography

    SciTech Connect

    Cromwell, W.E.

    1992-03-01

    The evolution of the new technology of producing CAD models by ultraviolet solidification of resin materials ( STEREOLITHOGRAPHY'') continues to progress. The potential application area of rigid fabrication of prototype investment castings is becoming more feasible as we continue to successfully yield experimental castings by the SHELL'' processing method. This supplemental (to 11/90 publication) report briefly reviews the original project objectives, activities related to these objectives since November 1990, and progress made through December 1991. We discuss several new case studies involving new resin materials (and other materials) tested along with investment casting processing results. The most recent success, the processing of the highly complex C'' HOUSING design by the shell'' mold process in both aluminum and steel, will be discussed. This is considered a major breakthrough toward establishing this new technology as a viable approach to the rapid development of prototype investment castings, employing the most common aerospace (precision) cast process. Our future planning calls for expanding the study to help the investment casting industry in refining related processing techniques and to continue our evaluation of new resins suitable for the casting process. Present project planning calls for the completion of this study by the third quarter FY93 or sooner. We believe that with the continued excellent cooperation of our casting supplier study team and an accelerated effort by resin materials producers to further refine related materials, we can achieve all objectives during the planned time frame.

  10. AMCC casting development, volume 2

    NASA Technical Reports Server (NTRS)

    1995-01-01

    PCC successfully cast and performed nondestructive testing, FPI and x-ray, on seventeen AMCC castings. Destructive testing, lab analysis and chemical milling, was performed on eleven of the castings and the remaining six castings were shipped to NASA or Aerojet. Two of the six castings shipped, lots 015 and 016, were fully processed per blueprint requirements. PCC has fully developed the gating and processing parameters of this part and feels the part could be implemented into production, after four more castings have been completed to ensure the repeatability of the process. The AMCC casting has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or thermal gradient control. This method of setting up thermal gradients in the casting during solidification represents a significant process improvement for PCC and has been successfully implemented on other programs. The alloy, JBK75, is a relatively new alloy in the investment casting arena and required our engineering staff to learn the gating, processing, and dimensional characteristics of the material.

  11. Characterization of Spray Lubricants for the Die Casting Process

    SciTech Connect

    Sabau, Adrian S

    2008-01-01

    During the die casting process, lubricants are sprayed in order to cool the dies and facilitate the ejection of the casting. The cooling effects of the die lubricant were investigated using Thermogravimetric analysis (TGA), heat flux sensors (HFS), and infrared imaging. The evolution of the heat flux and pictures taken using a high speed infrared camera revealed that lubricant application was a transient process. The short time response of the HFS allows the monitoring and data acquisition of the surface temperature and heat flux without additional data processing. A similar set of experiments was performed with deionized water in order to assess the lubricant effect. The high heat flux obtained at 300 C was attributed to the wetting and absorbant properties of the lubricant. Pictures of the spray cone and lubricant flow on the die were also used to explain the heat flux evolution.

  12. Lab experiments on the innovative rapid thick strip casting process

    NASA Astrophysics Data System (ADS)

    Nagy, Richard; Senk, Dieter

    2012-05-01

    Rapid thick strip casting (RTSC) by Anton Hulek, Inventmetall®, is an innovative concept for the production of hot strips with a final as-cast thickness of about 25 mm before rolling. The innovation of the mechanism consists in a vertical mould performing a caterpillar motion. This moving mould has an unconventional parallelogram-shaped cross-section. The conventional rectangular shape is formed in the shaping machine, which is placed straight below the mould. Further elements of the technology are state-of-the-art. For the investigation of this new casting system theoretical calculations were complemented with practical experiments. The investigation focused mainly on two key aspects: the characteristics of the mould and the shaping process. For the practical analysis a static mould with three pairs of elements in laboratory scale was developed and commissioned by the Dept. of Ferrous Metallurgy @ RWTH Aachen University. The shaping experiments were carried out in model scale with two different materials and in variable boundary conditions. The results of these experiments delivered important mechanical as well as thermal informations about the casting system.

  13. Process modelings and simulations of heavy castings and forgings

    NASA Astrophysics Data System (ADS)

    Li, Dianzhong; Sun, Mingyue; Wang, Pei; Kang, Xiuhong; Fu, Paixian; Li, Yiyi

    2013-05-01

    The Materials Process Modeling Division, IMR, CAS has been promoting for more than 10 years research activities on modeling and experimental studies on heavy castings and forgings. In this report, we highlight some selected achievements and impacts in this area: To satisfy domestic strategic requirements, such as nuclear and hydraulic power, marine projects and high speed rail, we have developed a number of casting and forging technologies, which combine advanced computing simulations, X-ray real time observation techniques and industrial-scaled trial experiments. These technologies have been successfully applied in various industrial areas and yielded a series of scientific and technological breakthroughs and innovation. Important examples of this strategic research include the hot-processing technologies of the Three Gorge water turbine runner, marine crankshaft manufacturers, backup rolls for hot rolling mills and the production of hundreds-ton steel ingot.

  14. Liquid Metal Processing and Casting Experiences at the U.S. Department of Energy's Albany Research Center

    SciTech Connect

    Jablonski, Paul D.; Turner, Paul C.

    2005-09-01

    In this paper we will discuss some of the early pioneering work as well as some of our more recent research. The Albany Research Center (ARC) has been involved with the melting and processing of metals since it was established in 1942. In the early days, hardly anything was known about melting refractory or reactive metals and as such, virtually everything had to be developed in-house. Besides the more common induction heated air-melt furnaces, ARC has built and/or utilized a wide variety of furnaces including vacuum arc remelt ingot and casting furnaces, cold wall induction furnaces, electric arc furnaces, cupola furnaces and reverberatory furnaces. The melt size of these furnaces range from several grams to a ton or more. We have used these furnaces to formulate custom alloys for wrought applications as well as for such casting techniques as spin casting, investment casting and lost foam casting among many. Two early spin-off industrializations were Wah Chang (wrought zirconium alloys for military and commercial nuclear applications) and Oremet (both wrought and cast Ti). Both of these companies are now part of the ATI Allegheny Ludlum Corporation.

  15. Investigation on the Interface Characteristics of Al/Mg Bimetallic Castings Processed by Lost Foam Casting

    NASA Astrophysics Data System (ADS)

    Jiang, Wenming; Li, Guangyu; Fan, Zitian; Wang, Long; Liu, Fuchu

    2016-05-01

    The lost foam casting (LFC) process was used to prepare the A356 aluminum and AZ91D magnesium bimetallic castings, and the interface characteristics of the reaction layer between aluminum and magnesium obtained by the LFC process were investigated in the present work. The results indicate that a uniform and compact interface between the aluminum and magnesium was formed. The reaction layer of the interface with an average thickness of approximately 1000 μm was mainly composed of Al3Mg2 and Al12Mg17 intermetallic compounds, including the Al3Mg2 layer adjacent to the aluminum insert, the Al12Mg17 middle layer, and the Al12Mg17 + δ eutectic layer adjacent to the magnesium base. Meanwhile, the Mg2Si intermetallic compound was also detected in the reaction layer. An oxide film mainly containing C, O, and Mg elements generated at the interface between the aluminum and magnesium, due to the decomposed residue of the foam pattern, the oxidations of magnesium and aluminum alloys as well as the reaction between the magnesium melt and the aluminum insert. The microhardness tests show that the microhardnesses at the interface were obviously higher than those of the magnesium and aluminum base metals, and the Al3Mg2 layer at the interface had a high microhardness compared with the Al12Mg17 and Al12Mg17 + δ eutectic layers, especially the eutectic layer.

  16. Casting process modeling using ProCAST and CAST2D -- Mold filling, solidification and structural response

    SciTech Connect

    Stein, W.; Shapiro, A.B.

    1992-04-01

    Correctly modeling the fluid flow and heat transfer during the filling of a mold with a molten fluid is important in predicting the quality of a cast part. Determining the dynamics of the flow and the free surface shape during filling are essential in establishing the temperature gradients in the melt and in the mold. After filling the mold, solidification may be greatly affected by natural convection effects. Further, correctly modeling the physics across the solidifying part-mold interface is crucial in predicting the part final shape. Most metals undergo a volume change on solidification (e.g. aluminum-6.6%) and shrinkage on cooling. As the cast metal shrinks, it pulls away from the mold wall creating a gap. This gap affects the thermal contact resistance between the part and mold. The thermal contact resistance increases as the gap widens. This directly affects the cooling rate and ultimately the final cast shape, stress state, and quality of the cast part.

  17. Minimization of Macrosegregation in DC Cast Ingots Through Jet Processing

    NASA Astrophysics Data System (ADS)

    Wagstaff, Samuel R.; Allanore, Antoine

    2016-10-01

    With an increase in demand for aluminum alloys, industrial suppliers are seeking to increase the size and speed of casting processes. Unfortunately operating the existing Direct-Chill (DC) process in such conditions tends to enhance metallurgical defects. Perhaps the most recognized of these defects is macrosegregation, whose effects are permanent once the material is solidified. In order to facilitate the expansion of the DC process without increasing the presence of macrosegregation, a novel jet mixing method to distribute the liquid metal is presented. The governing equations for this process are derived and the operating parameters necessary to minimize the centerline macrosegregation are predicted. The results of commercial-scale tests are presented, validating the predictive equations and performance of this process.

  18. Minimization of Macrosegregation in DC Cast Ingots Through Jet Processing

    NASA Astrophysics Data System (ADS)

    Wagstaff, Samuel R.; Allanore, Antoine

    2016-06-01

    With an increase in demand for aluminum alloys, industrial suppliers are seeking to increase the size and speed of casting processes. Unfortunately operating the existing Direct-Chill (DC) process in such conditions tends to enhance metallurgical defects. Perhaps the most recognized of these defects is macrosegregation, whose effects are permanent once the material is solidified. In order to facilitate the expansion of the DC process without increasing the presence of macrosegregation, a novel jet mixing method to distribute the liquid metal is presented. The governing equations for this process are derived and the operating parameters necessary to minimize the centerline macrosegregation are predicted. The results of commercial-scale tests are presented, validating the predictive equations and performance of this process.

  19. Vacuum forming of thermoplastic sheet results in low-cost investment casting patterns

    NASA Technical Reports Server (NTRS)

    Clarke, A. E., Jr.

    1964-01-01

    Vacuum forming of a sheet of thermoplastic material around a mandrel conforming to the shape of the finished object provides a pattern for an investment mold. The thickness of the metal part is determined by the thickness of the plastic pattern.

  20. Investment casting using multi-jet modelling patterns: the thermogravimetric analysis of visijet® SR200 UV curable acrylate plastic

    NASA Astrophysics Data System (ADS)

    Hafsa, M. N.; Ibrahim, M.; Sharif, S.

    2013-12-01

    Rapid Prototyping (RP) technology is actively studied to be implemented in Investment Casting (IC) process. Nowadays RP techniques are studied for their feasibility as IC master patterns, in terms of pattern collapsibility and drainage during burnout. The purpose of the study is to determine the characteristic of Visijet® SR200 acrylate material during burnout process. Traditional IC patterns made from wax have properties that limit their application in precision casting, especially for parts with thin geometries that readily break or deform when handled or dipped in the refractory slurry. Furthermore, it is not economical when producing a small number of parts. Non wax patterns fabricated for IC process, revealed ceramic shell cracking due to excessive thermal expansions, incomplete collapsibility of pattern during burnout, residual ash and poor surface finish. Thermogravimetric analysis (TGA) was used to measured the weight loss of acrylate material as the temperature was increased. TGA measured the change of material's mass as it is heated. It represents the decomposition temperature after being subjected to varying temperatures, as well as the amount of residual ash. In this experiment, the temperature range was from 20°C to 700°C with 5°C increment. Experiment results show the values of material's optimum reaction temperature and decomposing temperature of Visijet® SR200 acrylate. The percentages of remaining materials were also monitored throughout the process to obtain the amount of residual ash. All of the temperature values obtained is a resemblance for the actual burnout process and can be used as references.

  1. Composite Materials Processing of Cast Iron and Ceramics Using Compo-Casting Technology

    NASA Astrophysics Data System (ADS)

    Tomita, Yoshihiro; Sumimoto, Haruyoshi

    The compo-casting technology of ceramics and cast iron is expected to be one of the major casting technologies that can expand the application fields of cast iron. This technique allows the heat energy of the molten metal to be utilized to produce cast iron products which are added with functions of ceramic materials. The largest problem in compo-casting technology is generation of cracks caused by thermal shock. Although this crack generation can be prevented by reducing the thermal stress by means of preheating ceramics, the necessary preheating temperature is considerably high and its precise controlling is difficult at the practical foundry working sites. In this study, we tried to numerically predict the critical preheating temperature of ceramics using the thermal stress analysis in unsteady heat transfer and the Newman's diagram, and found that the preheating of ceramics to reduce thermal stress could be substituted with placing an appropriate cast iron cover around the ceramics. Excellent results were obtained by using a method whereby a ceramic bar was covered with a flake graphite cast iron cover and fixed in a sand mold and then molten metal was poured. Then, two or three ceramics were examined at the same time under the compocasting condition. As a result, three specimens could be done at the same time by adjusting the cover space to 15mm. Moreover, irregular shape ceramics were examined under the compocasting condition. As a result, the compocasting could be done by devising the cover shape. In each condition, it was confirmed that the cover shape made from the analytical result was effective to the compocasting by doing the thermometry of the specimens.

  2. Engineering scale demonstration of a prospective Cast Stone process

    SciTech Connect

    Cozzi, A.; Fowley, M.; Hansen, E.; Fox, K.; Miller, D.; Williams, M.

    2014-09-30

    This report documents an engineering-scale demonstration with non-radioactive simulants that was performed at SRNL using the Scaled Continuous Processing Facility (SCPF) to fill an 8.5 ft container with simulated Cast Stone grout. The Cast Stone formulation was chosen from the previous screening tests. Legacy salt solution from previous Hanford salt waste testing was adjusted to correspond to the average composition generated from the Hanford Tank Waste Operation Simulator (HTWOS). The dry blend materials, ordinary portland cement (OPC), Class F fly ash, and ground granulated blast furnace slag (GGBFS or BFS), were obtained from Lafarge North America in Pasco, WA. Over three days, the SCPF was used to fill a 1600 gallon container, staged outside the facility, with simulated Cast Stone grout. The container, staged outside the building approximately 60 ft from the SCPF, was instrumented with x-, y-, and z-axis thermocouples to monitor curing temperature. The container was also fitted with two formed core sampling vials. For the operation, the targeted grout production rate was 1.5 gpm. This required a salt solution flow rate of approximately 1 gpm and a premix feed rate of approximately 580 lb/h. During the final day of operation, the dry feed rate was increased to evaluate the ability of the system to handle increased throughput. Although non-steady state operational periods created free surface liquids, no bleed water was observed either before or after operations. The final surface slope at a fill height of 39.5 inches was 1-1.5 inches across the 8.5 foot diameter container, highest at the final fill point and lowest diametrically opposed to the fill point. During processing, grout was collected in cylindrical containers from both the mixer discharge and the discharge into the container. These samples were stored in a humid environment either in a closed box proximal to the container or inside the laboratory. Additional samples collected at these sampling points

  3. Thermal casting process for the preparation of membranes

    DOEpatents

    Caneba, G.T.M.; Soong, D.S.

    1985-07-10

    Disclosed is a method for providing anisotropic polymer membrane from a binary polymer/solvent solution using a thermal inversion process. A homogeneous binary solution is cast onto a support and cooled in such a way as to provide a differential in cooling rate across the thickness of the resulting membrane sheet. Isotropic or anisotropic structures of selected porosities can be produced, depending on the initial concentration of polymer in the selected solvent and on the extent of the differential in cooling rate. This differential results in a corresponding gradation in pore size. The method may be modified to provide a working skin by applying a rapid, high-temperature pulse to redissolve a predetermined thickness of the membrane at one of its faces and then freezing the entire structure.

  4. Through process numerical simulation of a heavy hydro turbine blade casting

    NASA Astrophysics Data System (ADS)

    Kang, J. W.; Wang, T. J.; Y Huang, T.; Liu, B. C.

    2012-07-01

    Heavy Hydro turbine castings, made of martensitic stainless steel, of spatially twisted shape, are susceptible to deformation during both casting and heat treatment processes. During production, uneven heating and cooling, phase transformation, stress and stain are responsible for the deformation of castings. However, the current research most focus on casting process or heat treatment process or both but separately, martensitic phase transformation is usually neglected in casting process. In this paper, a coupled thermo-martensitic phase transformation-stress model is established. And it is implemented by secondary development of ABAQUS, which deals the finite element model change and incorporates multi thermal and mechanical boundaries during casting and heat treatment processes as well, such as the contact pair between casting and mold during casting process. The stress analysis of a heavy hydro blade casting was performed by this system. The stress, displacement and phase are obtained. The effect of martensitic phase transformation on the stress and deformation is discussed. The simulated deformation is compared with measured results, and their agreement is improved by the through process simulation.

  5. Heat treatment of investment cast PH 13-8 Mo stainless steel: Part I. Mechanical properties and microstructure

    NASA Astrophysics Data System (ADS)

    Hochanadel, P. W.; Edwards, G. R.; Robino, C. V.; Cieslak, M. J.

    1994-04-01

    The microstructure of investment cast PH 13-8 Mo stainless steel heat-treated to various conditions was studied using light and electron microscopy, electron probe microanalysis, and Mössbauer spectroscopy. The mechanical properties were investigated by using uniaxial tensile testing, hardness testing, and Charpy impact testing. The Β-NiAl strengthening precipitates, though detectable by electron diffraction, were difficult to resolve by transmission electron microscopy (TEM) in specimens aged at low temperatures (566 °C and below). A high dislocation density was observed in the lath martensitic structure. The higher strength and lower ductility observed at low aging temperatures was attributed to both the high dislocation density and the precipitation of Β-NiAl. When samples were aged at high temperatures (> 566 °C), a lower dislocation density and a reverted austenite fraction on the order of 15 pct were observed. Spherical Β-NiAl precipitates were observed in the overaged condition. The decrease in strength and corresponding increase in ductility observed in samples aged at temperatures above 566 °C were attributed to the reverted austenite and recovery. Mechanical properties were improved when the homogenizing temperature and time were increased. Electron probe microanalysis quantified the increased homogeneity realized by increasing homogenizing temperature and time. Elimination of the refrigeration step, which normally follows the solution treatment, did not degrade the mechanical properties. Mössbauer spectroscopy showed only minor decreases in the fraction of retained austenite when refrigeration followed the solution treatment.

  6. Software Analytical Instrument for Assessment of the Process of Casting Slabs

    SciTech Connect

    Franek, Zdenek; Kavicka, Frantisek; Stetina, Josef; Masarik, Milos

    2010-06-15

    The paper describes the original proposal of ways of solution and function of the program equipment for assessment of the process of casting slabs. The program system LITIOS was developed and implemented in EVRAZ Vitkovice Steel Ostrava on the equipment of continuous casting of steel (further only ECC). This program system works on the data warehouse of technological parameters of casting and quality parameters of slabs. It enables an ECC technologist to analyze the course of casting melt and with using statistics methods to set the influence of single technological parameters on the duality of final slabs. The system also enables long term monitoring and optimization of the production.

  7. Heat treatment of investment cast PH 13-8 Mo stainless steel: Part II. Isothermal aging kinetics

    NASA Astrophysics Data System (ADS)

    Robino, C. V.; Cieslak, M. J.; Hochanadel, P. W.; Edwards, G. R.

    1994-04-01

    The hardening response of investment cast PH 13-8 Mo stainless steel has been evaluated by hardness measurements following aging in the temperature range normally specified for this alloy (510 °C to 593 °C). A new relationship between fraction transformed and hardness was developed, and analysis of the data in terms of the kinetics of precipitation, in a manner similar to that frequently applied to other precipitation-hardenable martensitic steels, yielded low time exponents and a low value for the apparent activation energy. The values of the time exponents were 0.49, 0.37, 0.56, and 0.53 at 510 °C, 538 °C, 566 °C, and 593 °C, respectively, and that for the apparent activation energy was 139 kJ/mole. As has been proposed for other maraging type steels, these estimates suggest that Β-NiAl precipitates along or near dislocations and that growth of the precipitates is dominated by dislocation pipe diffusion. However, these predictions were neither supported nor refuted by transmission electron microscopy (TEM) because of difficulties in imaging the Β-NiAl precipitates at the aging times and temperatures used. Further, analysis of the data using the formalism of Wert and Zener for the growth of precipitates with interfering diffusion fields indicated that the estimates of fraction transformed from hardness data are not fully appropriate for maraging type steels. Consideration of the nature of the Avrami analysis and the electron microscopy results suggests that other phenomena, including dislocation recovery and reversion of martensite to austenite, occur at rates sufficient to convolute the Avrami analysis. It is further suggested that these results cast doubt on the fundamental implications of previous analyses of precipitation kinetics in age-hardening martensitic steels. Although the Avrami analysis was found not to provide a tenable description of the precipitation kinetics, it does provide a reasonable methodology for portrayal of the hardening response

  8. Report of Separate Effects Testing for Modeling of Metallic Fuel Casting Process

    SciTech Connect

    Crapps, Justin M.; Galloway, Jack D.; Decroix, David S.; Korzekwa, David A.; Aikin, Robert M. Jr.; Unal, Cetin; Fielding, R.; Kennedy, R

    2012-06-29

    In order to give guidance regarding the best investment of time and effort in experimental determination of parameters defining the casting process, a Flow-3D model of the casting process was used to investigate the most influential parameters regarding void fraction of the solidified rods and solidification speed for fluid flow parameters, liquid heat transfer parameters, and solid heat transfer parameters. Table 1 summarizes the most significant variables for each of the situations studied. A primary, secondary, and tertiary effect is provided for fluid flow parameters (impacts void fraction) and liquid heat transfer parameters (impacts solidification). In Table 1, the wetting angle represents the angle between the liquid and mold surface as pictured in Figure 1. The viscosity is the dynamic viscosity of the liquid and the surface tension is the property of the surface of a liquid that allows it to resist an external force. When only considering solid heat transfer properties, the variations from case to case were very small. Details on this conclusion are provided in the section considering solid heat transfer properties. The primary recommendation of the study is to measure the fluid flow parameters, specifically the wetting angle, surface tension, and dynamic viscosity, in order of importance, as well as the heat transfer parameters latent heat and specific heat of the liquid alloy. The wetting angle and surface tension can be measured simultaneously using the sessile drop method. It is unclear whether there is a temperature dependency in these properties. Thus measurements for all three parameters are requested at 1340, 1420, and 1500 degrees Celsius, which correspond to the minimum, middle, and maximum temperatures of the liquid alloy during the process. In addition, the heat transfer coefficient between the mold and liquid metal, the latent heat of transformation, and the specific heat of the liquid metal all have strong influences on solidification. These

  9. The application of quality criteria for the prediction of porosity in the design of casting processes

    SciTech Connect

    Viswanathan, S.; Sikka, V.K.; Brody, H.D.

    1993-12-31

    Solidification parameters calculated from temperature measurements and experimentally determined distributions of porosity in gain- refined Al-4.5% Cu alloy castings are linked to provide quality criteria for the prediction of porosity in the computer-aided design and analysis of casting processes. The quality criteria applicable to a particular casting process are dependent on the thermal conditions and the solidification mode of the alloy. Accordingly, casting processes and alloy types are divided into four groups according to whether porosity distribution is dominated by liquid transport, dendrite structure, or bubble pressure, and a different set of quality criteria is obtained for each group. Results from test castings of Al-4.5% Cu alloy cast in a variety of configurations and mold media are used to develop models and extract quality criteria. The results obtained on Al-4.5% Cu alloy are tested on data on Al-7% Si-0.3% Mg alloy castings reported in the literature. The results show that the quality criteria developed for USSR Cu alloy are also applicable to other alloy systems. The procedure for applying quality criteria for the prediction of microporosity distributions in commercial casting processes is outlined.

  10. The application of quality criteria for the prediction of porosity in the design of casting processes

    SciTech Connect

    Viswanathan, S.; Sikka, V.K. ); Brody, H.D. . School of Engineering)

    1993-01-01

    Solidification parameters calculated from temperature measurements and experimentally determined distributions of porosity in gain- refined Al-4.5% Cu alloy castings are linked to provide quality criteria for the prediction of porosity in the computer-aided design and analysis of casting processes. The quality criteria applicable to a particular casting process are dependent on the thermal conditions and the solidification mode of the alloy. Accordingly, casting processes and alloy types are divided into four groups according to whether porosity distribution is dominated by liquid transport, dendrite structure, or bubble pressure, and a different set of quality criteria is obtained for each group. Results from test castings of Al-4.5% Cu alloy cast in a variety of configurations and mold media are used to develop models and extract quality criteria. The results obtained on Al-4.5% Cu alloy are tested on data on Al-7% Si-0.3% Mg alloy castings reported in the literature. The results show that the quality criteria developed for USSR Cu alloy are also applicable to other alloy systems. The procedure for applying quality criteria for the prediction of microporosity distributions in commercial casting processes is outlined.

  11. Numerical simulation of the solidification processes of copper during vacuum continuous casting

    NASA Astrophysics Data System (ADS)

    Tsai, D. C.; Hwang, W. S.

    2012-03-01

    A numerical simulation method is used to analyze the microstructure evolution of 8-mm-diameter copper rods during the vacuum continuous casting (VCC) process. The macro-microscopic coupling method is adopted to develop a temperature field model and a microstructure prediction model. The effects of casting parameters, including casting speed, pouring temperature, cooling rate, and casting dimension on the location and shape of the solid-liquid (S/L) interface and solidified microstructure are considered. Simulation results show that the casting speed has a large effect on the position and shape of the S/L interface and grain morphology. With an increase of casting speed, the shape of the S/L interface changes from a planar shape into an elliptical shape or a narrow, pear shape, and the grain morphology indicates a change from axial growth to axial-radial growth or completely radial growth. The simulation predictions agree well with the microstructure observations of cast specimens. Further analysis of the effects of other casting parameters on the position and shape of the S/L interface reveals that the casting dimension has more influence on the position and shape of the S/L interface and grain morphology than do pouring temperature and cooling rate. The simulation results can be summarized to obtain a discriminant of shape factor (η), which defines the shape of the S/L interface and grain morphology.

  12. Multiscale Modeling and Simulation of Directional Solidification Process of Turbine Blade Casting with MCA Method

    NASA Astrophysics Data System (ADS)

    Xu, Qingyan; Zhang, Hang; Qi, Xiang; Liu, Baicheng

    2014-04-01

    Nickel-based superalloy turbine blade castings are widely used as a key part in aero engines. However, due to the complex manufacturing processes, the complicated internal structure, and the interaction between different parts of the turbine blade, casting defects, such as stray grains, often happen during the directional solidification of turbine blade castings, which causes low production yield and high production cost. To improve the quality of the directionally solidified turbine blade castings, modeling and simulation technique has been employed to study the microstructure evolution as well as to optimize the casting process. In this article, a modified cellular automaton (MCA) method was used to simulate the directional solidification of turbine blade casting. The MCA method was coupled with macro heat transfer and micro grain growth kinetics to simulate the microstructure evolution during the directional solidification. In addition, a ray tracing method was proposed to calculate the heat transfer, especially the heat radiation of multiple blade castings in a Bridgman furnace. A competitive mechanism was incorporated into the grain growth model to describe the grain selection behavior phenomena of multiple columnar grains in the grain selector. With the proposed models, the microstructure evolution and related defects could be simulated, while the processing parameters optimized and the blade casting quality guaranteed as well. Several experiments were carried out to validate the proposed models, and good agreement between the simulated and experimental results was achieved.

  13. Numerical simulation of casting process to assist in defects reduction in complex steel tidal power component

    NASA Astrophysics Data System (ADS)

    Guo, E. J.; Zhao, S. C.; Wang, L. P.; Wu, T.; Xin, B. P.; Tan, J. J.; Jia, H. L.

    2016-03-01

    In order to reduce defects and improve casting quality, ProCAST software is performed to study the solidification process of discharge bowl. Simulated results of original casting process show that the hot tearing is serious at the intersection of blades and outer or inner rings. The shrinkage porosity appears at the bottom of discharge bowl and the transition area of wall thickness. Based on the formation mechanisms of the defects, the structure of chills attached on the outer surface of discharge bowl casting is optimized. The thickness of chills ranges from 25mm to 35mm. The positions of chills corresponded to the outer surface of the T-shaped parts. Compared to the original casting design (without chills), the hot tearing and shrinkage porosity of the discharge bowl are greatly improved with addition of chills.

  14. Multiphysics modeling of the steel continuous casting process

    NASA Astrophysics Data System (ADS)

    Hibbeler, Lance C.

    This work develops a macroscale, multiphysics model of the continuous casting of steel. The complete model accounts for the turbulent flow and nonuniform distribution of superheat in the molten steel, the elastic-viscoplastic thermal shrinkage of the solidifying shell, the heat transfer through the shell-mold interface with variable gap size, and the thermal distortion of the mold. These models are coupled together with carefully constructed boundary conditions with the aid of reduced-order models into a single tool to investigate behavior in the mold region, for practical applications such as predicting ideal tapers for a beam-blank mold. The thermal and mechanical behaviors of the mold are explored as part of the overall modeling effort, for funnel molds and for beam-blank molds. These models include high geometric detail and reveal temperature variations on the mold-shell interface that may be responsible for cracks in the shell. Specifically, the funnel mold has a column of mold bolts in the middle of the inside-curve region of the funnel that disturbs the uniformity of the hot face temperatures, which combined with the bending effect of the mold on the shell, can lead to longitudinal facial cracks. The shoulder region of the beam-blank mold shows a local hot spot that can be reduced with additional cooling in this region. The distorted shape of the funnel mold narrow face is validated with recent inclinometer measurements from an operating caster. The calculated hot face temperatures and distorted shapes of the mold are transferred into the multiphysics model of the solidifying shell. The boundary conditions for the first iteration of the multiphysics model come from reduced-order models of the process; one such model is derived in this work for mold heat transfer. The reduced-order model relies on the physics of the solution to the one-dimensional heat-conduction equation to maintain the relationships between inputs and outputs of the model. The geometric

  15. Advances in multi-scale modeling of solidification and casting processes

    NASA Astrophysics Data System (ADS)

    Liu, Baicheng; Xu, Qingyan; Jing, Tao; Shen, Houfa; Han, Zhiqiang

    2011-04-01

    The development of the aviation, energy and automobile industries requires an advanced integrated product/process R&D systems which could optimize the product and the process design as well. Integrated computational materials engineering (ICME) is a promising approach to fulfill this requirement and make the product and process development efficient, economic, and environmentally friendly. Advances in multi-scale modeling of solidification and casting processes, including mathematical models as well as engineering applications are presented in the paper. Dendrite morphology of magnesium and aluminum alloy of solidification process by using phase field and cellular automaton methods, mathematical models of segregation of large steel ingot, and microstructure models of unidirectionally solidified turbine blade casting are studied and discussed. In addition, some engineering case studies, including microstructure simulation of aluminum casting for automobile industry, segregation of large steel ingot for energy industry, and microstructure simulation of unidirectionally solidified turbine blade castings for aviation industry are discussed.

  16. PREFACE: MCWASP XIV: International Conference on Modelling of Casting, Welding and Advanced Solidification Processes

    NASA Astrophysics Data System (ADS)

    Yasuda, H.

    2015-06-01

    The current volume represents contributed papers of the proceedings of the 14th international conference on ''Modeling of Casting, Welding and Advanced Solidification Processes (MCWASP XIV)'', Yumebutai International Conference Center, Awaji island, Hyogo, Japan on 21 - 26 June, 2016. The first conference of the series 'Modeling of Casting, Welding and Advanced Solidification Processes (MCWASP)' was started up in 1980, and this is the 14th conference. The participants are more than 100 scientists from industry and academia, coming from 19 countries. In the conference, we have 5 invited, 70 oral and 31 poster presentations on different aspects of the modeling. The conference deals with various casting processes (Ingot / shape casting, continuous casting, direct chill casting and welding), fundamental phenomena (nucleation and growth, dendritic growth, eutectic growth, micro-, meso- and macrostructure formation and defect formation), coupling problems (electromagnetic interactions, application of ultrasonic wave), development of experimental / computational methods and so on. This volume presents the cutting-edge research in the modeling of casting, welding and solidification processes. I would like to thank MAGMA Giessereitechnologie GmbH, Germany and SCSK Corporation, Japan for supporting the publication of contributed papers. Hideyuki Yasuda Conference Chairman Department of Materials Science and Engineering, Kyoto University Japan

  17. Thermo-mechanical phenomena in high speed continuous casting processes

    NASA Astrophysics Data System (ADS)

    Park, Joong Kil

    Thermo-mechanical phenomena during continuous thin slab casting have been studied with the objectives of understanding the mechanism of mold crack formation, and the effect of mold design upon the mechanical behavior of the stand. To achieve these goals, several finite element models have been developed in conjunction with a series of industrial plant trials. First, an investigation of mold crack formation in thin slab casting was undertaken to elucidate the mechanism by which cracks develop and to evaluate possible solutions to the problem. Three-dimensional finite-element thermal-stress models were developed to predict temperature, distortion, and residual stress in thin-slab casting molds, comparing funnel-shaped to parallel molds. Mold wall temperatures were obtained from POSCO in Korea and analyzed to determine the corresponding heat-flux profiles in thin-slab molds. This data was utilized in an elastic-visco-plastic analysis to investigate the deformation of the molds in service for the two different mold shapes. The results of a metallurgical investigation of mold samples containing cracks were used together with the results of the mathematical models, to determine mechanisms and to suggest solutions for the formation of mold cracks. Large cyclic inelastic strains were found in the funnel transition region just below the meniscus, due to the slightly higher temperature at that location. The cracks appear to have propagated by thermal fatigue caused by major level fluctuations. Next, two-dimensional thermo-elastic-visco-plastic analysis was performed for a horizontal slice of the solidifying strand, which moves vertically down the mold during casting. The model calculates the temperature distributions, the stresses and the strains in the solidifying shell, and the air gap between the casting mold and the solidifying strand. Model predictions were verified with an analytical solution and plant trials that were carried out during billet casting at POSCO. The

  18. The increase in use of isostatic processing for aluminum alloy castings

    SciTech Connect

    Geaman, V.

    1996-12-31

    The castings industry originally perceived isostatic processing as a means of reducing scrap rates. Prior to the development of HIP`ing no other non-destructive technique was available which let to improved economics. However in recent years the emphasis has changed towards the exploitation of improved properties as design engineers realize that cast parts which have been HIP`d can develop capabilities similar to those of forged components. This paper presents experimental data regarding compaction during HIP and CIP processes, applied to various aluminum castings alloys which are used extensively in the Romanian automotive industry.

  19. Computational modeling of structure of metal matrix composite in centrifugal casting process

    NASA Astrophysics Data System (ADS)

    Zagórski, Roman

    2007-04-01

    The structure of alumina matrix composite reinforced with crystalline particles obtained during centrifugal casting process are studied. Several parameters of cast process like pouring temperature, temperature, rotating speed and size of casting mould which influent on structure of composite are examined. Segregation of crystalline particles depended on other factors such as: the gradient of density of the liquid matrix and reinforcement, thermal processes connected with solidifying of the cast, processes leading to changes in physical and structural properties of liquid composite are also investigated. All simulation are carried out by CFD program Fluent. Numerical simulations are performed using the FLUENT two-phase free surface (air and matrix) unsteady flow model (volume of fluid model — VOF) and discrete phase model (DPM).

  20. Wireless accelerometer network for process monitoring during mold forming in lost foam casting

    NASA Astrophysics Data System (ADS)

    Whelan, Matthew J.; Janoyan, Kerop D.

    2006-03-01

    Lost Foam Casting (LFC) enables the production of complex castings while offering the advantages of consolidation of components, reduced machining, and recirculation of the casting mold material. In the process, a replica of the desired product is produced of blown polystyrene, coated in refractory slurry, and cast in a dense, unbonded sand mold. In order for the unbonded sand mold to fill into pattern holes and to provide sufficient confining force to prevent the advancing molten front from penetrating beyond the mold boundaries, the sand mold is produced by an overhead raining and flask vibration schedule that encourages fluidization and subsequent densification. The amplitude, frequency, and duration of the flask vibration as well as the rate of sand filling are critical parameters in achieving quality castings. Currently, many foundries use an often-lengthy trial-and-error process for determining an acceptable raining and vibration schedule for each specific mold and rely heavily on simple measurements and operator experience to control the mold making process on the foundry line. This study focuses on developing a wireless sensor network of accelerometers to monitor vibrational characteristics of the casting flask during the mold making stage of LFC. Transformations in the vibrational characteristics of the flask can provide a "signature" for indicating the condition of the unbonded sand mold. Additionally, the wireless nature of the sensor nodes enables the technology to travel across the foundry floor during the casting cycle eliminating the necessity of routine placement and setup.

  1. Materials processing threshold report: 2. Use of low gravity for cast iron process development

    NASA Technical Reports Server (NTRS)

    Frankhouser, W. L.

    1980-01-01

    Potential applications of a low gravity environment of interest to the commercial producers of cast iron were assessed to determine whether low gravity conditions offer potential opportunities to producers for improving cast iron properties and expanding the use of cast irons. The assessment is limited to the gray and nodular types of iron, however, the findings are applicable to all cast irons. The potential advantages accrued through low gravity experiments with cast irons are described.

  2. A Thermal Simulation Method for Solidification Process of Steel Slab in Continuous Casting

    NASA Astrophysics Data System (ADS)

    Zhong, Honggang; Chen, Xiangru; Han, Qingyou; Han, Ke; Zhai, Qijie

    2016-07-01

    Eighty years after the invention of continuous cast of steels, reproducibility from few mm3 samples in the laboratory to m3 product in plants is still a challenge. We have engineered a thermal simulation method to simulate the continuous casting process. The temperature gradient (G L ) and dendritic growth rate (v) of the slab were reproduced by controlling temperature and cooling intensity at hot and chill end, respectively, in our simulation samples. To verify that our samples can simulate the cast slab in continuous casting process, the heat transfer, solidification structure, and macrosegregation of the simulating sample were compared to those of a much larger continuous casting slab. The morphology of solid/liquid interface, solidified shell thickness, and dendritic growth rate were also investigated by in situ quenching the solidifying sample. Shell thickness (δ) determined by our quenching experiment was related to solidification time (τ) by equation: δ = 4.27 × τ 0.38. The results indicated that our method closely simulated the solidification process of continuous casting.

  3. A Thermal Simulation Method for Solidification Process of Steel Slab in Continuous Casting

    NASA Astrophysics Data System (ADS)

    Zhong, Honggang; Chen, Xiangru; Han, Qingyou; Han, Ke; Zhai, Qijie

    2016-10-01

    Eighty years after the invention of continuous cast of steels, reproducibility from few mm3 samples in the laboratory to m3 product in plants is still a challenge. We have engineered a thermal simulation method to simulate the continuous casting process. The temperature gradient ( G L ) and dendritic growth rate ( v) of the slab were reproduced by controlling temperature and cooling intensity at hot and chill end, respectively, in our simulation samples. To verify that our samples can simulate the cast slab in continuous casting process, the heat transfer, solidification structure, and macrosegregation of the simulating sample were compared to those of a much larger continuous casting slab. The morphology of solid/liquid interface, solidified shell thickness, and dendritic growth rate were also investigated by in situ quenching the solidifying sample. Shell thickness ( δ) determined by our quenching experiment was related to solidification time ( τ) by equation: δ = 4.27 × τ 0.38. The results indicated that our method closely simulated the solidification process of continuous casting.

  4. Evaluation of Interfacial Interactions Between Ti-6Al-4V and Mold Use Ti-Added Backup Coat in Investment Casting

    NASA Astrophysics Data System (ADS)

    Cheng, Xu; Chai, Lianjing; Wu, Guoqing; Wang, Hong; Nan, Hai

    2016-05-01

    In this article, the chemical inertness of shell using Ti-added mullite backup coat against molten Ti-6Al-4V (Ti64) alloy was investigated. The metal/shell interfacial microstructures and compositions were characterized using an optical microscope, scanning electron microscope, roughness tester, and X-ray diffractometer; the hardened layer thickness was evaluated using a microhardness tester. By adding titanium powder into the mullite backup coat, the alpha case and hardened layer thickness of the Ti64 castings were largely reduced with good surface finishing. Silicon ions, from the backup coat, penetrated into the alloy and coarsened the β lath at the metal/shell interfacial area. The Ti powder in the mullite backup coat oxidized and interacted with silica during mold firing and casting, which reduced the silicon and oxygen concentrations at the metal/shell interfacial area. The oxygen penetration depth is thicker than the alpha case layer thickness, and around 0.26 wt pct, oxygen can obviously coarsen the alpha lath at the metal/shell interfacial area during investment casting.

  5. Influence of the casting processing route on the corrosion behavior of dental alloys.

    PubMed

    Galo, Rodrigo; Rocha, Luis Augusto; Faria, Adriana Claudia; Silveira, Renata Rodrigues; Ribeiro, Ricardo Faria; de Mattos, Maria da Gloria Chiarello

    2014-12-01

    Casting in the presence of oxygen may result in an improvement of the corrosion performance of most alloys. However, the effect of corrosion on the casting without oxygen for dental materials remains unknown. The aim of this study was to investigate the influence of the casting technique and atmosphere (argon or oxygen) on the corrosion behavior response of six different dental casting alloys. The corrosion behavior was evaluated by electrochemical measurements performed in artificial saliva for the different alloys cast in two different conditions: arc melting in argon and oxygen-gas flame centrifugal casting. A slight decrease in open-circuit potential for most alloys was observed during immersion, meaning that the corrosion tendency of the materials increases due to the contact with the solution. Exceptions were the Co-based alloys prepared by plasma, and the Co-Cr-Mo and Ni-Cr-4Ti alloys processed by oxidized flame, in which an increase in potential was observed. The amount of metallic ions released into the artificial saliva solution during immersion was similar for all specimens. Considering the pitting potential, a parameter of high importance when considering the fluctuating conditions of the oral environment, Co-based alloys show the best performance in comparison with the Ni-based alloys, independent of the processing route.

  6. Technical development of double-clad process for thin strip casting of carbon steel

    SciTech Connect

    Brown, H.L.; Forkel, C.E.; Knudson, D.L.

    1984-08-01

    This report documents the technical development for a patent disclosure of a double-clad process for the continuous casting of thin-strip carbon steel. The fundamental idea of the disclosure is to form a product strip by depositing molten steel between two, cooled, clad strips of the same material. The claimed benefits include: (a) the conservation of energy in steel making through the elimination of soaking pits and reheat cycles, and (b) an improved surface on both sides of the as-cast product such that it will be suitable for direct feed to a cold-reduction mill. However, the process as conceived is not necessarily limited to the casting of carbon steel, but may be also applied to other metals and alloys. The work is described under three headings as follows. Preliminary Considerations and Scoping Analysis presents the basic idea of the double-clad, thin-strip casting process; the energy conservation potential; scoping heat transfer calculations for the casting process; and independent review of this work. Thermal Analysis for Roller Configuration of Double-Clad Process, presents the development, results, and independent review of a finite-element thermal analysis for the casting process as originally conceived (using only chilled rollers in direct contact with the clad material of the product strip). Further Considerations for Belt Configuration of Double-Clad Process deals with a modified equipment design which interposes two product support belts, one on each side of the product, between the clad strip and the rollers. In addition to the process description, this section presents the preliminary mechanical calculations for the endless metal belts and the work scope and results for the computer model revision and thermal analysis for the modified concept.

  7. HANFORD CONTAINERIZED CAST STONE FACILITY TASK 1 PROCESS TESTING & DEVELOPMENT FINAL TEST REPORT

    SciTech Connect

    LOCKREM, L L

    2005-07-13

    Laboratory testing and technical evaluation activities on Containerized Cast Stone (CCS) were conducted under the Scope of Work (SOW) contained in CH2M HILL Hanford Group, Inc. (CHG) Contract No. 18548 (CHG 2003a). This report presents the results of testing and demonstration activities discussed in SOW Section 3.1, Task I--''Process Development Testing'', and described in greater detail in the ''Containerized Grout--Phase I Testing and Demonstration Plan'' (CHG, 2003b). CHG (2003b) divided the CCS testing and evaluation activities into six categories, as follows: (1) A short set of tests with simulant to select a preferred dry reagent formulation (DRF), determine allowable liquid addition levels, and confirm the Part 2 test matrix. (2) Waste form performance testing on cast stone made from the preferred DRF and a backup DRF, as selected in Part I, and using low activity waste (LAW) simulant. (3) Waste form performance testing on cast stone made from the preferred DRF using radioactive LAW. (4) Waste form validation testing on a selected nominal cast stone formulation using the preferred DRF and LAW simulant. (5) Engineering evaluations of explosive/toxic gas evolution, including hydrogen, from the cast stone product. (6) Technetium ''getter'' testing with cast stone made with LAW simulant and with radioactive LAW. In addition, nitrate leaching observations were drawn from nitrate leachability data obtained in the course of the Parts 2 and 3 waste form performance testing. The nitrate leachability index results are presented along with other data from the applicable activity categories.

  8. Process for Producing a Cast Article from a Hypereutectic Aluminum-Silicon Alloy

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2003-01-01

    A process for making a cast article from an aluminum alloy includes first casting an article from an alloy having the following composition, in weight percent: Silicon (Si) 14.0-25.0, Copper (CU) 5.5-8.0, Iron (Fe) 0-0.8, Magnesium (Mg) 0.5-1.5, Nickel (Ni) 0.05-1.2, Manganese (Mn) 0-1.0, Titanium (Ti) 0.05-1.2, Zirconium (Zr) 0.12-1.2, Vanadium (V) 0.05-1.2, Zinc (Zn) 0-0.9, Phosphorus (P) 0.001-0.1, Aluminum, balance. In this alloy the ration of Si:Mg is 15-35, and the ratio of Cu:Mg is 4-15. After an article is cast from the alloy, the cast article is aged at a temperature within the range of 400 F to 500 F for a time period within the range of four to 16 hours. It has been found especially advantageous if the cast article is first exposed to a solutionizing step prior to the aging step. This solutionizing step is carried out by exposing the cast article to a temperature within the range of 875 F to 1025 F for a time period of fifteen minutes to four hours. It has also been found to be especially advantageous if the solutionizing step is followed directly with a quenching step, wherein the cast article is quenched in a quenching medium such as water at a temperature within the range of 120 F to 300 F. The resulting cast article is highly suitable in a number of high temperature applications, such as heavy-duty pistons for internal combustion engines.

  9. Observation of the Mold-Filling Process of a Large Hydro-Turbine Guide Vane Casting

    NASA Astrophysics Data System (ADS)

    Kang, Jinwu; Long, Haimin; Li, Yongjie; You, Rui; Hao, Xiaokun; Nie, Gang; Wang, Tianjiao; Zhang, Chengchun

    2015-02-01

    The mold-filling process has a determining effect on the quality of castings, and it has always been a hot but difficult research topic. The authors developed a wireless monitoring system for the mold-filling process of castings based on a contact time method and an observation system based on heat-resistant high-speed cameras. By using these two systems, the filling process of a turbine guide vane casting with a stepped gating system was investigated. The filling profile of the casting was recorded, and the filling time of nine typical positions was acquired. These results show that at the beginning, the liquid steel flowed out from the top ingate, which was designed to be the last to fill. The numerical simulation of the filling of the guide vane was performed, and the outflow from the top ingate were predicted. Finally, the gating system of the casting was improved with enlarged sprue. The new design features bigger sprue to ingate ratio; therefore, it could avoid the overflow from the top ingate and realize stable filling.

  10. Development of low-temperature high-strength integral steel castings for offshore construction by casting process engineering

    NASA Astrophysics Data System (ADS)

    Lim, Sang-Sub; Mun, Jae-Chul; Kim, Tae-Won; Kang, Chung-Gil

    2014-12-01

    In casting steels for offshore construction, manufacturing integral casted structures to prevent fatigue cracks in the stress raisers is superior to using welded structures. Here, mold design and casting analysis were conducted for integral casting steel. The laminar flow of molten metal was analyzed and distributions of hot spots and porosities were studied. A prototype was subsequently produced, and air vents were designed to improve the surface defects caused by the release of gas. A radiographic test revealed no internal defects inside the casted steel. Evaluating the chemical and mechanical properties of specimens sampled from the product revealed that target values were quantitatively satisfied. To assess weldability in consideration of repair welding, the product was machined with grooves and welded, after which the mechanical properties of hardness as well as tensile, impact, and bending strengths were evaluated. No substantive differences were found in the mechanical properties before and after welding.

  11. Semi-Solid Processing by Electric Current During Sand Casting of Aluminium Alloys

    NASA Astrophysics Data System (ADS)

    Prodhan, Anjan

    2016-02-01

    This study reports the effect of DC and 50Hz AC treatment (ECT) on aluminium or aluminium alloys during solidification in sand moulds i.e., at their semisolid state. Castings, with different geometry, were made in open or closed sand moulds. It is observed that ECT (a) reduces dissolved gas, (b) reduces internal shrinkage and (c) metal mould reactions in castings. It is also observed that the AC treatment is more effective compared to DC treatment. ECT changes the movement of solidification front. The optical microstructures of ECT samples are quite similar to the samples treated in other semisolid processing methods.

  12. Part I: In-situ fluorometric quantification of microalgal neutral lipids. Part II: Thermal degradation behavior of investment casting polymer patterns

    NASA Astrophysics Data System (ADS)

    Zhao, Hongfang

    Research described in this dissertation covers two topics. Part-I is focused on in-situ determination of neutral lipid content of microalgae using a lipophilic fluorescent dye. The traditional Nile red stain-based method for detecting microalgal intracellular lipids is limited due to varying composition and thickness of rigid cell walls. In this study, the addition of dilute acid and heating of solution, were found to greatly enhance staining efficiency of Nile red for microalgal species evaluated. Oil-in-water (O/W) microemulsion stabilized by a non-ionic surfactant was employed as a pseudo-standard that mimics lipid-bearing microalgal cells suspended in water. The average neutral lipid contents determined were very close to the results obtained by traditional gravimetric method and solid phase extraction. Part II of the dissertation explores thermo-physico-chemical properties of polymeric pattern materials, including expanded polystyrene (EPS) foam, polyurethane foam, and epoxy stereolithography (SLA) patterns, that are used in investment casting. Density, elastic modulus, expansion coefficient, thermal degradation behavior, etc. were experimentally investigated for their effects on metal casting quality. The reduction in toxic hydrogen cyanide (HCN) generated during thermal decomposition of polyurethane pattern was achieved by increasing either oxidant level or residence time in heated zone. Thermal degradation kinetics of the pattern materials were examined with a thermogravimetric analysis and activation energies were determined by Kissinger and Flynn-Wall-Ozawa methods.

  13. Workplace Basic Skills in the Metal Casting Industry for World Class Process and Technology.

    ERIC Educational Resources Information Center

    Rasmussen, Bonnie

    A workplace basic skills project for the metal casting industry was established jointly by Central Alabama Community College and Robinson Foundry, Inc. Evaluation of the project was made through a commercial test of hourly workers' general literacy level gains, instructor-developed pre- and posttests of mastery of the industrial process and…

  14. The Influence of Casting Conditions on the Microstructure of As-Cast U-10Mo Alloys: Characterization of the Casting Process Baseline

    SciTech Connect

    Nyberg, Eric A.; Joshi, Vineet V.; Lavender, Curt A.; Paxton, Dean M.; Burkes, Douglas

    2013-12-13

    Sections of eight plate castings of uranium alloyed with 10 wt% molybdenum (U-10Mo) were sent from Y-12 to the Pacific Northwest National Laboratory (PNNL) for microstructural characterization. This report summarizes the results from this study.

  15. Prototype casting fabrication by stereolithography

    SciTech Connect

    Cromwell, W.E.

    1990-11-01

    A new product development technology is emerging which could have a major impact on the investment casting industry. It's identified by several names, the most common of which is STEREOLITHOGRAPHY.'' This technology involves a three-dimensional printing process which will yield plastic parts (polymer models) from solid, surface, or wireframe CAD files. The concept links a CAD database to a process which guides a laser beam to solidify liquid photo-curable polymer into a programmed shaped. The process can produce models in far less time and at far less cost than can be done by other known (conventional) model producing methods. Parts that would normally require weeks or months to prototype with conventional processes can be produced in a matter of hours by Stereolithography. The Allied-Signal Inc., Kansas City Division, is engaged in a development project (funded by the Department of Energy) which is aimed at establishing this process as a practical, expedient, and cost-effective method fabricating prototype investment castings. The early phases of the project include procurement of a special designed test unit for several companies (Service Centers) involved in fabrication of models. These models are produced in various materials and used in experimental casting programs being conducted with four casting suppliers (two ferrous and two non-ferrous). This presentation will cover the objectives of the project and the results obtained up to this time. We will also briefly review future plans for the continuation of the project, until this new technology has been proven as a viable process for rapid development of investment castings.

  16. Biostratinomic processes for the development of mud-cast logs in Carboniferous and Holocene swamps

    SciTech Connect

    Gastaldo, R.A.; Demko, T.M.; Liu, Yuejin; Keefer, W.D.; Abston, S.L. )

    1989-08-01

    Prostrate trees are common features of fossil forest litters, and are frequently preserved as mud-casts. Specimens of Carboniferous mud-cast trees and a mud-filled incipient cast of a Holocene Taxodium have been investigated to determine the biostratinomic processes responsible for their formation. These processes are complex. Hollowing of tree trunks may take place during life or by degradation after death. Once the trunk has fallen, the hollow cavity is supported by surrounding wood and/or bark tissues and acts as a conduit for sediment-laden waters. Leaf litter may be preserved on bedding surfaces. The infilling sequence of horizontal, parallel bedded, fine-grained sediment is deposited from suspended load during multiple overbank flooding events. These results differ from experimentally produced pith casts in which the sediment grain size is of fine sand. In Holocene specimens, alluvial mud within the log may provide a substrate for infaunal invertebrates. No evidence of infaunal burrowing in Carboniferous analogues exists.

  17. Understanding how processing additives tune nanoscale morphology of high efficiency organic photovoltaic blends: From casting solution to spun-cast thin film

    SciTech Connect

    Shao, Ming; Keum, Jong Kahk; Kumar, Rajeev; Chen, Jihua; Browning, Jim; Chen, Wei; Jianhui, Hou; Do, Changwoo; Littrell, Ken; Sanjib, Das; Rondinone, Adam Justin; Geohegan, David B; Sumpter, Bobby G; Xiao, Kai

    2014-01-01

    Adding a small amount of a processing additive to the casting solution of organic blends has been demonstrated to be an effective method for achieving improved power conversion efficiency (PCE) in organic photovoltaics (OPVs). However, an understanding of the nano-structural evolution occurring in the transformation from casting solution to thin photoactive films is still lacking. In this report, we investigate the effects of the processing additive diiodooctane (DIO) on the morphology of OPV blend of PBDTTT-C-T and fullerene derivative, PC71BM in a casting solution and in spun-cast thin films by using neutron/x-ray scattering, neutron reflectometry and other characterization techniques. The results reveal that DIO has no effect on the solution structures of PBDTTT-C-T and PC71BM. In the spun-cast films, however, DIO is found to promote significantly the molecular ordering of PBDTTT-C-T and PC71BM, and phase segregation, resulting in the improved PCE. Thermodynamic analysis based on Flory-Huggins theory provides a rationale for the effects of DIO on different characteristics of phase segregation as a solvent and due to evaporationg during the film formation. Such information may enable improved rational design of ternary blends to more consistently achieve improved PCE for OPVs.

  18. Numerical simulation of solid liquid interface behavior during continuous strip casting process.

    PubMed

    Lee, Changbum; Yoon, Wooyoung; Shin, Seungwon; Lee, Jaewoo; Jang, Bo-Yun; Kim, Joonsoo; Ahn, Youngsoo; Lee, Jinseok

    2013-05-01

    A new metal-strip-casting process called continuous strip-casting (CSC) has been developed for making thin metal strips. A numerical simulation model to help understand solid-liquid interface behavior during CSC has been developed and used to identify the solidification morphologies of the strips and to determine the optimum processing conditions. In this study, we used a modified level contour reconstruction method (LCRM) and the sharp interface method to modify interface tracking, and performed a simulation analysis of the CSC process. The effects of process parameters such as heat-transfer coefficient and extrusion velocity on the behavior of the solid-liquid interface were estimated and used to improve the apparatus. A Sn (Tin) plate of dimensions 200 x 50 x 1 mm3 was successfully produced by CSC for a heat-transfer coefficient of 104 W/m2 K and an extrusion velocity of 0.2 m/s.

  19. The GTAW of Ti-6Al-4V castings and its effect on microstructural and mechanical properties

    NASA Astrophysics Data System (ADS)

    Ault, James; Pillers, James; Veeck, Stewart

    2005-11-01

    The gas-tungsten arc welding of Ti-6Al-4V investment castings is an integral part of titanium casting processing due to the need to repair casting defects. It is speculated that the refined alpha/beta microstructure produced by faster solidification of the weld metal can affect the static and dynamic properties of the casting. This report examines the effects of weld repair on microstructure and mechanical properties.

  20. The potential of centrifugal casting for the production of near net shape uranium parts

    SciTech Connect

    Robertson, E.

    1993-09-01

    This report was written to provide a detailed summary of a literature survey on the near net shape casting process of centrifugal casting. Centrifugal casting is one potential casting method which could satisfy the requirements of the LANL program titled Near Net Shape Casting of Uranium for Reduced Environmental, Safety and Health Impact. In this report, centrifugal casting techniques are reviewed and an assessment of the ability to achieve the near net shape and waste minimization goals of the LANL program by using these techniques is made. Based upon the literature reviewed, it is concluded that if properly modified for operation within a vacuum, vertical or horizontal centrifugation could be used to safely cast uranium for the production of hollow, cylindrical parts. However, for the production of components of geometries other than hollow tubes, vertical centrifugation could be combined with other casting methods such as semi-permanent mold or investment casting.

  1. Shape Memory Effect in Cast Versus Deformation-Processed NiTiNb Alloys

    NASA Astrophysics Data System (ADS)

    Hamilton, Reginald F.; Lanba, Asheesh; Ozbulut, Osman E.; Tittmann, Bernhard R.

    2015-06-01

    The shape memory effect (SME) response of a deformation-processed NiTiNb shape memory alloy is benchmarked against the response of a cast alloy. The insoluble Nb element ternary addition is known to widen the hysteresis with respect to the binary NiTi alloy. Cast microstructures naturally consist of a cellular arrangement of characteristic eutectic microconstituents surrounding primary matrix regions. Deformation processing typically aligns the microconstituents such that the microstructure resembles discontinuous fiber-reinforced composites. Processed alloys are typically characterized for heat-to-recover applications and thus deformed at constant temperature and subsequently heated for SME recovery, and the critical stress levels are expected to facilitate plastic deformation of the microconstituents. The current work employs thermal cycling under constant bias stresses below those critical levels. This comparative study of cast versus deformation-processed NiTiNb alloys contrasts the strain-temperature responses in terms of forward Δ T F = M s - M f and reverse Δ T R = A f - A s temperature intervals, the thermal hysteresis, and the recovery ratio. The results underscore that the deformation-processed microstructure inherently promotes irreversibility and differential forward and reverse transformation pathways.

  2. Numerical Simulation of Cast Distortion in Gas Turbine Engine Components

    NASA Astrophysics Data System (ADS)

    Inozemtsev, A. A.; Dubrovskaya, A. S.; Dongauser, K. A.; Trufanov, N. A.

    2015-06-01

    In this paper the process of multiple airfoilvanes manufacturing through investment casting is considered. The mathematical model of the full contact problem is built to determine stress strain state in a cast during the process of solidification. Studies are carried out in viscoelastoplastic statement. Numerical simulation of the explored process is implemented with ProCASTsoftware package. The results of simulation are compared with the real production process. By means of computer analysis the optimization of technical process parameters is done in order to eliminate the defect of cast walls thickness variation.

  3. Numerical Simulation of Filling Process During Twin-Roll Strip Casting

    NASA Astrophysics Data System (ADS)

    Liu, Zhiyu; Wang, Bo; Zhang, Qinghua; Ma, Jie; Zhang, Jieyu

    2014-01-01

    The modeling and controlling of flow and solidification of melt metal in the filling process is important for obtaining the optimal pool level and the formation of the solidified metal layer on the surface of twin-rolls during the twin-roll strip casting. The proper delivery system and processing parameters plays a key role to control flow characteristics in the initial filling stage of the twin-roll strip casting process. In this paper, a commercial CFD software was employed to simulate the transient fluid flow, heat transfer, and solidifications behaviors during the pouring stage of twin-roll strip casting process using different delivery systems. A 3D model was set up to solve the coupled set of governing differential equations for mass, momentum, and energy balance. The transient free-surface problem was treated with the volume of fluid approach, a k-ɛ turbulence model was employed to handle the turbulence effect and an enthalpy method was used to predict phase change during solidification. The predicted results showed that a wedge-shaped delivery system might have a beneficial impact on the distribution of molten steel and solidification. The predicted surface profile agreed well with the measured values in water model.

  4. Determination of the heat transfer coefficient at the metal-sand mold interface of lost foam casting process

    NASA Astrophysics Data System (ADS)

    Zhang, Liqiang; Tan, Wenfang; Hu, Hao

    2016-06-01

    For modeling solidification process of casting accurately, a reliable heat transfer boundary condition data is required. In this paper, an inverse conduction model was established to determine the heat flux and heat transfer coefficient at the metal-sand mold interface for cylindrical casting in the lost foam process. The numerically calculated temperature was compared with analytic solution and simulation solution obtained by commercial software ProCAST to investigate the accuracy of heat conduction model. The instantaneous cast and sand mold temperatures were measured experimentally and these values were used to determine the interfacial heat transfer coefficient (IHTC). The IHTC values during lost foam casting were shown to vary from 20 to 800 W m-2 K-1. Additionally, the characteristics of the time-varying IHTC have also been discussed in this study.

  5. Processing of Advanced Cast Alloys for A-USC Steam Turbine Applications

    NASA Astrophysics Data System (ADS)

    Jablonski, Paul D.; Hawk, Jeffery A.; Cowen, Christopher J.; Maziasz, Philip J.

    2012-02-01

    The high-temperature components within conventional supercritical coal-fired power plants are manufactured from ferritic/martensitic steels. To reduce greenhouse-gas emissions, the efficiency of pulverized coal steam power plants must be increased to as high a temperature and pressure as feasible. The proposed steam temperature in the DOE/NETL Advanced Ultra Supercritical power plant is high enough (760°C) that ferritic/martensitic steels will not work for the majority of high-temperature components in the turbine or for pipes and tubes in the boiler due to temperature limitations of this class of materials. Thus, Ni-based superalloys are being considered for many of these components. Off-the-shelf forged nickel alloys have shown good promise at these temperatures, but further improvements can be made through experimentation within the nominal chemistry range as well as through thermomechanical processing and subsequent heat treatment. However, cast nickel-based superalloys, which possess high strength, creep resistance, and weldability, are typically not available, particularly those with good ductility and toughness that are weldable in thick sections. To address those issues related to thick casting for turbine casings, for example, cast analogs of selected wrought nickel-based superalloys such as alloy 263, Haynes 282, and Nimonic 105 have been produced. Alloy design criteria, melt processing experiences, and heat treatment are discussed with respect to the as-processed and heat-treated microstructures and selected mechanical properties. The discussion concludes with the prospects for full-scale development of a thick section casting for a steam turbine valve chest or rotor casing.

  6. Thermo-Mechanical Behavior of the Continuous Casting Bloom in the Heavy Reduction Process

    NASA Astrophysics Data System (ADS)

    Ji, Cheng; Wu, Chen-hui; Zhu, Miao-yong

    2016-08-01

    A two-stage sequential heavy reduction (HR) method, in which the reduction amount was increased both before and after the solidification end, is presented to simultaneously improve the homogeneity and compactness of the continuous casting bloom. With bearing steel GCr15 chosen as the specific research steel, a three-dimensional thermal-mechanical finite element model was developed to simulate and analyze the thermal and mechanical behaviors of the continuous casting bloom during the HR process. In order to ensure the accuracy of the simulation, the constitutive model parameters were derived from the experimental results. The predicted temperature distribution and shell thickness were verified using a thermal infrared camera and nail shooting results, respectively. The real measured relationship between the HR pressure and amount were applied to verify the mechanical model. The explorative application results showed that the quality of the bloom center and compactness of rolled bars have both been significantly improved after the HR was applied.

  7. Fatigue behaviour of friction stir processed AZ91 magnesium alloy produced by high pressure die casting

    SciTech Connect

    Cavaliere, P. . E-mail: pasquale.cavaliere@unile.it; De Marco, P.P.

    2007-03-15

    The room temperature fatigue properties of AZ91 magnesium alloy produced by high pressure die casting (HPDC) as cast, heat treated, friction stir processed (FSP) and FSP and heat treated were studied. The fatigue properties of the material were evaluated for the HPDC magnesium alloy in the as-received state and after a solution treatment at 415 deg. C for 2 h and an ageing treatment at 220 deg. C for 4 h. The heat treatment resulted in a significant increase in the fatigue properties of the HPDC material, while no significance influence of heat treatment was recorded in the FSP condition. The morphology of fracture surfaces was examined by employing a field emission gun scanning electron microscope (FEGSEM)

  8. Bond Strength of Multicomponent White Cast Iron Coatings Applied by HVOF Thermal Spray Process

    NASA Astrophysics Data System (ADS)

    Maranho, Ossimar; Rodrigues, Daniel; Boccalini, Mario; Sinatora, Amilton

    2009-12-01

    Multicomponent white cast iron is a new alloy that belongs to system Fe-C-Cr-W-Mo-V, and because of its excellent wear resistance it is used in the manufacture of hot rolling mills rolls. To date, this alloy has been processed by casting, powder metallurgy, and spray forming. The high-velocity oxyfuel process is now also considered for the manufacture of components with this alloy. The effects of substrate, preheating temperature, and coating thickness on bond strength of coatings have been determined. Substrates of AISI 1020 steel and of cast iron with preheating of 150 °C and at room temperature were used to apply coatings with 200 and 400 μm nominal thickness. The bond strength of coatings was measured with the pull-off test method and the failure mode by scanning electron microscopic analysis. Coatings with thickness of 200 μm and applied on substrates of AISI 1020 steel with preheating presented bond strength of 87 ± 4 MPa.

  9. Development of an Innovative Laser-Assisted Coating Process for Extending Lifetime of Metal Casting Dies. Final Report

    SciTech Connect

    Madhav Rao Gonvindaraju

    1999-10-18

    Die casting dies used in the metal casting industry fail due to thermal fatigue cracking accompanied by the presence of residual tensile stresses, corrosion, erosion and wear of die surfaces. This phase 1 SBIR Final Report summarize Karta Technologies research involving the development of an innovative laser coating technology for metal casting dies. The process involves depositing complex protective coatings of nanocrystalline powders of TiC followed by a laser shot peening. The results indicate a significant improvement in corrosion and erosion resistance in molten aluminum for H13 die casting die steels. The laser-coated samples also showed improved surface finish, a homogeneous and uniform coating mircrostructure. The technology developed in this research can have a significant impact on the casting industry by saving the material costs involved in replacing dies, reducing downtime and improving the quality.

  10. The Computational Fluid Dynamic (CFD) Modeling of the Horizontal Single Belt Casting (HSBC) Processing of Al-Mg-Sc-Zr Alloy Strips

    NASA Astrophysics Data System (ADS)

    Ge, S.; Isac, M.; Guthrie, R. I. L.

    2015-10-01

    Al-Mg-Sc-Zr alloys have shown exceptional potential as structural materials for transportation applications. These alloys have proved to be good candidates to be processed as thin strips via the horizontal single belt casting (HSBC) process. The HSBC process is a near-net-shape casting technology, which involves casting molten metal directly into thin strips, close to the final product thickness, at higher cooling rates than conventional continuous casting and thin-slab casting processes. It offers an efficient, economical, and environmentally friendly approach to the production of metal strips. Fluid mechanics and associated heat transfer are important aspects of any casting process, and the novel HSBC process is no exception. Three-dimensional computational fluid dynamics simulations using ANSYS FLUENT 14.5 were performed, in order to assess the importance and effects of the various operational conditions of the HSBC process. This enabled process parameter optimization. Numerical predictions were validated against experimental casting results.

  11. AMCC casting development. Volume 1: Executive Summary

    NASA Astrophysics Data System (ADS)

    1995-03-01

    The Advanced Combustion Chamber Casting (AMCC) has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or Thermal Gradient Control. This method, of setting up thermal gradients in the casting during solidification, represents a significant process improvement for PCC and has been successfully implemented on other programs. Metallurgical integrity of the final four castings was very good. Only the areas of the parts that utilized 'TGC Shape & Location System #2' showed any significant areas of microshrinkage when evaluated by non-destructive tests. Alumina oxides detected by FPI on the 'float' surfaces (top sid surfaces of the casting during solidification) of the part were almost entirely less than the acceptance criteria of .032 inches in diameter. Destructive chem mill of the castings was required to determine the effect of the process variables used during the processing of these last four parts (with the exception of the 'Shape & Location of TGC' variable).

  12. AMCC casting development. Volume 1: Executive Summary

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The Advanced Combustion Chamber Casting (AMCC) has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or Thermal Gradient Control. This method, of setting up thermal gradients in the casting during solidification, represents a significant process improvement for PCC and has been successfully implemented on other programs. Metallurgical integrity of the final four castings was very good. Only the areas of the parts that utilized 'TGC Shape & Location System #2' showed any significant areas of microshrinkage when evaluated by non-destructive tests. Alumina oxides detected by FPI on the 'float' surfaces (top sid surfaces of the casting during solidification) of the part were almost entirely less than the acceptance criteria of .032 inches in diameter. Destructive chem mill of the castings was required to determine the effect of the process variables used during the processing of these last four parts (with the exception of the 'Shape & Location of TGC' variable).

  13. PREFACE: MCWASP XIII: International Conference on Modeling of Casting, Welding and Advanced Solidification Processes

    NASA Astrophysics Data System (ADS)

    Ludwig, Andreas

    2012-07-01

    Due to fast-paced development in computer technologies during the last three decades, computer-based process modeling has become an important tool for the improvement of existing process technologies and the development of new, innovative technologies. With the help of numerical process simulations, complex and costly experimental trials can now be reduced to a minimum. For metallurgical processes in particular, computer simulations are of outstanding importance, as the flow and solidification of molten alloys or the formation of microstructure and defects can hardly be observed experimentally. Corresponding computer simulations allow us inside views into the key process phenomena and so offer great potential for optimization. In 1980 the conference series 'Modeling of Casting, Welding and Advanced Solidification Processes (MCWASP)' was started up, and has now been continued by holding the 13th international conference on 'Modeling of Casting, Welding and Advanced Solidification Processes', MCWASP XIII, in Schladming, Austria, from June 17-22 2012. Around 200 scientists from industry and academia, coming from 20 countries around the globe attended 78 oral and 50 poster presentations on different aspects of solidification-related modeling topics. Besides process-related sessions such as (i) Ingot and Shape Casting, (ii) Continuous Casting and Direct Chill Casting, (iii) Directional Solidification and Zone Melting, (iv) Welding, and (v) Centrifugal Casting, a larger focus was put on (vi) Experimental Investigation and In-Situ Observations. In recent years, this topic has been significantly strengthened as advanced synchrotron technologies allow fantastic in-situ observations of phenomena happening inside small metallic samples. These observations will definitely serve as a benchmark for the modeling community. Further macroscopic aspects of advanced solidification science were tackled in the sessions (vii) Electromagnetic Coupling, (viii) Thermomechanics, (ix

  14. Structure and properties of polypropylene cast films: Polymer type and processing effects

    NASA Astrophysics Data System (ADS)

    Mileva, Daniela; Gahleitner, Markus; Gloger, Dietrich

    2016-05-01

    The influence of processing parameters in a cast film extrusion process of thin films of isotactic polypropylene homopolymer and random propylene-ethylene copolymer was analyzed. Variation of the chill roll temperature allowed changing the supercooling of the melt and thus the generation of different crystal polymorphs of iPP. Additional focus was placed on the effect of flow induced crystallization via changing the output rate of the line. The crystal structure and morphology of the materials were evaluated and correlated to selected optical and mechanical properties.

  15. A study on atomic diffusion behaviours in an Al-Mg compound casting process

    SciTech Connect

    Liu, Yongning; Chen, Yiqing; Yang, Chunhui

    2015-08-15

    Al and Mg alloys are main lightweight alloys of research interest and they both have superb material properties, i.e., low density and high specific strength, etc. Being different from Al alloys, the corrosion of Mg alloys is much more difficult to control. Therefore to combine merits of these two lightweight alloys as a composite-like structure is an ideal solution through using Al alloys as a protective layer for Mg alloys. Compound casting is a realistic technique to manufacture such a bi-metal structure. In this study, a compound casting technique is employed to fabricate bi-layered samples using Al and Mg and then the samples are analysed using electron probe micro-analyzer (EPMA) to determine diffusion behaviours between Al and Mg. The diffusion mechanism and behaviours between Al and Mg are studied numerically at atomic scale using molecular dynamics (MD) and parametric studies are conducted to find out influences of ambient temperature and pressure on the diffusion behaviours between Al and Mg. The results obtained clearly show the effectiveness of the compound casting process to increase the diffusion between Al and Mg and thus create the Al-base protection layer for Mg.

  16. Influence of macromolecular architecture on necking in polymer extrusion film casting process

    SciTech Connect

    Pol, Harshawardhan; Banik, Sourya; Azad, Lal Busher; Doshi, Pankaj; Lele, Ashish; Thete, Sumeet

    2015-05-22

    Extrusion film casting (EFC) is an important polymer processing technique that is used to produce several thousand tons of polymer films/coatings on an industrial scale. In this research, we are interested in understanding quantitatively how macromolecular chain architecture (for example long chain branching (LCB) or molecular weight distribution (MWD or PDI)) influences the necking and thickness distribution of extrusion cast films. We have used different polymer resins of linear and branched molecular architecture to produce extrusion cast films under controlled experimental conditions. The necking profiles of the films were imaged and the velocity profiles during EFC were monitored using particle tracking velocimetry (PTV) technique. Additionally, the temperature profiles were captured using an IR thermography and thickness profiles were calculated. The experimental results are compared with predictions of one-dimensional flow model of Silagy et al{sup 1} wherein the polymer resin rheology is modeled using molecular constitutive equations such as the Rolie-Poly (RP) and extended Pom Pom (XPP). We demonstrate that the 1-D flow model containing the molecular constitutive equations provides new insights into the role of macromolecular chain architecture on film necking.{sup 1}D. Silagy, Y. Demay, and J-F. Agassant, Polym. Eng. Sci., 36, 2614 (1996)

  17. Modeling of microstructure evolution of magnesium alloy during the high pressure die casting process

    NASA Astrophysics Data System (ADS)

    Wu, Mengwu; Xiong, Shoumei

    2012-07-01

    Two important microstructure characteristics of high pressure die cast magnesium alloy are the externally solidified crystals (ESCs) and the fully divorced eutectic which form at the filling stage of the shot sleeve and at the last stage of solidification in the die cavity, respectively. Both of them have a significant influence on the mechanical properties and performance of magnesium alloy die castings. In the present paper, a numerical model based on the cellular automaton (CA) method was developed to simulate the microstructure evolution of magnesium alloy during cold-chamber high pressure die casting (HPDC) process. Modeling of dendritic growth of magnesium alloy with six-fold symmetry was achieved by defining a special neighbourhood configuration and calculating of the growth kinetics from complete solution of the transport equations. Special attention was paid to establish a nucleation model considering both of the nucleation of externally solidified crystals in the shot sleeve and the massive nucleation in the die cavity. Meanwhile, simulation of the formation of fully divorced eutectic was also taken into account in the present CA model. Validation was performed and the capability of the present model was addressed by comparing the simulated results with those obtained by experiments.

  18. Study on Fabrication of AA4032/AA6069 Cladding Billet Using Direct Chill Casting Process

    NASA Astrophysics Data System (ADS)

    Han, Xing; Zhang, Haitao; Shao, Bo; Li, Lei; Liu, Xuan; Cui, Jianzhong

    2016-04-01

    AA4032/AA6069 cladding billet in size of φ130 mm/φ110 mm was prepared by the modified direct chill casting process, and the parametric effect on casting performance was investigated using numerical simulation. Microstructures, elements distribution, and mechanical properties of the bonding interface were examined. The results show that metallurgical bonding interface can be obtained with the optimal parameters: the casting speed of 130 to 140 mm/min, the internal liquid level height of 50 to 60 mm, and the contact height of 40 to 50 mm. The metallurgical bonding interface is free of any discontinuities due to the fact that the alloying elements diffused across the interface and formed Ni-containing phase. Tensile strength of the cladding billet reaches 225.3 MPa, and the fracture position was located in AA6069 side, suggesting that the interface bonding strength is higher than the strength of AA6069. The interfacial shearing strength is 159.3 MPa, indicating excellent metallurgical bonding.

  19. Influence of macromolecular architecture on necking in polymer extrusion film casting process

    NASA Astrophysics Data System (ADS)

    Pol, Harshawardhan; Banik, Sourya; Azad, Lal Busher; Thete, Sumeet; Doshi, Pankaj; Lele, Ashish

    2015-05-01

    Extrusion film casting (EFC) is an important polymer processing technique that is used to produce several thousand tons of polymer films/coatings on an industrial scale. In this research, we are interested in understanding quantitatively how macromolecular chain architecture (for example long chain branching (LCB) or molecular weight distribution (MWD or PDI)) influences the necking and thickness distribution of extrusion cast films. We have used different polymer resins of linear and branched molecular architecture to produce extrusion cast films under controlled experimental conditions. The necking profiles of the films were imaged and the velocity profiles during EFC were monitored using particle tracking velocimetry (PTV) technique. Additionally, the temperature profiles were captured using an IR thermography and thickness profiles were calculated. The experimental results are compared with predictions of one-dimensional flow model of Silagy et al1 wherein the polymer resin rheology is modeled using molecular constitutive equations such as the Rolie-Poly (RP) and extended Pom Pom (XPP). We demonstrate that the 1-D flow model containing the molecular constitutive equations provides new insights into the role of macromolecular chain architecture on film necking.1D. Silagy, Y. Demay, and J-F. Agassant, Polym. Eng. Sci., 36, 2614 (1996).

  20. Modeling of metal/pattern replacement in the lost foam casting process

    NASA Astrophysics Data System (ADS)

    Molibog, Taras Vitalyevich

    The Lost Foam Casting Process (LFCP), which employs expanded foam patterns placed in unbonded sand, is increasingly gaining popularity in the foundry industry. The time and cost associated with introducing new Lost Foam (LF) castings into production could be significantly reduced by using simulation codes capable of modeling metal fill and solidification and predicting defect formation. The development of accurate models of Lost Foam casting (LFC) has been hindered by a lack of understanding and data on the mechanism of metal/pattern exchange. This research work focused on developing a mathematical model of metal/pattern exchange and generating pattern and glue degradation data necessary for the model. The experimental work was conducted using the foam pyrolysis apparatus developed earlier in this research and included experiments to (a) evaluate the effects of the heater size and shape on foam pyrolysis, (b) observe the morphology of the heater/pattern interface, (c) extend the temperature capabilities of the foam pyrolysis apparatus to iron and steel pouring temperatures of 1600°C (2910°F), (d) measure the temperature of the gaseous degradation products of expanded polystyrene (EPS) exiting the kinetic zone (KZ), (e) measure the EPS degradation resistance pressure and the molecular weight of EPS liquid degradation products, and (f) develop quantitative glue joint degradation data. A simplified mathematical model of heat and mass transfer in the KZ was developed to calculate data necessary to predict the pattern resistance to metal flow. KZ parameters, including KZ thickness and temperature, density and viscosity of degradation products, and heat flux, were calculated for aluminum casting conditions using experimental pattern degradation data. The predicted heat flux values showed good agreement with measured. Modeling of different aspects of LFC, such as fluid flow, heat transfer, and defect formation, is discussed.

  1. Evaluation of the Effects of Rotary Degassing Process Variables on the Quality of A357 Aluminum Alloy Castings

    NASA Astrophysics Data System (ADS)

    Mostafaei, M.; Ghobadi, M.; Eisaabadi B., Ghasem; Uludağ, Muhammet; Tiryakioğlu, Murat

    2016-08-01

    The effects of rotary degassing process variables on the melt and casting quality have been investigated using reduced pressure test results and quality index calculations from tensile data. The results showed that the effectiveness of the rotary degassing process of Al alloys is highly dependent on the combination of rotational speed and the gas flow rate, and that the wrong combination of these factors may result in no improvement or even degradation in quality of castings. For the first time, it has been found that the effectiveness of the pouring and filling system to produce high-quality castings can be characterized numerically. This new method of quantifying the casting system is introduced as a new quality improvement tool for materials and process engineers.

  2. Effects of casting conditions and deformation processing on A356 aluminum and A356-20 vol. pct SiC composites

    NASA Technical Reports Server (NTRS)

    Rozak, G. A.; Lewandowski, J. J.; Wallace, J. F.; Altmisoglu, A.

    1992-01-01

    The effects of casting conditions and deformation processing on the mechanical properties of unreinforced A356 aluminum and A356-20 vol pct SiC composite were investigated by tensile properties in these compounds fabricated by either sand casting or squeeze casting techniques followed by hot working to 33, 50, 90, and 95 percent reductions. The evolution of the microstructure and values of tensile properties were evaluated for the cast materials in each of the hot worked conditions. It was found that, while the deformation processing of the sand-cast composite resulted in banding of the Al and SiC particles within the microstructure, such features were not observed in the squeeze-cast microstructure. The tensile strengths of the squeeze cast materials was found to be higher than those of the sand cast materials, for both the unreinforced and composite samples, while increased amounts of deformation were found to improve the ductility of the composite.

  3. Quantitative characterization of processing-microstructure-properties relationships in pressure die-cast magnesium alloys

    NASA Astrophysics Data System (ADS)

    Lee, Soon Gi

    The central goal of this research is to quantitatively characterize the relationships between processing, microstructure, and mechanical properties of important high-pressure die-cast (HPDC) Mg-alloys. For this purpose, a new digital image processing technique for automatic detection and segmentation of gas and shrinkage pores in the cast microstructure is developed and it is applied to quantitatively characterize the effects of HPDC process parameters on the size distribution and spatial arrangement of porosity. To get better insights into detailed geometry and distribution of porosity and other microstructural features, an efficient and unbiased montage based serial sectioning technique is applied for reconstruction of three-dimensional microstructures. The quantitative microstructural data have been correlated to the HPDC process parameters and the mechanical properties. The analysis has led to hypothesis of formation of new type of shrinkage porosity called, "gas induced shrinkage porosity" that has been substantiated via simple heat transfer simulations. The presence of inverse surface macrosegregation has been also shown for the first time in the HPDC Mg-alloys. An image analysis based technique has been proposed for simulations of realistic virtual microstructures that have realistic complex pore morphologies. These virtual microstructures can be implemented in the object oriented finite elements framework to model the variability in the fracture sensitive mechanical properties of the HPDC alloys.

  4. Study on Pot Forming of Induction Heater Type Rice Cookers by Forging Cast Process

    NASA Astrophysics Data System (ADS)

    Ohnishi, Masayuki; Yamaguchi, Mitsugi; Ohashi, Osamu

    This paper describes a study result on pot fabrication by the forging cast process of stainless steel with aluminum. Rice cooked with the new bowl-shaped pot for the induction heater type rice cookers is better tasting than rice cooked with the conventional cylindrical one, due to the achievement of better heat conduction and convection. The conventional pot is made of the clad sheet, consisting of stainless steel and aluminum. However, it is rather difficult to form a bowl shape from the clad sheet, primarily due to the problem of a material spring back. The fabrication of a new type of a pot was made possible by means of the adoption of a forging cast process instead of the clad sheet. In this process, iron powder is inserted between stainless steel and aluminum in order to alleviate the large difference on the coefficient of expansion between each material. It was made clear that the application of two kinds of iron particle, namely 10 μm size powder on the stainless steel side and 44 μm on the aluminum side, enables the joints to become strong enough. The joint strength of the new pot by this fabrication process was confirmed by the tests of the shear strength and the fatigue tests together with the stress analysis.

  5. [Studies on the proper processing of silver-palladium casting alloys].

    PubMed

    Lenz, E; Płonka, B

    1979-01-01

    The internal structure and the hardness of three silver-palladium alloys (Sipal 306, Spall WT 52, Bego Gold-EWL G) were investigated in the as-cast condition, after homogenization and after salt-bath hardening. From the results obtained it is concluded that the optimal processing conditions for Sipal 306 and Spall WT 52 are: homogenization at 850 degrees C for more than 2 hours, and hardening at 430--450 degrees C for 15 minutes. The hardness values thus obtained meet the requirements of the type IV indication of the FDI specification no. 7; however, the inhomogenous structure causes a lower resistance to tarnish.

  6. Mechanical Strength and Failure Characteristics of Cast Mg-9 pctAl-1 pctZn Alloys Produced by a Heated-Mold Continuous Casting Process: Tensile Properties

    NASA Astrophysics Data System (ADS)

    Okayasu, Mitsuhiro; Takeuchi, Shuhei; Ohfuji, Hiroaki

    2014-11-01

    The mechanical properties and failure characteristics of a cast Mg alloy (AZ91: Mg-Al8.9-Zn0.6-Mn0.2) produced by a heated-mold continuous casting process (HMC) are investigated. In a modification of the original HMC process, the cooling of the liquid alloy by direct water spray is carried out in an atmosphere of high-purity argon gas. The HMC-AZ91 alloy exhibits excellent mechanical properties (high strength and high ductility) that are about twice as high as those for the same alloy produced by conventional gravity casting. The increased material strength and ductility of the HMC sample are attributed to nanoscale and microscale microstructural characteristics. The fine grains and tiny spherical eutectic structures ( e.g., Mg17Al12 and Al6Mn) distributed randomly in the matrix of the HMC alloy result in resistance to dislocation movement, leading to high tensile strength. Basal slip on (0001) planes in the relatively organized crystal orientation of the HMC alloy, as well as grain boundary sliding through tiny spherical eutectic structures, results in high ductility. Details of the failure mechanism under static loading in the HMC alloy are also discussed using failure models.

  7. EBSD Study on Grain Boundary and Microtexture Evolutions During Friction Stir Processing of A413 Cast Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Shamanian, Morteza; Mostaan, Hossein; Safari, Mehdi; Szpunar, Jerzy A.

    2016-07-01

    The as-cast Al alloys contain heterogeneous distributions of non-deforming particles due to non-equilibrium solidification effects. Therefore, these alloys have poor tribological and mechanical behaviors. It is well known that using friction stir processing (FSP), very fine microstructure is created in the as-cast Al alloys, while their wear resistance can be improved. In this research work, FSP is used to locally refine a surface layer of the coarse as-cast microstructure of cast A413 Al alloy. The main objective of this study is to investigate the effect of FSP on microstructure and microtexture evolutions in A413 cast Al alloy. The grain boundary character distribution, grain structure, and microtexture evolutions in as-cast and friction stir processed A413 Al alloy are analyzed by electron back scatter diffraction technique. It is found that with the FSP, the fraction of low ∑boundary such as ∑3, 7, and 9 are increased. The obtained results show that there are no deformation texture components in the structure of friction stir processed samples. However, some of the main recrystallization texture components such as BR and cubeND are formed during FSP which indicate the occurrence of dynamic recrystallization phenomenon due to the severe plastic deformation induced by the rotation of tool.

  8. Numerical Simulation of Infiltration and Solidification Processes for Squeeze Cast Al Composites with Parametric Study

    NASA Astrophysics Data System (ADS)

    Jung, C. K.; Jang, J. H.; Han, K. S.

    2008-11-01

    An axisymmetric finite element (FE) model is developed for the process of squeeze casting the metal-matrix composites (MMCs). The flow in the mold, the infiltration into the porous preform, and the solidification of the molten metal are studied numerically. The saturated porous flow model is adopted to simulate metal infiltration into the fibrous preform. To track the fluid front during the mold filling and infiltration, the level-set method is used. The enthalpy method is used to deal with transient heat transfer, including phase changes. Also, a simple preform deformation model is used to predict the permeability change caused by preform compression during infiltration. A numerical model representing the experiment setup is proposed. The infiltration and cooling behaviors during a process were calculated using pure aluminum as the matrix and a Saffil fiber preform. To validate the assumptions used in the numerical model, a series of infiltration experiments was carried out. The infiltration kinetics and the preform deformation were studied at different inlet pressures and at different preheat temperatures of the aluminum and the mold. A comparison with the experimental data shows that the developed FE program successfully predicts the actual squeeze casting process.

  9. Colloidal processing, tape casting and sintering of PLZT for development of piezoceramic/polymer interlayered composites

    NASA Astrophysics Data System (ADS)

    Feng, Jian-Huei

    Piezoceramic/polymer composites possess many advantages as compared to single-phase piezoceramics. One typical form of the composites is the interlayered structure, where the main requirement is to obtain thin, flat and dense ceramic sheets. Tape casting is a reliable process for producing such high-quality sheets. The colloidal processing of tape casting slurries is a critical step to achieve uniform ceramic bodies. Lanthanum-modified lead zirconate titanate (PLZT) was selected for making piezoceramic sheets due to its superior piezoelectric properties. The quality of green tapes depends mainly on the solvents and organic additives of tape casting slurries. The effects of xylenes/ethanol solvent mixtures on non-aqueous slurries were first investigated. Well-dispersed colloidal suspensions were obtained in xylenes-rich solvents with a minimum amount of menhaden fish oil as a dispersant. Adsorption of dispersant and PLZT solids content of unfired tapes are strongly affected by the solvent(s) utilized. Furthermore, when selecting solvent mixtures, one needs to consider other additives, such as binder that can affect the viscosity of slurries. Aqueous tape casting was performed using a polyelectrolyte dispersant, poly(vinyl alcohol) (PVA) binders and various plasticizers. Zeta potential, conductivity and viscosity of PLZT suspensions containing dispersant were characterized. The effects of plasticizers and binders on properties of unfired tapes were also investigated. The tapes made from low molecular weight plasticizers showed higher plasticity. Glycerol was shown to be the most effective plasticizer for PVA. Strong hydrogen bonding in high hydrolysis PVA led to high strength and high bulk density of green tapes, but also caused deformation of the tapes after drying. There are many challenges for sintering PLZT tapes due to volatilization of PbO component at high temperatures and fragility of thin tapes. By using the proper setter powders and the sandwich method

  10. Coupled turbulent flow, heat, and solute transport in continuous casting processes

    NASA Astrophysics Data System (ADS)

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

    1995-08-01

    A fully coupled fluid flow, heat, and solute transport model was developed to analyze turbulent flow, solidification, and evolution of macrosegregation in a continuous billet caster. Transport equations of total mass, momentum, energy, and species for a binary iron-carbon alloy system were solved using a continuum model, wherein the equations are valid for the solid, liquid, and mushy zones in the casting. A modified version of the low-Reynolds number k-ɛ model was adopted to incorporate turbulence effects on transport processes in the system. A control-volume-based finite-difference procedure was employed to solve the conservation equations associated with appropriate boundary conditions. Because of high nonlinearity in the system of equations, a number of techniques were used to accelerate the convergence process. The effects of the parameters such as casting speed, steel grade, nozzle configuration on flow pattern, solidification profile, and carbon segregation were investigated. From the computed flow pattern, the trajectory of inclusion particles, as well as the density distribution of the particles, was calculated. Some of the computed results were compared with available experimental measurements, and reasonable agreements were obtained.

  11. An evaluation of direct pressure sensors for monitoring the aluminum die casting process

    SciTech Connect

    Zhang, X.

    1997-12-31

    This study was conducted as part of the US Department of Energy (DOE) sponsored project Die Cavity Instrumentation. One objective of that project was to evaluate thermal, pressure, and gas flow process monitoring sensors in or near the die cavity as a means of securing improved process monitoring and control and better resultant part quality. The objectives of this thesis are to (1) evaluate a direct cavity pressure sensor in a controlled production campaign at the GM Casting Advanced Development Center (CADC) at Bedford, Indiana; and (2) develop correlations between sensor responses and product quality in terms of the casting weight, volume, and density. A direct quartz-based pressure sensor developed and marked by Kistler Instrument Corp. was acquired for evaluating as an in-cavity liquid metal pressure sensor. This pressure sensor is designed for use up to 700 C and 2,000 bars (29,000 psi). It has a pressure overload capacity up to 2,500 bars (36,250 psi).

  12. Fabrication of TiO2/PU Superhydrophobic Film by Nanoparticle Assisted Cast Micromolding Process.

    PubMed

    Li, Jie; Zheng, Jianyong; Zhang, Jing; Feng, Jie

    2016-06-01

    Lotus-like surfaces have attracted great attentions in recent years for their wide applications in water repellency, anti-fog and self-cleaning. This paper introduced a novel process, nanoparticle assisted cast micromolding, to create polymer film with superhydrophobic surface. Briefly, waterborne polyurethane (WPU) sol and nano TiO2/WPU sol were each cast onto the featured surfaces of the poly(dimethylsiloxane) (PDMS) stamps replicated from fresh lotus leaves. After being dried and peeled off from the stamps, PU and TiO2/WPU replica films were created respectively. To the former, only high hydrophobic property was observed with static water contact angle (WCA) at 142.5 degrees. While to the later, superhydrophobic property was obtained with WCA more than 150 degrees and slide angle less than 3 degrees. Scanning electron microscopy (SEM) imaging showed that the PU replica film only had the micro-papillas and the TiO2/PU replica film not only had micro papillas but also had a large number of nano structures distributed on and between the micro-papillas. Such nano and micro hierarchical structures were very similar with those on the natural lotus leaf surface, thus was the main reason for causing superhydrophobic property. Although an elastic PDMS stamp from lotus leaf was used in herein process, hard molds may also be used in theory. This study supplied an alternative technique for large scale production of polymeric films with superhydrophobic. PMID:27427647

  13. Fabrication of TiO2/PU Superhydrophobic Film by Nanoparticle Assisted Cast Micromolding Process.

    PubMed

    Li, Jie; Zheng, Jianyong; Zhang, Jing; Feng, Jie

    2016-06-01

    Lotus-like surfaces have attracted great attentions in recent years for their wide applications in water repellency, anti-fog and self-cleaning. This paper introduced a novel process, nanoparticle assisted cast micromolding, to create polymer film with superhydrophobic surface. Briefly, waterborne polyurethane (WPU) sol and nano TiO2/WPU sol were each cast onto the featured surfaces of the poly(dimethylsiloxane) (PDMS) stamps replicated from fresh lotus leaves. After being dried and peeled off from the stamps, PU and TiO2/WPU replica films were created respectively. To the former, only high hydrophobic property was observed with static water contact angle (WCA) at 142.5 degrees. While to the later, superhydrophobic property was obtained with WCA more than 150 degrees and slide angle less than 3 degrees. Scanning electron microscopy (SEM) imaging showed that the PU replica film only had the micro-papillas and the TiO2/PU replica film not only had micro papillas but also had a large number of nano structures distributed on and between the micro-papillas. Such nano and micro hierarchical structures were very similar with those on the natural lotus leaf surface, thus was the main reason for causing superhydrophobic property. Although an elastic PDMS stamp from lotus leaf was used in herein process, hard molds may also be used in theory. This study supplied an alternative technique for large scale production of polymeric films with superhydrophobic.

  14. The mechanical response of a uranium-nobium alloy: a comparison of cast versus wrought processing

    SciTech Connect

    Cady, Carl M; Gray, George T., III; Cerreta, Ellen K; Aikin, Robert M; Chen, Shuh - Rong; Trujillo, Carl P; Lopez, Mike F; Korzekwa, Deniece R; Kelly, Ann M

    2009-02-13

    A rigorous experimentation and validation program is being undertaken to create constitutive models that elucidate the fundamental mechanisms controlling plasticity in uranium-6 wt.% niobium alloys (U-6Nb). The first, 'wrought', material produced by processing a cast ingot I'ia forging and forming into plate was studied. The second material investigated is a direct cast U-6Nb alloy. The purpose of the investigation is to detennine the principal differences, or more importantly, similarities, between the two materials due to processing. It is well known that parameters like grain size, impurity size and chemistry affect the deformation and failure characteristics of materials. Metallography conducted on these materials revealed that the microstructures are quite different. Characterization techniques like tension, compression, and shear were performed to find the principal differences between the materials as a function of stress state. Dynamic characterization using a split Hopkinson pressure bar in conjunction with Taylor impact testing was conducted to derive and thereafter validate constitutive material models. The Mechanical Threshold Strength Model is shown to accurately capture the constitutive response of these materials and Taylor cylinder tests are used to provide a robust way to verify and validate the constitutive model predictions of deformation by comparing finite element simulations with the experimental results. The primary differences between the materials will be described and predictions about material behavior will be made.

  15. The effects of geometrical and process variables on the quality of cast-on-strap joints

    NASA Astrophysics Data System (ADS)

    Cook, S. M.; Lakshmi, C. S.; See, J. B.; Rice, D. M.

    An automated laboratory-scale, cast-on-strap joining process for lead/acid batteries has been developed. This allows tight control of relevant casting parameters such as strap mould and metal temperature, lug immersion speed, and the time between strap filling and lug entry into the molten strap. The joining of lead-antimony or lead-tin strap alloys with lead-antimony or lead-calcium-tin lugs is studied. It is found that lead-tin is not suitable as a strap alloy for the alloy combinations and joining conditions that have been investigated. Penetration depth of the lug into the strap is found to be critical and may be optimized for a given lug thickness under fixed process conditions. The joint quality improves with a deeper penetration of the thicker lugs for the geometrical configurations studied in this work. It is far easier to form a sound joint with thin lugs as these are not as sensitive as thick lugs to variations in the joining conditions.

  16. Phase field simulation on microstructure evolution in solidification and aging process of squeeze cast magnesium alloy

    NASA Astrophysics Data System (ADS)

    Pan, H. W.; Han, G. M.; Han, Z. Q.; Liu, B. C.

    2015-06-01

    Phase-field models have been developed to simulate the dendritic growth in pressurized solidification of Mg-Al alloy during squeeze casting and the precipitation of multivariant β-Mg17Al12 phases during the subsequent aging process. For the pressurized solidification, the effects of pressure on the Gibbs free energy and chemical potential of solid and liquid phases, and the solute diffusion coefficient were considered. For the precipitation during aging process, the effects of elastic strain energy, anisotropy of interfacial energy, and anisotropy of interface mobility coefficient were considered. The results showed that the dendritic growth rate tends to increase and the secondary dendrite arms are more developed as the pressure is increased from 0.1 to 100MPa, which showed a good agreement with the experimental results of direct squeeze casting of Mg-Al alloy. The 2D and 3D simulated precipitates had lath shapes with lozenge ends, and the precipitate variants were parallel to the basal plane and oriented in directions with an angular interval of 60 degrees, which is in good agreement with experimental observations.

  17. Semi-quantitative predictions of hot tearing and cold cracking in aluminum DC casting using numerical process simulator

    NASA Astrophysics Data System (ADS)

    Subroto, T.; Miroux, A.; Mortensen, D.; M'Hamdi, M.; Eskin, D. G.; Katgerman, L.

    2012-07-01

    Cracking is one of the most critical defects that may occur during aluminum direct-chill (DC) casting. There are two types of cracking typical of DC casting: hot tearing and cold cracking. To study and predict such defects, currently we are using a process simulator, ALSIM. ALSIM is able to provide semi-quantitative predictions of hot tearing and cold cracking susceptibility. In this work, we performed benchmark tests using predictions of both types of cracks and experimental results of DC casting trials. The trials series resulted in billets with hot tearing as well as cold cracking. The model was also used to study the influence of several casting variables such as casting speed and inlet geometry with respect to the cracking susceptibility in the ingots. In this work, we found that the sump geometry was changed by the feeding scheme, which played an important role in hot tear occurrence. Moreover, increasing the casting speed also increased the hot tear and cold crack susceptibility. In addition, from the result of simulation, we also observed a phenomenon that supported the hypotheses of connection between hot tearing and cold cracking.

  18. Development of Cast Alumina-forming Austenitic Stainless Steel Alloys for use in High Temperature Process Environments

    SciTech Connect

    Muralidharan, Govindarajan; Yamamoto, Yukinori; Brady, Michael P; Pint, Bruce A; Pankiw, Roman; Voke, Don

    2015-01-01

    There is significant interest in the development of alumina-forming, creep resistant alloys for use in various industrial process environments. It is expected that these alloys can be fabricated into components for use in these environments through centrifugal casting and welding. Based on the successful earlier studies on the development of wrought versions of Alumina-Forming Austenitic (AFA) alloys, new alloy compositions have been developed for cast products. These alloys achieve good high-temperature oxidation resistance due to the formation of protective Al2O3 scales while multiple second-phase precipitation strengthening contributes to excellent creep resistance. This work will summarize the results on the development and properties of a centrifugally cast AFA alloy. This paper highlights the strength, oxidation resistance in air and water vapor containing environments, and creep properties in the as-cast condition over the temperature range of 750°C to 900°C in a centrifugally cast heat. Preliminary results for a laboratory cast AFA composition with good oxidation resistance at 1100°C are also presented.

  19. Aluminum-Silicon Alloy Having Improved Properties At Elevated Temperatures and Process for Producing Cast Articles Therefrom

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2002-01-01

    A process for making a cast article from an aluminum alloy includes first casting an article from an alloy having the following composition, in weight percent: Silicon 11.0-14.0, Copper 5.6-8.0, Iron 0-0.8, Magnesium 0.5-1.5, Nickel 0.05-0.9, Manganese 0-1.0, Titanium 0.05-1.2, Zirconium 0.12-1.2, Vanadium 0.05-1.2, Zinc 0.05-0.9, Strontium 0.001-0.1, Aluminum balance . In this alloy the ratio of silicon to magnesium is 10 to 25, and the ratio of copper to magnesium is 4 to 15. After an article is cast from the alloy, the cast article is aged at a temperature within the range of 400F to 500F for a time period within the range of four to 16 hours. It has been found especially advantageous if the cast article is first exposed to a solutionizing step prior to the aging step. This solutionizing step is carried out by exposing the cast article to a temperature within the range of 900F to 1000F for a time period of fifteen minutes to four hours. It has also been found to be especially advantageous if the solutionizing step is followed directly with a quenching step, wherein the cast article is quenched in a quenching medium such as water at a temperature within the range of 120F to 300F. The resulting cast article is suitable in a number of high temperature applications, such as heavy-duty pistons for internal combustion engines.

  20. Emittance of investment casting molds

    SciTech Connect

    Havstad, M.A.

    1994-07-15

    This document describes measurements of the directional spectral emittance of four ceramic mold materials. The work was performed with the samples at {approximately} 900{degree}C in a vacuum vessel pumped to {approximately}3 {times} 10{sup {minus}6}Torr. Results conform to expectations derived from prior work done with similar samples.

  1. The development of ultrahigh strength low alloy cast steels with increased toughness

    NASA Astrophysics Data System (ADS)

    Lynch, Paul C.

    This work describes the initial work on the development of the next generation of ultrahigh strength low alloy (UHSLA) cast steels. These UHSLA cast steels have both ultrahigh strength levels and good impact toughness. The influence of heat treatment, secondary processing using hot isostatic processing (HIP), and chemical composition on the microstructure and properties of UHSLA cast steels have been evaluated. The extent of microsegregation reduction expected during the heat treatment of UHSLA cast steels has also been estimated by diffusion modeling. This new family of UHSLA cast steels is similar in composition and properties to UHSLA wrought steels. However, the heat treatment and secondary processing of the UHSLA cast steels is used to develop microstructures and properties typically developed through thermomechanical processing and heat treatment for wrought UHSLA steels. Two martensitic UHSLA steels, 4340+ (silicon modified 4340) and ES-1 were investigated for this study. For the 4340+ alloy, heat treatment variables evaluated include homogenization temperature and time, tempering temperature, and austempering temperature and time. For the ES-1 alloy, heat treatment variables evaluated include homogenization temperature and time, austenization temperature, cryogenic treatment, and tempering temperature. The effect of high temperature hot isostatic processing (HIP) on the 4340+ and ES- 1 alloys was also investigated. Tensile properties, charpy v-notch impact toughness (CVN), microstructures, and fractographs have all been characterized after heat treatment. The effects of HIP on microporosity reduction in the ES-1 alloy were also investigated. The experiments carried out on the investment cast 4340+ alloy have shown that increasing the homogenization temperature can increase CVN without changing the ultimate tensile strength (UTS) or yield strength (YS) of the cast material. By replacing the homogenization step in the conventional heat treatment process with

  2. In-situ real time monitoring of the polymerization in gel-cast ceramic processes

    SciTech Connect

    Ahuja, S.; Dieckman, S.L.; Bostrom, G.A.; Waterfield, L.G.; Raptis, A.C.; Omatete, O.O.

    1996-08-01

    Gelcasting requires making a mixture of a slurry of ceramic powder in a solution of organic monomers and casting it in a mold. Gelcasting is different from injection molding in that it separates mold filling from setting during conversion of the ceramic slurry to a formed green part. In this work, NMR spectroscopy and imaging were used for in-situ monitoring of the gelation process and gelcasting of alumina. {sup 1}H NMR spectra and images are obtained during polymerization of a mixture of soluble reactive acrylamide monomers. Polymerization was initiated by adding an initiator and an accelerator to form long- chain, crosslinked polymers. Multidimensional NMR imaging was used for in-situ monitoring of the process and for verification of homogeneous polymerization. Comparison of the modeled intensities with acquired images shows a direction extraction of T{sub 1} data from the images.

  3. Urinary casts

    MedlinePlus

    ... the urine; Fatty casts; Red blood cell casts; White blood cell casts ... with advanced kidney disease and chronic kidney failure . White blood cell (WBC) casts are more common with acute kidney ...

  4. Structure-Property-Processing Correlations in Freeze-Cast Hybrid Scaffolds

    NASA Astrophysics Data System (ADS)

    Hunger, Philipp Malte

    Porous materials are highly sought after for applications ranging from catalyst carriers to tissue scaffolds. Most applications require clearly defined structural features and a specific mechanical performance. Therefore, it is essential to establish systematic structure-property-processing correlations to be able to tailor both structure and mechanical properties for a particular application. Because the introduction of porosity is detrimental to the mechanical performance of highly porous structures, it is necessary to generate a structure that allows for the mechanical properties to be maximized. One example for such a structure are honeycombs. In addition to the porosity and pore morphology, the scaffold's performance depends on the properties inherent to the material from which it is made. Polymeric foams possess high toughness but low stiffness, whereas ceramic foams possess high stiffness but low toughness. Natural composites like bone, antler and nacre have both high stiffness and high toughness. This unusual set of mechanical properties is thought to be intricately linked to the multi-level hierarchical composite structure present in these materials. Great potential for the fabrication of stiff, strong and tough porous scaffolds is thus seen in nacre-like composite materials with a hierarchical, honeycomb-like structure. Freeze casting is a method with which such hybrid materials can be made, adding the third dimension to nacre by forming a highly porous, hierarchical bulk material, with dense, nacre-like cell walls. The nacre-like cell walls self-assemble during the directional freezing of a water-based ceramic-polymer slurry. Reported here are structure-property-processing correlations observed in these materials. They are unusual, because they are, like nacre, solely glued by a polymeric phase and not processed further by sintering. The results illustrate several pathways to control both structure and mechanical properties in freeze-cast composites and

  5. Machinability of Austempered Ductile Iron (ADI) Produced by Integrated Green Technology of Continuous Casting-Heat Treatment Processes

    NASA Astrophysics Data System (ADS)

    Meena, A.; El Mansori, M.; Ghidossi, P.

    2011-01-01

    This study presents the novel processing technique known as continuous casting-heat treatment processes to produce Austempered Ductile Iron (ADI) which is a new class of ductile iron. ADI is characterized by improved mechanical properties but has low machinability as compared to other cast irons and steel of similar strength. The novel technique is developed by the integration of casting (in die casting) and heat treatment processes in foundry to save cost energy and time. Specimens just after casting were austenitized at 930° C for 90 min and then austempered in fluidized bed at 380° C for 90 and 120 min. Hence, the effect of austempering time on the morphology of retained austenite and mechanical properties of the material were examined and compared with conventionally produced ADI. Drilling tests were then carried out to evaluate the machinability of ADI in terms of cutting forces, chip micro-hardness, chip morphology and surface roughness. The mechanical properties of ADI austempered for 120 min have found to be better as compare to the ADI austempered for 90 min.

  6. Machinability of Austempered Ductile Iron (ADI) Produced by Integrated Green Technology of Continuous Casting-Heat Treatment Processes

    SciTech Connect

    Meena, A.; El Mansori, M.; Ghidossi, P.

    2011-01-17

    This study presents the novel processing technique known as continuous casting-heat treatment processes to produce Austempered Ductile Iron (ADI) which is a new class of ductile iron. ADI is characterized by improved mechanical properties but has low machinability as compared to other cast irons and steel of similar strength. The novel technique is developed by the integration of casting (in die casting) and heat treatment processes in foundry to save cost energy and time. Specimens just after casting were austenitized at 930 deg. C for 90 min and then austempered in fluidized bed at 380 deg. C for 90 and 120 min. Hence, the effect of austempering time on the morphology of retained austenite and mechanical properties of the material were examined and compared with conventionally produced ADI. Drilling tests were then carried out to evaluate the machinability of ADI in terms of cutting forces, chip micro-hardness, chip morphology and surface roughness. The mechanical properties of ADI austempered for 120 min have found to be better as compare to the ADI austempered for 90 min.

  7. Analysis and Evaluation of Novel Al-Mg-Sc-Zr Aerospace Alloy Strip Produced Using the Horizontal Single Belt Casting (HSBC) Process

    NASA Astrophysics Data System (ADS)

    Ge, Sa; Celikin, Mert; Isac, Mihaiela; Guthrie, Roderick I. L.

    2015-04-01

    Horizontal single belt casting (HSBC) is a near net shape casting process in which molten metal is directly cast into thin strips, at high cooling rates (order of several 100 °C/s), with the potential for high volume, friction free, continuous production of metal strips. This casting process was used in the present work to produce strips of Al-Mg alloys in the AA5000 series, with additions of Sc and Zr. Such aluminum alloys show exceptional potential as a structural material for transportation/aerospace applications. To demonstrate the suitability of the HSBC process to manufacture competitive strip products of Al-Mg-Sc-Zr, the mechanical properties and microstructures of the strips produced using the HSBC process were compared with conventionally cast products. The effects of annealing on the mechanical properties of the strip-cast Al-Mg-Sc-Zr alloys were also investigated.

  8. Process simulator for time-dependent material and energy flow in a continuous casting system

    SciTech Connect

    Westerberg, K.W.; McClelland, M.A.

    1995-02-06

    A process simulator is developed for the material and energy flow in a continuous casting system which utilizes an electron-beam energy source. A time-dependent, one-dimensional model is used which accounts for energy transport within the ingot and transport to the surroundings by conduction, thermal radiation, and the formation of secondary electrons. Also included are the mass and energy additions associated with the poured metal. A modified finite element method is used to solve the energy equation while tracking boundaries at the pool surface and solidification zone. Model parameters are determined using results from a steady-state experiment and a more detailed two-dimensional model for fluid flow and energy transport. For a transient experiment with pouring, a comparison is made between predicted and measured heat flows.

  9. Thermal casting process for the preparation of anisotropic membranes and the resultant membrane

    DOEpatents

    Caneba, Gerard T. M.; Soong, David S.

    1987-01-01

    A method for providing anisotropic polymer membranes from a binary polymer/solvent solution using a thermal inversion process. A homogeneous binary solution is cast onto a support and cooled in such a way as to provide a differential in cooling rate across the thickness of the resulting membrane sheet. Isotropic or anisotropic structures of selected porosities can be produced, depending on the initial concentration of polymer in the selected solvent and on the extent of the differential in cooling rate. This differential results in a corresponding gradation in pore size. The method may be modified to provide a working skin by applying a rapid, high-temperature pulse to redissolve a predetermined thickness of the membrane at one of its faces and then freezing the entire structure.

  10. ToxCast Workflow: High-throughput screening assay data processing, analysis and management (SOT)

    EPA Science Inventory

    US EPA’s ToxCast program is generating data in high-throughput screening (HTS) and high-content screening (HCS) assays for thousands of environmental chemicals, for use in developing predictive toxicity models. Currently the ToxCast screening program includes over 1800 unique c...

  11. Achieving Investment Autonomy.

    ERIC Educational Resources Information Center

    Flynn, Jeffrey B.

    1988-01-01

    Public investors can lower commissions through investment autonomy, that is, implementing the investment decision process without outside input. Details some techniques for fine-tuning the investment process. (MLF)

  12. Study on Venture Capital Investment Risk Avoiding Base on Option Pricing in Agricultural Production and Processing Enterprises

    NASA Astrophysics Data System (ADS)

    Zhang, Xubo

    This paper uses the approaches and models of option theory to analyze two-stage venture capital investment in agricultural production and processing enterprises decision-making under uncertainty. Mathematics expressions of this two-stage venture capital investment decision-making are presented. An option value model about two-stage venture capital investment decision-making base on options pricing theory under the uncertainty is presented. Get the solution of option pricing model which we present.

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  14. Microstructure Analysis on 6061 Aluminum Alloy after Casting and Diffuses Annealing Process

    NASA Astrophysics Data System (ADS)

    Wang, H. Q.; Sun, W. L.; Xing, Y. Q.

    One factory using semi-continuous casting process produce the ф200×6000 mm 6061 aluminium alloy barstock, and then rotary forged for car wheels. 6061 distorting aluminium alloy is an forged aluminum alloy, and mainly containing Mg, Si, Cu and other alloying elements. The main strengthening phase is Mg2Si, and also has few phase of (FeMn) 3Si2Al15. In order to eliminate the segregation and separation which present in the crystal boundary, and make the distortion to be uniform, and does not present ear and fracture defects after the forging. So the 6061 distorting aluminium alloy adopt the diffusion annealing heat treatment before the forging process.According to the current conditions, we use the diffusion annealing which have the different heating temperature and different holding time.The best process we can obtain from the test which can improve the production efficiency and reduce the material waste, improve the mechanical properties, and eliminate the overheated film on the surface.Then,we using OM,SEM and EDS to analyse the microstructure and the chemical composition of compound between the surface and centre. The result shows that the amount of segregation were different in the surface and in the center, and the different diffusion annealing can cause the phase change in the surface and the center.

  15. LLNL casting technology

    SciTech Connect

    Shapiro, A.B.; Comfort, W.J. III

    1994-01-01

    Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US compentiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective, experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.

  16. LLNL casting technology

    NASA Astrophysics Data System (ADS)

    Shapiro, A. B.; Comfort, W. J., III

    1994-01-01

    Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US competiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.

  17. Anisotropic constitutive model and FE simulation of the sintering process of slip cast traditional porcelain

    NASA Astrophysics Data System (ADS)

    Sarbandi, B.; Besson, J.; Boussuge, M.; Ryckelynck, D.

    2010-06-01

    Slip cast ceramic components undergo both sintering shrinkage and creep deformation caused by gravity during the firing cycle. In addition sintering may be anisotropic due to the development of preferential directions during slip casting. Both phenomena induce complex deformations of parts which make the design of casting molds difficult. To help solving this problem, anisotropic constitutive equations are proposed to represent the behavior of the ceramic compacts during sintering. The model parameters are identified using tests allowing to characterize both sintering and creep. The model was implemented in a finite element software and used to simulate the deformation of a traditional ceramic object during sintering.

  18. Anisotropic constitutive model and FE simulation of the sintering process of slip cast traditional porcelain

    SciTech Connect

    Sarbandi, B.; Besson, J.; Boussuge, M.; Ryckelynck, D.

    2010-06-15

    Slip cast ceramic components undergo both sintering shrinkage and creep deformation caused by gravity during the firing cycle. In addition sintering may be anisotropic due to the development of preferential directions during slip casting. Both phenomena induce complex deformations of parts which make the design of casting molds difficult. To help solving this problem, anisotropic constitutive equations are proposed to represent the behavior of the ceramic compacts during sintering. The model parameters are identified using tests allowing to characterize both sintering and creep. The model was implemented in a finite element software and used to simulate the deformation of a traditional ceramic object during sintering.

  19. Process-directed self-assembly of multiblock copolymers: Solvent casting vs spray coating

    NASA Astrophysics Data System (ADS)

    Tang, Q.; Tang, J.; Müller, M.

    2016-07-01

    Using computer simulation of a soft, coarse-grained model and self-consistent field theory we investigate how collapsed, globular chain conformations in the initial stages of structure formation, which are produced by spray-coating, affect the single-chain structure and morphology of microphase-separated multiblock copolymers. Comparing spray-coated films with films that start from a disordered state of Gaussian chains, we observe that the collapsed molecular conformations in the initial stage give rise to (1) a smaller fraction of blocks that straddle domains (bridges), (2) a significant reduction of the molecular extension normal to the internal interfaces, and (3) a slightly larger lamellar domain spacing in the final morphology. The relaxation of molecular conformations towards equilibrium is very protracted for both processes - solvent casting and spray coating. These findings illustrate that the process conditions of the copolymer materials may significantly affect materials properties (such as mechanical properties) because the system does not reach thermal equilibrium on the relevant time scales.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  1. Metal particle compaction during drop-substrate impact for inkjet printing and drop-casting processes

    NASA Astrophysics Data System (ADS)

    Clancy, I.; Amarandei, G.; Nash, C.; Glowacki, B. A.

    2016-02-01

    Direct coating methods using metal particles from aqueous solutions or solvent-based inks become central in the roll-to-roll fabrication processes as these methods can lead to continuous or pre-defined conductive layers on a large variety of substrates. For good electrical conductivity, the metal particles have to be brought into contact, and traditionally, additional sintering treatments are required. Such treatments can degrade the sensitive substrates as paper or polymer films. In this study, the possibility of obtaining conductive layers at room temperature is investigated for direct coating methods with an emphasis on drop-casting and inkjet printing. Thus, it is shown that electrical conductive layers can be achieved if the metal particles can compact during the drop-substrate impact interaction. It is theoretically shown that the compaction process is directly related to the particle and ink drop size, the initial fractional particle loading of the ink, solvent viscosity, and drop velocity. The theoretical predictions on compaction are experimentally validated, and the particle compaction's influence on changes in the electrical conductivity of the resulting layers is demonstrated.

  2. Process for casting hard-faced, lightweight camshafts and other cylindrical products

    DOEpatents

    Hansen, Jeffrey S.; Turner, Paul C.; Argetsinger, Edward R.; Wilson, Rick D.

    1996-01-01

    A process for casting a hard-faced cylindrical product such as an automobile camshaft includes the steps of: (a) preparing a composition formed from a molten base metal and an additive in particle form and having a hardness value greater than the hardness value of the base metal; (b) introducing the composition into a flask containing a meltable pattern of a cylindrical product such as an automobile camshaft to be manufactured and encased in sand to allow the composition to melt the pattern and assume the shape of the pattern within the sand; and (c) rotating the flask containing the pattern about the longitudinal axes of both the flask and the pattern as the molten base metal containing the additive in particle form is introduced into the flask to cause particles of the additive entrained in the molten base metal to migrate by centrifugal action to the radial extremities of the pattern and thereby provide a cylindrical product having a hardness value greater at it's radial extremities than at its center when the molten base metal solidifies.

  3. Spectrally selective, matched emitters for thermophotovoltaic energy conversion fabricated by tape casting process

    NASA Astrophysics Data System (ADS)

    Ferguson, Lucian Garret

    The thermophotovoltaic (TPV) generator converts radiant energy from a high temperature emitter element into electric power using infrared responding photovoltaic cells. Spectral control is a primary issue in TPV applications. Conventional TPV generators have relied on filters to achieve selectivity and spectral control with near-blackbody ceramic emitters. Several practical problems have limited the success of this approach, particularly the present lack of a satisfactory wide-band infrared filter. A new, spectrally selective emitter is described in this work, and will be called the "bandgap matched emitter" because its emissive power spectrum is very efficiently matched with the infrared response of the GaSb photovoltaic cell. The superior spectral efficiency has been achieved with a novel combination of spectrally active, transition-metal dopants within an infrared-transparent magnesium oxide ceramic matrix. High mechanical integrity, thermal shock resistance, excellent heat transfer characteristics, and near-ideal spectral efficiency have all been achieved for the first time by fabricating composite emitters from thin sheets of flexible ceramic ribbons made by the tape casting process.

  4. Isotope biogeochemical assessment of natural biodegradation processes in open cast pit mining landscapes

    NASA Astrophysics Data System (ADS)

    Jeschke, Christina; Knöller, Kay; Koschorreck, Matthias; Ussath, Maria; Hoth, Nils

    2014-05-01

    In Germany, a major share of the energy production is based on the burning of lignite from open cast pit mines. The remediation and re-cultivation of the former mining areas in the Lusatian and Central German lignite mining district is an enormous technical and economical challenge. After mine closures, the surrounding landscapes are threatened by acid mine drainage (AMD), i.e. the acidification and mineralization of rising groundwater with metals and inorganic contaminants. The high content of sulfur (sulfuric acid, sulfate), nitrogen (ammonium) and iron compounds (iron-hydroxides) deteriorates the groundwater quality and decelerates sustainable development of tourism in (former) mining landscapes. Natural biodegradation or attenuation (NA) processes of inorganic contaminants are considered to be a technically low impact and an economically beneficial solution. The investigations of the stable isotope compositions of compounds involved in NA processes helps clarify the dynamics of natural degradation and provides specific informations on retention processes of sulfate and nitrogen-compounds in mine dump water, mine dump sediment, and residual pit lakes. In an active mine dump we investigated zones where the process of bacterial sulfate reduction, as one very important NA process, takes place and how NA can be enhanced by injecting reactive substrates. Stable isotopes signatures of sulfur and nitrogen components were examined and evaluated in concert with hydrogeochemical data. In addition, we delineated the sources of ammonium pollution in mine dump sediments and investigated nitrification by 15N-labeling techniques to calculate the limit of the conversion of harmful ammonium to nitrate in residual mining lakes. Ultimately, we provided an isotope biogeochemical assessment of natural attenuation of sulfate and ammonium at mine dump sites and mining lakes. Also, we estimated the risk potential for water in different compartments of the hydrological system. In

  5. SLIP CASTING METHOD

    DOEpatents

    Allison, A.G.

    1959-09-01

    S>A process is described for preparing a magnesium oxide slip casting slurry which when used in conjunction with standard casting techniques results in a very strong "green" slip casting and a fired piece of very close dimensional tolerance. The process involves aging an aqueous magnestum oxide slurry, having a basic pH value, until it attains a specified critical viscosity at which time a deflocculating agent is added without upsetting the basic pH value.

  6. Distortion Behavior of a Heavy Hydro Turbine Blade Casting During Forced Air Cooling in Normalizing Treatment Process

    NASA Astrophysics Data System (ADS)

    Yu, Hai-Liang; Kang, Jin-Wu; Wang, Tian-Jiao; Ma, Ji-Yu; Hu, Yong-Yi; Huang, Tian-You; Wang, Shi-Bin; Wu, Ying; Zhang, Cheng-Chun; Dai, Yan-Tao; Li, Peng

    2012-01-01

    Distortion behavior of blade castings in heat treatment process determines their geometrical accuracy, and improper control of it may result in additional repair, shape righting, or even rejection. This article presents a novel approach for discovering the distortion behavior of heavy blade castings during heat treatment process in production. Real-time measurements of distortion and temperature field of a heavy hydro turbine blade casting weighted 17 ton during forced air cooling in normalizing treatment process were carried out by using deformation measurement instruments and an infrared thermal imaging camera. The distortion processes of the typical locations of blade and the temperature field of the blade were obtained. One corner on the blade outlet edge side exhibits variation of distortion with two peaks and a valley. The range reaches 97 mm and the final distortion value is 76 mm. The maximum temperature difference on blade surface reaches 460 °C after 80 min of cooling. Influences of thermal stress and phase transformation stress on the distortion of the blade were elucidated and discussed. The results are of great significance for the understanding and control of the distortion behavior of hydro turbine blades in heat treatment.

  7. CC process optimization through an improved thermal modeling of the cast steel products

    SciTech Connect

    Selaries, J.; Hoffbeck, AM.; Jolivet, JM.; Niederlaender, M.; Perrin, G.; Bobadilla, M.

    1997-12-31

    Heat transfer models developed for continuous casting are more and more becoming simulation tools for defining, from metallurgical criteria, the values of casting parameters (superheat, primary and secondary cooling, casting speed,...) in order to obtain quality products (free from surface cracks and having a low level of central segregation) in the framework of a given production. From this outlook, it is important to have reliable models for the description of the basic mechanisms (heat transfer, microsegregation) as well as for the values relative to the thermophysical data to be used (thermal conductivity, density, enthalpy,...). The studies conducted by IRSID in these fields have made it possible to define the improvements to be brought to the thermal models of continuous casting that are already available. In the first part of this paper, the principles of the improvements brought to the basic models are presented in detail: mathematical formulation taking into account the evolution of the thermal conductivity and the density of steel with temperature, introduction of the microsegregation model adapted to various steel grades (low carbon steels, high carbon steels, stainless steels,...) and selection of the thermophysical data (thermal conductivity, density, enthalpy) with respect to the steel grade. In the second part, some industrial applications of the new model for heat transfers in continuous casting are presented.

  8. Energy Saving Melting and Revert Reduction (E-SMARRT): Precision Casting of Steel

    SciTech Connect

    Dr. Von L. Richards

    2011-09-30

    This project addresses improvements in metal casting processes by reducing scrap and reducing the cost of production, due to scrap reduction from investment casting and yield improvement offered by lost foam casting as compared to no-bake or green sand molding. The objectives for the investment casting portion of the subtask are to improve knowledge of fracture toughness of mold shells and the sources of strength limiting flaws and to understand the effects of wax reclamation procedures on wax properties. Applying 'clean steel' approaches to pouring technology and cleanliness in investment casting of steel are anticipated to improve incoming materials inspection procedures as they affect the microstructure and toughness of the shell. This project focused on two areas of study in the production of steel castings to reduce scrap and save energy: (1) Reducing the amount of shell cracking in investment cast steel production; (2) Investigate the potential of lost foam steel casting The basic findings regarding investment casting shell cracking were: (1) In the case of post pouring cracking, this could be related to phase changes in silica upon cooling and could be delayed by pouring arrangement strategies that maintained the shell surface at temperature for longer time. Employing this delay resulted in less adherent oxidation of castings since the casting was cooler at the time o fair exposure. (2) A model for heat transfer through water saturated shell materials under steam pressure was developed. (3) Initial modeling result of autoclave de-waxing indicated the higher pressure and temperature in the autoclave would impose a steeper temperature gradient on the wax pattern, causing some melt flow prior to bulk expansion and decreasing the stress on the green shell. Basic findings regarding lost foam casting of steel at atmospheric pressure: (1) EPS foam generally decomposes by the collapse mode in steel casting. (2) There is an accumulation of carbon pick-up at the end

  9. Development of a CFD code for casting simulation

    NASA Technical Reports Server (NTRS)

    Murph, Jesse E.

    1993-01-01

    Because of high rejection rates for large structural castings (e.g., the Space Shuttle Main Engine Alternate Turbopump Design Program), a reliable casting simulation computer code is very desirable. This code would reduce both the development time and life cycle costs by allowing accurate modeling of the entire casting process. While this code could be used for other types of castings, the most significant reductions of time and cost would probably be realized in complex investment castings, where any reduction in the number of development castings would be of significant benefit. The casting process is conveniently divided into three distinct phases: (1) mold filling, where the melt is poured or forced into the mold cavity; (2) solidification, where the melt undergoes a phase change to the solid state; and (3) cool down, where the solidified part continues to cool to ambient conditions. While these phases may appear to be separate and distinct, temporal overlaps do exist between phases (e.g., local solidification occurring during mold filling), and some phenomenological events are affected by others (e.g., residual stresses depend on solidification and cooling rates). Therefore, a reliable code must accurately model all three phases and the interactions between each. While many codes have been developed (to various stages of complexity) to model the solidification and cool down phases, only a few codes have been developed to model mold filling.

  10. LOST FOAM CASTING OF MAGNESIUM ALLOYS

    SciTech Connect

    Han, Qingyou; Dinwiddie, Ralph Barton; Sklad, Philip S; Currie, Kenneth; Abdelrahman, Mohamed; Vondra, Fred; Walford, Graham; Nolan, Dennis J

    2007-01-01

    The lost foam casting process has been successfully used for making aluminum and cast iron thin walled castings of complex geometries. Little work has been carried out on cast magnesium alloys using the lost foam process. The article describes the research activities at Oak Ridge National Laboratory and Tennessee Technological University on lost foam casting of magnesium alloys. The work was focused on castings of simple geometries such as plate castings and window castings. The plate castings were designed to investigate the mold filling characteristics of magnesium and aluminum alloys using an infrared camera. The pate castings were then characterized for porosity distribution. The window castings were made to test the castability of the alloys under lost foam conditions. Significant differences between lost foam aluminum casting and lost foam magnesium casting have been observed.

  11. WTEC panel report on advanced casting technologies in Japan and Europe

    SciTech Connect

    Flemings, M.C.; Apelian, D.; Bertram, D.; Hayden, W.; Mikkola, P.H.; Piwonka, T.S.

    1997-03-01

    This report presents the results and conclusions from a study of the Japanese foundry industry conducted by a WTEC study team in January 1996. Results of that study were supplemented by additional visits later in the spring to foundries and foundry laboratories in Europe. During its week in Japan, subgroups of the team visited 22 facilities. Included in these were four metal mold foundries, five iron and steel (sand mold) foundries, four investment casting foundries, four industrial research laboratories, four universities, and one government office. In Chapter 2, Melting and Handling, Diran Apelian discusses what he considers the most critical components in the overall metal casting operation: the melting of the metal and the process of liquid metal handling. Chapter 3 written by H.W. Hayden, reports findings on active R and D efforts in the Japanese casting companies directed to the development of new cast alloys and materials, new ceramic and cermet materials for application by the foundry industry, and major new process/product developments such as amorphous metals and magnetohydrodynamic (MHD) effects on the continuous casting of steel rolling ingots. The next chapter, Metal Mold Casting by Diran Apelian, discusses casting technologies in which the mold cavity is made of a metallic material. The fifth chapter, Japanese and European New Cast Product Development by Paul H. Mikkola, reports findings on new cast products being developed in both Japan and Europe. In Chapter 6, Specialized Sand Casting Technologies, Thomas S. Piwonka assesses the current state of innovation in the field of sand casting in Japan and Europe. In Chapter 7, Current Investment Casting Technology, Thomas S. Piwonka looks at the US precision investment casting industry, which developed during the Second World War. Chapter 8 by Dennis Bertram, assesses the state of manufacturing in Japan: how the Japanese use foundry processes, specialized equipment, alloys, human resources, and the

  12. Expendable Pattern Casting Technology

    NASA Astrophysics Data System (ADS)

    1990-07-01

    The expendable pattern casting (EPC) process is a potential casting process breakthrough which could dramatically improve the competitiveness of the U.S. foundry industry. Cooperatively supported by U.S. Industry and the Department of Energy and managed by the American Foundrymen's Society, a project was started in May 1989 to develop and optimize expendable pattern casting technology. Four major tasks were conducted in the first phase of the project. Those tasks involved: (1) reviewing published literature to determine the major problems in the EPC process; (2) evaluating factors influencing sand flow and compaction; (3) evaluating and comparing casting precision obtained in the EPC process with that obtained in other processes; and (4) identifying critical parameters that control dimensional precision and defect formation in EP castings.

  13. A Neuroeconomics Analysis of Investment Process with Money Flow Information: The Error-Related Negativity.

    PubMed

    Wang, Cuicui; Vieito, João Paulo; Ma, Qingguo

    2015-01-01

    This investigation is among the first ones to analyze the neural basis of an investment process with money flow information of financial market, using a simplified task where volunteers had to choose to buy or not to buy stocks based on the display of positive or negative money flow information. After choosing "to buy" or "not to buy," participants were presented with feedback. At the same time, event-related potentials (ERPs) were used to record investor's brain activity and capture the event-related negativity (ERN) and feedback-related negativity (FRN) components. The results of ERN suggested that there might be a higher risk and more conflict when buying stocks with negative net money flow information than positive net money flow information, and the inverse was also true for the "not to buy" stocks option. The FRN component evoked by the bad outcome of a decision was more negative than that by the good outcome, which reflected the difference between the values of the actual and expected outcome. From the research, we could further understand how investors perceived money flow information of financial market and the neural cognitive effect in investment process. PMID:26557139

  14. A Neuroeconomics Analysis of Investment Process with Money Flow Information: The Error-Related Negativity

    PubMed Central

    Wang, Cuicui; Vieito, João Paulo; Ma, Qingguo

    2015-01-01

    This investigation is among the first ones to analyze the neural basis of an investment process with money flow information of financial market, using a simplified task where volunteers had to choose to buy or not to buy stocks based on the display of positive or negative money flow information. After choosing “to buy” or “not to buy,” participants were presented with feedback. At the same time, event-related potentials (ERPs) were used to record investor's brain activity and capture the event-related negativity (ERN) and feedback-related negativity (FRN) components. The results of ERN suggested that there might be a higher risk and more conflict when buying stocks with negative net money flow information than positive net money flow information, and the inverse was also true for the “not to buy” stocks option. The FRN component evoked by the bad outcome of a decision was more negative than that by the good outcome, which reflected the difference between the values of the actual and expected outcome. From the research, we could further understand how investors perceived money flow information of financial market and the neural cognitive effect in investment process. PMID:26557139

  15. A Neuroeconomics Analysis of Investment Process with Money Flow Information: The Error-Related Negativity.

    PubMed

    Wang, Cuicui; Vieito, João Paulo; Ma, Qingguo

    2015-01-01

    This investigation is among the first ones to analyze the neural basis of an investment process with money flow information of financial market, using a simplified task where volunteers had to choose to buy or not to buy stocks based on the display of positive or negative money flow information. After choosing "to buy" or "not to buy," participants were presented with feedback. At the same time, event-related potentials (ERPs) were used to record investor's brain activity and capture the event-related negativity (ERN) and feedback-related negativity (FRN) components. The results of ERN suggested that there might be a higher risk and more conflict when buying stocks with negative net money flow information than positive net money flow information, and the inverse was also true for the "not to buy" stocks option. The FRN component evoked by the bad outcome of a decision was more negative than that by the good outcome, which reflected the difference between the values of the actual and expected outcome. From the research, we could further understand how investors perceived money flow information of financial market and the neural cognitive effect in investment process.

  16. Processing and Characterization of Functionally Graded Aluminum (A319)—SiCp Metallic Composites by Centrifugal Casting Technique

    NASA Astrophysics Data System (ADS)

    Jayakumar, E.; Jacob, Jibin C.; Rajan, T. P. D.; Joseph, M. A.; Pai, B. C.

    2016-08-01

    Functionally graded materials (FGM) are successfully adopted for the design and fabrication of engineering components with location-specific properties. The present study describes the processing and characterization of A319 Aluminum functionally graded metal matrix composites (FGMMC) with 10 and 15 wt pct SiCp reinforcements. The liquid stir casting method is used for composite melt preparation followed by FGMMC formation by vertical centrifugal casting method. The process parameters used are the mold preheating temperature of 523 K (250 °C), melt pouring temperature of 1013 K (740 °C), and mold rotation speed of 1300 rpm. The study analyzes the distribution and concentration of reinforcement particles in the radial direction of the FGMMC disk along with the effects of gradation on density, hardness, mechanical strength, the variation in coefficient of thermal expansion and the wear resistance properties at different zones. Microstructures of FGMMC reveal an outward radial gradient distribution of reinforcements forming different zones. Namely, matrix-rich inner, transition, particles-rich outer, and chill zone of a few millimeters thick at the outer most periphery of the casting are formed. From 10-FGM, a radial shift in the position of SiCp maxima is observed in 15-FGM casting. The mechanical characterization depicts enhanced properties for the particle-rich zone. The hardness shows a graded nature in correlation with particle concentration and a maximum of 94.4 HRB has been obtained at the particle-rich region of 15-FGM. In the particle-rich zone, the lowest CTE value of 20.1 µm/mK is also observed with a compressive strength of 650 MPa and an ultimate tensile strength of 279 MPa. The wear resistance is higher at the particle-rich zone of the FGMMC.

  17. Energy Saving Melting and Revert Reduction Technology: Improved Die Casting Process to Preserve the Life of the Inserts

    SciTech Connect

    David Schwam, PI; Xuejun Zhu, Sr. Research Associate

    2012-09-30

    The goal of this project was to study the combined effects of die design, proper internal cooling and efficient die lubricants on die life. The project targeted improvements in die casting insert life by: Optomized Die Design for Reduced Surface Temperature: The life of die casting dies is significantly shorter when the die is exposed to elevated temperature for significant periods of time. Any die operated under conditions leading to surface temperature in excess of 1050oF undergoes structural changes that reduce its strength. Optimized die design can improve die life significantly. This improvement can be accomplished by means of cooling lines, baffles and bubblers in the die. A key objective of the project was to establish criteria for the minimal distance of the cooling lines from the surface. This effort was supported with alloys and machining by BohlerUddeholm, Dunn Steel, HH Stark and Rex Buckeye. In plant testing and evaluation was conducted as in-kind cost share at St. Clair Die Casting. The Uddeholm Dievar steel evaluated in this program showed superior resistance to thermal fatigue resistance. Based on the experimental evidence, cooling lines could be placed as close as 0.5" from the surface. Die Life Extension by Optimized Die Lubrication: The life of die casting dies is affected by additions made to its surface with the proper lubricants. These lubricants will protect the surface from the considerable temperature peaks that occur when the molten melt enters the die. Dies will reach a significantly higher temperature without this lubricant being applied. The amount and type of the lubricant are critical variables in the die casting process. However, these lubricants must not corrode the die surface. This effort was supported with alloys and machining by BohlerUddeholm, Dunn Steel, HH Stark and Rex Buckeye. In plant testing and evaluation was conducted as in-kind cost share at St. Clair Die Casting. Chem- Trend participated in the program with die

  18. Expandable pattern casting research

    NASA Astrophysics Data System (ADS)

    1993-09-01

    The Expandable Pattern Casting (EPC) Process is a developing foundry technology that allows designers the opportunity to consolidate parts, reduce machining, and minimize assembly operations. An air gauging system was developed for measuring foam patterns; exact shrinkage depended on type and density of the foam. Compaction studies showed that maximum sand densities in cavities and under overhangs are achieved with vibrational amplitudes 0.001-0.004 in., and that sand moved most freely within a few inches of the top free surface. Key to complete mold filling while minimizing casting defects lies in removing the foam decomposition products. The most precise iron castings were made by EPC in four commercial EPC foundries, with attention paid to molding and compaction. EP cast 60-45-12 ductile iron had yield strengths, ultimate strengths, and elastic modulus similar to conventionally cast ductile iron cast from the same ladle.

  19. User`s guide for the casting process simulator software CaPS-2D, Version 1.0

    SciTech Connect

    Domanus, H.M.; Schmitt, R.C.; Ahuja, S.

    1993-07-01

    Most casting defects occur during initial pouring and therefore the design of the running system, which guides the metal from the ladle into the mold, is crucial. Traditionally, the running system and mold filling are designed by trial and error, which is tedious, time consuming. and expensive. The uncertainties that remain can be overcome by a computer simulation that demonstrates the actual process of mold filling and subsequent solidification. Computer simulation of various processes has become more and more common in recent years. The cost-effectiveness of making flawless castings has made the foundry worker more aware of the process of mold filling, identification of hot spots, etc. The macroscopic Casting Process Simulator (CaPS) software combines heat transfer and fluid flow aspects and can describe a variety of solidification aspects, including mold filling. CaPS is a two-dimensional time-dependent computer code involving a finite-volume formulation for the mass, momentum. and energy equations. CaPS has the following characteristics: CaPS uses the PATRAN geometric modeling package for constructing the geometry, generating a neutral file consisting of a list of named components, and post-processing of the simulation results; building the geometry independently of the mesh is a time-saving procedure. A structured mesh generator of structured regular cells is included and is interfaced with the neutral-file output of the solid geometric package. Visual user interfaces have been developed on the basis of the HOOPS package, which contains a hierarchical database of geometric information. The CaPS shell scripts interactively provide a step-by-step procedure to simulate the solidification process, thus making the software very user-friendly.

  20. Casting materials

    DOEpatents

    Chaudhry, Anil R.; Dzugan, Robert; Harrington, Richard M.; Neece, Faurice D.; Singh, Nipendra P.

    2011-06-14

    A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

  1. Anisotropic Responses of Mechanical and Thermal Processed Cast Al-Si-Mg-Cu Alloy

    NASA Astrophysics Data System (ADS)

    Adeosun, S. O.; Akpan, E. I.; Balogun, S. A.; Onoyemi, O. K.

    2015-05-01

    The effects of ambient directional rolling and heat treatments on ultimate tensile strength (UTS), hardness (HD), percent elongation (PE), and impact energy (IE) on Al-Si-Mg-Cu alloy casting with reference to inclination to rolling direction are discussed in this article. The results show that rolled and quenched (CQ) sample possess superior UTS and HD to as-cast and those of rolled and aged samples (CA). Improved IE resistance with ductility is shown by both CQ and CA samples. However, these mechanical properties are enhanced as changes in the test sample direction moved away from rolling direction for all heat-treated samples. The CQ samples displayed highest tensile strength (108 MPa) and PE (19.8%) in the 90° direction.

  2. Assessment of Computer Simulation Software and Process Data for High Pressure Die Casting of Magnesium

    SciTech Connect

    Sabau, Adrian S; Hatfield, Edward C; Dinwiddie, Ralph Barton; Kuwana, Kazunori; Viti, Valerio; Hassan, Mohamed I; Saito, Kozo

    2007-09-01

    Computer software for the numerical simulation of solidification and mold filling is an effective design tool for cast structural automotive magnesium components. A review of commercial software capabilities and their validation procedures was conducted. Aside form the software assessment, the program addressed five main areas: lubricant degradation, lubricant application, gate atomization, and heat transfer at metal mold interfaces. A test stand for lubricant application was designed. A sensor was used for the direct measurement of heat fluxes during lubricant application and casting solidification in graphite molds. Spray experiments were conducted using pure deionized water and commercial die lubricants. The results show that the sensor can be used with confidence for measuring heat fluxes under conditions specific to the die lube application. The data on heat flux was presented in forms suitable for use in HPDC simulation software. Severe jet breakup and atomization phenomena are likely to occur due to high gate velocities in HPDC. As a result of gate atomization, droplet flow affects the mold filling pattern, air entrapment, skin formation, and ensuing defects. Warm water analogue dies were designed for obtaining experimental data on mold filling phenomena. Data on break-up jet length, break-up pattern, velocities, and droplet size distribution were obtained experimentally and was used to develop correlations for jet break-up phenomena specific to die casting gate configurations.

  3. Interplay Between Residual Stresses, Microstructure, Process Variables and Engine Block Casting Integrity

    NASA Astrophysics Data System (ADS)

    Lombardi, Anthony; D'Elia, Francesco; Ravindran, Comondore; Sediako, Dimitry; Murty, B. S.; MacKay, Robert

    2012-12-01

    The replacement of nodular cast iron with 319 type aluminum (Al) alloys in gasoline engine blocks is an example of the shift towards the use of lighter alloys in the automotive industry. However, excessive residual stress along the cylinder bore may lead to bore distortion, significantly reducing engine operating efficiency. In the current study, microstructure, mechanical properties and residual stress were characterized along the cylinder bridge of engine blocks following thermal sand reclamation (TSR), T7 heat treatment, and service testing of the casting. Neutron diffraction was effectively used to quantify the residual stress along both the Al cylinder bridge and the adjacent gray cast iron cylinder liners in the hoop, radial, and axial orientations with respect to the cylinder axis. The results suggest that an increase in cooling rate along the cylinder caused a significant refinement in microstructure at the bottom of the cylinder. In turn, this suggested an increase in alloy strength at the bottom of the cylinder relative to the top. This increased strength at the bottom of the cylinder likely reduced the susceptibility of the cylinder to rapid relief of residual stress at elevated temperature. In contrast, the coarse microstructure at the top of the cylinder likely triggered stress relief at an elevated temperature.

  4. Material Characterization of Austempered Ductile Iron (ADI) Produced by a Sustainable Continuous Casting-Heat Treatment Process

    NASA Astrophysics Data System (ADS)

    Meena, Anil; El Mansori, Mohamed

    2012-12-01

    Selecting a suitable manufacturing process is one way of achieving sustainability of a product by diminishing energy consumption during its production cycle and improving material efficiency. The article attempts to explore the new processing technology for direct manufacturing of lightweight austempered ductile iron (ADI) casting in a permanent mold. The new processing technology is based on the innovative integrated approach toward casting and heat-treatment process. In this technology, the ductile iron samples obtained using the permanent mold are first austenized immediately after solidification process followed by austempering heat treatment in the fluidized bed and then air cooled at room temperature to obtain ADI material. The influence of austempering time on the microstructural characteristics, mechanical properties, and strain-hardening behavior of ADI was studied. Optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were performed to correlate the mechanical properties with microstructural characteristics. It was observed that the mechanical properties of resulting ADI samples were influenced by the microstructural transformations and varied retained austenite volume fractions obtained due to different austempering time. The results indicate that the strain-hardening behavior of the ADI material is influenced by the carbon content of retained austenite.

  5. Influence of processing variables and aluminum content on the microstructure and mechanical properties of cast Mg-Al alloys

    NASA Astrophysics Data System (ADS)

    Carlson, Blair Edward

    solution heat treat times while maintaining optimal properties. The effect of strain rate appears to be secondary compared to the effect of porosity level on the die cast mechanical properties. This fact indicates that development of a reduced-porosity high volume die casting process would greatly expand the envelope within which to design Mg-Al components.

  6. Measurement of Heat Flux and Heat Transfer Coefficient Due to Spray Application for the Die Casting Process

    SciTech Connect

    Sabau, Adrian S

    2007-01-01

    Lubricant spray application experiments were conducted for the die casting process. The heat flux was measured in situ using a differential thermopile sensor for three application techniques. First, the lubricant was applied under a constant flowrate while the nozzle was held in the same position. Second, the lubricant was applied in a pulsed, static manner, in which the nozzle was held over the same surface while it was turned on and off several times. Third, the lubricant was applied in a sweeping manner, in which the nozzle was moved along the die surface while it was held open. The experiments were conducted at several die temperatures and at sweep speeds of 20, 23, and 68 cm/s. The heat flux data, which were obtained with a sensor that was located in the centre of the test plate, were presented and discussed. The sensor can be used to evaluate lubricants, monitor the consistency of die lubrication process, and obtain useful process data, such as surface temperature, heat flux, and heat transfer coefficients. The heat removed from the die surface during lubricant application is necessary for (a) designing the cooling channels in the die, i.e. their size and placement, and (b) performing accurate numerical simulations of the die casting process.

  7. Study on Efficient Numerical Simulation Technology of Mold Filling Process of Casting

    NASA Astrophysics Data System (ADS)

    Yang, Liushuan; Wang, Xiao; Huang, Jinliang; Zhang, Shaoli

    The paper based on the SOLA-VOF, depended on the meaning of the equation result in the algebra and geometry, brings forward a new idea and the rapid iterative arithmetic. According to the rapid iterative arithmetic, a program of the rapid calculating method of flow field and the numerical simulation experiment using the standard casting have been made by the author. The result showed that the calculating efficiency has increased by 3~4 times than before, the accuracy equals to the SOLA-VOF, which can meet the requirements of the application.

  8. Evolution of microstructure, texture and inhibitor along the processing route for grain-oriented electrical steels using strip casting

    SciTech Connect

    Liu, Hai-Tao; Yao, Sheng-Jie; Sun, Yu; Gao, Fei; Song, Hong-Yu; Liu, Guo-Huai; Li, Lei; Geng, Dian-Qiao; Liu, Zhen-Yu; Wang, Guo-Dong

    2015-08-15

    In the present work, a regular grade GO sheet was produced successively by strip casting, hot rolling, normalizing annealing, two-stage cold rolling with intermediate annealing, primary recrystallization annealing, secondary recrystallization annealing and purification. The aim of this paper was to characterize the evolution of microstructure, texture and inhibitor along the new processing route by comprehensive utilization of optical microscopy, X-ray diffraction and transmission electron microscopy. It was found that a fine microstructure with the ferrite grain size range of 7–12 μm could be obtained in the primary recrystallization annealed sheet though a very coarse microstructure was produced in the initial as-cast strip. The main finding was that the “texture memory” effect on Goss texture started on the through-thickness intermediate annealed strip after first cold rolling, which was not similar to the “texture memory” effect on Goss texture starting on the surface layers of the hot rolled strip in the conventional production route. As a result, the origin of Goss nuclei capable of secondary recrystallization lied in the grains already presented in Goss orientation in the intermediate annealed strip after first cold rolling. Another finding was that fine and dispersive inhibitors (mainly AlN) were easy to be produced in the primary recrystallization microstructure due to the initial rapid solidification during strip casting and the subsequent rapid cooling, and the very high temperature reheating usually used before hot rolling in the conventional production route could be avoided. - Highlights: • A regular grade grain-oriented electrical steel was produced. • Evolution of microstructure, texture and inhibitor was characterized. • Origin of Goss nuclei lied in the intermediate annealed strip. • A fine primary recrystallization microstructure could be produced. • Effective inhibitors were easy to be obtained in the new processing route.

  9. Joining of Cast ZE41A Mg to Wrought 6061 Al by the Cold Spray Process and Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Champagne, Victor Kenneth; West, Michael K.; Reza Rokni, M.; Curtis, Todd; Champagne, Victor; McNally, Baillie

    2016-01-01

    This paper presents a novel method for joining cast ZE41A-T5 Mg to wrought 6061-T6 Al, without forming deleterious, coarse intermetallic compounds, which is not currently possible with conventional technologies. The novel aspect of the process includes the development of a joint design using cold spray (CS) as the enabling technology, to produce a transitional layer onto which a conventional welding technique can be employed to join the two dissimilar materials. The emphasis in this study will be on the CS transitional layer (T-layer) which enables the joining of cast ZE41A-T5 magnesium (Mg) and wrought 6061-T6 aluminum (Al) by friction-stir welding and the subsequent materials characterization to show the structural integrity of the entire joint. In order to join Mg and Al plates by this method, a transitional layer of CS Al is first deposited along the edge of cast ZE41A Mg plate. The CS Al T-layer enables the Mg to be friction stir welded to a plate of wrought 6061 Al, thereby completing the Mg plate to Al plate joint. Friction stir welding was chosen in this study to join the CS Al T-layer to the wrought Al plate; however, other conventional welding techniques could also be employed for joining Mg to Al in this manner. The CS Al T-layer is compatible to the wrought 6061 Al plate and serves as an insulating layer that prevents heat generated during the friction stir welding process from extending into the magnesium, thus preventing the formation of intermetallics. In this study, two sets of samples were produced joining cast ZE41A-T5 magnesium (Mg) and wrought 6061-T6 aluminum: one set using CS 6061 Al as the transition material between the ZE41A Mg plate and 6061 Al plate and the other set using CS 5056 Al as the transition material. Microstructural analysis by scanning and transmission electron microscopy and optical microscopy, along with mechanical test results including triple lug shear, tension, and micro hardness will be presented. Comparisons will be

  10. Clean Metal Casting

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The objective of this project is to develop a technology for clean metal processing that is capable of consistently providing a metal cleanliness level that is fit for a given application. The program has five tasks: Development of melt cleanliness assessment technology, development of melt contamination avoidance technology, development of high temperature phase separation technology, establishment of a correlation between the level of melt cleanliness and as cast mechanical properties, and transfer of technology to the industrial sector. Within the context of the first task, WPI has developed a standardized Reduced Pressure Test that has been endorsed by AFS as a recommended practice. In addition, within the context of task1, WPI has developed a melt cleanliness sensor based on the principles of electromagnetic separation. An industrial partner is commercializing the sensor. Within the context of the second task, WPI has developed environmentally friendly fluxes that do not contain fluorine. Within the context of the third task, WPI modeled the process of rotary degassing and verified the model predictions with experimental data. This model may be used to optimize the performance of industrial rotary degassers. Within the context of the fourth task, WPI has correlated the level of melt cleanliness at various foundries, including a sand casting foundry, a permanent mold casting foundry, and a die casting foundry, to the casting process and the resultant mechanical properties. This is useful in tailoring the melt cleansing operations at foundries to the particular casting process and the desired properties of cast components.

  11. Modelling of heat transfer and solidification processes in horizontal twin-roll casting of magnesium AZ31

    NASA Astrophysics Data System (ADS)

    Miehe, A.; Gross, U.

    2012-07-01

    Magnesium is a desirable material for lightweight construction due to its low density and high strength-to-weight ratio. The disadvantage of low cold formability may be overcome for sheet production by combining casting and forming within horizontal twin-roll casting (TRC). During this process, the molten alloy is fed between two counter-rotating rolls water cooled from the inside. In this paper, numerical simulations using the commercial CFD software Star-CCM+ are presented. The code provides the model based on an incompressible, steady-state solver for laminar flow. To describe the solidification, an exponential increase in viscosity for decreasing temperature is employed in addition to the fraction-of-solid approach based on a linear equation for the release of latent heat. The counter-rotating rolls are exposed to a constant heat transfer coefficient and specify the characteristic velocity of the case. Using the full domain for the simulation of the TRC process provides asymmetric velocity profiles resulting in asymmetric temperature profiles and thus temperature differences between the two rolls. Symmetric results should not be enforced by using only half domain as the asymmetric profiles evoke recirculation zones differing in size which might influence the solidification rates.

  12. Elastomeric inverse moulding and vacuum casting process characterization for the fabrication of arrays of concave refractive microlenses

    NASA Astrophysics Data System (ADS)

    Desmet, L.; Van Overmeire, S.; Van Erps, J.; Ottevaere, H.; Debaes, C.; Thienpont, H.

    2007-01-01

    We present a complete and precise quantitative characterization of the different process steps used in an elastomeric inverse moulding and vacuum casting technique. We use the latter replication technique to fabricate concave replicas from an array of convex thermal reflow microlenses. During the inverse elastomeric moulding we obtain a secondary silicone mould of the original silicone mould in which the master component is embedded. Using vacuum casting, we are then able to cast out of the second mould several optical transparent poly-urethane arrays of concave refractive microlenses. We select ten particular representative microlenses on the original, the silicone moulds and replica sample and quantitatively characterize and statistically compare them during the various fabrication steps. For this purpose, we use several state-of-the-art and ultra-precise characterization tools such as a stereo microscope, a stylus surface profilometer, a non-contact optical profilometer, a Mach-Zehnder interferometer, a Twyman-Green interferometer and an atomic force microscope to compare various microlens parameters such as the lens height, the diameter, the paraxial focal length, the radius of curvature, the Strehl ratio, the peak-to-valley and the root-mean-square wave aberrations and the surface roughness. When appropriate, the microlens parameter under test is measured with several different measuring tools to check for consistency in the measurement data. Although none of the lens samples shows diffraction-limited performance, we prove that the obtained replicated arrays of concave microlenses exhibit sufficiently low surface roughness and sufficiently high lens quality for various imaging applications.

  13. Energy use in selected metal casting facilities - 2003

    SciTech Connect

    Eppich, Robert E.

    2004-05-01

    This report represents an energy benchmark for various metal casting processes. It describes process flows and energy use by fuel type and processes for selected casting operations. It also provides recommendations for improving energy efficiency in casting.

  14. System and process for the abatement of casting pollution, reclaiming resin bonded sand, and/or recovering a low Btu fuel from castings

    DOEpatents

    Scheffer, K.D.

    1984-07-03

    Air is caused to flow through the resin bonded mold to aid combustion of the resin binder to form a low Btu gas fuel. Casting heat is recovered for use in a waste heat boiler or other heat abstraction equipment. Foundry air pollutis reduced, the burned portion of the molding sand is recovered for immediate reuse and savings in fuel and other energy is achieved. 5 figs.

  15. System and process for the abatement of casting pollution, reclaiming resin bonded sand, and/or recovering a low BTU fuel from castings

    DOEpatents

    Scheffer, Karl D.

    1984-07-03

    Air is caused to flow through the resin bonded mold to aid combustion of the resin binder to form a low BTU gas fuel. Casting heat is recovered for use in a waste heat boiler or other heat abstraction equipment. Foundry air pollution is reduced, the burned portion of the molding sand is recovered for immediate reuse and savings in fuel and other energy is achieved.

  16. Model Investigations on the Stability of the Steel-Slag Interface in Continuous-Casting Process

    NASA Astrophysics Data System (ADS)

    Hagemann, René; Schwarze, Rüdiger; Heller, Hans P.; Scheller, Piotr R.

    2013-02-01

    In the continuous-casting mold, the mold powder in contact with the liquid steel surface forms a liquid slag layer. The flow along the steel-slag interface generates shear stress at the interface, waves, and leads to fingerlike protrusions of liquid slag into steel. Reaching a critical flow velocity and thereby shear stress, the protrusions can disintegrate into slag droplets following the flow in the liquid steel pool. These entrained droplets can form finally nonmetallic inclusions in steel material, cause defects in the final product, and therefore, should be avoided. In the current work, the stability of a liquid-liquid interface without mass transfer between phases was investigated in cold model study using a single-roller driven flow in oil-water systems with various oil properties. Applying the similarity theory, two dimensionless numbers were identified, viz. capillary number Ca and the ratio of kinematic viscosities ν 1/ ν 2, which are suitable to describe the force balance for the problem treated. The critical values of the dimensionless capillary number Ca* marking the start of lighter phase entrainment into the heavier fluid, are determined over a wide range of fluid properties. The dimensionless number ν 1/ ν 2 was defined as the ratio of kinematic viscosities of the lighter phase ν 1 and heavier phase ν 2. The ratios of kinematic viscosities of different steel-slag systems were calculated using measured thermophysical properties. With the knowledge of thermophysical properties of steel-slag systems, Ca* for slag entrainment as a function of v 1/ v 2 is derived. Assuming no reaction between the phases and no interfacial flow, slag entrainment should not occur under the usual casting conditions.

  17. Effect of Friction Stir Processing on Microstructure and Mechanical Properties of AZ91C Magnesium Cast Alloy Weld Zone

    NASA Astrophysics Data System (ADS)

    Hassani, Behzad; Karimzadeh, Fathallah; Enayati, Mohammad Hossein; Sabooni, Soheil; Vallant, Rudolf

    2016-07-01

    In this study, friction stir processing (FSP) was applied to the GTAW (TIG)-welded AZ91C cast alloy to refine the microstructure and optimize the mechanical properties of the weld zone. Microstructural investigation of the samples was performed by optical microscopy and the phases in the microstructure were determined by x-ray diffraction (XRD). The microstructural evaluations showed that FSP destroys the coarse dendritic microstructure. Furthermore, it dissolves the secondary hard and brittle β-Mg17Al12 phase existing at grain boundaries of the TIG weld zone. The closure and decrease in amount of porosities along with the elimination of the cracks in the microstructure were observed. These changes were followed by a significant grain refinement to an average value of 11 µm. The results showed that the hardness values increased to the mean ones, respectively, for as-cast (63 Hv), TIG weld zone (67 Hv), and stir zone (79 Hv). The yield and ultimate strength were significantly enhanced after FSP. The fractography evaluations, by scanning electron microscopy (SEM), indicated to a transition from brittle to ductile fracture surface after applying FSP to the TIG weld zone.

  18. Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions

    NASA Technical Reports Server (NTRS)

    Gandin, Charles-Andre; Ratke, Lorenz

    2008-01-01

    The Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions (MSL-CETSOL and MICAST) are two investigations which supports research into metallurgical solidification, semiconductor crystal growth (Bridgman and zone melting), and measurement of thermo-physical properties of materials. This is a cooperative investigation with the European Space Agency (ESA) and National Aeronautics and Space Administration (NASA) for accommodation and operation aboard the International Space Station (ISS). Research Summary: Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing (CETSOL) and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions (MICAST) are two complementary investigations which will examine different growth patterns and evolution of microstructures during crystallization of metallic alloys in microgravity. The aim of these experiments is to deepen the quantitative understanding of the physical principles that govern solidification processes in cast alloys by directional solidification.

  19. Final Technical Report Quantification and Standardization of Pattern Properties for the Control of the Lost Foam Casting Process

    SciTech Connect

    Ronald Michaels

    2005-09-30

    This project takes a fresh look at the ''white side'' of the lost foam casting process. We have developed the gel front hypothesis for foam pyrolysis behavior and the magnetic metal pump method for controlling lost foam casting metal fill event. The subject of this report is work done in the improvement of the Lost Foam Casting Process. The original objective of this project was to improve the control of metal fill by understanding the influence of foam pattern and coating properties on the metal fill event. Relevant pattern properties could then be controlled, providing control of the metal fill event. One of the original premises of this project was that the process of metal fill was relatively well understood. Considerable previous work had been done to develop fluid mechanical and heat transfer models of the process. If we could just incorporate measured pattern properties into these models we would be able predict accurately the metal fill event. As we began to study the pyrolysis behavior of EPS during the metal fill event, we discovered that the chemical nature of this event had been completely overlooked in previous research. Styrene is the most prevalent breakdown product of EPS pyrolysis and it is a solvent for polystyrene. Much of the styrene generated by foam pyrolysis diffuses into intact foam, producing a molten gel of mechanically entangled polystyrene molecules. Much of the work of our project has centered on validation of this concept and producing a qualitative model of the behavior of EPS foam undergoing pyrolysis in a confined environment. A conclusion of this report is that styrene dissolution in EPS is a key phenomenon in the pyrolysis process and deserves considerable further study. While it is possible to continue to model the metal fill event parametrically using empirical data, we recommend that work be undertaken by qualified researchers to directly characterize and quantify this phenomenon for the benefit of modelers, researchers, and

  20. CENTRIFUGAL CASTING MACHINE

    DOEpatents

    Shuck, A.B.

    1958-04-01

    A device is described that is specifically designed to cast uraniumn fuel rods in a vacuunn, in order to obtain flawless, nonoxidized castings which subsequently require a maximum of machining or wastage of the expensive processed material. A chamber surrounded with heating elements is connected to the molds, and the entire apparatus is housed in an airtight container. A charge of uranium is placed in the chamber, heated, then is allowed to flow into the molds While being rotated. Water circulating through passages in the molds chills the casting to form a fine grained fuel rod in nearly finished form.

  1. Control of Crystal Morphology for Mold Flux During High-Aluminum AHSS Continuous Casting Process

    NASA Astrophysics Data System (ADS)

    GUO, Jing; SEO, Myung-Duk; SHI, Cheng-Bin; CHO, Jung-Wook; KIM, Seon-Hyo

    2016-08-01

    In the present manuscript, the efforts to control the crystal morphology are carried out aiming at improving the lubrication of lime-alumina-based mold flux for casting advanced high-strength steel with high aluminum. Jackson α factors for crystals of melt crystallization in multi-component mold fluxes are established and reasonably evaluated by applying thermodynamic databases to understand the crystal morphology control both in lime-alumina-based and lime-silica-based mold fluxes. The results show that Jackson α factor and supercooling are the most critical factors to determine the crystal morphology in a mold flux. Crystals precipitating in mold fluxes appear with different morphologies due to their different Jackson α factors and are likely to be more faceted with higher Jackson α factor. In addition, there is a critical supercooling degree for crystal morphology dendritic transition. When the supercooling over the critical value, the crystals transform from faceted shape to dendritic ones in morphology as the kinetic roughening occurs. Typically, the critical supercooling degrees for cuspidine dendritic transition in the lime-silica-based mold fluxes are evaluated to be between 0.05 and 0.06. Finally, addition of a small amount of Li2O in the mold flux can increase the Jackson α factor and decrease the supercooling for cuspidine precipitation; thus, it is favorable to enhance a faceted cuspidine crystal.

  2. Casting larger polycrystalline silicon ingots

    SciTech Connect

    Wohlgemuth, J.; Tomlinson, T.; Cliber, J.; Shea, S.; Narayanan, M.

    1995-08-01

    Solarex has developed and patented a directional solidification casting process specifically designed for photovoltaics. In this process, silicon feedstock is melted in a ceramic crucible and solidified into a large grained semicrystalline silicon ingot. In-house manufacture of low cost, high purity ceramics is a key to the low cost fabrication of Solarex polycrystalline wafers. The casting process is performed in Solarex designed casting stations. The casting operation is computer controlled. There are no moving parts (except for the loading and unloading) so the growth process proceeds with virtually no operator intervention Today Solarex casting stations are used to produce ingots from which 4 bricks, each 11.4 cm by 11.4 cm in cross section, are cut. The stations themselves are physically capable of holding larger ingots, that would yield either: 4 bricks, 15 cm by 15 an; or 9 bricks, 11.4 cm by 11.4 an in cross-section. One of the tasks in the Solarex Cast Polycrystalline Silicon PVMaT Program is to design and modify one of the castings stations to cast these larger ingots. If successful, this effort will increase the production capacity of Solarex`s casting stations by 73% and reduce the labor content for casting by an equivalent percentage.

  3. Distributed cognition and social brains: reductions in mushroom body investment accompanied the origins of sociality in wasps (Hymenoptera: Vespidae).

    PubMed

    O'Donnell, Sean; Bulova, Susan J; DeLeon, Sara; Khodak, Paulina; Miller, Skye; Sulger, Elisabeth

    2015-07-01

    The social brain hypothesis assumes the evolution of social behaviour changes animals' ecological environments, and predicts evolutionary shifts in social structure will be associated with changes in brain investment. Most social brain models to date assume social behaviour imposes additional cognitive challenges to animals, favouring the evolution of increased brain investment. Here, we present a modification of social brain models, which we term the distributed cognition hypothesis. Distributed cognition models assume group members can rely on social communication instead of individual cognition; these models predict reduced brain investment in social species. To test this hypothesis, we compared brain investment among 29 species of wasps (Vespidae family), including solitary species and social species with a wide range of social attributes (i.e. differences in colony size, mode of colony founding and degree of queen/worker caste differentiation). We compared species means of relative size of mushroom body (MB) calyces and the antennal to optic lobe ratio, as measures of brain investment in central processing and peripheral sensory processing, respectively. In support of distributed cognition predictions, and in contrast to patterns seen among vertebrates, MB investment decreased from solitary to social species. Among social species, differences in colony founding, colony size and caste differentiation were not associated with brain investment differences. Peripheral lobe investment did not covary with social structure. These patterns suggest the strongest changes in brain investment--a reduction in central processing brain regions--accompanied the evolutionary origins of eusociality in Vespidae.

  4. Melting and casting of FeAl-based cast alloy

    SciTech Connect

    Sikka, V.K.; Wilkening, D.; Liebetrau, J.; Mackey, B.

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  5. Pigmented casts.

    PubMed

    Miteva, Mariya; Romanelli, Paolo; Tosti, Antonella

    2014-01-01

    Pigmented casts have been reported with variable frequency in scalp biopsies from alopecia areata, trichotillomania, chemotherapy-induced alopecia and postoperative (pressure induced) alopecia. Their presence and morphology in other scalp disorders has not been described. The authors assessed for the presence and morphology of pigmented casts in 308 transversely bisected scalp biopsies from nonscarring and scarring alopecia, referred to the Department of Dermatology, University of Miami within a year. The pigmented casts were present in 21 of 29 cases of alopecia areata (72%), 7 of 7 cases of trichotillomania (100%), 1 case of friction alopecia, 4 of 28 cases of central centrifugal cicatricial alopecia (14%), and 4 of 4 cases of dissecting cellulitis (100%). They did not show any distinguishing features except for the morphology in trichotillomania, which included twisted, linear (zip), and "button"-like pigment aggregation. The linear arrangement was found also in friction alopecia and dissecting cellulitis. Pigmented casts in the hair canals of miniaturized/vellus hairs was a clue to alopecia areata. Pigmented casts can be observed in biopsies of different hair disorders, but they are not specific for the diagnosis. Horizontal sections allow to better assess their morphology and the follicular level of presence of pigmented casts, which in the context of the other follicular findings may be a clue to the diagnosis. PMID:23823025

  6. Lost-Soap Aluminum Casting.

    ERIC Educational Resources Information Center

    Mihalow, Paula

    1980-01-01

    Lost-wax casting in sterling silver is a costly experience for the average high school student. However, this jewelry process can be learned at no cost if scrap aluminum is used instead of silver, and soap bars are used instead of wax. This lost-soap aluminum casting process is described. (Author/KC)

  7. Stress-Strain Predictions of Semisolid Al-Mg-Mn Alloys During Direct Chill Casting: Effects of Microstructure and Process Variables

    NASA Astrophysics Data System (ADS)

    Jamaly, Nasim; Phillion, A. B.; Drezet, J.-M.

    2013-10-01

    The occurrence of hot tearing during the industrial direct chill (DC) casting process results in significant quality issues and a reduction in productivity. In order to investigate their occurrence, a new semisolid constitutive law (Phillion et al.) for AA5182 that takes into account cooling rate, grain size, and porosity has been incorporated within a DC casting finite element process model for round billets. A hot tearing index was calculated from the semisolid strain predictions from the model. This hot tearing index, along with semisolid stress-strain predictions from the model, was used to perform a sensitivity analysis on the relative effects of microstructural features ( e.g., grain size, coalescence temperature) as well as process parameters ( e.g., casting speed) on hot tearing. It was found that grain refinement plays an important role in the formation of hot cracks. In addition, the combination of slow casting speeds and a low temperature for mechanical coalescence was found to improve hot tearing resistance.

  8. Cast dielectric composite linear accelerator

    DOEpatents

    Sanders, David M.; Sampayan, Stephen; Slenes, Kirk; Stoller, H. M.

    2009-11-10

    A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.

  9. A Winning Cast

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Howmet Research Corporation was the first to commercialize an innovative cast metal technology developed at Auburn University, Auburn, Alabama. With funding assistance from NASA's Marshall Space Flight Center, Auburn University's Solidification Design Center (a NASA Commercial Space Center), developed accurate nickel-based superalloy data for casting molten metals. Through a contract agreement, Howmet used the data to develop computer model predictions of molten metals and molding materials in cast metal manufacturing. Howmet Metal Mold (HMM), part of Howmet Corporation Specialty Products, of Whitehall, Michigan, utilizes metal molds to manufacture net shape castings in various alloys and amorphous metal (metallic glass). By implementing the thermophysical property data from by Auburn researchers, Howmet employs its newly developed computer model predictions to offer customers high-quality, low-cost, products with significantly improved mechanical properties. Components fabricated with this new process replace components originally made from forgings or billet. Compared with products manufactured through traditional casting methods, Howmet's computer-modeled castings come out on top.

  10. Residual Stress, Structure and Other Properties Formation by Combined Thermo-Hardening Processing of Surface Layer of Gray Cast Iron Parts

    NASA Astrophysics Data System (ADS)

    Rakhimyanov, Kh M.; Nikitin, Yu V.; Semenova, Yu S.; Eremina, A. S.

    2016-04-01

    The proposed combined thermo-hardening processing of gray cast iron enables to control the surface layer structure and mechanical properties formation. The processing includes high-speed heating by low-temperature plasma source and ultrasonic surface plastic deformation. The algorithm of calculation the stress-strain state of a surface layer at combined processing of gray cast iron is developed. This algorithm is based on method of sections. The ultrasonic surface deformation contribution is determined during formation of residual stresses. It is established that the combination of the thermal and deformation effects on the material provides an additional increment of microhardness and increase of surface layer thickness. Experimental results shows that the features of structural and phase transformations in a surface layer are revealed without a surface melting by energy of low-temperature plasma. The top of a layer does not contain inclusions of graphite that testifies to change of structural transformations in conditions of combined processing.

  11. Casting system effectiveness--measurement and theory.

    PubMed

    Luk, H W; Darvell, B W

    1992-03-01

    Evaluating castability as a property of dental casting alloys is an unworkable concept, since any measure is demonstrably affected by several external factors. Casting System Effectiveness (CSE) is shown experimentally and theoretically to depend primarily upon the time taken for the advancing front to freeze. A spiral tube mold was used to measure casting length obtained under variations in casting temperature; this pattern is proposed as a standard measure of CSE. A Bernoulli 'free-fall' numerical model is shown to reproduce the principal features of such casting, with some evidence of viscosity limitation of the turbulent flow at long casting lengths. Direct measurement of melt velocities confirmed turbulent flow in the mold. A method is also suggested for assessing the influence of investment porosity on CSE.

  12. Distributed cognition and social brains: reductions in mushroom body investment accompanied the origins of sociality in wasps (Hymenoptera: Vespidae)

    PubMed Central

    O'Donnell, Sean; Bulova, Susan J.; DeLeon, Sara; Khodak, Paulina; Miller, Skye; Sulger, Elisabeth

    2015-01-01

    The social brain hypothesis assumes the evolution of social behaviour changes animals' ecological environments, and predicts evolutionary shifts in social structure will be associated with changes in brain investment. Most social brain models to date assume social behaviour imposes additional cognitive challenges to animals, favouring the evolution of increased brain investment. Here, we present a modification of social brain models, which we term the distributed cognition hypothesis. Distributed cognition models assume group members can rely on social communication instead of individual cognition; these models predict reduced brain investment in social species. To test this hypothesis, we compared brain investment among 29 species of wasps (Vespidae family), including solitary species and social species with a wide range of social attributes (i.e. differences in colony size, mode of colony founding and degree of queen/worker caste differentiation). We compared species means of relative size of mushroom body (MB) calyces and the antennal to optic lobe ratio, as measures of brain investment in central processing and peripheral sensory processing, respectively. In support of distributed cognition predictions, and in contrast to patterns seen among vertebrates, MB investment decreased from solitary to social species. Among social species, differences in colony founding, colony size and caste differentiation were not associated with brain investment differences. Peripheral lobe investment did not covary with social structure. These patterns suggest the strongest changes in brain investment—a reduction in central processing brain regions—accompanied the evolutionary origins of eusociality in Vespidae. PMID:26085587

  13. The effect of porous coating processing on the corrosion behavior of cast Co-Cr-Mo surgical implant alloys.

    PubMed

    Jacobs, J J; Latanision, R M; Rose, R M; Veeck, S J

    1990-11-01

    The manufacture of porous coated cobalt-based surgical implant alloys requires sintering--a high temperature process above the incipient melting temperature of this alloy system. The metallurgical changes produced by the high temperature sinter cycle consist of dissolution of interdendritic carbides, massive precipitation of lamellar carbide eutectic phases at grain boundaries, localized porosity from incipient melting that is not completely eliminated by subsequent hot isostatic pressing, and grain growth in fine-grained materials. These microstructural changes, which are known to affect the mechanical properties, do not affect the static in vitro localized and generalized corrosion behavior of the bulk material as determined by anodic polarization measurements in a buffered saline environment and direct examination by scanning electron and optical microscopy. Additionally, cast Co-Cr-Mo surgical implant alloys are found to be immune to crevice corrosion (in the absence of mechanical fretting) in the saline environment studied. The hysteretic component of the anodic polarization curve is not due to crevice corrosion; rather, as suggested by the electrochemical tests and Auger spectroscopy, the hysteresis is due to redox reactions in the chromium-rich surface layer. PMID:2213344

  14. Energy Consumption of Die Casting Operations

    SciTech Connect

    Jerald Brevick; clark Mount-Campbell; Carroll Mobley

    2004-03-15

    Molten metal processing is inherently energy intensive and roughly 25% of the cost of die-cast products can be traced to some form of energy consumption [1]. The obvious major energy requirements are for melting and holding molten alloy in preparation for casting. The proper selection and maintenance of melting and holding equipment are clearly important factors in minimizing energy consumption in die-casting operations [2]. In addition to energy consumption, furnace selection also influences metal loss due to oxidation, metal quality, and maintenance requirements. Other important factors influencing energy consumption in a die-casting facility include geographic location, alloy(s) cast, starting form of alloy (solid or liquid), overall process flow, casting yield, scrap rate, cycle times, number of shifts per day, days of operation per month, type and size of die-casting form of alloy (solid or liquid), overall process flow, casting yield, scrap rate, cycle times, number of shifts per day, days of operation per month, type and size of die-casting machine, related equipment (robots, trim presses), and downstream processing (machining, plating, assembly, etc.). Each of these factors also may influence the casting quality and productivity of a die-casting enterprise. In a die-casting enterprise, decisions regarding these issues are made frequently and are based on a large number of factors. Therefore, it is not surprising that energy consumption can vary significantly from one die-casting enterprise to the next, and within a single enterprise as function of time.

  15. RSP Tooling - A Revolutionary New Process to Manufacture Die Cast Production Tooling in Prototype Timing

    SciTech Connect

    Mc Hugh, Kevin Matthew; Knirsch, James; Folkestad, James

    2002-10-01

    RSP Tooling, LLC (Solon, OH) has signed an exclusive license with the Idaho National Engineered and Environmental Laboratory - INEEL (Idaho Falls, ID) - for the development and commercialization of the rapid solidification process within the field of tooling (RSP tooling), which is a recent revolution in the moldmaking industry. The first production machine is scheduled for delivery this year. This machine will be able to produce a 6 x 6 x 4 inch tool with finished cavities in two hours. Such a production rate is revolutionary, and will likely change the tooling industry dramatically.

  16. Method For Removing Volatile Components From A Gel-Cast Ceramic Article

    DOEpatents

    Klug, Frederic Joseph; DeCarr, Sylvia Marie

    2004-09-07

    A method of removing substantially all of the volatile component in a green, volatile-containing ceramic article is disclosed. The method comprises freezing the ceramic article; and then subjecting the frozen article to a vacuum for a sufficient time to freeze-dry the article. Frequently, the article is heated while being freeze-dried. Use of this method efficiently reduces the propensity for any warpage of the article. The article is often formed from a ceramic slurry in a gel-casting process. A method for fabricating a ceramic core used in investment casting is also described.

  17. Integrated Assessment and Improvement of the Quality Assurance System for the Cosworth Casting Process

    NASA Astrophysics Data System (ADS)

    Yousif, Dilon

    The purpose of this study was to improve the Quality Assurance (QA) System at the Nemak Windsor Aluminum Plant (WAP). The project used Six Sigma method based on Define, Measure, Analyze, Improve, and Control (DMAIC). Analysis of in process melt at WAP was based on chemical, thermal, and mechanical testing. The control limits for the W319 Al Alloy were statistically recalculated using the composition measured under stable conditions. The "Chemistry Viewer" software was developed for statistical analysis of alloy composition. This software features the Silicon Equivalency (SiBQ) developed by the IRC. The Melt Sampling Device (MSD) was designed and evaluated at WAP to overcome traditional sampling limitations. The Thermal Analysis "Filters" software was developed for cooling curve analysis of the 3XX Al Alloy(s) using IRC techniques. The impact of low melting point impurities on the start of melting was evaluated using the Universal Metallurgical Simulator and Analyzer (UMSA).

  18. Fillability of Thin-Wall Steel Castings

    SciTech Connect

    Robert C. Voigt; Joseph Bertoletti; Andrew Kaley; Sandi Ricotta; Travis Sunday

    2002-07-30

    The use of steel components is being challenged by lighter nonferrous or cast iron components. The development of techniques for enhancing and ensuring the filability of thin-wall mold cavities is most critical for thinner wall cast steel production. The purpose of this research was to develop thin-wall casting techniques that can be used to reliably produce thin-wall castings from traditional gravity poured sand casting processes. The focus of the research was to enhance the filling behavior to prevent misrunds. Experiments were conducted to investigate the influence of various foundry variables on the filling of thin section steel castings. These variables include casting design, heat transfer, gating design, and metal fluidity. Wall thickness and pouring temperature have the greatest effect on casting fill. As wall thickness increases the volume to surface area of the casting increases, which increases the solidification time, allowing the metal to flow further in thicker sect ions. Pouring time is another significant variable affecting casting fill. Increases or decreases of 20% in the pouring time were found to have a significant effect on the filling of thin-wall production castings. Gating variables, including venting, pouring head height, and mold tilting also significantly affected thin-wall casting fill. Filters offer less turbulent, steadier flow, which is appropriate for thicker castings, but they do not enhance thin-wall casting fill.

  19. [The formation of ordered microstructures by slip casting and related processes]. Progress report

    SciTech Connect

    Not Available

    1992-03-01

    The existing three-year grant pertaining to ``The control of microstructures during consolidation and injection molding of colloidal dispersions`` began July 1, 1988 as a continuation of a previous grant. The overall effort seeks to answer fundamental questions relevant to the colloidal processing of submicron particles leading to ceramic materials for structural, electronic, or optical applications. At the outset two distinct projects were envisioned, an exploration of the ultrasonic enhancement of disorder-order transitions and a detailed study of injection molding of very dense dispersions, with each weighted toward experiments but with theoretical components. As the effort evolved the focus shifted in response to the interests of the students attracted to the project, the identification of interesting related problems through technical meetings, and different insights gained during participation in a DOE sponsored workshop. The scope that has emerged encompasses completion of research begun during the first grant period on disorder-order transitions occurring during sedimentation, the consolidation of flocculated dispersions via filtration, and the assembly of nanometer- sized particle into dense packings.

  20. (The formation of ordered microstructures by slip casting and related processes)

    SciTech Connect

    Not Available

    1992-01-01

    The existing three-year grant pertaining to The control of microstructures during consolidation and injection molding of colloidal dispersions'' began July 1, 1988 as a continuation of a previous grant. The overall effort seeks to answer fundamental questions relevant to the colloidal processing of submicron particles leading to ceramic materials for structural, electronic, or optical applications. At the outset two distinct projects were envisioned, an exploration of the ultrasonic enhancement of disorder-order transitions and a detailed study of injection molding of very dense dispersions, with each weighted toward experiments but with theoretical components. As the effort evolved the focus shifted in response to the interests of the students attracted to the project, the identification of interesting related problems through technical meetings, and different insights gained during participation in a DOE sponsored workshop. The scope that has emerged encompasses completion of research begun during the first grant period on disorder-order transitions occurring during sedimentation, the consolidation of flocculated dispersions via filtration, and the assembly of nanometer- sized particle into dense packings.

  1. Project CAST.

    ERIC Educational Resources Information Center

    Charles County Board of Education, La Plata, MD. Office of Special Education.

    The document outlines procedures for implementing Project CAST (Community and School Together), a community-based career education program for secondary special education students in Charles County, Maryland. Initial sections discuss the role of a learning coordinator, (including relevant travel reimbursement and mileage forms) and an overview of…

  2. Casting methods

    DOEpatents

    Marsden, Kenneth C.; Meyer, Mitchell K.; Grover, Blair K.; Fielding, Randall S.; Wolfensberger, Billy W.

    2012-12-18

    A casting device includes a covered crucible having a top opening and a bottom orifice, a lid covering the top opening, a stopper rod sealing the bottom orifice, and a reusable mold having at least one chamber, a top end of the chamber being open to and positioned below the bottom orifice and a vacuum tap into the chamber being below the top end of the chamber. A casting method includes charging a crucible with a solid material and covering the crucible, heating the crucible, melting the material, evacuating a chamber of a mold to less than 1 atm absolute through a vacuum tap into the chamber, draining the melted material into the evacuated chamber, solidifying the material in the chamber, and removing the solidified material from the chamber without damaging the chamber.

  3. CASTING APPARATUS

    DOEpatents

    Gray, C.F.; Thompson, R.H.

    1958-09-23

    An apparatus is described for casting small quantities of uranlum. It consists of a crucible having a hole in the bottom with a mold positioned below. A vertical rcd passes through the hole in the crucible and has at its upper end a piercing head adapted to break the oxide skin encasing a molten uranium body. An air tight cylinder surrounds the crucible and mold, and is arranged to be evacuated.

  4. Land-based turbine casting initiative

    SciTech Connect

    Mueller, B.A.; Spicer, R.A.

    1995-12-31

    To meet goals for the ATS program, technical advances developed for aircraft gas turbine engines need to be applied to land-based gas turbines. These advances include directionally solidified and single crystal castings, alloys tailored to exploit these microstructures, complex internal cooling schemes, and coatings. The proposed program to scale aircraft gas turbine casting technology up to land based gas turbine size components is based on low sulfur alloys, casting process development, post-cast process development, and establishing casting defect tolerance levels. The inspection side is also discussed.

  5. Deletion of the presynaptic scaffold CAST reduces active zone size in rod photoreceptors and impairs visual processing.

    PubMed

    tom Dieck, Susanne; Specht, Dana; Strenzke, Nicola; Hida, Yamato; Krishnamoorthy, Vidhyasankar; Schmidt, Karl-Friedrich; Inoue, Eiji; Ishizaki, Hiroyoshi; Tanaka-Okamoto, Miki; Miyoshi, Jun; Hagiwara, Akari; Brandstätter, Johann H; Löwel, Siegrid; Gollisch, Tim; Ohtsuka, Toshihisa; Moser, Tobias

    2012-08-29

    How size and shape of presynaptic active zones are regulated at the molecular level has remained elusive. Here we provide insight from studying rod photoreceptor ribbon-type active zones after disruption of CAST/ERC2, one of the cytomatrix of the active zone (CAZ) proteins. Rod photoreceptors were present in normal numbers, and the a-wave of the electroretinogram (ERG)--reflecting their physiological population response--was unchanged in CAST knock-out (CAST(-/-)) mice. Using immunofluorescence and electron microscopy, we found that the size of the rod presynaptic active zones, their Ca(2+) channel complement, and the extension of the outer plexiform layer were diminished. Moreover, we observed sprouting of horizontal and bipolar cells toward the outer nuclear layer indicating impaired rod transmitter release. However, rod synapses of CAST(-/-) mice, unlike in mouse mutants for the CAZ protein Bassoon, displayed anchored ribbons, normal vesicle densities, clustered Ca(2+) channels, and essentially normal molecular organization. The reduction of the rod active zone size went along with diminished amplitudes of the b-wave in scotopic ERGs. Assuming, based on the otherwise intact synaptic structure, an unaltered function of the remaining release apparatus, we take our finding to suggest a scaling of release rate with the size of the active zone. Multielectrode-array recordings of retinal ganglion cells showed decreased contrast sensitivity. This was also observed by optometry, which, moreover, revealed reduced visual acuity. We conclude that CAST supports large active zone size and high rates of transmission at rod ribbon synapses, which are required for normal vision.

  6. Prediction of Microporosity in Shrouded Impeller Castings

    SciTech Connect

    Viswanathan, S. Nelson, C.D.

    1998-09-01

    The purpose of this Cooperative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory (ORNL) and Morris Bean and Company was to link computer models of heat and fluid flow with previously developed quality criteria for the prediction of microporosity in a Al-4.5% Cu alloy shrouded impeller casting. The results may be used to analyze the casting process design for the commercial production of 206 o alloy shrouded impeller castings. Test impeller castings were poured in the laboratory for the purpose of obtaining thermal data and porosity distributions. Also, a simulation of the test impeller casting was conducted and the results validated with porosity measurements on the test castings. A comparison of the predicted and measured microporosity distributions indicated an excellent correlation between experiments and prediction. The results of the experimental and modeling studies undertaken in this project indicate that the quality criteria developed for the prediction of microporosity in Al-4.5% Cu alloy castings can accurately predict regions of elevated microporosity even in complex castings such as the shrouded impeller casting. Accordingly, it should be possible to use quality criteria for porosity prediction in conjunction with computer models of heat and fluid flow to optimize the casting process for the production of shrouded impeller castings. Since high levels of microporosity may be expected to result in poor fatigue properties, casting designs that are optimized for low levels of microporosity should exhibit superior fatigue life.

  7. Uniform distribution of BeO particles in Be casting produced in rocket free fall. [for space processing feasibility

    NASA Technical Reports Server (NTRS)

    Wouch, G.; Frost, R. T.; Pinto, N. P.; Keith, G. H.; Lord, A. E., Jr.

    1978-01-01

    An experiment at zero-g aboard a NASA sounding rocket was conducted to evaluate the distribution of BeO particles in a Be casting. A distinction is drawn between the downward settling of particles in a quiescent melt, and the velocity gradient collisions of particles in a melt agitated by electromagnetic stirring. A similar experiment was conducted on earth using the same melting and solidification of a 0.922 cm spheroid of HIP-50 as was carried out in space; the only difference arising from the effect of gravity. Under zero-g conditions, the time needed for agglomeration was lengthened considerably, but the result was a casting of more uniform particle distribution.

  8. Surface smoothness and marginal fit with phosphate-bonded investments.

    PubMed

    Cooney, J P; Doyle, T M; Caputo, A A

    1979-04-01

    Two phosphate-bonded investments and one calcium sulfate investment were evaluated for the surface smoothness and marginal fit they impart to gold castings. A modified technique was also evaluated for each phosphate-bonded investment, where the silica sol was not diluted and the spatulation time was reduced. The results of this study lead to the following conclusions: 1. The marginal fits obtained with all four phosphate-bonded methods were comparable to each other and superior to that obtained with the calcium sulfate investment. 2. The presence of nodules on the surface of the castings was more prevalent with the phosphate-bonded investments. However, this effect was not statistically significant. 3. Clinical assessment of the roughness of the castings revealed that all the methods tested produced clinically acceptable castings. 4. Visual observation by five dentists revealed that both the recommended and modified techniques for one of the phosphate-bonded investments (Ceramigold) produced a smoother surface than any other investment tested. Rating of scanning electron microscope photographs (X600) revealed no difference in the surface roughness between any of the castings. Consequently, no definitive relation between investment type or technique and surface roughness was established. 5. No correlation was demonstrated between surface roughness, as evaluated by either clinical observation or scanning electron microscope photography, and marginal fit of the castings.

  9. Prediction of Part Distortion in Die Casting

    SciTech Connect

    R. Allen Miller

    2005-03-30

    The die casting process is one of the net shape manufacturing techniques and is widely used to produce high production castings with tight tolerances for many industries. An understanding of the stress distribution and the deformation pattern of parts produced by die casting will result in less deviation from the part design specification, a better die design and eventually more productivity and cost savings. This report presents methods that can be used to simulate the die casting process in order to predict the deformation and stresses in the produced part and assesses the degree to which distortion modeling is practical for die casting at the current time. A coupled thermal-mechanical finite elements model was used to simulate the die casting process. The simulation models the effect of thermal and mechanical interaction between the casting and the die. It also includes the temperature dependant material properties of the casting. Based on a designed experiment, a sensitivity analysis was conducted on the model to investigate the effect of key factors. These factors include the casting material model, material properties and thermal interaction between casting and dies. To verify the casting distortion predictions, it was compared against the measured dimensions of produced parts. The comparison included dimensions along and across the parting plane and the flatness of one surface.

  10. Biomimetic Materials by Freeze Casting

    NASA Astrophysics Data System (ADS)

    Porter, Michael M.; Mckittrick, Joanna; Meyers, Marc A.

    2013-06-01

    Natural materials, such as bone and abalone nacre, exhibit exceptional mechanical properties, a product of their intricate microstructural organization. Freeze casting is a relatively simple, inexpensive, and adaptable materials processing method to form porous ceramic scaffolds with controllable microstructural features. After infiltration of a second polymeric phase, hybrid ceramic-polymer composites can be fabricated that closely resemble the architecture and mechanical performance of natural bone and nacre. Inspired by the narwhal tusk, magnetic fields applied during freeze casting can be used to further control architectural alignment, resulting in freeze-cast materials with enhanced mechanical properties.

  11. Pressure Rig for Repetitive Casting

    NASA Technical Reports Server (NTRS)

    Vasquez, P.; Hutto, W. R.

    1986-01-01

    Equipment life increased by improved insulation. New design cuts time of preparation for casting from several days to about 1 hour. Savings due to elimination of lengthy heating and drying operations associated with preparation of ceramic mold. Quality of casting improved because moisture in cavity eliminated by use of insulating material, and more uniform pressure applied to process. Commercial blanket insulator protects components from heat, increasing life of pressure rig and enabling repeated use. Improved heat protection allows casting of brass and other alloys with higher melting temperatures in pressure rig.

  12. Investment Avenues

    NASA Astrophysics Data System (ADS)

    Jain, Priyanka

    2012-11-01

    Investors are a heterogeneous group, they may be large or small, rich or poor, expert or lay man and not all investors need equal degree of protection (Mayya, 1996). An investor has three objectives while investing his money, namely safety of invested money, liquidity position of invested money and return on investment. The return on investment may further be divided into capital gain and the rate of return on investment as interest or dividend. Among all investment options available, securities are considered the most challenging as well as rewarding. Securities include shares, debentures, derivatives, units of mutual funds, Government securities etc. An investor may be an individual or corporate legal entity investing funds with a view to derive maximum economic advantage from investment such as rate of return, capital appreciation, marketability, tax advantage and convenience of investment.The Capital market facilitates mobilization of savings of individuals and pools them into reservoir of capital which can be used for the economic development of a country. An efficient capital market is essential for raising capital by the corporate sector of the economy and for the protection of the interest of investors in corporate securities. There arises a need to strike a balance between raising of capital for economic development on one side and protection of investors on the other. Unless the interests of investors are protected, raising of capital, by corporates is not possible. Like, the primary objective of a senior citizenís asset allocation is the generation of regular income.

  13. Computer simulation applied to jewellery casting: challenges, results and future possibilities

    NASA Astrophysics Data System (ADS)

    Tiberto, Dario; Klotz, Ulrich E.

    2012-07-01

    Computer simulation has been successfully applied in the past to several industrial processes (such as lost foam and die casting) by larger foundries and direct automotive suppliers, while for the jewelry sector it is a procedure which is not widespread, and which has been tested mainly in the context of research projects. On the basis of a recently concluded EU project, the authors here present the simulation of investment casting, using two different softwares: one for the filling step (Flow-3D®), the other one for the solidification (PoligonSoft®). A work on material characterization was conducted to obtain the necessary physical parameters for the investment (used for the mold) and for the gold alloys (through thermal analysis). A series of 18k and 14k gold alloys were cast in standard set-ups to have a series of benchmark trials with embedded thermocouples for temperature measurement, in order to compare and validate the software output in terms of the cooling curves for definite test parts. Results obtained with the simulation included the reduction of micro-porosity through an optimization of the feeding channels for a controlled solidification of the metal: examples of the predicted porosity in the cast parts (with metallographic comparison) will be shown. Considerations on the feasibility of applying the casting simulation in the jewelry sector will be reached, underlining the importance of the software parametrization necessary to obtain reliable results, and the discrepancies found with the experimental comparison. In addition an overview on further possibilities of application for the CFD in jewellery casting, such as the modeling of the centrifugal and tilting processes, will be presented.

  14. A Political Investment: Revisiting Race and Racism in the Research Process

    ERIC Educational Resources Information Center

    Rollock, Nicola

    2013-01-01

    This paper draws upon a two-year Economic and Social Research Council (ESRC) funded study into the educational strategies of the black middle classes to examine the role of race and racism in the research process. Specifically, it explores how my political positioning and experiences of racism, as a black female scholar, shaped not only my…

  15. Laser surface texturing of cast iron steel: dramatic edge burr reduction and high speed process optimisation for industrial production using DPSS picosecond lasers

    NASA Astrophysics Data System (ADS)

    Bruneel, David; Kearsley, Andrew; Karnakis, Dimitris

    2015-07-01

    In this work we present picosecond DPSS laser surface texturing optimisation of automotive grade cast iron steel. This application attracts great interest, particularly in the automotive industry, to reduce friction between moving piston parts in car engines, in order to decrease fuel consumption. This is accomplished by partially covering with swallow microgrooves the inner surface of a piston liner and is currently a production process adopting much longer pulse (microsecond) DPSS lasers. Lubricated interface conditions of moving parts require from the laser process to produce a very strictly controlled surface topography around the laser formed grooves, whose edge burr height must be lower than 100 nm. To achieve such a strict tolerance, laser machining of cast iron steel was investigated using an infrared DPSS picosecond laser (10ps duration) with an output power of 16W and a repetition rate of 200 kHz. The ultrashort laser is believed to provide a much better thermal management of the etching process. All studies presented here were performed on flat samples in ambient air but the process is transferrable to cylindrical geometry engine liners. We will show that reducing significantly the edge burr below an acceptable limit for lubricated engine production is possible using such lasers and remarkably the process window lies at very high irradiated fluences much higher that the single pulse ablation threshold. This detailed experimental work highlights the close relationship between the optimised laser irradiation conditions as well as the process strategy with the final size of the undesirable edge burrs. The optimised process conditions are compatible with an industrial production process and show the potential for removing extra post)processing steps (honing, etc) of cylinder liners on the manufacturing line saving time and cost.

  16. Sixty Years of Casting Research

    NASA Astrophysics Data System (ADS)

    Campbell, John

    2015-11-01

    The 60 years of solidification research since the publication of Chalmer's constitutional undercooling in 1953 has been a dramatic advance of understanding which has and continues to be an inspiration. In contrast, 60 years of casting research has seen mixed fortunes. One of its success stories relates to improvements in inoculation of gray irons, and another to the discovery of spheroidal graphite iron, although both of these can be classified as metallurgical rather than casting advances. It is suggested that true casting advances have dated from the author's lab in 1992 when a critical surface turbulence condition was defined for the first time. These last 20 years have seen the surface entrainment issues of castings developed to a sufficient sophistication to revolutionize the performance of light alloy and steel foundries. However, there is still a long way to go, with large sections of the steel and Ni-base casting industries still in denial that casting defects are important or even exist. The result has been that special ingots are still cast poorly, and shaped casting operations have suffered massive losses. For secondary melted and cast materials, electro-slag remelting has the potential to be much superior to expensive vacuum arc remelting, which has cost our aerospace and defense industries dearly over the years. This failure to address and upgrade our processing of liquid metals is a serious concern, since the principle entrainment defect, the bifilm, is seen as the principle initiator of cracks in metals; in general, bifilms are the Griffith cracks that initiate failures by cracking. A new generation of crack resistant metals and engineering structures can now be envisaged.

  17. Comparison of Lost Foam Casting of AM60B Alloy and A356 Alloy

    SciTech Connect

    Han, Qingyou; Dinwiddie, Ralph Barton; Sklad, Philip S; Currie, Kenneth; Vondra, Fred; Abdelrahman, Mohamed; Walford, Graham; Nolan, Dennis J; Nedkova, Teodora

    2007-01-01

    The article describes the research activities at Oak Ridge National Laboratory and Tennessee Technological University on lost foam casting of magnesium alloys. The work was focused on castings of simple geometries such as plate castings and window castings in order to compare the difference in castability between magnesium alloys and aluminum alloy using the lost foam casting process. Significant differences between lost foam aluminum casting and lost foam magnesium casting have been observed.

  18. Effect of melt homogenization temperature on the cast structures of in 738 LC superalloy

    SciTech Connect

    Liu, L.; Zhen, B.L.; Banerji, A.; Reif, W. . Inst. fuer Metallforschung-Metallkunde); Sommer, F. . Inst. fuer Werkstoffwissenschaft)

    1994-03-01

    The structure of investment cast superalloys can be controlled by optimizing the process variables such as melt treatment, including melt superheating (T[sub s]) and the time of homogenization (t[sub h]), as well as casting parameters including mold preheating temperature (T[sub m]) and pouring temperature of the melt (T[sub p]). The effect of casting parameters has been extensively studied for several superalloys. A variation of the melt superheat, i.e. the temperature above the liquidus of the alloy, produces a significant effect on the cast microstructure. The melt must be superheated sufficiently above the liquidus temperature of the alloy to homogenize the melt by dissolving all the previously present phases in the charge. It is generally known that low superheating temperatures cause significant reductions in the grain size. There is no report on the details of the processing and mechanism of this effect. This paper presents the results of heterogeneous nucleation of the primary crystallites of [gamma]-phase and some modes of carbide precipitation in the nickel-base superalloy Inconel 738 LC cast with low melt superheating temperatures.

  19. A Novel Method to Reduce Time Investment When Processing Videos from Camera Trap Studies

    PubMed Central

    Swinnen, Kristijn R. R.; Reijniers, Jonas; Breno, Matteo; Leirs, Herwig

    2014-01-01

    Camera traps have proven very useful in ecological, conservation and behavioral research. Camera traps non-invasively record presence and behavior of animals in their natural environment. Since the introduction of digital cameras, large amounts of data can be stored. Unfortunately, processing protocols did not evolve as fast as the technical capabilities of the cameras. We used camera traps to record videos of Eurasian beavers (Castor fiber). However, a large number of recordings did not contain the target species, but instead empty recordings or other species (together non-target recordings), making the removal of these recordings unacceptably time consuming. In this paper we propose a method to partially eliminate non-target recordings without having to watch the recordings, in order to reduce workload. Discrimination between recordings of target species and non-target recordings was based on detecting variation (changes in pixel values from frame to frame) in the recordings. Because of the size of the target species, we supposed that recordings with the target species contain on average much more movements than non-target recordings. Two different filter methods were tested and compared. We show that a partial discrimination can be made between target and non-target recordings based on variation in pixel values and that environmental conditions and filter methods influence the amount of non-target recordings that can be identified and discarded. By allowing a loss of 5% to 20% of recordings containing the target species, in ideal circumstances, 53% to 76% of non-target recordings can be identified and discarded. We conclude that adding an extra processing step in the camera trap protocol can result in large time savings. Since we are convinced that the use of camera traps will become increasingly important in the future, this filter method can benefit many researchers, using it in different contexts across the globe, on both videos and photographs. PMID:24918777

  20. Effect of processing variables (different compression packing processes and investment material types) and time on the dimensional accuracy of polymethyl methacrylate denture bases.

    PubMed

    Baydas, Seyfettin; Bayindir, Funda; Akyil, M Samil

    2003-06-01

    In this study we determined the effect of different compression packing processes, investment materials (a hemihydrate and dental stone) and time on the dimensional accuracy of polymethyl metacrylate denture bases. Square stainless steel plates (15 mm x 15 mm x 5 mm) were prepared to make an acrylic resin specimen. The linear dimensional changes of acrylic resin were determined by measuring the distances of fix points. Measurements were made at 24 hours, 48 hours, 12 days and 30 days after setting with a digital compass. Dimensional changes of test specimens that were obtained with three different flasks and two press techniques were compared by univariate analysis. Measurements of the linear dimensions of specimens cured by different compression packing techniques suggested that differences existed. The time interval differences were not significant. According to the results; flask and investment material types affect the dimensional accuracy of test specimens (p < 0.05). The least dimensional change observed in the specimens was obtained with Type 1 flask-dental stone-manual press combinations.

  1. Investment in higher order central processing regions is not constrained by brain size in social insects

    PubMed Central

    Muscedere, Mario L.; Gronenberg, Wulfila; Moreau, Corrie S.; Traniello, James F. A.

    2014-01-01

    The extent to which size constrains the evolution of brain organization and the genesis of complex behaviour is a central, unanswered question in evolutionary neuroscience. Advanced cognition has long been linked to the expansion of specific brain compartments, such as the neocortex in vertebrates and the mushroom bodies in insects. Scaling constraints that limit the size of these brain regions in small animals may therefore be particularly significant to behavioural evolution. Recent findings from studies of paper wasps suggest miniaturization constrains the size of central sensory processing brain centres (mushroom body calyces) in favour of peripheral, sensory input centres (antennal and optic lobes). We tested the generality of this hypothesis in diverse eusocial hymenopteran species (ants, bees and wasps) exhibiting striking variation in body size and thus brain size. Combining multiple neuroanatomical datasets from these three taxa, we found no universal size constraint on brain organization within or among species. In fact, small-bodied ants with miniscule brains had mushroom body calyces proportionally as large as or larger than those of wasps and bees with brains orders of magnitude larger. Our comparative analyses suggest that brain organization in ants is shaped more by natural selection imposed by visual demands than intrinsic design limitations. PMID:24741016

  2. Investigation on the Effect of Mold Constraints and Cooling Rate on Residual Stress During the Sand-Casting Process of 1086 Steel by Employing a Thermomechanical Model

    NASA Astrophysics Data System (ADS)

    Baghani, Amir; Davami, Parviz; Varahram, Naser; Shabani, Mohsen Ostad

    2014-06-01

    In this study, the effects of mold constraints and cooling rate on residual stress were analyzed during the shaped casting process. For this purpose, an H-shaped sample was designed in which the contraction of its middle portion is highly restricted by the mold during the cooling process. The effects of an increasing cooling rate combined with mold constraints were analyzed by reducing the thickness of the middle portion in the second sample. A three-dimensional coupled temperature-displacement analysis was performed in finite-element code ABAQUS to simulate residual stress distribution, and then numerical results were verified by the hole-drilling strain-gauge method. It was concluded that the mold constraints have a greater effect on the values of residual stress than the cooling rate (thin section) in steel sand casting. Increasing the cooling rate would increase the amount of residual stress, only in the presence of mold constraints. It is also suggested that employing the elastic-plastic stress model for the sand mold will satisfy the experimental results and avoid exaggerated values of residual stress in simulation.

  3. Thin Wall Iron Castings

    SciTech Connect

    J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka

    2001-10-31

    Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.

  4. Study on the microstructural evolution of AZ31 magnesium alloy in a vertical twin-roll casting process

    NASA Astrophysics Data System (ADS)

    Chen, Ming; Hu, Xiao-Dong; Han, Bing; Deng, Xiao-Hu; Ju, Dong-Ying

    2016-02-01

    Finite element method was employed to calculate the macroflow velocity and temperature distribution of the pool domain's biting zone in twin-roll casting. Macroanalysis results were inducted as boundary conditions into microanalysis. Phase field method (PFM) was adopted to investigate the microstructure evolution. Based on the Kim-Kim-Suzuki model, the effect of metal flow velocity was coupled on the solute gradient item, and the real physical parameters of AZ31 were inducted into the numerical calculation. We used the marker and cell method in the discrete element solution of microstructural pattern prediction of AZ31 magnesium alloys. The different flow velocity values that predicted the columnar dendrite evolution were discussed in detail. Numerical simulation results were also compared with the experiment analysis. The microstructure obtained by PFM agrees with the actual pattern observed via optical microscopy.

  5. Mathematical Modeling of High-Temperature Constitutive Equations and Hot Processing Maps for As-Cast SA508-3 Steel

    NASA Astrophysics Data System (ADS)

    Sui, Dashan; Wang, Tao; Zhu, Lingling; Gao, Liang; Cui, Zhenshan

    2016-08-01

    The hot deformation behavior and hot workability characteristics of as-cast SA508-3 steel were studied by modeling the constitutive equations and developing hot processing maps. The isothermal compression experiments were carried out at temperatures of 950°C, 1050°C, 1150°C, and 1250°C and strain rates of 0.001 s-1, 0.01 s-1, 0.1 s-1, and 1 s-1 respectively. The two-stage flow stress models were established through the classical theories on work hardening and softening, and the solution of activation energy for hot deformation was 355.0 kJ mol-1 K-1. Based on the dynamic material model, the power dissipation and instability maps were developed separately at strains of 0.2, 0.4, 0.6 and 0.8. The power dissipation rate increases with both the increase of temperature and the decrease of strain rate, and the instable region mainly appears on the conditions of low temperature and high strain rate. The optimal hot working parameters for as-cast SA508-3 steel are 1050-1200°C/0.001-0.1 s-1, with about 25-40% peak efficiency of power dissipation.

  6. Some Metallurgical Issues Concerning Austenite Conditioning in Nb-Ti and Nb-Mo Microalloyed Steels Processed by Near-Net-Shape Casting and Direct Rolling Technologies

    NASA Astrophysics Data System (ADS)

    López, Beatriz; Rodriguez-Ibabe, Jose M.

    2016-08-01

    As thin slab direct rolling technologies are moving to the production of higher quality steel grades, chemical compositions based on Nb-Ti and Nb-Mo become a good option. However, with the use of multiple microalloying additions, the as-cast austenite conditioning becomes more complex. This paper analyzes some of the microstructural features that should be taken into account during the as-cast austenite conditioning in Nb-Ti and Nb-Mo microalloyed steel grades. In the case of Nb-Ti grades, it has been observed that the process parameters during solidification and post-solidification steps affect the austenite evolution during hot rolling. This is due to the differences in the size and volume fraction of TiN particles that can be formed. Fine TiN precipitates have been shown to be able to delay recrystallization kinetics. Moreover, the solute drag effect of Ti cannot be ignored in the case of hyperstoichiometric Ti/N ratios. It is observed that Nb-Ti grades tend to have lower non-recrystallization temperatures compared to Nb grades, which means that pancaking of the austenite is more difficult for these steels. The opposite is observed for the Nb-Mo grades, although in both cases the behavior is affected by the nominal content of Nb.

  7. 17 CFR 275.204-2 - Books and records to be maintained by investment advisers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... each vote cast by the investment adviser on behalf of a client. An investment adviser may satisfy this... the vote cast (provided that the adviser has obtained an undertaking from the third party to provide a... demand, at its principal office in Washington, DC, or at any Regional Office of the Commission...

  8. 17 CFR 275.204-2 - Books and records to be maintained by investment advisers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... each vote cast by the investment adviser on behalf of a client. An investment adviser may satisfy this... the vote cast (provided that the adviser has obtained an undertaking from the third party to provide a... demand, at its principal office in Washington, DC, or at any Regional Office of the Commission...

  9. 17 CFR 275.204-2 - Books and records to be maintained by investment advisers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... each vote cast by the investment adviser on behalf of a client. An investment adviser may satisfy this... the vote cast (provided that the adviser has obtained an undertaking from the third party to provide a... demand, at its principal office in Washington, DC, or at any Regional Office of the Commission...

  10. Final report on Expendable Pattern Casting Technology

    SciTech Connect

    Not Available

    1990-07-01

    The Expendable Pattern Casting (EPC) process is a potential casting process breakthrough which could dramatically improve the competitiveness of the US foundry industry. Cooperatively supported by US Industry and the Department of Energy and managed by the American Foundrymen's Society, a project was started in May 1989 to develop and optimize expendable pattern casting technology. Four major tasks were conducted in the first phase of the project. Those tasks involved: (1) reviewing published literature to determine the major problems in the EPC process, (2) evaluating factors influencing sand flow and compaction, (3) evaluating and comparing factors influencing sand flow and compaction, (3) evaluating and comparing casting precision obtained in the EPC process with that obtained in other processes, and (4) identifying critical parameters that control dimensional precision and defect formation in EP castings. 26 refs., 27 figs., 11 tabs.

  11. Effect of thermal fatigue on the wear resistance of graphite cast iron with bionic units processed by laser cladding WC

    NASA Astrophysics Data System (ADS)

    Jing, Zhengjun; Zhou, Hong; Zhang, Peng; Wang, Chuanwei; Meng, Chao; Cong, Dalong

    2013-04-01

    Thermal fatigue and wear exist simultaneously during the service life of brake discs. Previous researchers only studied thermal fatigue resistance or abrasion resistance of compact graphite cast iron (CGI), rather than combining them together. In this paper, wear resistance after thermal fatigue of CGI was investigated basing on the principle of bionics, which was close to actual service condition of the brake discs. In the meanwhile, the effect of thermal fatigue on wear resistance was also discussed. Non-smooth bionic units were fabricated by laser cladding WC powder with different proportions (50 wt.%, 60 wt.%, 70 wt.%). Microstructure and microhardness of the units were investigated, and wear mass losses of the samples were also compared. The results indicate that thermal fatigue has a negative effect on the wear resistance. After the same thermal fatigue cycles times, the wear resistance of laser cladding WC samples is superior to that of laser remelting ones and their wear resistance enhances with the increase of WC content.

  12. Improved ceramic slip casting technique. [application to aircraft model fabrication

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M. (Inventor); Vasquez, Peter (Inventor)

    1993-01-01

    A primary concern in modern fluid dynamics research is the experimental verification of computational aerothermodynamic codes. This research requires high precision and detail in the test model employed. Ceramic materials are used for these models because of their low heat conductivity and their survivability at high temperatures. To fabricate such models, slip casting techniques were developed to provide net-form, precision casting capability for high-purity ceramic materials in aqueous solutions. In previous slip casting techniques, block, or flask molds made of plaster-of-paris were used to draw liquid from the slip material. Upon setting, parts were removed from the flask mold and cured in a kiln at high temperatures. Casting detail was usually limited with this technique -- detailed parts were frequently damaged upon separation from the flask mold, as the molded parts are extremely delicate in the uncured state, and the flask mold is inflexible. Ceramic surfaces were also marred by 'parting lines' caused by mold separation. This adversely affected the aerodynamic surface quality of the model as well. (Parting lines are invariably necessary on or near the leading edges of wings, nosetips, and fins for mold separation. These areas are also critical for flow boundary layer control.) Parting agents used in the casting process also affected surface quality. These agents eventually soaked into the mold, the model, or flaked off when releasing the case model. Different materials were tried, such as oils, paraffin, and even an algae. The algae released best, but some of it remained on the model and imparted an uneven texture and discoloration on the model surface when cured. According to the present invention, a wax pattern for a shell mold is provided, and an aqueous mixture of a calcium sulfate-bonded investment material is applied as a coating to the wax pattern. The coated wax pattern is then dried, followed by curing to vaporize the wax pattern and leave a shell

  13. Government Strategic Support for Investment Activity

    ERIC Educational Resources Information Center

    Turekulova, Assiya N.; Mukhambetova, Lyazzat K.; Doshan, Almagul S.; Issabekov, Baurzhan N.; Chimgentbayeva, Gulbakyt K.; Turegeldinova, Aliya Zh.

    2016-01-01

    When system risks are high most investors choose to exit the market; however, there are some contrarian investors who opt to make investments. The authors analyzed the main goals of the investment process and measures that should be provided by the government to stimulate investments and innovation especially by means of investment banking. The…

  14. Iron/Phosphorus Alloys for Continuous Casting

    NASA Technical Reports Server (NTRS)

    Dufresne, E. R.

    1986-01-01

    Continuous casting becomes practicable because of reduced eutectic temperature. Experimental ferrous alloy has melting point about 350 degrees C lower than conventional steels, making possible to cast structural members and eliminating need for hot rolling. Product has normal metal structure and good physical properties. Process used to make rails, beams, slabs, channels, and pipes.

  15. Plastic casting resin poisoning

    MedlinePlus

    Epoxy poisoning; Resin poisoning ... Epoxy and resin can be poisonous if they are swallowed or their fumes are breathed in. ... Plastic casting resins are found in various plastic casting resin products.

  16. Cool Cast Facts

    MedlinePlus

    ... outer layer is usually made of plaster or fiberglass. Fiberglass casts are made of fiberglass, which is a plastic that can be shaped. Fiberglass casts come in many different colors — if you' ...

  17. Electromagnetic Casting of Copper Alloys

    NASA Astrophysics Data System (ADS)

    Tyler, D. E.; Lewis, B. G.; Renschen, P. D.

    1985-09-01

    Electromagnetic (EMC) casting technology has been successfully developed for copper base alloys. This casting technique eliminates the mold related defects normally encountered in direct chill (DC) mold casting, and provides castings with greatly improved hot workability.

  18. An investigation of squeeze-cast alloy 718

    NASA Technical Reports Server (NTRS)

    Gamwell, W. R.

    1993-01-01

    Alloy 718 billets produced by the squeeze-cast process have been evaluated for use as potential replacements for propulsion engine components which are normally produced from forgings. Alloy 718 billets were produced using various processing conditions. Structural characterizations were performed on 'as-cast' billets. As-cast billets were then homogenized and solution treated and aged according to conventional heat-treatment practices for this alloy. Mechanical property evaluations were performed on heat-treated billets. As-cast macrostructures and microstructures varied with squeeze-cast processing parameters. Mechanical properties varied with squeeze-cast processing parameters and heat treatments. One billet exhibited a defect free, refined microstructure, with mechanical properties approaching those of wrought alloy 718 bar, confirming the feasibility of squeeze-casting alloy 718. However, further process optimization is required, and further structural and mechanical property improvements are expected with process optimization.

  19. Cast adrift: Gortex cast liners allow greater patient activity.

    PubMed

    Dubowitz, Gerald; Miller, Deborah M

    2003-01-01

    Extremity fractures are a common injury, with nearly 1.5 million cases reported in the United States in 1998. Treatment often involves lengthy periods of immobilization. This report outlines the use of a Gortex cast liner by a subject who was able to engage in swimming and scuba diving during the healing process. We report that a Gortex cast liner may be considered for an active patient who is keen to return to limited activities during fracture healing. Apparently because of a lack of knowledge of their existence, physicians currently are underutilizing this method of casting in active patients. The use of Gortex liners elsewhere has been reported to have higher patient and physician satisfaction in both use and performance, with no reported detrimental effects on outcome.

  20. Cast Aluminum Alloy for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2003-01-01

    Originally developed by NASA as high performance piston alloys to meet U.S. automotive legislation requiring low exhaust emission, the novel NASA alloys now offer dramatic increase in tensile strength for many other applications at elevated temperatures from 450 F (232 C) to about 750 F (400 C). It is an ideal low cost material for cast automotive components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. It can be very economically produced from conventional permanent mold, sand casting or investment casting, with silicon content ranging from 6% to 18%. At high silicon levels, the alloy exhibits excellent dimensional stability, surface hardness and wear resistant properties.

  1. Advanced Lost Foam Casting Technology

    SciTech Connect

    Charles E. Bates; Harry E. Littleton; Don Askeland; Taras Molibog; Jason Hopper; Ben Vatankhah

    2000-11-30

    This report describes the research done under the six tasks to improve the process and make it more functional in an industrial environment. Task 1: Pattern Pyrolysis Products and Pattern Properties Task 2: Coating Quality Control Task 3: Fill and Solidification Code Task 4: Alternate Pattern Materials Task 5: Casting Distortion Task 6: Technology Transfer

  2. Clean Cast Steel Technology - Machinability and Technology Transfer

    SciTech Connect

    C. E. Bates; J. A. Griffin

    2000-05-01

    There were two main tasks in the Clean Cast Steel Technology - Machinability and Technology Transfer Project. These were (1) determine the processing facts that control the machinability of cast steel and (2) determine the ability of ladle stirring to homogenize ladle temperature, reduce the tap and pouring temperatures, and reduce casting scrap.

  3. Application of TRIZ Theory in Patternless Casting Manufacturing Technique

    NASA Astrophysics Data System (ADS)

    Yang, Weidong; Gan, Dequan; Jiang, Ping; Tian, Yumei

    The ultimate goal of Patternless Casting Manufacturing (referred to as PCM) is how to obtain the casts by casting the sand mold directly. In the previous PCM, the resin content of sand mold is much higher than that required by traditional resin sand, so the casts obtained are difficult to be sound and qualified products, which limits the application of this technique greatly. In this paper, the TRIZ algorithm is introduced to the innovation process in PCM systematically.

  4. Microvasculature of the retina, ciliary processes and choroid in the North American raccoon (Procyon lotor) eye: a scanning electron microscopic study of corrosion casts.

    PubMed

    Ninomiya, Hiroyoshi; Inomata, Tomo; Kanemaki, Nobuyuki

    2005-06-01

    We have studied the vasculature of the retina, ciliary processes and choroid in the North American raccoon (Procyon lotor), a nocturnal mammal, using light and scanning electron microscopic examination of corrosion casts. We carried out an identical study in the crab-eating macaque (Macaca fascicularis), which forages only during the daytime, in order to compare the ocular vasculature with that of nocturnal mammals. Our observations in raccoons demonstrated a photoreceptor layer associated with rich lymph and a poorly vascularized retina. The meridian region of the eye, which lies in the horizontal plane and pass around the optic disc, had a markedly sparse capillary network. This horizontal sparse vascular band may correspond to a visual streak. Ciliary process capillaries were delicate, and formed a well-developed and compact network. Choriocapillaries were quite thin and formed a coarse capillary network. This contrasted with the dense retinal and well-extended choroidal capillary networks noted in the macaques. Our findings suggest that the sparse retinal capillary network in raccoons is extremely beneficial for photon capture, thereby allowing the raccoon to see well at night, as the retinal vessels restrict the inflow of photons toward the photoreceptors. The well-developed lymph probably compensates for the sparse retinal capillaries and choriocapillaries and nourishes the retina in the nocturnal raccoon.

  5. Cast iron-base alloy for cylinder/regenerator housing: Final report

    SciTech Connect

    Witter, S.L.; Simmons, H.E.; Woulds, M.J.

    1985-08-01

    The objective is to develop an Fe-base alloy that can meet the requirements of the automotive Stirling engine cylinders and regenerator housings. The scope of work was to test various alloys and select the one best demonstrating the following characteristics: It must be a cast alloy, using nonstrategic metals. It must withstand stresses for a 2500-hr rupture life at 200 MPa/775/degree/C. Oxidation/corrosion resistance must be comparable to that of N-155. It must be compatible with hydrogen. Fatigue properties must be superior to alloy XF 818. Cost must be less than or equal to that of 19-9DL. Major tests were designed to include the following: Selection, processing, and evaluation of candidate alloys within each alloy group system. Determination of casting parameters. Selection of a candidate alloy and establishment of a data base for this alloy. In the initial phase of the program designated as Round 1, a series of alloys representing each alloy system was cast and tested. In all there were 5 alloys of the nickel-manganese Group 1, 13 alloys of the nickel Group 2, and 3 alloys of the manganese Group 3. The aim was to maintain the chemistry of the major element(s) shown and vary the percentage of other elements to study their influence. Evaluation of results obtained from this series of tests enabled us to closely define the chemistry range for our candidate alloy, designated NASACC-1. A master heat was made to this composition. The heat was melted and poured under controlled casting conditions previously established and poured into investment shell molds. All castings and test bars were heat treated before actual testing. NASACC-1 proved to be an excellent alloy for casting. It could be melted in air and had good fluidity and fill characteristics. The alloy met or exceeded all program goals. 28 refs., 47 figs., 44 tabs.

  6. Microporosity Prediction and Validation for Ni-based Superalloy Castings

    NASA Astrophysics Data System (ADS)

    Guo, J.; Beckermann, C.; Carlson, K.; Hirvo, D.; Bell, K.; Moreland, T.; Gu, J.; Clews, J.; Scott, S.; Couturier, G.; Backman, D.

    2015-06-01

    Microporosityin high performance aerospace castings can reduce mechanical properties and consequently degrade both component life and durability. Therefore, casting engineers must be able to both predict and reduce casting microporosity. A dimensionless Niyama model has been developed [1] that predicts local microporosity by accounting for local thermal conditions during casting as well as the properties and solidification characteristics of the cast alloy. Unlike the well-known Niyama criterion, application of the dimensionless Niyama model avoids the need to find a threshold Niyama criterion below which shrinkage porosity forms - a criterion which can be determined only via extensive alloy dependent experimentation. In the present study, the dimensionless Niyama model is integrated with a commercial finite element casting simulation software, which can now more accurately predict the location-specific shrinkage porosity volume fraction during solidification of superalloy castings. These microporosity predictions are validated by comparing modelled results against radiographically and metallographically measured porosity for several Ni-based superalloy equiaxed castings that vary in alloy chemistry with a focus on plates of changing draft angle and thickness. The simulation results agree well with experimental measurements. The simulation results also show that the dimensionless Niyama model can not only identify the location but also the average volume fraction of microporosity distribution in these equiaxed investment cast Ni-based superalloy experiments of relatively simple geometry.

  7. An accelerated clinical chairside technique for casting overdenture attachment copings.

    PubMed

    Scherer, Michael D; Campagni, Wayne V

    2011-11-01

    An accelerated technique for casting a direct-pattern post and core restoration for use in fixed prosthodontics has been previously described. Similar techniques for use in removable prosthodontics show potential for clinical use, specifically for the fabrication of radicular stud overdenture attachments and their corresponding copings. The procedure uses a chairside technique and readily available components to fabricate a direct, acrylic resin pattern combining the elements of a cast coping with a fixed radicular attachment. This pattern can subsequently be invested, cast, finished and polished, luted, and attached to the removable prosthesis in a single clinical appointment. PMID:22024184

  8. The role of water in slip casting

    NASA Technical Reports Server (NTRS)

    Mccauley, R. A.; Phelps, G. W.

    1984-01-01

    Slips and casting are considered in terms of physical and colloidal chemistry. Casting slips are polydisperse suspensions of lyophobic particles in water, whose degree of coagulation is controlled by interaction of flocculating and deflocculating agents. Slip casting rate and viscosity are functions of temperature. Slip rheology and response to deflocculating agents varies significantly as the kinds and amounts of colloid modifiers change. Water is considered as a raw material. Various concepts of water/clay interactions and structures are discussed. Casting is a de-watering operation in which water moves from slip to cast to mold in response to a potential energy termed moisture stress. Drying is an evaporative process from a free water surface.

  9. Modeling of nickel and iron aluminide castings

    SciTech Connect

    Viswanathan, S.; Duncan, A.J.; Porter, W.D.; Webb, D.S.

    1996-12-31

    This paper addresses some issues in producing Ni and Fe aluminide castings and illustrates use of computer simulation of the casting process to solve these problems. Available casting software and issues in their use are reviewed. Importance of availability of accurate thermophysical properties is illustrated by comparing sensitivity of computed cooling curves to changes in these properties. If constant thermophysical properties must be used in solidification simulation, the values at the solidus temperature are likely to provide greatest accuracy; significant errors may be incurred by use of constant room temperature properties. Examples are given of the mold filling analysis of sand cast heat treating trays and centrifugally cast transfer rolls of Ni aluminide alloy. In the case of sand cast heat treating trays, the simulation of mold filling is used to illustrate benefits of pouring the mold at a tilt to reduce turbulence in the runner. In the case of centrifugally cast rolls, the simulation is used to illustrate effect of inlet velocity during the pour on casting quality.

  10. Dimensional variability of production steel castings

    SciTech Connect

    Peters, F.E.; Risteu, J.W.; Vaupel, W.G.; DeMeter, E.C.; Voigt, R.C.

    1994-12-31

    Work is ongoing to characterize the dimensional variability of steel casting features. Data are being collected from castings produced at representative Steel Founders` Society of America foundries. Initial results based on more than 12,500 production casting feature measurements are presented for carbon and low alloy steel castings produced in green sand, no-bake, and shell molds. A comprehensive database of casting, pattern, and feature variables has been developed so that the influence of the variables on dimensional variability can be determined. Measurement system analysis is conducted to insure that large measurement error is not reported as dimensional variability. Results indicate that the dimensional variability of production casting features is less than indicated in current US (SFSA) and international (ISO) standards. Feature length, casting weight, parting line and molding process all strongly influence dimensional variability. Corresponding pattern measurements indicate that the actual shrinkage amount for casting features varies considerably. This variation in shrinkage will strongly influence the ability of the foundry to satisfy customer dimensional requirements.

  11. Investing in Youth: Lithuania

    ERIC Educational Resources Information Center

    OECD Publishing, 2016

    2016-01-01

    The series Investing in Youth builds on the expertise of the Organisation for Economic Cooperation and Development (OECD) on youth employment, social support and skills. It covers both OECD countries and countries in the process of accession to the OECD, as well as some emerging economies. The present report on Lithuania is the fourth of a new…

  12. Investing in Youth: Brazil

    ERIC Educational Resources Information Center

    OECD Publishing, 2014

    2014-01-01

    The series Investing in Youth builds on the expertise of the Organisation for Economic Cooperation and Development (OECD) on youth employment, social support and skills. It covers both OECD countries and countries in the process of accession to the OECD, as well as some emerging economies. This report provides a detailed diagnosis of the youth…

  13. Investing in Youth: Latvia

    ERIC Educational Resources Information Center

    OECD Publishing, 2015

    2015-01-01

    The series Investing in Youth builds on the expertise of the Organisation for Economic Cooperation and Development (OECD) on youth employment, social support and skills. It covers both OECD countries and countries in the process of accession to the OECD, as well as some emerging economies. This report provides a detailed diagnosis of the youth…

  14. Vacuum casting of thick polymeric films

    NASA Technical Reports Server (NTRS)

    Cuddihy, E. F.; Moacanin, J.

    1979-01-01

    Bubble formation and layering, which often plague vacuum-evaporated films, are prevented by properly regulating process parameters. Vacuum casting may be applicable to forming thick films of other polymer/solvent solutions.

  15. Heat Transfer Model of Directional Solidification by LMC Process for Superalloy Casting Based on Finite Element Method

    NASA Astrophysics Data System (ADS)

    Cao, Liu; Liao, Dunming; Lu, Yuzhang; Chen, Tao

    2016-09-01

    With the rapid development of the aviation industry, the turbine blade, a critical component of the aeronautical engine, has come to be widely produced by liquid-metal cooling (LMC) process. A temperature- and time-dependent heat transfer coefficient was used to represent the heat convection between the shell and the cooling liquid, and an improved Monte Carlo ray-tracing approach was adopted to handle the boundary of radiation heat transfer. Unstructured mesh was used to fit the irregular shell boundary, and the heat transfer model of directional solidification by LMC process based on finite element method (FEM) was established. The concept of local matrix was here proposed to guarantee computational efficiency. The pouring experiments of directional solidification by LMC process were carried out, then simulation and experimental results were compared here. The accuracy of the heat transfer model was validated by the cooling curves and grain morphology, and the maximum relative error between simulation and experimental cooling curve was 2 pct. The withdrawal rate showed an important influence on the shape of solidification interface, and stray grain is liable to be generated on the bottom of platform at an excessive withdrawal rate.

  16. Influence of processing route on electrical properties of Bi{sub 4}Ti{sub 3}O{sub 12} ceramics obtained by tape-casting technology

    SciTech Connect

    Ranieri, M.G.A.; Aguiar, E.C.; Cilense, M.; Stojanovic, B.D.; Simões, A.Z.; Varela, J.A.

    2015-10-15

    Highlights: • Bi{sub 4}Ti{sub 3}O{sub 12} thick films were obtained by SSR and PPM methods. • Both systems crystallize in an orthorhombic structure. • Textured characteristics were evidenced. • Grain morphology affects the P–E loops. - Abstract: Bismuth titanate powders (Bi{sub 4}Ti{sub 3}O{sub 12}-BIT) were fabricated by solid state reaction (SSR) and polymeric precursor method (PPM). From these powders, Bi{sub 4}Ti{sub 3}O{sub 12} pellets were obtained by tape-casting using plate-like templates particles prepared by a molten salt method. The BIT phase crystallizes in an orthorhombic structure type with space group Fmmm. Agglomeration of the particles, which affects the densification of the ceramic, electrical conduction and leakage current at high electric fields, was monitored by transmission electronic microscopy (TEM) analyses. FEG-SEM indicated that different shape of grains of BIT ceramics was influenced by the processing route. Both SSR and PPM methods lead to unsaturated P–E loops of BIT ceramics originating from the highly c-axis orientation and high conductivity which was affected by charge carriers flowing normally to the grain boundary of the crystal lattice.

  17. Computed Tomography For Internal Inspection Of Castings

    NASA Technical Reports Server (NTRS)

    Hanna, Timothy L.

    1995-01-01

    Computed tomography used to detect internal flaws in metal castings before machining and otherwise processing them into finished parts. Saves time and money otherwise wasted on machining and other processing of castings eventually rejected because of internal defects. Knowledge of internal defects gained by use of computed tomography also provides guidance for changes in foundry techniques, procedures, and equipment to minimize defects and reduce costs.

  18. Ladle and Continuous Casting Process Models for Reduction of SiO2 in SiO2-Al2O3-CaO Slags by Al in Fe-Al(-Si) Melts

    NASA Astrophysics Data System (ADS)

    Park, Jiwon; Sridhar, S.; Fruehan, Richard J.

    2015-02-01

    Based on a mixed control or two-phase mass transfer model considering mass transport in the metal and the slag phases, process models for ladle and continuous castor mold were developed to predict the changes in the metal and the slag chemistry and viscosity. In the ladle process model, the rate of reaction is primarily determined by stirring gas flow rate, which greatly alters the mass transports of the metal and the slag phases. In the continuous casting process model, the effects of the Al, Si, and SiO2 contents in the incoming flow of the fluid phases, casting speed, mold flux consumption rate, and depth of the liquid mold flux pool on the steady-state compositions of the metal and the mold flux were assessed.

  19. Metallic Fuel Casting Development and Parameter Optimization Simulations

    SciTech Connect

    R.S. Fielding; J. Crapps; C. Unal; J.R. Kennedy

    2013-03-01

    One of the advantages of metallic fuel is the abilility to cast the fuel slugs to near net shape with little additional processing. However, the high aspect ratio of the fuel is not ideal for casting. EBR-II fuel was cast using counter gravity injection casting (CGIC) but, concerns have been raised concerning the feasibility of this process for americium bearing alloys. The Fuel Cycle Research and Development program has begun developing gravity casting techniques suitable for fuel production. Compared to CGIC gravity casting does not require a large heel that then is recycled, does not require application of a vacuum during melting, and is conducive to re-usable molds. Development has included fabrication of two separate benchscale, approximately 300 grams, systems. To shorten development time computer simulations have been used to ensure mold and crucible designs are feasible and to identify which fluid properties most affect casting behavior and therefore require more characterization.

  20. Advanced lost foam from casting technology

    SciTech Connect

    Bates, C. E.; Littleton, H. E.; Askeland, D.; Griffin, J.; Miller, B. A.; Sheldon, D. S.

    1996-05-01

    Previous research made significant advances in understanding the Lost Foam Casting (LFC) Process and clearly identified areas where additional research was needed to improve the process and make it more functional in an industrial environment. The current project focused on five areas listed as follows: Task 1: Precision Pattern Production Task 2: Pattern Coating Consistency Task 3: Sand Fill and Compaction Effects Task 4: Pattern Gating Task 5: Mechanical Properties of Castings. This report summarizes the work done under the current contract in all five areas in the period of October 1, 1994 through December 31, 1995. Twenty-eight (28) companies jointly participate in the project. These companies represent a variety of disciplines, including pattern designers, pattern producers, coating manufacturers, plant design companies, compaction equipment manufacturers, casting producers, and casting buyers.

  1. Characterization of Technetium Speciation in Cast Stone

    SciTech Connect

    Um, Wooyong; Jung, Hun Bok; Wang, Guohui; Westsik, Joseph H.; Peterson, Reid A.

    2013-11-11

    This report describes the results from laboratory tests performed at Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE) EM-31 Support Program (EMSP) subtask, “Production and Long-Term Performance of Low Temperature Waste Forms” to provide additional information on technetium (Tc) speciation characterization in the Cast Stone waste form. To support the use of Cast Stone as an alternative to vitrification for solidifying low-activity waste (LAW) and as the current baseline waste form for secondary waste streams at the Hanford Site, additional understanding of Tc speciation in Cast Stone is needed to predict the long-term Tc leachability from Cast Stone and to meet the regulatory disposal-facility performance requirements for the Integrated Disposal Facility (IDF). Characterizations of the Tc speciation within the Cast Stone after leaching under various conditions provide insights into how the Tc is retained and released. The data generated by the laboratory tests described in this report provide both empirical and more scientific information to increase our understanding of Tc speciation in Cast Stone and its release mechanism under relevant leaching processes for the purpose of filling data gaps and to support the long-term risk and performance assessments of Cast Stone in the IDF at the Hanford Site.

  2. The Development of CaO-SiO2-B2O3-based Fluorine-Free Mold Flux for a Continuous Casting Process

    NASA Astrophysics Data System (ADS)

    Zhou, Lejun; Wang, Wanlin

    2016-05-01

    Designing and developing high-performance fluorine-free (F-free) mold flux has become a hot topic in steel continuous casting processes, with concerns of environment protection and energy saving. In conventional commercial mold flux, fluorine plays important roles on the properties as it works as a fluxing agent; however, it tends to cause serious environmental and health problems. In this paper, a new F-free mold flux based on the CaO-SiO2-B2O3 slag system has been introduced through summarizing previous works. The melting temperature range of F-free mold flux decreases with the addition of Na2O/Li2O and B2O3; the viscosity and heat flux decrease with the increase of basicity and Na2O/Li2O, as well as the decrease of B2O3 contents. Also, the crystallization temperatures of F-free mold fluxes increase with the increase of basicity and Na2O/Li2O content. The analyses of EDS and XRD show that Ca11Si4B2O22 and Ca14Mg2(SiO4)8 are the two main precipitated crystalline phases in F-free mold fluxes, and that the Ca11Si4B2O22 is a common and stable crystalline phase in the designed F-free mold fluxes system that shows the potential to replace Ca4Si2O7F2 in conventional flourine-containing mold fluxes.

  3. The Development of CaO-SiO2-B2O3-based Fluorine-Free Mold Flux for a Continuous Casting Process

    NASA Astrophysics Data System (ADS)

    Zhou, Lejun; Wang, Wanlin

    2016-09-01

    Designing and developing high-performance fluorine-free (F-free) mold flux has become a hot topic in steel continuous casting processes, with concerns of environment protection and energy saving. In conventional commercial mold flux, fluorine plays important roles on the properties as it works as a fluxing agent; however, it tends to cause serious environmental and health problems. In this paper, a new F-free mold flux based on the CaO-SiO2-B2O3 slag system has been introduced through summarizing previous works. The melting temperature range of F-free mold flux decreases with the addition of Na2O/Li2O and B2O3; the viscosity and heat flux decrease with the increase of basicity and Na2O/Li2O, as well as the decrease of B2O3 contents. Also, the crystallization temperatures of F-free mold fluxes increase with the increase of basicity and Na2O/Li2O content. The analyses of EDS and XRD show that Ca11Si4B2O22 and Ca14Mg2(SiO4)8 are the two main precipitated crystalline phases in F-free mold fluxes, and that the Ca11Si4B2O22 is a common and stable crystalline phase in the designed F-free mold fluxes system that shows the potential to replace Ca4Si2O7F2 in conventional flourine-containing mold fluxes.

  4. Social Affiliation and the Demand for Health Services: Caste and Child Health in South India *

    PubMed Central

    Luke, Nancy; Munshi, Kaivan

    2007-01-01

    This paper assesses the role of social affiliation, measured by caste, in shaping investments in child health. The special setting that we have chosen for the analysis – tea estates in the South Indian High Range – allows us to control nonparametrically for differences in income, access to health services, and patterns of morbidity across low caste and high caste households. In this controlled setting, low caste households spend more on their children's health than high caste households, reversing the pattern we would expect to find elsewhere in India. Moreover, health expenditures do not vary by gender within either caste group, in contrast once again with the male preference documented throughout the country. A simple explanation, based on differences in the returns to human capital across castes in the tea estates is proposed to explain these striking results. PMID:18046465

  5. The relationship of pattern position to the flow of gold and casting completeness.

    PubMed

    DeWald, E

    1979-05-01

    To minimize the possibility of incomplete casting due to improper pattern orientation relative to the sprue and direction of the casting arm motion, the following precautions should be taken. 1. Locate the pattern in the trailing half of the casting ring 90 to 135 degrees away from the sprue position. 2. Once the pattern is in the position described, locate it downward in the lower outer quarter of the trailing half of the casting ring and secure it in that position. 3. Mark the ring or sprue former so that the invested pattern can be oriented properly in the casting arm. 4. When using an electric casting machine, be certain that the pyrometer is correct. If in doubt, it is advisable to check the melt state of the gold before casting. PMID:374713

  6. Effect of processing parameters on surface finish for fused deposition machinable wax patterns

    NASA Technical Reports Server (NTRS)

    Roberts, F. E., III

    1995-01-01

    This report presents a study on the effect of material processing parameters used in layer-by-layer material construction on the surface finish of a model to be used as an investment casting pattern. The data presented relate specifically to fused deposition modeling using a machinable wax.

  7. Characterization of Ni-Cr alloys using different casting techniques and molds.

    PubMed

    Chen, Wen-Cheng; Teng, Fu-Yuan; Hung, Chun-Cheng

    2014-02-01

    This study differentiated the mechanical properties of nickel-chromium (Ni-Cr) alloys under various casting techniques (different casting molds and casting atmospheres). These techniques were sampled by a sand mold using a centrifugal machine in ambient air (group I) and electromagnetic induction in an automatic argon castimatic casting machine (group II). The specimen casting used a graphite mold by a castimatic casting machine (group III). The characteristics of the Ni-Cr alloys, yield and ultimate tensile strength, bending modulus, microhardness, diffraction phase, grindability, ability to spring back, as well as ground microstructure and pattern under different casting conditions were evaluated. The group III specimens exhibited the highest values in terms of strength, modulus, hardness, and grindability at a grind rate of 500 rpm. Moreover, group III alloys exhibited smaller grain sizes, higher ability to spring back, and greater ductility than those casted by sand investment (groups I and II). The main factor, "casting mold," significantly influenced all mechanical properties. The graphite mold casting of the Ni-Cr dental alloys in a controlled atmosphere argon casting system provided an excellent combination of high mechanical properties and good ability to spring back, and preserved the ductile properties for application in Ni-Cr porcelain-fused system. The results can offer recommendations to assist a prosthetic technician in selecting the appropriate casting techniques to obtain the desired alloy properties. PMID:24411373

  8. Causal Inferences from Mining ToxCast Data and the Biomedical Literature for Molecular Pathways and Cellular Processes in Cleft Palate (SOT)

    EPA Science Inventory

    Sixty-five chemicals in the ToxCast high-throughput screening (HTS) dataset have been linked to cleft palate based on data from ToxRefDB (rat or rabbit prenatal developmental toxicity studies) or from literature reports. These compounds are structurally diverse and thus likely to...

  9. INTERIOR VIEW WITH LARGE PIPE CASTING MACHINE CASTING A 48' ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW WITH LARGE PIPE CASTING MACHINE CASTING A 48' PIPE OPERATOR SPRAYING A POWDER TO HELP SOLIDIFY THE PIPE BEING CENTRIFUGALLY CAST. - United States Pipe & Foundry Company Plant, Pipe Casting & Testing Area, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  10. Symptomatic stent cast.

    PubMed

    Keohane, John; Moore, Michael; O'Mahony, Seamus; Crosbie, Orla

    2008-02-01

    Biliary stent occlusion is a major complication of endoscopic stent insertion and results in repeat procedures. Various theories as to the etiology have been proposed, the most frequently studied is the attachment of gram negative bacteria within the stent. Several studies have shown prolongation of stent patency with antibiotic prophylaxis. We report the case of stent occlusion from a cast of a previously inserted straight biliary stent; a "stent cast" in an 86-year-old woman with obstructive jaundice. This was retrieved with the lithotrypter and she made an uneventful recovery. This is the first reported case of a biliary stent cast.

  11. CASTING METHOD AND APPARATUS

    DOEpatents

    Gray, C.F.; Thompson, R.H.

    1958-10-01

    An improved apparatus for the melting and casting of uranium is described. A vacuum chamber is positioned over the casting mold and connected thereto, and a rod to pierce the oxide skin of the molten uranium is fitted into the bottom of the melting chamber. The entire apparatus is surrounded by a jacket, and operations are conducted under a vacuum. The improvement in this apparatus lies in the fact that the top of the melting chamber is fitted with a plunger which allows squeezing of the oxide skin to force out any molten uranium remaining after the skin has been broken and the molten charge has been cast.

  12. Effect of casting/mould interfacial heat transfer during solidification of aluminium alloys cast in CO2-sand mould

    NASA Astrophysics Data System (ADS)

    Kulkarni, S. N.; Radhakrishna, D. K.

    2011-06-01

    The ability of heat to flow across the casting and through the interface from the casting to the mold directly affects the evolution of solidification and plays a notable role in determining the freezing conditions within the casting, mainly in foundry systems of high thermal diffusivity such as chill castings. An experimental procedure has been utilized to measure the formation process of an interfacial gap and metal-mould interfacial movement during solidification of hollow cylindrical castings of Al-4.5 % Cu alloy cast in CO2-sand mould. Heat flow between the casting and the mould during solidification of Al-4.5 % Cu alloy in CO2-sand mould was assessed using an inverse modeling technique. The analysis yielded the interfacial heat flux ( q), heat transfer coefficient ( h) and the surface temperatures of the casting and the mould during solidification of the casting. The peak heat flux was incorporated as a dimensionless number and modeled as a function of the thermal diffusivities of the casting and the mould materials. Heat flux transients were normalized with respect to the peak heat flux and modeled as a function of time. The heat flux model proposed was to estimate the heat flux transients during solidification of Al-4.5 % Cu alloy cast in CO2-sand moulds.

  13. Subcritical Measurements Multiple HEU Metal Castings

    SciTech Connect

    Mihalczo, John T; Archer, Daniel E; Wright, Michael C

    2008-01-01

    Experiments with the standard annular highly enriched uranium (HEU) metal castings at Y-12 were performed in which up to 5 castings ({approx}90kg) were assembled in a tightly packed array with minimal spacing between castings. The fission chain multiplication process was initiated by a time tagged {sup 253}Cf spontaneously fissioning neutron source or time and directionally tagged neutrons from a small portable DT neutron generator and the prompt neutron time behavior measured with plastic scintillation detectors sensitive the fast neutron (>1 MeV) and gamma ray without distinction. These experiments were performed to provide data to benchmark methods for the calculation of the prompt neutron time behavior. Previous measurements with a single casting have been reported. This paper presents the experimental results for multiple castings. The prompt time decay was obtained by time coincidence correlation measurements between the detectors and the time tagged neutron source emission (equivalent to randomly pulsed neutron measurements) and between pairs of plastic scintillation detectors (equivalent to a 2-detector Rossi-alpha measurement). These standard HEU storage castings at the Y-12 plant had 5.000-in-OD, 3.500-in-ID, masses between 17,636 and 17,996 g, impurity content of 992 ppm, density of 18.75 g/cm{sup 3} and average enrichment of 93.16 wt % {sup 235}U. The castings were in tight fitting 025-in.-thick, 8.0-in-high stainless steel (SS-304) cylindrical cans for contamination control which were 8.0 in high. One can had an inside diameter of 3.0 in so that the Cf source could be located on the axes of this casting. Four 1 x 1 x 6 in plastic scintillators with the long dimension perpendicular to axes of the castings and adjacent to the outer surface of the casting cans were used. The detectors were enclosed in 1/4.-in.-thick lead shields on four 1 x 6 surfaces and on the 1 x 1 surface. The small surface of the lead shield was adjacent to the steel table. The

  14. A new casting defect healing technology

    SciTech Connect

    Hodge, E.S.; Reddoch, T.W.; Viswanathan, S.

    1997-01-01

    A new technology is presented for healing of defects in 356 aluminium alloys that provides economic upgrading of these cast alloys. It uses pneumatic isostatic forging (PIF) to produce high quality Al alloys products with enhanced mechanical properties uniform throughout the part, allowing higher design allowables and increased usage of Al alloy castings. The fundamental mechanism underlying PIF is a single mode plastic deformation process that uses isostatic application of pressures for 10-30 seconds at temperature. The process can be integrated in-line with other production operations, i.e., using the latent heat from the previous casting step. Results of applying the PIF process indicate lower cost and significant improvement in mechanical properties that rival and often exceed corresponding properties of other technologies like hot isostatic pressing and related processes. This process offers many advantages that are described in this paper in addition to presenting case histories of property enhancement by PIF and the mechanism responsible for property enhancement.

  15. 17 CFR 275.204-2 - Books and records to be maintained by investment advisers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Electronic Data Gathering, Analysis, and Retrieval (EDGAR) system. (iii) A record of each vote cast by the... third party to make and retain, on the investment adviser's behalf, a record of the vote cast (provided... its principal office in Washington, DC, or at any Regional Office of the Commission designated in...

  16. Casting Characteristics of Aluminum Die Casting Alloys

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

  17. Cast Metals Coalition Technology Transfer and Program Management Final Report

    SciTech Connect

    Gwyn, Mike

    2009-03-31

    The Cast Metals Coalition (CMC) partnership program was funded to ensure that the results of the Department of Energy's (DOE) metalcasting research and development (R&D) projects are successfully deployed into industry. Specifically, the CMC program coordinated the transfer and deployment of energy saving technologies and process improvements developed under separately funded DOE programs and projects into industry. The transition of these technologies and process improvements is a critical step in the path to realizing actual energy savings. At full deployment, DOE funded metalcasting R&D results are projected to save 55% of the energy used by the industry in 1998. This closely aligns with DOE's current goal of driving a 25% reduction in industrial energy intensity by 2017. In addition to benefiting DOE, these energy savings provide metalcasters with a significant economic advantage. Deployment of already completed R&D project results and those still underway is estimated to return over 500% of the original DOE and industry investment. Energy savings estimates through December 2008 from the Energy-Saving Melting and Revert Reduction Technology (E-SMARRT) portfolio of projects alone are 12 x 1012 BTUs, with a projection of over 50 x 1012 BTUs ten years after program completion. These energy savings and process improvements have been made possible through the unique collaborative structure of the CMC partnership. The CMC team consists of DOE's Office of Industrial Technology, the three leading metalcasting technical societies in the U.S: the American Foundry Society; the North American Die Casting Association; and the Steel Founders Society of America; and the Advanced Technology Institute (ATI), a recognized leader in distributed technology management. CMC provides collaborative leadership to a complex industry composed of approximately 2,100 companies, 80% of which employ less than 100 people, and only 4% of which employ more than 250 people. Without collaboration

  18. Method of casting aerogels

    SciTech Connect

    Poco, J.F.

    1993-09-07

    The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm[sup 3] to 0.6 g/cm[sup 3]. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of aerogel which occurs during the drying step of supercritical extraction of solvent. 2 figures.

  19. MOLDS FOR CASTING PLUTONIUM

    DOEpatents

    Anderson, J.W.; Miley, F.; Pritchard, W.C.

    1962-02-27

    A coated mold for casting plutonium comprises a mold base portion of a material which remains solid and stable at temperatures as high as the pouring temperature of the metal to be cast and having a thin coating of the order of 0.005 inch thick on the interior thereof. The coating is composed of finely divided calcium fluoride having a particle size of about 149 microns. (AEC)

  20. Method of casting aerogels

    DOEpatents

    Poco, John F.

    1993-01-01

    The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm.sup.3 to 0.6 g/cm.sup.3. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of alcogel which occurs during the drying step of supercritical extraction of solvent.

  1. Mathematical Modeling of Surface Roughness of Castings Produced Using ZCast Direct Metal Casting

    NASA Astrophysics Data System (ADS)

    Chhabra, M.; Singh, R.

    2015-04-01

    Aim of this investigation is to develop a mathematical model for predicting surface roughness of castings produced using ZCast process by employing Buckingham's π-theorem. A relationship has been proposed between surface roughness of castings and shell wall thickness of the shell moulds fabricated using 3D printer. Based on model, experiments were performed to obtain the surface roughness of aluminium, brass and copper castings produced using ZCast process based on 3D printing technique. Based on experimental data, three best fitted third-degree polynomial equations have been established for predicting the surface roughness of castings. The predicted surface roughness values were then calculated using established best fitted equations. An error analysis was performed to compare the experimental and predicted data. The average prediction errors obtained for aluminium, brass and copper castings are 10.6, 2.43 and 3.12 % respectively. The obtained average surface roughness (experimental and predicted) values of castings produced are acceptable with the sand cast surface roughness values range (6.25-25 µm).

  2. Salvaged castings and methods of salvaging castings with defective cast cooling bumps

    DOEpatents

    Johnson, Robert Alan; Schaeffer, Jon Conrad; Lee, Ching-Pang; Abuaf, Nesim; Hasz, Wayne Charles

    2002-01-01

    Castings for gas turbine parts exposed on one side to a high-temperature fluid medium have cast-in bumps on an opposite cooling surface side to enhance heat transfer. Areas on the cooling surface having defectively cast bumps, i.e., missing or partially formed bumps during casting, are coated with a braze alloy and cooling enhancement material to salvage the part.

  3. Evaluation of cast titanium alloy compressor components. Volume I. Final report May 76-Aug 78. [Ti-6Al-4V

    SciTech Connect

    Hammer, A.N.

    1981-11-01

    The objective of this program was to characterize the properties of cast titanium alloy compressor impellers to provide a background for design, processing, and qualification for service in the Solar T62T-40 Titan auxiliary power unit and similar small radial gas turbine engines. Four titanium alloy investment casting foundries participated in the production of straight vane test wheels, a low-cost representation of the compressor impellers. As-cast and hot isostatic pressed (HIPed) Ti-6A1-4V was seen to have less than half the high cycle fatigue strength (20 to 30 ksi versus 60 ksi) of equvalent sections from forged and machined impellers. A modified solution heat treatment and aging cycle was developed which restored the fatigue strength to approximately 50 ksi, and which provided adequate tensile strength and ductility. High cycle fatigue strength of weld repaired vanes was significantly lower than that of unwelded, however. Cast and machined wheels offer substantial cost savings over wheels conventionally machined from forgings. These savings may be as much as 50%, or about $900 per wheel.

  4. Precision Casting via Advanced Simulation and Manufacturing

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A two-year program was conducted to develop and commercially implement selected casting manufacturing technologies to enable significant reductions in the costs of castings, increase the complexity and dimensional accuracy of castings, and reduce the development times for delivery of high quality castings. The industry-led R&D project was cost shared with NASA's Aerospace Industry Technology Program (AITP). The Rocketdyne Division of Boeing North American, Inc. served as the team lead with participation from Lockheed Martin, Ford Motor Company, Howmet Corporation, PCC Airfoils, General Electric, UES, Inc., University of Alabama, Auburn University, Robinson, Inc., Aracor, and NASA-LeRC. The technical effort was organized into four distinct tasks. The accomplishments reported herein. Task 1.0 developed advanced simulation technology for core molding. Ford headed up this task. On this program, a specialized core machine was designed and built. Task 2.0 focused on intelligent process control for precision core molding. Howmet led this effort. The primary focus of these experimental efforts was to characterize the process parameters that have a strong impact on dimensional control issues of injection molded cores during their fabrication. Task 3.0 developed and applied rapid prototyping to produce near net shape castings. Rocketdyne was responsible for this task. CAD files were generated using reverse engineering, rapid prototype patterns were fabricated using SLS and SLA, and castings produced and evaluated. Task 4.0 was aimed at developing technology transfer. Rocketdyne coordinated this task. Casting related technology, explored and evaluated in the first three tasks of this program, was implemented into manufacturing processes.

  5. The Investment Paradigm

    ERIC Educational Resources Information Center

    Perna, Mark C.

    2005-01-01

    Is marketing an expense or an investment? Most accountants will claim that marketing is an expense, and clearly that seems true when cutting the checks to fund these efforts. When it is done properly, marketing is the best investment. A key principle to Smart Marketing is the Investment Paradigm. The Investment Paradigm is understanding that every…

  6. Investing for the Future.

    ERIC Educational Resources Information Center

    Goodall, Leonard E.

    1992-01-01

    Four steps to retirement planning, intended to demystify retirement investment, are offered for college faculty: (1) establish diversification goals; (2) urge their institutions to offer more investment options; (3) coordinate retirement investments with other investments; and (4) take steps to guarantee against inflation. Typical age-related…

  7. Centrifugal Casting Features/Metallurgical Characterization of Aluminum Alloys

    SciTech Connect

    Chirita, G.; Soares, D.; Cruz, D.; Silva, F. S.; Stefanescu, I.

    2008-02-15

    This paper deals with the study of centrifugal effects on aluminium castings under high G values. Most of the studies in this domain (FGMs obtained by centrifugal casting) deal with functionally graded composites reinforced with a solid phase such as silicon particles or others. However, in this study it will be shown that unreinforced aluminium alloys may be significantly influenced by the centrifugal effect and that functionally graded castings are also obtained. It has been observed that the centrifugal effect may increase in some alloys, depending on the relative position in the castings, the rupture strength by approx. 50%, and rupture strain by about 300%, as compared to the gravity casting technique. The Young's modulus may also increase by about 20%. It has also been reported that in vertical centrifugal castings there are mainly three aspects that affect the components thus obtained, namely: fluid dynamics; vibration (inherent to the system); and centrifugal force. These features have a different effect on the castings depending on the aluminium alloy. In this paper, an analysis of the most important effects of the centrifugal casting process on metallurgical features is conducted. A solidification characterization at several points along the mould will be made in order to have an accurate idea of both the fluid dynamics inside the mould during the casting and the solidification behavior in different parts of the component. These two analyses will be related to the metallurgical properties (phase distribution; SDAS; eutectic silicon content and shape, pores density and shape) along the component and mainly along the direction of the centrifugal pressure. A comparison between castings obtained by both centrifugal casting technique and gravity casting technique is made for reference (gravity casting)

  8. From SRI to ESG: The Changing World of Responsible Investing

    ERIC Educational Resources Information Center

    Caplan, Lauren; Griswold, John S.; Jarvis, William F.

    2013-01-01

    Thoughtful investment professionals continue to debate whether a portfolio's long-term performance can be enhanced by including environmental, social, and governance (ESG) considerations in the security selection process, but responsible investing is more than a passing trend. The terms socially-responsible investing, mission-related investing,…

  9. 13 CFR 301.7 - Investment Assistance application.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 13 Business Credit and Assistance 1 2013-01-01 2013-01-01 false Investment Assistance application... COMMERCE ELIGIBILITY, INVESTMENT RATE AND APPLICATION REQUIREMENTS Application Requirements; Evaluation Criteria § 301.7 Investment Assistance application. (a) The EDA Investment Assistance process begins...

  10. 13 CFR 301.7 - Investment Assistance application.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 13 Business Credit and Assistance 1 2014-01-01 2014-01-01 false Investment Assistance application... COMMERCE ELIGIBILITY, INVESTMENT RATE AND APPLICATION REQUIREMENTS Application Requirements; Evaluation Criteria § 301.7 Investment Assistance application. (a) The EDA Investment Assistance process begins...

  11. 13 CFR 301.7 - Investment Assistance application.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 13 Business Credit and Assistance 1 2012-01-01 2012-01-01 false Investment Assistance application... COMMERCE ELIGIBILITY, INVESTMENT RATE AND APPLICATION REQUIREMENTS Application Requirements; Evaluation Criteria § 301.7 Investment Assistance application. (a) The EDA Investment Assistance process begins...

  12. 13 CFR 301.7 - Investment Assistance application.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 13 Business Credit and Assistance 1 2011-01-01 2011-01-01 false Investment Assistance application... COMMERCE ELIGIBILITY, INVESTMENT RATE AND APPLICATION REQUIREMENTS Application Requirements; Evaluation Criteria § 301.7 Investment Assistance application. (a) The EDA Investment Assistance process begins...

  13. Japanese R&D on new cast alloys and materials

    SciTech Connect

    Hayden, H.W.

    1996-05-01

    On the basis of observations of the JTEC team, it appears that Japanese universities and research institutes are leading long-term R&D thrusts for development of new materials casting technologies. Significant efforts include amorphous metals, intermetallics, application of MHD in continuous casting of steel, and energy efficient furnace technology. Industrial R&D seems focused more on process improvements than on new product technologies, but significant efforts in new cast materials included cast metal matrix composites, materials substitutions for thinner wall products, and advanced ceramic products for foundry industry applications.

  14. Heat exchanger-ingot casting/slicing process, phase 1: Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Schmid, F.; Khattak, C. P.

    1977-01-01

    A controlled growth, heat-flow and cool-down process is described that yielded silicon with a high degree of single crystallinity. Even when the seed melted out, very large grains formed. Solar cell samples made from cast material yielded conversion efficiency of over 9%. Representative characterizations of grown silicon demonstrated a dislocation density of less than 100/sq cm and a minority carrier diffusion length of 31 micron. The source of silicon carbide in silicon ingots was identified to be from graphite retainers in contact with silica crucibles. Higher growth rates were achieved with the use of a graphite plug at the bottom of the silica crucible.

  15. Computer simulation with CaPS of an aluminum plate casting

    SciTech Connect

    Domanus, H.M.; Schmitt, R.C.; Chuzhoy, L.; Nastac, L.

    1995-12-31

    A simulation of a benchmark test casting has been performed with the CaPS-3D casting process simulator software. The test casting was made at the University of Birmingham in the UK for the 7th International Conference on the Modeling of Casting, Welding and Advanced Solidification Processes. The measured results were not available prior to the simulation, hence the simulation is a blind prediction.

  16. Electrochemical characterization of cast titanium alloys.

    PubMed

    Cai, Zhuo; Shafer, Ty; Watanabe, Ikuya; Nunn, Martha E; Okabe, Toru

    2003-01-01

    A reaction layer forms on cast titanium alloy surfaces due to the reaction of the molten metal with the investment. This surface layer may affect the corrosion of the alloy in the oral environment. The objective of this study was to characterize the in vitro corrosion behavior of cast titanium alloys. ASTM Grade 2 CP titanium, Ti-6Al-4V, Ti-6Al-7Nb and Ti-13Nb-13Zr alloys were cast into a MgO-based investment. Experiments were performed on castings (N=4) with three surface conditions: (A) as-cast surface after sandblasting, (B) polished surface after removal of the reaction layer, and (C) sandblasted surface after removal of the reaction layer. Open-circuit potential (OCP) measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air+10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was subsequently conducted in the same medium deaerated with N(2)+10% CO(2) gas 2 h before and during the experiment. Polarization resistance (R(P)) and corrosion rate (I(CORR)) were calculated. Numerical results were subjected to nonparametric statistical analysis at alpha=0.05. The OCP stabilized for all the specimens after 6 x 10(4)s. Apparent differences in anodic polarization were observed among the different surfaces for all the metals. A passivation region followed by breakdown and repassivation were seen on specimens with surfaces A and C. An extensive passive region was observed on all the metals with surface B. The Kruskal-Wallis test showed no significant differences in OCP, R(p), I(CORR) or break down potential for each of the three surfaces among all the metals. The Mann-Whitney test showed significantly lower R(P) and higher I(CORR) values for surface C compared to the other surfaces. Results indicate that the surface condition has more effect on corrosion of these alloys than the surface reaction layer. Within the oxidation potential range of the oral cavity, all the metal

  17. Electrochemical characterization of cast titanium alloys.

    PubMed

    Cai, Zhuo; Shafer, Ty; Watanabe, Ikuya; Nunn, Martha E; Okabe, Toru

    2003-01-01

    A reaction layer forms on cast titanium alloy surfaces due to the reaction of the molten metal with the investment. This surface layer may affect the corrosion of the alloy in the oral environment. The objective of this study was to characterize the in vitro corrosion behavior of cast titanium alloys. ASTM Grade 2 CP titanium, Ti-6Al-4V, Ti-6Al-7Nb and Ti-13Nb-13Zr alloys were cast into a MgO-based investment. Experiments were performed on castings (N=4) with three surface conditions: (A) as-cast surface after sandblasting, (B) polished surface after removal of the reaction layer, and (C) sandblasted surface after removal of the reaction layer. Open-circuit potential (OCP) measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air+10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was subsequently conducted in the same medium deaerated with N(2)+10% CO(2) gas 2 h before and during the experiment. Polarization resistance (R(P)) and corrosion rate (I(CORR)) were calculated. Numerical results were subjected to nonparametric statistical analysis at alpha=0.05. The OCP stabilized for all the specimens after 6 x 10(4)s. Apparent differences in anodic polarization were observed among the different surfaces for all the metals. A passivation region followed by breakdown and repassivation were seen on specimens with surfaces A and C. An extensive passive region was observed on all the metals with surface B. The Kruskal-Wallis test showed no significant differences in OCP, R(p), I(CORR) or break down potential for each of the three surfaces among all the metals. The Mann-Whitney test showed significantly lower R(P) and higher I(CORR) values for surface C compared to the other surfaces. Results indicate that the surface condition has more effect on corrosion of these alloys than the surface reaction layer. Within the oxidation potential range of the oral cavity, all the metal

  18. CAST FLOOR WITH VIEW OF TORPEDO LADLE (BENEATH CAST FLOOR) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CAST FLOOR WITH VIEW OF TORPEDO LADLE (BENEATH CAST FLOOR) AND KEEPERS OF THE CAST HOUSE FLOOR, S.L. KIMBROUGH AND DAVID HOLMES. - U.S. Steel, Fairfield Works, Blast Furnace No. 8, North of Valley Road, West of Ensley-Pleasant Grove Road, Fairfield, Jefferson County, AL

  19. AUTOMATED MALLEABLE ANNEALING OVENS SLOWLY HEAT AND COOL CASTINGS AS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    AUTOMATED MALLEABLE ANNEALING OVENS SLOWLY HEAT AND COOL CASTINGS AS THEY MOVE IN BINS ALONG TRACKS IN THE OVEN BOTTOM IN THE MALLEABLE ANNEALING BUILDING. THIS PROCESS TRANSFORMS BRITTLE WHITE IRON CASTINGS INTO SOFTER, STRONGER MALLEABLE IRON. - Stockham Pipe & Fittings Company, Malleable Annealing Building, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  20. 126. EXTERIOR VIEW, LOOKING NORTH, SHOWING CAST SHED NO. 2, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    126. EXTERIOR VIEW, LOOKING NORTH, SHOWING CAST SHED NO. 2, FURNACE NO. 2, STOVES, POWER HOUSE, STACKS, FURNACE NO. 1 CAST SHED. FURNACE NO. 2 IS IN PROCESS OF RESTORATION. - Sloss-Sheffield Steel & Iron, First Avenue North Viaduct at Thirty-second Street, Birmingham, Jefferson County, AL

  1. 91. VIEW NORTHWEST OF SCRAP HOUSE AND CAST HOUSE, BUILDINGS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    91. VIEW NORTHWEST OF SCRAP HOUSE AND CAST HOUSE, BUILDINGS 101 AND 72; BUILDING 101 IN THE CENTER OF THE PHOTOGRAPH HOUSED SCRAP METAL CLEANING AND PROCESSING FACILITIES; BUILDING 72 AT RIGHT CENTER HOUSED MELTING FURNACES AND CONTINUOUS CASTING MACHINERY - Scovill Brass Works, 59 Mill Street, Waterbury, New Haven County, CT

  2. 8. VIEW OF A MOLD FOR PRECISION CASTING. THE MOLD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW OF A MOLD FOR PRECISION CASTING. THE MOLD WAS USED IN FOUNDRY OPERATIONS THAT CAST PLUTONIUM EITHER AS INGOTS SUITABLE FOR ROLLING AND FURTHER WROUGHT PROCESSING OR INTO SHAPES AMENABLE TO DIRECT MACHINING OPERATIONS. (5/6/59) - Rocky Flats Plant, Plutonium Fabrication, Central section of Plant, Golden, Jefferson County, CO

  3. Method for casting polyethylene pipe

    NASA Technical Reports Server (NTRS)

    Elam, R. M., Jr.

    1973-01-01

    Short lengths of 7-cm ID polyethylene pipe are cast in a mold which has a core made of room-temperature-vulcanizable (RTV) silicone. Core expands during casting and shrinks on cooling to allow for contraction of the polyethylene.

  4. Partnering for Quality under the Workforce Investment Act: A Tool Kit for One-Stop System Building. Module 5: Building a Process for Continuous Improvement. Training Manual with Participant Workbook.

    ERIC Educational Resources Information Center

    Kogan, Deborah; Koller, Vinz; Kozumplik, Richalene; Lawrence, Mary Ann

    This document is part of a five-module training package to help employment and training service providers comply with the Workforce Investment Act (WIA) of 1998 and develop a one-stop training and employment services system. It consists of the participant workbook, trainer manual, and activity worksheets for a module on building a process for…

  5. Casting Of Multilayer Ceramic Tapes

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr.

    1991-01-01

    Procedure for casting thin, multilayer ceramic membranes, commonly called tapes, involves centrifugal casting at accelerations of 1,800 to 2,000 times normal gravitational acceleration. Layers of tape cast one at a time on top of any previous layer or layers. Each layer cast from slurry of ground ceramic suspended in mixture of solvents, binders, and other components. Used in capacitors, fuel cells, and electrolytic separation of oxygen from air.

  6. Casting and Angling.

    ERIC Educational Resources Information Center

    Smith, Julian W.

    As part of a series of books and pamphlets on outdoor education, this manual consists of easy-to-follow instructions for fishing activities dealing with casting and angling. The manual may be used as a part of the regular physical education program in schools and colleges or as a club activity for the accomplished weekend fisherman or the…

  7. Extrusion cast explosive

    DOEpatents

    Scribner, Kenneth J.

    1985-01-01

    Improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst are disclosed. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants.

  8. ShakeCast Manual

    USGS Publications Warehouse

    Lin, Kuo-Wan; Wald, David J.

    2008-01-01

    ShakeCast is a freely available, post-earthquake situational awareness application that automatically retrieves earthquake shaking data from ShakeMap, compares intensity measures against users? facilities, and generates potential damage assessment notifications, facility damage maps, and other Web-based products for emergency managers and responders.

  9. Mix/Cast Contamination Control

    NASA Technical Reports Server (NTRS)

    Wallentine, M.

    2005-01-01

    Presented is a training handbook for Mix/Cast Contamination Control; a part of a series of training courses to qualify access to Mix/Cast facilities. Contents: List Contamination Control Requirements; Identify foreign objects debris (FOD), Control Areas and their guidelines; Describe environmental monitoring; List Contamination Control Initiatives; Describe concern for Controlled Materials; Identify FOD Controlled Areas in Mix/Cast.

  10. Modeling of casting microstructures and defects

    SciTech Connect

    Shapiro, A.B.; Summers, L.T.; Eckels, D.J.; Sahai, V.

    1997-09-26

    Casting is an ancient art that has been a trial-and-error process for more than 4000 years. To predict the size, shape, and quality of a cast product, casting manufacturers typically cast full-size prototypes. If one part of the process is done incorrectly, the entire process is repeated until an acceptable product is achieved. One way to reduce the time, cost, and waste associated with casting is to use computer modeling to predict not only the quality of a product on the macro- scale, such as distortion and part shape, but also on the micro-scale such as grain defects. Modeling of solidification is becoming increasingly feasible with the advent of parallel computers. There are essentially two approaches to solidification modeling.The first is that of macro-modeling where heat transfer codes model latent heat release during solidification as a constant and based solely on the local temperature. This approach is useful in predicting large scale distortion and final part shape. The second approach, micro-modeling, is more fundamental. The micro-models estimate the latent heat release during solidification using nucleation and grain growth kinetics. Micro-models give insight into cast grain morphology and show promise in the future to predict engineering properties such as tensile strength. The micro-model solidification kinetics can be evaluated using first principles or they can be evaluated using experiments. This work describes an implementation of a micro-model for uranium which uses experimental results to estimate nucleation and growth kinetics.

  11. Casting dimensional control and fatigue life prediction for permanent mold casting dies. Technical report, September 29, 1993--May 31, 1997

    SciTech Connect

    1997-06-01

    Efforts as part of a three year program to address metal casting dimensional control and fatigue life prediction for permanent mold casting dies are described. Procedures have been developed and implemented to collect dimensional variability data from production steel casting. The influence of process variation and casting geometry variables on dimensional tolerances have been investigated. Also efforts leading to the developments and validation of a CAD/CAE model to predict the thermal fatigue life of permanent molds for aluminum castings are described. An appropriate thermomechanical property database for metal, mold and coating materials has been constructed. A finite element model has been developed to simulate the mold temperature distribution during repeated casting cycles. Validation trials using a permanent mold casting machine have indicated the success of the temperature distribution model developed. A combination of experimental and modeling techniques have been employed to extend their knowledge of permanent mold casting. The influence of coatings on casting solidification and mold temperatures has been determined. The computer model has been extended to predict thermally induced stresses and strains in the mold and to predict the number of cycles required to crack the mold. Experimental results have been used to validate the extended model.

  12. Grain Refinement of Permanent Mold Cast Copper Base Alloys

    SciTech Connect

    M.Sadayappan; J.P.Thomson; M.Elboujdaini; G.Ping Gu; M. Sahoo

    2005-04-01

    Grain refinement is a well established process for many cast and wrought alloys. The mechanical properties of various alloys could be enhanced by reducing the grain size. Refinement is also known to improve casting characteristics such as fluidity and hot tearing. Grain refinement of copper-base alloys is not widely used, especially in sand casting process. However, in permanent mold casting of copper alloys it is now common to use grain refinement to counteract the problem of severe hot tearing which also improves the pressure tightness of plumbing components. The mechanism of grain refinement in copper-base alloys is not well understood. The issues to be studied include the effect of minor alloy additions on the microstructure, their interaction with the grain refiner, effect of cooling rate, and loss of grain refinement (fading). In this investigation, efforts were made to explore and understand grain refinement of copper alloys, especially in permanent mold casting conditions.

  13. Spray casting project final report

    SciTech Connect

    Churnetski, S.R.; Thompson, J.E.

    1996-08-01

    Lockheed Martin Energy Systems, Inc. (Energy Systems), along with other participating organizations, has been exploring the feasibility of spray casting depleted uranium (DU) to near-net shape as a waste minimization effort. Although this technology would be useful in a variety of applications where DU was the material of choice, this effort was aimed primarily at gamma-shielding components for use in storage and transportation canisters for high-level radioactive waste, particularly in the Multipurpose Canister (MPC) application. In addition to the waste-minimization benefits, spray casting would simplify the manufacturing process by allowing the shielding components for MPC to be produced as a single component, as opposed to multiple components with many fabrication and assembly steps. In earlier experiments, surrogate materials were used to simulate the properties (specifically reactivity and density) of DU. Based on the positive results from those studies, the project participants decided that further evaluation of the issues and concerns that would accompany spraying DU was warranted. That evaluation occupied substantially all of Fiscal Year 1995, yielding conceptual designs for both an intermediate facility and a production facility and their associated engineering estimates. An intermediate facility was included in this study to allow further technology development in spraying DU. Although spraying DU to near-net shape seems to be feasible, a number of technical, engineering, and safety issues would need to be evaluated before proceeding with a production facility. This report is intended to document the results from the spray-casting project and to provide information needed by anyone interested in proceeding to the next step.

  14. On the damping capacity of cast irons

    NASA Astrophysics Data System (ADS)

    Golovin, S. A.

    2012-07-01

    The treatment of experimental data on the amplitude-dependent internal friction (ADIF) in terms of various theoretical models has revealed a staged character and the main mechanisms of the processes of energy dissipation in graphite with increasing amplitude of vibrations upon cyclic loading. It is shown that the level of the damping capacity of lamellar cast iron depends on the relationship between the elastic and strength characteristics of graphite and the matrix phase. In cast irons with a rigid matrix structure (pearlite, martensite), the energy dissipation is determined by the volume fraction and morphology of the initial graphite phase. In cast irons with a softer metallic phase (ferrite), the contact interaction of graphite inclusions with the matrix and the properties of the matrix introduce additional sources of high damping.

  15. Determination of 2-propanol in surface cleaning solutions used for copper continuous casting process by flow injection-spectrophotometric detection with on-line column separation.

    PubMed

    Hayashibe, Yutaka; Tokuda, Masahiro; Takeya, Minoru

    2003-09-01

    A flow-injection system has been developed for the determination of 2-propanol in the surface cleaning solutions used in the copper continuous cast rod making system. Adsorption chromatography in nitric acid medium was used for the on-line separation of oily substances in the sample solution. Cerium(IV) diammonium nitrate was utilized as the chromogenic reagent for the spectrophotometric detection of 2-propanol. The system permits a throughput of one sample per hour for the oily sample, and of 12 samples per hour for the none-oily sample. The reproducibility has been proven to be satisfactory with a relative standard deviation of less than 6.0% (2.2%(V/V) 2-propanol level, n = 23). The detection limit is 0.01% (V/V).

  16. Characterization of Bimetallic Castings with an Austenitic Working Surface Layer and an Unalloyed Cast Steel Base

    NASA Astrophysics Data System (ADS)

    Wróbel, Tomasz

    2014-05-01

    The paper presents the technology of bimetallic castings based on the founding method of layer coating directly in the cast process of the so-called method of mold cavity preparation. The prepared castings consist of two fundamental parts, i.e., the base and the working surface layer. The base part of the bimetallic casting is typical foundry material, i.e., unalloyed cast steel, whereas the working layer is a plate of austenitic alloy steel sort X2CrNi 18-9. The quality of the joint between the base part and the working layer was evaluated on the basis of ultrasonic non-destructive testing and structure examinations containing metallographic macro- and microscopic studies with the use of a light microscope (LOM) with microhardness measurements and a scanning electron microscope (SEM) with microanalysis of the chemical composition (energy dispersive spectroscopy—EDS). On the basis of the obtained results it was confirmed that the decisive phenomena needed to create a permanent joint between the two components of the bimetallic casting are carbon and heat transport in the direction from the high-carbon and hot base material which was poured into the mold in the form of liquid metal to the low-carbon and cold material of the working layer which was placed in the mold cavity in the form of a monolithic insert.

  17. Structure and Property Studies on Austempered and As-Cast Ausferritic Gray Cast Irons

    NASA Astrophysics Data System (ADS)

    Vadiraj, Aravind; Balachandran, G.; Kamaraj, M.

    2010-10-01

    A high-strength and wear-resistant alloyed gray iron with ausferritic microstructure on solidification directly from molten condition could be made in a Ni and Mo alloyed gray cast iron. The as-cast ausferritic cast iron was compared with two conventionally austempered gray iron with and without Ni and Mo additions. The various phase constitution and volume fractions were analyzed using optical, SEM and XRD analyses. The various aspects of the alloy chemistry and processing conditions have been correlated with the microstructure and mechanical properties obtained. The analysis showed that the Ni-Mo alloyed austempered gray iron and the directly as-cast austempered gray iron had similar phase constitutions. The strength of the direct as-cast alloy with ausferritic microstructure was higher than the others due to its higher austenite content and carbide distribution. The wear rate of the conventionally austempered Ni and Mo containing alloy and direct as-cast ausferritic alloys is 20% of the austempered gray iron without Ni and Mo with friction coefficient less than 0.4.

  18. Solidification Structure and Macrosegregation of Billet Continuous Casting Process with Dual Electromagnetic Stirrings in Mold and Final Stage of Solidification: A Numerical Study

    NASA Astrophysics Data System (ADS)

    Jiang, D.; Zhu, M.

    2016-08-01

    Coupling macroscale heat transfer and fluid flow with microscale grain nucleation and crystal growth, a mixed columnar-equiaxed solidification model was established to study the SWRT82B steel solidification structure and macrosegregation in 160 mm × 160 mm billet continuous casting with dual electromagnetic stirrings in mold and final stage of solidification (M-EMS and F-EMS). In the model, the phases of liquid, columnar, and equiaxed were treated separately and the initial growing equiaxed phase, which could move freely with liquid, was regarded as slurry. To obtain the equiaxed grains nucleation and columnar front evolution, the unit tracking method and the columnar front tracking model were built. The model was validated by magnetic induction intensity of stirrer, billet surface temperature, and carbon segregation. The equiaxed phase evolution and the solute transport with effect of fluid flow and grains transport were described in this article. The results show that the equiaxed phase ratio will not increase obviously with higher current intensity of M-EMS, while the negative segregation near the strand surface becomes more serious. The negative segregation zone near the billet center and the center positive segregation come into being with the effect of equiaxed grains sedimentation and liquid thermosolutal flow. It is also found that the liquid solute transport in the F-EMS zone becomes the main factor with higher current intensity rather than the solidification rate, and therefore, the final billet center segregation decreases first and then turns to rise with the current intensity. The optimal current intensities of M-EMS and F-EMS proposed for SWRT82B billet continuous casting are 200 and 400 A, respectively.

  19. AIS/DOE Technology Roadmap Program: Strip Casting: Anticipating New Routes To Steel Sheet

    SciTech Connect

    Prof. Alan W. Camb; Prof. Anthony Rollett

    2001-08-31

    To determine the potential for strip casting in the steel industry and to develop the fundamental knowledge necessary to allow the role of strip casting in the modern steel industry to be understood. Based upon a study of carbon steel strip castings that were either produced for the program at British Steel or were received from a pre-commercial production machine, the following conclusions were made. Strip casting of carbon steels is technically feasible for sheet material from slightly less than 1 mm thick to 3 mm thick, and, assuming that it is economically viable, it will be first applied in carbon steel markets that do not require stringent surface quality or extensive forming. The potential of strip casting as a casting process to be developed for steel castings is very high as the cast strip has some very novel characteristics. Direct cast carbon strip has better surface quality, shape and profile than any other casting process currently available. The more rapidly solidified structure of direct cast strip tends to be strong with low ductility; however, with adequate thermal treatment, it is possible to develop a variety of properties from the same grade. The process is more amenable at this time to production tonnages per year of the order of 500,000 tons and as such will first find niche type applications. This technology is an additional technology for steel production and will be in addition to, rather than a replacement for, current casting machines.

  20. Carbon investment funds

    SciTech Connect

    2007-01-15

    The report is a study of the development of funds to invest in the purchase of carbon credits. It takes a look at the growing market for carbon credits, the rise of carbon investment funds, and the current state of carbon investing. Topics covered in the report include: Overview of climate change, greenhouse gases, and the Kyoto Protocols. Analysis of the alternatives for reducing carbon emissions including nitrous oxide reduction, coal mine methane capture and carbon capture and storage; Discussion of the different types of carbon credits; Discussion of the basics of carbon trading; Evaluation of the current status of carbon investing; and Profiles of 37 major carbon investment funds worldwide.

  1. Spall behavior of cast iron with varying microstructures

    SciTech Connect

    Plume, Gifford; Rousseau, Carl-Ernst

    2014-07-21

    The spall strength of cast iron with varying microstructures has been investigated using plate impact at moderate speed. Stress history measurements were made with manganin stress gauges embedded between the back face of the specimen and a low impedance polycarbonate backing. Five separate cast irons were tested. Four of these consisted of gray cast iron with graphite in flake form, with three classified as Type VII A2 and the fourth containing a bimodal distribution of Types VII A4 and VII D8. The fifth casting consisted of ductile cast iron with graphite in nodular form, classified as Type I, size class 5. The spall strength for the Type VII A2 gray cast irons varied between 40 and 370 MPa, and that of the additional gray cast iron, between 410 and 490 MPa. The spall strength of the ductile cast iron fell within the range of 0.94–1.2 GPa. It is shown that the spall strength is linked to the damage level at the spall plane, where an increased level of tensile stress is required to generate higher levels of damage. Post mortem analysis was performed on the recovered samples, revealing the graphite phase to be the primary factor governing the spall fracture of cast irons, where crack nucleation is directly correlated to the debonding of graphite from the metal matrix. The average length of graphite found within a casting is linked to the material's strength, where strength increases as a function of decreasing length. The morphology and mean free path of graphite precipitates further govern the subsequent coalescence of initiated cracks to form a complete fracture plane. In cases where graphite spacing is large, increased energy level is required to complete the fracture process. A secondary factor governing the spall fracture of cast irons has also been linked to the microstructure of the metal matrix, with pearlite yielding higher spall strengths than free ferrite.

  2. Nuclear-waste encapsulation by metal-matrix casting

    SciTech Connect

    Nelson, R.G.; Nesbitt, J.F.; Slate, S.C.

    1981-05-01

    Several encapsulation casting processes are described that were developed or used at the Pacific Northwest Laboratory to embed simulated high-level wastes of two different forms (glass marbles and ceramic pellets) in metal matrices. Preliminary evaluations of these casting processes and the products are presented. Demonstrations have shown that 5- to 10-mm-dia glass marbles can be encapsulated on an engineering scale with lead or lead alloys by gravity or vacuum processes. Marbles approx. 12 mm in dia were successfully encapsulated in a lead alloy on a production scale. Also, 4- to 9-mm-dia ceramic pellets in containers of various sizes were completely penetrated and the individual pellets encased with aluminum-12 wt % silicon alloy by vacuum processes. Indications are that of the casting processes tested, aluminum 12 wt % silicon alloy vacuum-cast around ceramic pellets had the highest degree of infiltration or coverage of pellet surfaces.

  3. Volume MLS ray casting.

    PubMed

    Ledergerber, Christian; Guennebaud, Gaël; Meyer, Miriah; Bächer, Moritz; Pfister, Hanspeter

    2008-01-01

    The method of Moving Least Squares (MLS) is a popular framework for reconstructing continuous functions from scattered data due to its rich mathematical properties and well-understood theoretical foundations. This paper applies MLS to volume rendering, providing a unified mathematical framework for ray casting of scalar data stored over regular as well as irregular grids. We use the MLS reconstruction to render smooth isosurfaces and to compute accurate derivatives for high-quality shading effects. We also present a novel, adaptive preintegration scheme to improve the efficiency of the ray casting algorithm by reducing the overall number of function evaluations, and an efficient implementation of our framework exploiting modern graphics hardware. The resulting system enables high-quality volume integration and shaded isosurface rendering for regular and irregular volume data.

  4. Extrusion cast explosive

    DOEpatents

    Scribner, K.J.

    1985-11-26

    Disclosed is an improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants. 1 fig.

  5. Extrusion cast explosive

    DOEpatents

    Scribner, K.J.

    1985-01-29

    Improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst are disclosed. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants. 1 fig.

  6. USGS ShakeCast

    USGS Publications Warehouse

    Wald, David; Lin, Kuo-Wan

    2007-01-01

    Automating, Simplifying, and Improving the Use of ShakeMap for Post-Earthquake Decisionmaking and Response. ShakeCast is a freely available, post-earthquake situational awareness application that automatically retrieves earthquake shaking data from ShakeMap, compares intensity measures against users facilities, and generates potential damage assessment notifications, facility damage maps, and other Web-based products for emergency managers and responders.

  7. A new freeze casting technique for ceramics

    NASA Astrophysics Data System (ADS)

    Araki, Kiyoshi

    A new freeze casting technique for ceramics capable of manufacturing near room temperature with a sublimable vehicle has been developed in order to eliminate expensive processes under extremely cold temperatures in the conventional freeze casting. Fluid concentrated slurries of Al2O 3 powder in molten camphene (C10H16) were successfully prepared at 55°C with a small amount of a dispersant. These slurries were quickly solidified (frozen) at room temperature to yield a rigid solid green body, where the frozen camphene was easily removed by sublimation (freeze-drying) with negligible shrinkage. Sintering was successfully conducted without any special binder burnout process to yield dense sintered bodies (over 98% T.D). An organic alloy with a eutectic composition in the naphthalene (C 10H8)-camphor (C10H16O) binary system with a eutectic temperature of 31°C was also found to be a successful vehicle for the new ceramic freeze casting. The fabrication processes are almost the same as those with camphene. It was found that vehicles with off-eutectic compositions resulted in large voids in the sintered body due to the ceramic particle rejection by pro-eutectic crystals during freezing. At the eutectic composition, fine lamellar microstructure in the solidified vehicle inhibits the particle rejection. The proposed advantages of the new freeze casting technique with a sublimable vehicle include; (1) elimination of extremely cold temperatures used in conventional freeze casting; (2) elimination of troublesome binder burnout process; and (3) fast manufacturing cycle due to quick solidification. Porous ceramic bodies with unique interconnected pore channels were fabricated by the new freeze casting with lower solid content. The unique channels surrounded by fully dense walls have nearly circular cross-sections unlike conventional aqueous freeze casting. The porosity and the channel diameters are controllable by the solid content in the slurry. The unique channels are

  8. A combined arc-melting and tilt-casting furnace for the manufacture of high-purity bulk metallic glass materials.

    PubMed

    Soinila, E; Pihlajamäki, T; Bossuyt, S; Hänninen, H

    2011-07-01

    An arc-melting furnace which includes a tilt-casting facility was designed and built, for the purpose of producing bulk metallic glass specimens. Tilt-casting was chosen because reportedly, in combination with high-purity processing, it produces the best fatigue endurance in Zr-based bulk metallic glasses. Incorporating the alloying and casting facilities in a single piece of equipment reduces the amount of laboratory space and capital investment needed. Eliminating the sample transfer step from the production process also saves time and reduces sample contamination. This is important because the glass forming ability in many alloy systems, such as Zr-based glass-forming alloys, deteriorates rapidly with increasing oxygen content of the specimen. The challenge was to create a versatile instrument, in which high purity conditions can be maintained throughout the process, even when melting alloys with high affinity for oxygen. Therefore, the design provides a high-vacuum chamber to be filled with a low-oxygen inert atmosphere, and takes special care to keep the system hermetically sealed throughout the process. In particular, movements of the arc-melting electrode and sample manipulator arm are accommodated by deformable metal bellows, rather than sliding O-ring seals, and the whole furnace is tilted for tilt-casting. This performance of the furnace is demonstrated by alloying and casting Zr(55)Cu(30)Al(10)Ni(5) directly into rods up to ø 10 mm which are verified to be amorphous by x-ray diffraction and differential scanning calorimetry, and to exhibit locally ductile fracture at liquid nitrogen temperature.

  9. A combined arc-melting and tilt-casting furnace for the manufacture of high-purity bulk metallic glass materials

    NASA Astrophysics Data System (ADS)

    Soinila, E.; Pihlajamäki, T.; Bossuyt, S.; Hänninen, H.

    2011-07-01

    An arc-melting furnace which includes a tilt-casting facility was designed and built, for the purpose of producing bulk metallic glass specimens. Tilt-casting was chosen because reportedly, in combination with high-purity processing, it produces the best fatigue endurance in Zr-based bulk metallic glasses. Incorporating the alloying and casting facilities in a single piece of equipment reduces the amount of laboratory space and capital investment needed. Eliminating the sample transfer step from the production process also saves time and reduces sample contamination. This is important because the glass forming ability in many alloy systems, such as Zr-based glass-forming alloys, deteriorates rapidly with increasing oxygen content of the specimen. The challenge was to create a versatile instrument, in which high purity conditions can be maintained throughout the process, even when melting alloys with high affinity for oxygen. Therefore, the design provides a high-vacuum chamber to be filled with a low-oxygen inert atmosphere, and takes special care to keep the system hermetically sealed throughout the process. In particular, movements of the arc-melting electrode and sample manipulator arm are accommodated by deformable metal bellows, rather than sliding O-ring seals, and the whole furnace is tilted for tilt-casting. This performance of the furnace is demonstrated by alloying and casting Zr55Cu30Al10Ni5 directly into rods up to ø 10 mm which are verified to be amorphous by x-ray diffraction and differential scanning calorimetry, and to exhibit locally ductile fracture at liquid nitrogen temperature.

  10. Technetium Getters to Improve Cast Stone Performance

    SciTech Connect

    Neeway, James J.; Lawter, Amanda R.; Serne, R. Jeffrey; Asmussen, Robert M.; Qafoku, Nikolla

    2015-10-15

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

  11. Method and apparatus for planar drag strip casting

    DOEpatents

    Powell, J.C.; Campbell, S.L.

    1991-11-12

    The present invention is directed to an improved process and apparatus for strip casting. The combination of a planar flow casting nozzle positioned back from the top dead center position with an attached nozzle extension, provides an increased level of casting control and quality. The nozzle extension provides a means of containing the molten pool above the rotating substrate to increase the control of molten metal at the edges of the strip and increase the range of coating thicknesses which may be produced. The level of molten metal in the containment means is regulated to be above the level of melt supplying the casting nozzle which produces a condition of planar drag flow with the casting substrate prior to solidification. 5 figures.

  12. Method and apparatus for planar drag strip casting

    DOEpatents

    Powell, John C.; Campbell, Steven L.

    1991-01-01

    The present invention is directed to an improved process and apparatus for strip casting. The combination of a planar flow casting nozzle positioned back from the top dead center position with an attached nozzle extension, provides an increased level of casting control and quality. The nozzle extension provides a means of containing the molten pool above the rotating substrate to increase the control of molten metal at the edges of the strip and increase the range of coating thicknesses which may be produced. The level of molten metal in the containment means is regulated to be above the level of melt supplying the casting nozzle which produces a condition of planar drag flow with the casting substrate prior to solidification.

  13. Modeling of cast systems using smoothed-particle hydrodynamics

    NASA Astrophysics Data System (ADS)

    Cleary, Paul; Prakash, Mahesh; Ha, Joseph; Sinnott, Matthew; Nguyen, Thang; Grandfield, John

    2004-03-01

    To understand and control the filling process for metals in high-pressure die casting and ingot casting, researchers have used new flow-simulation software for the modeling of mold filling. Smoothed-particle hydrodynamics (SPH) is a non-conventional computational fluid dynamics method that has been successfully applied to these problems. Due to its mesh-free nature, it can handle complex splashing free surface flows and the differential motion of multiple solid-casting equipment components relatively easily. The ability of SPH to predict the detailed filling patterns of real large-scale automotive die castings is demonstrated in this study, and the use of SPH simulation for wheel shape optimization in ingot casting based on minimizing oxide generation while increasing the throughput is also presented.

  14. Method to prevent/mitigate steam explosions in casting pits

    DOEpatents

    Taleyarkhan, R.P.

    1996-12-24

    Steam explosions can be prevented or mitigated during a metal casting process by the placement of a perforated flooring system in the casting pit. An upward flow of compressed gas through this perforated flooring system is introduced during the casting process to produce a buffer layer between any spilled molten metal and the cooling water in the reservoir. This buffer layer provides a hydrodynamic layer which acts to prevent or mitigate steam explosions resulting from hot, molten metal being spilled into or onto the cooling water. 3 figs.

  15. Method to prevent/mitigate steam explosions in casting pits

    DOEpatents

    Taleyarkhan, Rusi P.

    1996-01-01

    Steam explosions can be prevented or mitigated during a metal casting process by the placement of a perforated flooring system in the casting pit. An upward flow of compressed gas through this perforated flooring system is introduced during the casting process to produce a buffer layer between any spilled molten metal and the cooling water in the reservoir. This buffer layer provides a hydrodynamic layer which acts to prevent or mitigate steam explosions resulting from hot, molten metal being spilled into or onto the cooling water.

  16. Simulation Study of Al-1Mn/Al-10Si Circular Clad Ingots Prepared by Direct Chill Casting

    NASA Astrophysics Data System (ADS)

    Wu, Li; Kang, Huijun; Chen, Zongning; Fu, Ying; Wang, Tongmin

    2016-02-01

    A modified direct chill casting process based on Novelis FusionTM Technology co-casting process was used recently to prepare Al-1Mn/Al-10Si circular clad ingots. In the current study, a comprehensive simulation model was developed to investigate the direct chill casting process for preparing the Al-1Mn/Al-10Si circular clad ingots, and a parametric study and experimental research of the direct chill casting process was conducted to explore potential success and failure casting conditions. The simulation results revealed the bonding mechanism of the Al-1Mn/Al-10Si interface in the direct chill casting process and identified the effect of certain parameters on casting performance. The results indicated that the effect of casting speed and Al-1Mn casting temperature on the variations of the minimum solid fraction of Al-1Mn at the interface is stronger than that of cooling water flow rate in inner mold, while Al-10Si casting temperature is the weakest of the four casting parameters. The corresponding experimental results verified that Al-1Mn/Al-10Si circular clad ingot with acceptable metallurgical bonding can be successfully prepared by direct chill casting process under the proper casting parameters. The thickness of diffusion zone is about 40 μm, and the fractured position in tensile test was located in the Al-1Mn alloy side which indicated the strength of the interfacial region is higher than that of Al-1Mn alloy.

  17. Effect of flask vibration time on casting integrity, Surface Penetration and Coating Inclusion in lost foam casting of Al-Si Alloy

    SciTech Connect

    Karimian, Majid; Idris, M. H.; Ourdjini, A.; Muthu, Kali

    2011-01-17

    The paper presents the result of an experimental investigation conducted on medium aluminum silicon alloy casting- LM6, using no-vacuum assisted lost foam casting process. The study is directed for establishing the relationship between the flask vibrations times developed for molded sample on the casting integrity, surface penetration and coating inclusion defects of the casting. Four different flask vibration times namely 180, 120, 90 and 60 sec. were investigated. The casting integrity was investigated in terms of fulfilling in all portions and edges. The surface penetration was measured using optical microscope whilst image analyzer was used to quantify the percentage of coating inclusion in the casting. The results show that vibration time has significant influence on the fulfilling as well as the internal integrity of the lost foam casting. It was found that the lower vibration time produced comparatively sound casing.

  18. The development of high strength corrosion resistant precipitation hardening cast steels

    NASA Astrophysics Data System (ADS)

    Abrahams, Rachel A.

    , give poor estimates of secondary phases in PHCSS. No measureable retained austenite was observed in any of the CB7Cu-1 steels studied, in spite of the fact that austenite is predicted by the constitution diagrams. A designed experiment using computationally derived phase equilibrium diagrams and actual experimental tests on CB7Cu of different compositions suggests that the ferrite phase is less stable than the constitution diagrams for austenitic stainless steels suggest. Delta ferrite was also more stable in slower-cooled sand cast material as compared to thin, fast-cooled investment cast material. High temperature solutionizing treatments were effective in dissolving delta ferrite at temperatures above 1900°F (˜1040°C). Delta ferrite dissolution was found to proceed at high rates during initial dissolution, and then was found to slow after 1 hour. Diffusion during the later stages is well-predicted by classical diffusion models. Repeated solution treatments were found to modestly increase both ductility and strength, likely due to subgrain refinement through austenite regrowth. Multistaged aging provided superior strength and toughness increases over similarly peak-aged and near peak-aged material aged at a single temperature. Peak-aged material fractography suggested that low energy quasi-cleavage fracture was likely due to age precipitate embrittlement along with some nucleation of MnS particulates at prior austenite grain boundaries. Yield strengths approaching 190 ksi (1310MPa) can be achieved in CB7Cu-1 if appropriate best-practices "+" processing techniques are used. This includes hot isostatic processing to reduce solidification segregation and heal microporosity, high temperature homogenization for effective age hardening and ferrite reduction, double-cycle solutionizing for structure refinement, and multistaged age strengthening for finer precipitate control. The experimental prototype 11-11PH (Fe-Ni-Cr-Ti-Mo) casting alloys was cast and was found to be

  19. Metal Matrix Composite LOX Turbopump Housing Via Novel Tool-Less Net-Shape Pressure Infiltration Casting Technology

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Lee, Jonathan; Bhat, Biliyar; Wells, Doug; Gregg, Wayne; Marsh, Matthew; Genge, Gary; Forbes, John; Salvi, Alex; Cornie, James A.; Sung, Michael; Zhang, Shi-Yu; Gentz, Steven (Technical Monitor)

    2001-01-01

    Metal matrix composites (MMC) offer relatively higher specific strength, specific stiffness, lower coefficient of thermal expansion (CTE) and lower density as compared with conventional alloys. These unique properties make them very attractive for aerospace turbomachinery applications where there is ever increasing emphasis to reduce weight and cost, and to increase engine performance. Through a joint effort between NASA and Metal Matrix Cast Composites, Inc., a complex liquid oxygen (LOX) compatible turbopump housing is being redesigned and manufactured from hybrid (particulate and fibers) Aluminum MMC. To this end, a revolutionary tool-less pressure infiltration casting technology is being perfected. Ceramic preforms for the composite are 3-dimensionally printed using a stereolithography file, acquired from a CAD model. The preforms are then invested into a refractory material and pressure infiltrated with liquid metal. After casting, the refractory material is washed away leaving behind a near net-shape composite part. Benefits of this process include increased composite uniformity, no mold machining, short time from design to part, properties matching traditional methods, ability to make previously impossible to manufacture parts and no size limitations with a newly developed joining technology. The results of materials, manufacturing and design optimizations, preform joining, and sub-element tests will be presented.

  20. Metal Matrix Composite LOX Turbopump Housing Via Novel Tool-less Net-Shape Pressure Infiltration Casting Technology

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Lee, Jonathan; Bhat, Biliyar; Wells, Doug; Gregg, Wayne; Marsh, Matthew; Genge, Gary; Forbes, John; Salvi, Alex; Cornie, James A.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    Metal matrix composites (MMC) offer relatively higher specific strength, specific stiffness, lower coefficient of thermal expansion (CTE) and lower density as compared with conventional alloys. These unique properties make them very attractive for aerospace turbomachinery applications where there is ever increasing emphasis to reduce weight and cost, and to increase engine performance. Through a joint effort between NASA and Metal Matrix Cast Composites, Inc., a complex liquid oxygen (LOX) compatible turbopump housing is being redesigned and manufactured from hybrid (particulate and fibers) Aluminum MMC. To this end, a revolutionary toolless pressure infiltration casting technology is being perfected. Ceramic preforms for the composite are 3-dimensionally printed using a stereolithography file, acquired from a CAD model. The preforms are then invested into a refractory material and pressure infiltrated with liquid metal. After casting, the refractory material is washed away leaving behind a near net-shape composite part. Benefits of this process include increased composite uniformity, no mold machining, short time from design to part, properties matching traditional methods, ability to make previously impossible to manufacture parts and no size limitations with a newly developed joining technology. The results of materials, manufacturing and design optimizations, preform joining, and sub-element tests will be presented.

  1. Metal Matrix Composite LOX Turbopump Housing Via Novel Tool-Less Net-Shape Pressure Infiltration Casting Technology

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Lee, Jonathan; Bhat, Biliyar; Wells, Doug; Gregg, Wayne; Marsh, Matthew; Genge, Gary; Forbes, John; Salvi, Alex; Cornie, James A.; Gentz, Steven (Technical Monitor)

    2001-01-01

    Metal matrix composites (MMC) offer relatively higher specific strength, specific stiffness, lower coefficient of thermal expansion (CTE) and lower density as compared with conventional alloys. These unique properties make them very attractive for aerospace turbomachinery applications where there is ever increasing emphasis to reduce weight and cost, and to increase engine performance. Through a joint effort between NASA and Metal Matrix Cast Composites, Inc., a complex liquid oxygen (LOX) compatible turbopump housing is being redesigned and manufactured from hybrid (particulate and Fibers) Aluminum MMC. To this end, a revolutionary tool-less pressure infiltration casting technology is being perfected. Ceramic preforms for the composite are 3-dimensionally printed using a stereolithography file, acquired from a CAD model. The preforms are then invested into a refractory material and pressure infiltrated with liquid metal. After casting, the refractory material is washed away leaving behind a near net-shape composite part. Benefits of this process include increased composite uniformity, no mold machining, short time from design to part properties matching traditional methods, ability to make previously impossible to manufacture parts and no size limitations with a newly developed joining technology. The results of materials, manufacturing and design optimizations, preform joining, and sub element tests will be presented.

  2. High density tape casting system

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr. (Inventor)

    1989-01-01

    A system is provided for casting thin sheets (or tapes) of particles bound together, that are used for oxygen membranes and other applications, which enables the particles to be cast at a high packing density in a tape of uniform thickness. A slurry contains the particles, a binder, and a solvent, and is cast against the inside walls of a rotating chamber. Prior to spraying the slurry against the chamber walls, a solvent is applied to a container. The solvent evaporates to saturate the chamber with solvent vapor. Only then is the slurry cast. As a result, the slurry remains fluid long enough to spread evenly over the casting surface formed by the chamber, and for the slurry particles to become densely packed. Only then is the chamber vented to remove solvent, so the slurry can dry. The major novel feature is applying solvent vapor to a rotating chamber before casting slurry against the chamber walls.

  3. Cast Metal Coalition Research and Development Closeout Report

    SciTech Connect

    Allen, D.

    2000-08-01

    The Cast Metal Coalition, composed of more than 22 research providers and universities and 149 industrial partners, has completed a four-year research and development partnership with the Department of Energy. This report provides brief summaries of the 29 projects performed by the Coalition. These projects generated valuable information in such aspects of the metals industry as process prediction technologies, quality control, improved alloys, product machinability, and casting process improvements.

  4. Enhancements in Magnesium Die Casting Impact Properties

    SciTech Connect

    David Schwam; John F. Wallace; Yulong Zhu; Srinath Viswanathan; Shafik Iskander

    2000-06-30

    The need to produce lighter components in transportation equipment is the main driver in the increasing demand for magnesium castings. In many automotive applications, components can be made of magnesium or aluminum. While being lighter, often times the magnesium parts have lower impact and fatigue properties than the aluminum. The main objective of this study was to identify potential improvements in the impact resistance of magnesium alloys. The most common magnesium alloys in automotive applications are AZ91D, AM50 and AM60. Accordingly, these alloys were selected as the main candidates for the study. Experimental quantities of these alloys were melted in an electrical furnace under a protective atmosphere comprising sulfur hexafluoride, carbon dioxide and dry air. The alloys were cast both in a permanent mold and in a UBE 315 Ton squeeze caster. Extensive evaluation of tensile, impact and fatigue properties was conducted at CWRU on permanent mold and squeeze cast test bars of AZ91, AM60 and AM50. Ultimate tensile strength values between 20ksi and 30ksi were obtained. The respective elongations varied between 25 and 115. the Charpy V-notch impact strength varied between 1.6 ft-lb and 5 ft-lb depending on the alloy and processing conditions. Preliminary bending fatigue evaluation indicates a fatigue limit of 11-12 ksi for AM50 and AM60. This is about 0.4 of the UTS, typical for these alloys. The microstructures of the cast specimens were investigated with optical and scanning electron microscopy. Concomitantly, a study of the fracture toughness in AM60 was conducted at ORNL as part of the study. The results are in line with values published in the literature and are representative of current state of the art in casting magnesium alloys. The experimental results confirm the strong relationship between aluminum content of the alloys and the mechanical properties, in particular the impact strength and the elongation. As the aluminum content increases from about 5

  5. The Impact of a Holistic Conditional Cash Transfer Program in New York City on Parental Financial Investment, Student Time Use, and Educational Processes and Outcomes

    ERIC Educational Resources Information Center

    Aber, J. Lawrence; Morris, Pamela; Wolf, Sharon; Berg, Juliette

    2016-01-01

    This article examines the impacts of Opportunity New York City-Family Rewards, the first holistic conditional cash transfer (CCT) program evaluated in the United States, on parental financial investments in children, and high school students' academic time use, motivations and self-beliefs, and achievement outcomes. Family Rewards, launched by the…

  6. Bioinspired Design: Magnetic Freeze Casting

    NASA Astrophysics Data System (ADS)

    Porter, Michael Martin

    Nature is the ultimate experimental scientist, having billions of years of evolution to design, test, and adapt a variety of multifunctional systems for a plethora of diverse applications. Next-generation materials that draw inspiration from the structure-property-function relationships of natural biological materials have led to many high-performance structural materials with hybrid, hierarchical architectures that fit form to function. In this dissertation, a novel materials processing method, magnetic freeze casting, is introduced to develop porous scaffolds and hybrid composites with micro-architectures that emulate bone, abalone nacre, and other hard biological materials. This method uses ice as a template to form ceramic-based materials with continuously, interconnected microstructures and magnetic fields to control the alignment of these structures in multiple directions. The resulting materials have anisotropic properties with enhanced mechanical performance that have potential applications as bone implants or lightweight structural composites, among others.

  7. Method for removing volatile components from a ceramic article, and related processes

    DOEpatents

    Klug, Frederic Joseph; DeCarr, Sylvia Marie

    2002-01-01

    A method of removing substantially all of the volatile component in a green, volatile-containing ceramic article is disclosed. The method comprises freezing the ceramic article; and then subjecting the frozen article to a vacuum for a sufficient time to freeze-dry the article. Frequently, the article is heated while being freeze-dried. Use of this method efficiently reduces the propensity for any warpage of the article. The article is often formed from a ceramic slurry in a gel-casting process. A method for fabricating a ceramic core used in investment casting is also described.

  8. Venture Capital Investment Base on Grey Relational Theory

    NASA Astrophysics Data System (ADS)

    Zhang, Xubo

    This paper builds a venture capital investment projects selection evaluation model base on risk-weight investment return using grey relational analysis. The risk and return in venture capital investment projects selection process is analyses. These risk and return mainly constricted in management ability, operation ability, market ability, exit obtain and investment cost. The 18 sub-indicators are the impact factors contributed to these five evaluation aspects. Grey relation analysis is use to evaluate the venture capital investment selection. Get the optimal solution of risk-weight double objective investment selection evaluation model. An example is used to demonstrate the model in this paper.

  9. Replacing London's cast iron mains

    SciTech Connect

    Thorne, A. ); Mathews, P. )

    1992-07-01

    This paper discusses the cast iron gas distribution systems that exist in many cities and contains considerable amounts of pipe that vary in age from 20 to 150 years. In many ways, cast iron is an excellent material. It is inherently corrosion resistant, easy to install and cheap. However, it is also brittle and smaller diameter cast iron pipe has a relatively low beam strength. This can lead, under some circumstances, to failure without external warning, with typically a full-circumferential failure. In congested areas this can lead to serious consequences. As a result, cast iron replacement programs are a common feature in such urban gas distribution systems.

  10. Socially responsible investing. Is it successful?

    PubMed

    Camey, B F

    1994-11-01

    Socially responsible investing (SRI) has been defined as "the integration of social or ethical criteria into the investment decision-making process." Based on the values they hold, investors distinguish socially responsible investments from those which are not by implementing social screens: nonfinancial criteria applied in the decision-making process. Socially responsible investors typically follow one of three approaches to ethical investing: avoidance of businesses whose activities they do not support, a positive approach where they seek investments that will enhance the quality of life, and an activist approach where they attempt to influence the company's activities. In addition to individuals, many institutional investors are heavily involved with SRI. Activist investors can judge their investments' performance by the success of their shareholder activities. Investors might also look at the societal effects of their investments. If investors are seeking to change the corporation or society, SRI has proven to be successful. Empirical studies have shown mixed results with respect to the financial performance of SRI, but the findings tend to show that SRI has minimal impact, either positively or negatively, on investment returns. Nevertheless, many factors indicate that SRI may be here to stay. PMID:10137947

  11. Fluid flow and heat transfer modeling for castings

    SciTech Connect

    Domanus, H.M.; Liu, Y.Y.; Sha, W.T.

    1986-01-01

    Casting is fundamental to manufacturing of many types of equipment and products. Although casting is a very old technology that has been in existence for hundreds of years, it remains a highly empirical technology, and production of new castings requires an expensive and time-consuming trial-and-error approach. In recent years, mathematical modeling of casting has received increasing attention; however, a majority of the modeling work has been in the area of heat transfer and solidification. Very little work has been done in modeling fluid flow of the liquid melt. This paper presents a model of fluid flow coupled with heat transfer of a liquid melt for casting processes. The model to be described in this paper is an extension of the COMMIX code and is capable of handling castings with any shape, size, and material. A feature of this model is the ability to track the liquid/gas interface and liquid/solid interface. The flow of liquid melt through the sprue and runners and into the mold cavity is calculated as well as three-dimensional temperature and velocity distributions of the liquid melt throughout the casting process. 14 refs., 13 figs.

  12. Thin section casting program. Volume 4: Static cast product bending, straightening, and rolling

    NASA Astrophysics Data System (ADS)

    1989-01-01

    Statically cast 1/2 in., 3/4 in., and 1 in. thick steel slabs were subjected to hot rolling in a laboratory reversing mill and to simulated coiling-uncoiling on a three-point bender-unbender. Tensile properties and microstructures of hot bands thinner than 0.15 in. produced from the statically cast slabs were found to be independent of initial slab thickness and similar to those from conventionally cast 8 to 10 in. thick slabs. Cold rolled and batch annealed product from the statically cast slabs had mechanical properties equivalent to those of conventionally processed deep-drawing quality steel. Overall, the results of this task indicated that 1/2 to 1 in. thick steel sections produced in a twin belt caster can be coiled and uncoiled in a hot coiler box downstream of the caster without generating any cracks in the product, and that the total range of hot and cold rolled sheet and strip products with qualities equivalent to those of conventionally produced can be obtained from the 1/2 in. to 1 in. thick sections. This report is the fifth of a six volume set on thin section casting.

  13. Thin section casting program: Volume 4, Static cast product bending, straightening, and rolling: Final report

    SciTech Connect

    Not Available

    1989-01-01

    Statically cast 1/2'', 3/4'', and 1'' thick steel slabs were subjected to hot rolling in a laboratory reversing mill and to simulated coiling-uncoiling on a three-point bender-unbender. Tensile properties and microstructures of hot bands thinner than 0.15'' produced from the statically cast slabs were found to be independent of initial slab thickness and similar to those from conventionally cast 8''-10'' thick slabs. Cold rolled and batch annealed product from the statically cast slabs had mechanical properties equivalent to those of conventionally processed deep-drawing quality steel. Overall, the results of this task indicated that 1/2''-1'' thick steel sections produced in a twin belt caster can be coiled and uncoiled in a hot coiler box downstream of the caster without generating any cracks in the product, and that the total range of hot and cold rolled sheet and strip products with qualities equivalent to those of conventionally produced can be obtained from the 1/2''-1'' thick sections. This report is the fifth of a six volume set on thin section casting.

  14. A combined experimental and modeling approach to uranium casting

    SciTech Connect

    Korzekwa, D.; Dunn, P.

    1994-08-01

    U casting was studied using a combined experimental and modeling approach; the U is cast into graphite molds using vacuum induction melting. Mold design and process parameters were varied. FLOW-3D and ABAQUS codes were used. Temperature predictions were compared with experimental data from thermcouples in the mold; initial metal and mold temperatures were used in input to FLOW-3D. Fluid flow predictions were validated using static and dynamic radiographic data. Dynamic radiographic videos of gold castings were compared to 3D simulations.

  15. Freeze Tape Casting of Functionally Graded Porous Ceramics

    NASA Technical Reports Server (NTRS)

    Sofie, Stephen W.

    2007-01-01

    Freeze tape casting is a means of making preforms of ceramic sheets that, upon subsequent completion of fabrication processing, can have anisotropic and/or functionally graded properties that notably include aligned and graded porosity. Freeze tape casting was developed to enable optimization of the microstructures of porous ceramic components for use as solid oxide electrodes in fuel cells: Through alignment and grading of pores, one can tailor surface areas and diffusion channels for flows of gas and liquid species involved in fuel-cell reactions. Freeze tape casting offers similar benefits for fabrication of optimally porous ceramics for use as catalysts, gas sensors, and filters.

  16. Rheology of composite solid propellants during motor casting

    NASA Technical Reports Server (NTRS)

    Rogers, C. J.; Smith, P. L.; Klager, K.

    1978-01-01

    In a study conducted to evaluate flow parameters of uncured solid composite propellants during motor casting, two motors (1.8M-lb grain wt) were cast with a PBAN propellant exhibiting good flow characteristics in a 260-in. dia solid rocket motor. Attention is given to the effects of propellant compositional and processing variables on apparent viscosity as they pertain to rheological behavior and grain defect formation during casting. It is noted that optimized flow behavior is impaired with solid propellant loading. Non-Newtonian pseudoplastic flow is observed, which is dependent upon applied shear stress and the age of the uncured propellant.

  17. The Properties of Ammonium Dinitramine (ADN): Part 2: Melt Casting

    NASA Astrophysics Data System (ADS)

    Hahma, A.; Edvinsson, H.; Östmark, H.

    2010-04-01

    A melt casting technique for ammonium dinitramine (ADN) and ADN/aluminum was developed. ADN proved relatively easy to cast, when 1% of magnesium oxide was used as a stabilizer and crystallization kernels. Densities of ADN/MgO 99/1 were 92 to 97% of theoretical mean density (TMD) and those of ADN/Al/MgO 64/35/1 were between 95 and 99% of TMD. Sedimentation of Al in the melt was prevented and the particle wetting was ensured by selecting a suitable particle size for Al. No gelling agents or other additives were used. The casting process and factors influencing it are discussed.

  18. When Your Child Needs a Cast

    MedlinePlus

    ... hard bandage that's usually made of material like fiberglass or plaster. Casts keep bones in place while ... water. Plaster of Paris casts are heavier than fiberglass casts and don't hold up as well ...

  19. Interface Formation During Fusion™ Casting of AA3003/AA4045 Aluminum Alloy Ingots

    NASA Astrophysics Data System (ADS)

    Di Ciano, Massimo; Caron, E. J. F. R.; Weckman, D. C.; Wells, M. A.

    2015-12-01

    Fusion™ casting is a unique Direct Chill continuous casting process whereby two different alloys can be cast simultaneously, producing a laminated ingot for rolling into clad sheet metal such as AA3003/AA4045 brazing sheet. Better understanding of the wetting and interface formation process during Fusion™ casting is required to further improve process yields and also explore use of other alloy systems for new applications. In this research, AA3003-core/AA4045-clad ingots were cast using a well-instrumented lab-scale Fusion™ casting system. As-cast Fusion™ interfaces were examined metallurgically and by mechanical testing. Computational fluid dynamic analyses of the FusionTM casts were also performed. It was shown that the liquid AA4045-clad alloy was able to successfully wet and create an oxide-free, metallurgical, and mechanically sound interface with the lightly oxidized AA3003-core shell material. Based on the results of this study, it is proposed that the bond formation process at the alloys interface during casting is a result of discrete penetration of AA4045 liquid at defects in the preexisting AA3003 oxide, dissolution of underlying AA3003 by liquid AA4045, and subsequent bridging between penetration sites. Spot exudation on the AA3003 chill cast surface due to remelting and inverse segregation may also improve the wetting and bonding process.

  20. Investment in Success

    ERIC Educational Resources Information Center

    Weinstein, Margery

    2010-01-01

    Operating a financial investment company in an unstable economy is not easy. But the right training at Vanguard ensures satisfied customers. The company made an investment of its own in learning and development that paid off big in 2009. The learning offerings, both innovative and efficient, keep its workers updated on strategies that bring…

  1. Investing in Innovation

    ERIC Educational Resources Information Center

    National Governors Association, 2007

    2007-01-01

    "Investing in Innovation" provides a snapshot of trends in the states and identifies a wide range of strategies now employed. California's big investments, such as $3 billion for stem cell research, have already grabbed national headlines. But states like Arizona, Indiana and North Dakota, which haven't historically been big research and…

  2. Investing in Faculty.

    ERIC Educational Resources Information Center

    New Directions for Higher Education, 2002

    2002-01-01

    Discusses why it is essential to look at costs related to science, technology, engineering, and mathematics (STEM) faculty not simply as a critical expense, but as part of an intentional investment strategy meant to produce an important and significant value-added benefit. Offers advice on planning, financing, and assessing this investment. (EV)

  3. Education and Caste in India

    ERIC Educational Resources Information Center

    Chauhan, Chandra Pal Singh

    2008-01-01

    This paper analyses the policy of reservation for lower castes in India. This policy is similar to that of affirmative action in the United States. The paper provides a brief overview of the caste system and discusses the types of groups that are eligible for reservation, based on data from government reports. The stance of this paper is that…

  4. An Energy Savings Model for the Heat Treatment of Castings

    SciTech Connect

    Y. Rong; R. Sisson; J. Morral; H. Brody

    2006-12-31

    An integrated system of software, databases, and design rules have been developed, verified, and to be marketed to enable quantitative prediction and optimization of the heat treatment of aluminum castings to increase quality, increase productivity, reduce heat treatment cycle times and reduce energy consumption. The software predicts the thermal cycle in critical locations of individual components in a furnace, the evolution of microstructure, and the attainment of properties in heat treatable aluminum alloy castings. The model takes into account the prior casting process and the specific composition of the component. The heat treatment simulation modules can be used in conjunction with software packages for simulation of the casting process. The system is built upon a quantitative understanding of the kinetics of microstructure evolution in complex multicomponent alloys, on a quantitative understanding of the interdependence of microstructure and properties, on validated kinetic and thermodynamic databases, and validated quantitative models.

  5. Advanced lost foam casting technology. 1995 summary report

    SciTech Connect

    Bates, C.E.; Littleton, H.E.; Askeland, D.; Griffin, J.; Miller, B.A.; Sheldon, D.S.

    1996-05-01

    Previous research made significant advances in understanding the Lost Foam Casting (LFC) Process and clearly identified areas where additional research was needed to improve the process and make it more functional in an industrial environment. The current project focused on five areas listed as follows: Task 1: Precision Pattern Production; Task 2: Pattern Coating Consistency; Task 3: Sand Fill and Compaction Effects; Task 4: Pattern Gating; and Task 5: Mechanical Properties of Castings. This report summarizes the work done under the current contract in all five areas. Twenty-eight (28) companies jointly participate in the project. These companies represent a variety of disciplines, including pattern designers, pattern producers, coating manufacturers, plant design companies, compaction equipment manufacturers, casting producers, and casting buyers. This report summarizes the work done in the past two years and the conclusions drawn from the work.

  6. Modified soft tissue cast for fixed partial denture: a technique

    PubMed Central

    2011-01-01

    In process of fabrication of a fixed partial denture, dies are trimmed to expose margins of the preparations. The need for the soft tissue cast is quite evident as the soft tissue emergence profile that surrounds the prepared tooth is destroyed in the process of fabrication. This article describes a modified technique to fabricate the soft tissue cast for the conventional fixed partial denture. The impression made with the polyvinylsiloxane was first poured to prepare the die cast. After retrieval of the cast, the same impression was poured second time with the resin based resilient material to cover the facial and proximal gingival areas. The remaining portion of the impression was poured with the gypsum material. This technique does not require additional clinical appointment, second impression procedure, technique sensitive manipulations with impression, or cumbersome laboratory procedures. The simplicity of this technique facilitates and justifies its routine use in fabrication of the fixed partial denture. PMID:21503191

  7. IMPROVED MAGNESIUM OXIDE SLIP CASTING METHOD

    DOEpatents

    Stoddard, S.D.; Nuckolls, D.E.

    1963-12-31

    A process for making an aqueous magnesium oxide slip casting slurry comprising the steps of mixing finely ground fused magnesium oxide with water, milling the slurry for at least 30 hours at a temperature of 2-10 deg C (the low temperature during milling inhibiting the formation of hydrated magnesium oxide), discharging the slurry from the mill, adding hydrochloric acid as a deflocculent, and adding a scum inhibitor is presented. (AEC)

  8. A comparative study of the microstructures observed in statically cast and continuously cast Bi-In-Sn ternary eutectic alloy

    SciTech Connect

    Sengupta, S.; Soda, H.; McLean, A.; Rutter, J.W.

    2000-01-01

    A ternary eutectic alloy with a composition of 57.2 pct Bi, 24.8 pct In, and 18 pct Sn was continuously cast into wire of 2 mm diameter with casting speeds of 14 and 79 mm/min using the Ohno Continuous Casting (OCC) process. The microstructures obtained were compared with those of statically cast specimens. Extensive segregation of massive Bi blocks, Bi complex structures, and tin-rich dendrites was found in specimens that were statically cast. Decomposition of {radical}Sn by a eutectoid reaction was confirmed based on microstructural evidence. Ternary eutectic alloy with a cooling rate of approximately 1 C/min formed a double binary eutectic. The double binary eutectic consisted of regions of BiIn and decomposed {radical}Sn in the form of a dendrite cell structure and regions of Bi and decomposed {radical}Sn in the form of a complex-regular cell. The Bi complex-regular cells, which are a ternary eutectic constituent, existed either along the boundaries of the BiIn-decomposed {radical}Sn dendrite cells or at the front of elongated dendrite cell structures. In the continuously cast wires, primary Sn dendrites coupled with a small Bi phase were uniformly distributed within the Bi-In alloy matrix. Neither massive Bi phase, Bi complex-regular cells, no BiIn eutectic dendrite cells were observed, resulting in a more uniform microstructure in contrast to the heavily segregated structures of the statically cast specimens.

  9. Development of dental casting and porcelainizing techniques for titanium alloys

    SciTech Connect

    Taira, M.

    1986-01-01

    Casting of titanium metals has been difficult due to their high chemical reactivity at elevated temperatures. Thus, special melting and mold materials are needed. This study investigated molds, Ti alloys, and porcelain applications, utilizing a new dental casting machine, Castmatic. It involved argon-arc melting and subsequent argon/vacuum pressurized casting. Special refractory oxides such as yttria or Zirconia A were utilized for a face coat under phosphate bonded silica investment. Studies of Ti alloys (Ti, Ti-6Al-4V, Ti-15V, Ti-20Cu and Ti-30Pd) involved metallography, phase identification (XRD), hardness, tensile tests, and electrochemical-corrosion tests. Preliminary porcelain studies included an experimental low fusing porcelain along with commercial low fusing porcelains. The bond was evaluated by three-point bending tests and SEM/EDX observations. The yttria face coat was inert, but lacked the necessary mechanical and thermal stability. The face coat, consisting of Zirconia A and zirconium acetate binder, was stable and resulted in less mold reactivity, good internal soundness, but slightly rough surfaces. Metallographs revealed quite larger grains in the cast structure, than in the wrought forms. XRD analysis showed that quasi-equilibrium phases present.

  10. Influence of mold length and mold heat transfer on horizontal continuous casting of nonferrous alloy rods

    NASA Astrophysics Data System (ADS)

    Verwijs, J. P.; Weckman, D. C.

    1988-04-01

    The influence of mold length and mold heat transfer on the conventional hot-top D.C. continuous casting process was studied through numerical simulations and experiments with horizontally cast 20 mm diameter lead and zinc rods. The minimum casting speed was found to be a nonlinear function of the mold length. For short molds, an inverse relationship between mold length and minimum casting speed was observed. However, the minimum casting speed for zinc cast from molds longer than 12 mm was constant at 2.5 mm/s. For lead cast in molds longer than 12 mm, the minimum observed casting speed was constant at 4.0 mm/s. The observed nonlinear relationship between minimum casting speed and mold length was predicted using a numerical model of the process. For this, an analytical expression for the mold boundary conditions was derived which included the influence of gas gap formation between the rod and the mold due to thermoelastic deformations of both the rod and the mold. Correlation between observed and predicted behavior was demonstrated for both the lead and zinc rods. Maximum casting speed was observed to increase with increased mold length; however, this speed was found to be critically dependent on process attributes such as mold and pinch wheel alignment and mold lubrication.

  11. The Effects of Externally Solidified Product on Wave Celerity and Quality of Die Cast Products

    SciTech Connect

    Carroll Mobley; Yogeshwar Sahai; Jerry Brevick

    2003-10-10

    The cold chamber die casting process is used to produce essentially all the die cast aluminum products and about 50% of the die cast magnesium products made today. Modeling of the cold chamber die casting process and metallographic observations of cold chamber die cast products indicate that typically 5 to 20% of the shot weight is solidified in the shot sleeve before or during cavity filling. The protion of the resulting die casting which is solidified in the shot sleeve is referred to as externally solidified product, or, when identified as a casting defect, as cold flakes. This project was directed to extending the understanding of the effects of externally solidified product on the cold chamber die casting process and products to enable the production of defect-free die castings and reduce the energy associated with these products. The projected energy savings from controlling the fraction of externally solidified product in die cast components is 40 x 10 Btu through the year 2025.

  12. Strip casting with fluxing agent applied to casting roll

    DOEpatents

    Williams, Robert S.; O'Malley, Ronald J.; Sussman, Richard C.

    1997-01-01

    A strip caster (10) for producing a continuous strip (24) includes a tundish (12) for containing a melt (14), a pair of horizontally disposed water cooled casting rolls (22) and devices (29) for electrostatically coating the outer peripheral chill surfaces (44) of the casting rolls with a powder flux material (56). The casting rolls are juxtaposed relative to one another for forming a pouting basin (18) for receiving the melt through a teeming tube (16) thereby establishing a meniscus (20) between the rolls for forming the strip. The melt is protected from the outside air by a non-oxidizing gas passed through a supply line (28) to a sealing chamber (26). A preferred flux is boron oxide having a melting point of about 550.degree. C. The flux coating enhances wetting of the steel melt to the casting roll and dissolves any metal oxide formed on the roll.

  13. Strip casting with fluxing agent applied to casting roll

    DOEpatents

    Williams, R.S.; O`Malley, R.J.; Sussman, R.C.

    1997-07-29

    A strip caster for producing a continuous strip includes a tundish for containing a melt, a pair of horizontally disposed water cooled casting rolls and devices for electrostatically coating the outer peripheral chill surfaces of the casting rolls with a powder flux material. The casting rolls are juxtaposed relative to one another for forming a pouting basin for receiving the melt through a teeming tube thereby establishing a meniscus between the rolls for forming the strip. The melt is protected from the outside air by a non-oxidizing gas passed through a supply line to a sealing chamber. A preferred flux is boron oxide having a melting point of about 550 C. The flux coating enhances wetting of the steel melt to the casting roll and dissolves any metal oxide formed on the roll. 3 figs.

  14. Cast iron-base alloy for cylinder/regenerator housing

    NASA Technical Reports Server (NTRS)

    Witter, Stewart L.; Simmons, Harold E.; Woulds, Michael J.

    1985-01-01

    NASACC-1 is a castable iron-base alloy designed to replace the costly and strategic cobalt-base X-40 alloy used in the automotive Stirling engine cylinder/generator housing. Over 40 alloy compositions were evaluated using investment cast test bars for stress-rupture testing. Also, hydrogen compatibility and oxygen corrosion resistance tests were used to determine the optimal alloy. NASACC-1 alloy was characterized using elevated and room temperature tensile, creep-rupture, low cycle fatigue, heat capacity, specific heat, and thermal expansion testing. Furthermore, phase analysis was performed on samples with several heat treated conditions. The properties are very encouraging. NASACC-1 alloy shows stress-rupture and low cycle fatigue properties equivalent to X-40. The oxidation resistance surpassed the program goal while maintaining acceptable resistance to hydrogen exposure. The welding, brazing, and casting characteristics are excellent. Finally, the cost of NASACC-1 is significantly lower than that of X-40.

  15. Strip casting apparatus and method

    DOEpatents

    Williams, R.S.; Baker, D.F.

    1988-09-20

    Strip casting apparatus including a molten-metal-holding container and a nozzle to deposit molten metal onto a moving chill drum to directly cast continuous metallic strip. The nozzle body includes a slot bounded between a back and a front lip. The slot width exceeds about 20 times the gap distance between the nozzle and the chill drum surface. Preferably, the slot width exceeds 0.5 inch. This method of strip casting minimizes pressure drop, insuring better metal-to-chill-drum contact which promotes heat transfer and results in a better quality metallic strip. 6 figs.

  16. Strip casting apparatus and method

    DOEpatents

    Williams, Robert S.; Baker, Donald F.

    1988-01-01

    Strip casting apparatus including a molten-metal-holding container and a nozzle to deposit molten metal onto a moving chill drum to directly cast continuous metallic strip. The nozzle body includes a slot bounded between a back and a front lip. The slot width exceeds about 20 times the gap distance between the nozzle and the chill drum surface. Preferably, the slot width exceeds 0.5 inch. This method of strip casting minimizes pressure drop, insuring better metal-to-chill-drum contact which promotes heat transfer and results in a better quality metallic strip.

  17. Phase Transformation in Cast Superaustenitic Stainless Steels

    SciTech Connect

    Lee Phillips, Nathaniel Steven

    2006-01-01

    Superaustenitic stainless steels constitute a group of Fe-based alloys that are compositionally balanced to have a purely austenitic matrix and exhibit favorable pitting and crevice corrosion resistant properties and mechanical strength. However, intermetallic precipitates such as sigma and Laves can form during casting or exposure to high-temperature processing, which degrade the corrosion and mechanical properties of the material. The goal of this study was to accurately characterize the solid-solid phase transformations seen in cast superaustenitic stainless steels. Heat treatments were performed to understand the time and temperature ranges for intermetallic phase formations in alloys CN3MN and CK3MCuN. Microstructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy and wavelength dispersive spectroscopy (EDS, WDS). The equilibrium microstructures, composed primarily of sigma and Laves within purely austenitic matrices, showed slow transformation kinetics. Factors that determine the extent of transformation, including diffusion, nucleation, and growth, are discussed.

  18. Volatile species retention during metallic fuel casting

    NASA Astrophysics Data System (ADS)

    Fielding, Randall S.; Porter, Douglas L.

    2013-10-01

    Metallic nuclear fuels are candidate transmutation fuel forms for advanced fuel cycles. Through the operation of the Experimental Breeder Reactor II metallic nuclear fuels have been shown to be robust and easily manufactured. However, concerns have been raised concerning loss of americium during the casting process because of its high vapor pressure. In order to address these concerns a gaseous diffusion model was developed and a series of experiments using both manganese and samarium as surrogates for americium were conducted. The modeling results showed that volatility losses can be controlled to essentially no losses with a modest overpressure. Experimental results also showed volatile species retention down to no detectable losses through overpressure, and although the loss values varied from the model results the same trend was seen. Based on these results it is very probable that americium losses through volatility can be controlled to no detectable losses through application of a modest overpressure during casting.

  19. Volatile Species Retention During Metallic Fuel Casting

    SciTech Connect

    Randall S. Fielding; Douglas L. Proter

    2013-10-01

    Metallic nuclear fuels are candidate transmutation fuel forms for advanced fuel cycles. Through the operation of the Experimental Breeder Reactor II metallic nuclear fuels have been shown to be robust and easily manufactured. However, concerns have been raised concerning loss of americium during the casting process because of its high vapor pressure. In order to address these concerns a gaseous diffusion model was developed and a series of experiments using both manganese and samarium as surrogates for americium were conducted. The modeling results showed that volatility losses can be controlled to essentially no losses with a modest overpressure. Experimental results also showed volatile species retention down to no detectable losses through overpressure, although the loss values varied from the model results the same trend was seen. Bases on these results it is very probably that americium losses through volatility can be controlled to no detectable losses through application of a modest overpressure during casting.

  20. Estimation of primary dendrite arm spacings in continuous casting products

    SciTech Connect

    Cicutti, C.; Bilmes, P.; Boeri, R.

    1997-09-01

    The proportion of steels produced by continuous casting has grown drastically during the last two decades, increasing to such an extent that in some countries, several grades of steel are exclusively made by this process. Many investigations recognized the significant influence of the solidification structure on the quality of cast products, and pointed out the importance of the development of appropriate tools to predict the microstructure as a function of thermal and physical parameters. The estimation of secondary dendrite arm spacings in continuously cast steel products has received some attention. However, very little effort has been focused on the prediction of primary dendrite arm spacings, to the best of the authors` knowledge. The main objective of this study is to develop simple expressions to estimate the variation of primary dendrite arm spacings through the section of continuous casting steel products.

  1. Continuous Casting for Aluminum Sheet: a Product Perspective

    NASA Astrophysics Data System (ADS)

    Sanders, Robert E.

    2012-02-01

    Continuous casting processes have been used successfully for more than 50 years to reduce the cost of manufacturing a variety of aluminum rolled products. Approximately 25% of North American flat-rolled sheet and foil is sourced from twin-roll cast or slab cast processes. Twin roll-casters provide a cost-effective solution for producing foil and light-gauge sheet from relatively low-alloyed aluminum (1xxx and 8xxx alloys). Slab casters, particularly Hazelett twin-belt machines, are well utilized in the production of 3xxx or 5xxx painted building products which require moderate strength and good corrosion resistance. Both foil and painted sheet are cost-sensitive commodity products with well-known metallurgical and quality requirements. There have been extensive trials and modest successes with continuous cast can stock and automotive sheet. However, they have not been widely adopted commercially due to generally lower levels of surface quality and formability compared with sheet produced from scalped direct chill (DC) cast ingot. The metallurgical requirements for can and auto sheet are considered in more detail with emphasis on the microstructural features which limit their application, e.g., particle distribution, grain size, and texture. Looking forward, slab casting offers the most viable opportunity for producing strong (i.e., higher alloy content), formable structural auto sheet with acceptable surface quality.

  2. 21 CFR 888.5940 - Cast component.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cast component. 888.5940 Section 888.5940 Food and... ORTHOPEDIC DEVICES Surgical Devices § 888.5940 Cast component. (a) Identification. A cast component is a device intended for medical purposes to protect or support a cast. This generic type of device...

  3. 21 CFR 880.6185 - Cast cover.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cast cover. 880.6185 Section 880.6185 Food and....6185 Cast cover. (a) Identification. A cast cover is a device intended for medical purposes that is made of waterproof material and placed over a cast to protect it from getting wet during a shower or...

  4. 21 CFR 880.6185 - Cast cover.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cast cover. 880.6185 Section 880.6185 Food and....6185 Cast cover. (a) Identification. A cast cover is a device intended for medical purposes that is made of waterproof material and placed over a cast to protect it from getting wet during a shower or...

  5. 21 CFR 880.6185 - Cast cover.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cast cover. 880.6185 Section 880.6185 Food and....6185 Cast cover. (a) Identification. A cast cover is a device intended for medical purposes that is made of waterproof material and placed over a cast to protect it from getting wet during a shower or...

  6. 21 CFR 888.5940 - Cast component.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cast component. 888.5940 Section 888.5940 Food and... ORTHOPEDIC DEVICES Surgical Devices § 888.5940 Cast component. (a) Identification. A cast component is a device intended for medical purposes to protect or support a cast. This generic type of device...

  7. 21 CFR 888.5940 - Cast component.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cast component. 888.5940 Section 888.5940 Food and... ORTHOPEDIC DEVICES Surgical Devices § 888.5940 Cast component. (a) Identification. A cast component is a device intended for medical purposes to protect or support a cast. This generic type of device...

  8. Investment, regulation, and uncertainty

    PubMed Central

    Smyth, Stuart J; McDonald, Jillian; Falck-Zepeda, Jose

    2014-01-01

    As with any technological innovation, time refines the technology, improving upon the original version of the innovative product. The initial GM crops had single traits for either herbicide tolerance or insect resistance. Current varieties have both of these traits stacked together and in many cases other abiotic and biotic traits have also been stacked. This innovation requires investment. While this is relatively straight forward, certain conditions need to exist such that investments can be facilitated. The principle requirement for investment is that regulatory frameworks render consistent and timely decisions. If the certainty of regulatory outcomes weakens, the potential for changes in investment patterns increases.   This article provides a summary background to the leading plant breeding technologies that are either currently being used to develop new crop varieties or are in the pipeline to be applied to plant breeding within the next few years. Challenges for existing regulatory systems are highlighted. Utilizing an option value approach from investment literature, an assessment of uncertainty regarding the regulatory approval for these varying techniques is undertaken. This research highlights which technology development options have the greatest degree of uncertainty and hence, which ones might be expected to see an investment decline. PMID:24499745

  9. A new method to acquire 3-D images of a dental cast

    NASA Astrophysics Data System (ADS)

    Li, Zhongke; Yi, Yaxing; Zhu, Zhen; Li, Hua; Qin, Yongyuan

    2006-01-01

    This paper introduced our newly developed method to acquire three-dimensional images of a dental cast. A rotatable table, a laser-knife, a mirror, a CCD camera and a personal computer made up of a three-dimensional data acquiring system. A dental cast is placed on the table; the mirror is installed beside the table; a linear laser is projected to the dental cast; the CCD camera is put up above the dental cast, it can take picture of the dental cast and the shadow in the mirror; while the table rotating, the camera records the shape of the laser streak projected on the dental cast, and transmit the data to the computer. After the table rotated one circuit, the computer processes the data, calculates the three-dimensional coordinates of the dental cast's surface. In data processing procedure, artificial neural networks are enrolled to calibrate the lens distortion, map coordinates form screen coordinate system to world coordinate system. According to the three-dimensional coordinates, the computer reconstructs the stereo image of the dental cast. It is essential for computer-aided diagnosis and treatment planning in orthodontics. In comparison with other systems in service, for example, laser beam three-dimensional scanning system, the characteristic of this three-dimensional data acquiring system: a. celerity, it casts only 1 minute to scan a dental cast; b. compact, the machinery is simple and compact; c. no blind zone, a mirror is introduced ably to reduce blind zone.

  10. Data Package for Secondary Waste Form Down-Selection—Cast Stone

    SciTech Connect

    Serne, R. Jeffrey; Westsik, Joseph H.

    2011-09-05

    Available literature on Cast Stone and Saltstone was reviewed with an emphasis on determining how Cast Stone and related grout waste forms performed in relationship to various criteria that will be used to decide whether a specific type of waste form meets acceptance criteria for disposal in the Integrated Disposal Facility (IDF) at Hanford. After the critical review of the Cast Stone/Saltstone literature, we conclude that Cast Stone is a good candidate waste form for further consideration. Cast stone meets the target IDF acceptance criteria for compressive strength, no free liquids, TCLP leachate are below the UTS permissible concentrations and leach rates for Na and Tc-99 are suiteably low. The cost of starting ingredients and equipment necessary to generate Cast Stone waste forms with secondary waste streams are low and the Cast Stone dry blend formulation can be tailored to accommodate variations in liquid waste stream compositions. The database for Cast Stone short-term performance is quite extensive compared to the other three candidate waste solidification processes. The solidification of liquid wastes in Cast Stone is a mature process in comparison to the other three candidates. Successful production of Cast Stone or Saltstone has been demonstrated from lab-scale monoliths with volumes of cm3 through m3 sized blocks to 210-liter sized drums all the way to the large pours into vaults at Savannah River. To date over 9 million gallons of low activity liquid waste has been solidified and disposed in concrete vaults at Savannah River.

  11. Strong and light plaster casts?

    PubMed

    Stewart, Todd; Cheong, Wen; Barr, Victoria; Tang, Daniel

    2009-08-01

    Three geometries of volar slab plaster cast for the stabilisation of wrist fractures were investigated. It was found that by moulding reinforcement ridges on the inferior surface of the slab the strength and stiffness could be doubled with only a 20% increase in weight. It was discovered that to provide the same increase in strength with a traditional cast the entire thickness of the cast would have to be doubled, with a 100% increase in weight that would be cumbersome to most users. Bending theory is presented in a simple manner to allow clinicians to understand how reinforcement mouldings can improve the strength and stiffness of plaster casts without adversely influencing weight, or cost.

  12. Casting Using A Polystyrene Pattern

    NASA Technical Reports Server (NTRS)

    Vasquez, Peter; Guenther, Bengamin; Vranas, Thomas; Veneris, Peter; Joyner, Michael

    1993-01-01

    New technique for making metal aircraft models saves significant amount of time and effort in comparison with conventional lost-wax method. Produces inexpensive, effective wind-tunnel models. Metal wind-tunnel model cast by use of polystyrene pattern.

  13. Optimization of Squeeze Casting for Aluminum Alloy Parts

    SciTech Connect

    David Schwam; John F. Wallace; Qingming Chang; Yulong Zhu

    2002-07-30

    This study was initiated with the installation of a new production size UBE 350 Ton VSC Squeeze Casting system in the Metal Casting Laboratory at Case Western University. A Lindberg 75k W electrical melting furnace was installed alongside. The challenge of installation and operation of such industrial-size equipment in an academic environment was met successfully. Subsequently, a Sterling oil die heater and a Visi-Track shot monitoring system were added. A significant number of inserts were designed and fabricated over the span of the project, primarily for squeeze casting different configurations of test bars and plates. A spiral ''ribbon insert'' for evaluation of molten metal fluidity was also fabricated. These inserts were used to generate a broad range of processing conditions and determine their effect on the quality of the squeeze cast parts. This investigation has studied the influence of the various casting variables on the quality of indirect squeeze castings primarily of aluminum alloys. The variables studied include gating design, fill time and fill patter, metal pressure and die temperature variations. The quality of the die casting was assessed by an analysis of both their surface condition and internal soundness. The primary metal tested was an aluminum 356 alloy. In addition to determining the effect of these casting variables on casting quality as measured by a flat plate die of various thickness, a number of test bar inserts with different gating designs have been inserted in the squeeze casting machine. The mechanical properties of these test bars produced under different squeeze casting conditions were measured and reported. The investigation of the resulting properties also included an analysis of the microstructure of the squeeze castings and the effect of the various structural constituents on the resulting properties. The main conclusions from this investigation are as follows: The ingate size and shape are very important since it must

  14. Computational algorithms to simulate the steel continuous casting

    NASA Astrophysics Data System (ADS)

    Ramírez-López, A.; Soto-Cortés, G.; Palomar-Pardavé, M.; Romero-Romo, M. A.; Aguilar-López, R.

    2010-10-01

    Computational simulation is a very powerful tool to analyze industrial processes to reduce operating risks and improve profits from equipment. The present work describes the development of some computational algorithms based on the numerical method to create a simulator for the continuous casting process, which is the most popular method to produce steel products for metallurgical industries. The kinematics of industrial processing was computationally reproduced using subroutines logically programmed. The cast steel by each strand was calculated using an iterative method nested in the main loop. The process was repeated at each time step (Δ t) to calculate the casting time, simultaneously, the steel billets produced were counted and stored. The subroutines were used for creating a computational representation of a continuous casting plant (CCP) and displaying the simulation of the steel displacement through the CCP. These algorithms have been developed to create a simulator using the programming language C++. Algorithms for computer animation of the continuous casting process were created using a graphical user interface (GUI). Finally, the simulator functionality was shown and validated by comparing with the industrial information of the steel production of three casters.

  15. Investing in river health.

    PubMed

    Bennett, J

    2002-01-01

    Rivers provide society with numerous returns. These relate to both the passive and extractive uses of the resources embodied in river environments. Some returns are manifest in the form of financial gains whilst others are non-monetary. For instance, rivers are a source of monetary income for those who harvest their fish. The water flowing in rivers is extracted for drinking and to water crops and livestock that in turn yield monetary profits. However, rivers are also the source of non-monetary values arising from biological diversity. People who use them for recreation (picnicking, swimming, boating) also receive non-monetary returns. The use of rivers to yield these returns has had negative consequences. With extraction for financial return has come diminished water quantity and quality. The result has been a diminished capacity of rivers to yield (non-extractive) environmental returns and to continue to provide extractive values. A river is like any other asset. With use, the value of an asset depreciates because its productivity declines. In order to maintain the productive capacity of their assets, managers put aside from their profits depreciation reserves that can be invested in the repair or replacement of those assets. Society now faces a situation in which its river assets have depreciated in terms of their capacity to provide monetary and non-monetary returns. An investment in river "repair" is required. But, investment means that society gives up something now in order to achieve some benefit in the future. Society thus has to grapple wih the choice between investing in river health and other investments--such as in hospitals, schools, defence etc. - as well as between investing in river health and current consumption--such as on clothes, food, cars etc. A commonly used aid for investment decision making in the public sector is benefit cost analysis. However, its usefulness in tackling the river investment problem is restricted because it requires all

  16. Investing in river health.

    PubMed

    Bennett, J

    2002-01-01

    Rivers provide society with numerous returns. These relate to both the passive and extractive uses of the resources embodied in river environments. Some returns are manifest in the form of financial gains whilst others are non-monetary. For instance, rivers are a source of monetary income for those who harvest their fish. The water flowing in rivers is extracted for drinking and to water crops and livestock that in turn yield monetary profits. However, rivers are also the source of non-monetary values arising from biological diversity. People who use them for recreation (picnicking, swimming, boating) also receive non-monetary returns. The use of rivers to yield these returns has had negative consequences. With extraction for financial return has come diminished water quantity and quality. The result has been a diminished capacity of rivers to yield (non-extractive) environmental returns and to continue to provide extractive values. A river is like any other asset. With use, the value of an asset depreciates because its productivity declines. In order to maintain the productive capacity of their assets, managers put aside from their profits depreciation reserves that can be invested in the repair or replacement of those assets. Society now faces a situation in which its river assets have depreciated in terms of their capacity to provide monetary and non-monetary returns. An investment in river "repair" is required. But, investment means that society gives up something now in order to achieve some benefit in the future. Society thus has to grapple wih the choice between investing in river health and other investments--such as in hospitals, schools, defence etc. - as well as between investing in river health and current consumption--such as on clothes, food, cars etc. A commonly used aid for investment decision making in the public sector is benefit cost analysis. However, its usefulness in tackling the river investment problem is restricted because it requires all

  17. Application of statistical methods for analyzing the relationship between casting distortion, mold filling, and interfacial heat transfer in sand molds

    SciTech Connect

    Y. A. Owusu

    1999-03-31

    This report presents a statistical method of evaluating geometric tolerances of casting products using point cloud data generated by coordinate measuring machine (CMM) process. The focus of this report is to present a statistical-based approach to evaluate the differences in dimensional and form variations or tolerances of casting products as affected by casting gating system, molding material, casting thickness, and casting orientation at the mold-metal interface. Form parameters such as flatness, parallelism, and other geometric profiles such as angularity, casting length, and height of casting products were obtained and analyzed from CMM point cloud data. In order to relate the dimensional and form errors to the factors under consideration such as flatness and parallelism, a factorial analysis of variance and statistical test means methods were performed to identify the factors that contributed to the casting distortion at the mold-metal interface.

  18. Thin section casting program. Volume 3: Vertical TSC (Thin-Section Casting) approach

    NASA Astrophysics Data System (ADS)

    1989-01-01

    A prototype vertical twin belt caster was designed, constructed and tested at Bethlehem Steel Corporation's Homer Research Laboratory for the development of a thin section casting process. In the prototype caster, the moving mold was aligned vertically and each of the two endless steel belts was tensioned around an upper and a lower large pulley by means of a third smaller pulley. The mold consisted of a long parallel lower section and a shorter V-shaped top section into which liquid steel was fed from a tundish via a submerged refractory nozzle. Mold length, defined as the distance from the meniscus in the V-mouth to the tangent point of the lower pulleys, was about eleven feet. The length of the V-mouth was 27 in. The belts were continuously supported between the upper and lower pulleys by a unique back-up system. Downstream support consisted of two pairs of foot rolls and a vertical water-cooled steel structure that would permit a cast length of about nineteen feet. A chain driven bar was used to start a cast and support the slab. The aim was to cast 1 in. by 17 in. sections at 250 in./min. The details of the prototype vertical caster, except the end walls, are given.

  19. Oscillator for continuous casting mold

    SciTech Connect

    Behrends, G.

    1993-06-15

    In a continuous casting machine comprising a chilled mold disposed to receive molten metal which is discharged from the mold as a curved casting having a predetermined casting radius, and an oscillating drive for oscillating the mold relative to the casting, wherein the improvement described comprises mold guidance means having a first tensile element having an inner end and an outer end, the outer end being anchored to a fixed external frame and the inner end being secured to move with the mold, the first tensile element lying on a first radius extending from the center of curvature of said pre-determined casting radius; and a second tensile element having an inner and an outer end both anchored to a fixed external frame and secured to move with the mold intermediate the inner and outer ends, at least one end having variable tensioning means adapted to apply a tensile force to the second tensile element, the second tensile element lying on a second radius extending from the center of curvature of said predetermined casting radius.

  20. Anisotropic shrinkage characteristics of tape cast alumina

    NASA Astrophysics Data System (ADS)

    Patwardhan, Jaideep Suresh

    Dimensional control during sintering is a major issue in ceramics processing to avoid high post-sintering costs associated with machining of the fired ceramic part to desired tolerances and dimensions. Ceramic forming processes such as tape casting, injection molding, and extrusion involve shear of anisotropic particles resulting in preferential alignment of the particles in the green body. This preferential alignment causes directionality in mechanical, electrical, optical, and magnetic properties and most importantly warpage or distortion during sintering. A large effort has been devoted to synthesizing ceramic green bodies with minimal density gradients and uniform packing and modeling the sintering behavior evolution but little effort has been devoted to characterizing orientation of particles and the effect of preferential alignment on sintering shrinkage anisotropy. A systematic study was initiated to study the effect of processing variables such as shear rate, solids loading, temperature, and binder content on aqueous tape cast alumina. Three different alumina systems: A16-SG, Baikowski RC-UFX DBM and RC-LS DBM were investigated. Aqueous tapes of high solids loading alumina (56 vol. %) were tape cast at various speeds and thicknesses and assuming plane Couette flow a shear rate regime of 21--270 s-1 was investigated. Higher shear rates and high solids loading resulted in higher in-plane anisotropy whereas the anisotropy in the thickness direction was higher for low solids loading systems. The anisotropy was found to be fairly constant above a certain critical shear rate (˜100 s-1) irrespective of the temperature and the solids loading and this correlated with the viscosity-shear rate relationship of the cast slips. The higher shrinkage anisotropy in the thickness direction for the low solids loading systems (35 and 45 vol. %) was attributed to the higher amount of organics in the slip required to sustain the suitable viscosity for tape casting and

  1. Electromagnetic continuous casting project: Final report

    SciTech Connect

    Battles, J.E.; Rote, D.M.; Misra, B.; Praeg, W.F.; Hull, J.R.; Turner, L.R.; Shah, V.L.; Lari, R.J.; Gopalsami, N.; Wiencek, T.

    1988-10-01

    This report describes the work on development of an electromagnetic casting process for steel, which was carried out at Argonne National Laboratory between January 1985 and December 1987. This effort was concerned principally with analysis and design work on magnet technology, liquid metal feed system, coolant system, and sensors and process controllers. Experimentation primarily involved (1) electromagnetic studies to determine the conditions and controlling parameters for stable levitation and (2) feed-system studies to establish important parameters that control and influence fluid flow from the liquid metal source to the caster. 73 refs., 91 figs., 11 tabs.

  2. Seal welded cast iron nuclear waste container

    DOEpatents

    Filippi, Arthur M.; Sprecace, Richard P.

    1987-01-01

    This invention identifies methods and articles designed to circumvent metallurgical problems associated with hermetically closing an all cast iron nuclear waste package by welding. It involves welding nickel-carbon alloy inserts which are bonded to the mating plug and main body components of the package. The welding inserts might be bonded in place during casting of the package components. When the waste package closure weld is made, the most severe thermal effects of the process are restricted to the nickel-carbon insert material which is far better able to accommodate them than is cast iron. Use of nickel-carbon weld inserts should eliminate any need for pre-weld and post-weld heat treatments which are a problem to apply to nuclear waste packages. Although the waste package closure weld approach described results in a dissimilar metal combination, the relative surface area of nickel-to-iron, their electrochemical relationship, and the presence of graphite in both materials will act to prevent any galvanic corrosion problem.

  3. Automated multiple view inspection of metal castings

    NASA Astrophysics Data System (ADS)

    Mery, Domingo; Carrasco, Miguel

    2007-01-01

    Automated visual inspection of metal castings is defined as a quality control task that determines automatically if a casting deviates from a given set of specifications using visual data. Many research directions in this field have been exploited, some very different principles have been adopted and a wide variety of algorithms have been appeared in the literature. However, the developed approaches are tailored to the inspection task, i.e., there is no common approach applicable to all cases because the development is an ad hoc process. Additionally, detection accuracy should be improved, because there is a fundamental trade off between false alarms and miss detections. For these reasons, we proposed a novel methodology, called Automated Multiple View Inspection, that uses redundant views of the test object to perform the inspection task. The method is opening up new possibilities in inspection field by taking into account the useful information about the correspondence between the different views. It is very robust because in first step it identifies potential defects in each view and in second step it finds correspondences between potential defects, and only those that are matched in different views are detected as real defects. In this paper, we review the advances done in this field giving an overview of the multiple view inspection and showing experimental results obtained on metal castings.

  4. CAST: An Inspiring Axion Helioscope ala Sikivie

    SciTech Connect

    Zioutas, K.; Anastassopoulos, V.; Tsagri, M.; Semertzidis, Y.; Papaevangelou, T.

    2010-08-30

    CAST is a data taking axion helioscope using a recycled LHC test magnet, CERN's detector technology and cryogenics expertise. An imaging X-ray telescope improves substantially the detection sensitivity and axion-ID. Massive axion-like particles of the Kaluza-Klein type were first introduced to explain the paradox of the hot corona, which is even hotter at locations overlying magnetic spots. This is suggesting that the CAST detection principle might be at work there, but being somehow modified and performing better. Remarkably, the density profile of the Sun allows for resonance crossing (m{sub axion}c{sup 2{approx_equal}}h{omega}{sub plasma}), which axion helioscopes are aiming to reach. The restless Sun favours this occasionally even further. Then, such processes can give rise to a chimera of converted axions or the like, making the Sun appear, within known physics, as mysterious and unpredictable as it is. CAST axion limits were used to conclude also for the hidden sector paraphotons. This is then suggestive for novel helioscopes for exotica like paraphotons, chameleons, etc. Pierre Sikivie's pioneering idea was to use a magnetic field as a catalyst to transform particles from the dark sector to ours, and vice versa.

  5. Aging degradation of cast stainless steel

    SciTech Connect

    Chopra, O.K.; Chung, H.M.

    1985-10-01

    A program is being conducted to investigate the significance of in-service embrittlement of cast-duplex stainless steels under light-water reactor operating conditions. Data from room-temperature Charpy-impact tests for several heats of cast stainless steel aged up to 10,000 h at 350, 400, and 450/sup 0/C are presented and compared with results from other studies. Microstructures of cast-duplex stainless steels subjected to long-term aging either in the laboratory or in reactor service have been characterized. The results indicate that at least two processes contribute to the low-temperature embrittleent of duplex stainless steels, viz., weakening of the ferrite/austenite phase boundary by carbide precipitation and embrittlement of ferrite matrix by the formation of additional phases such as G-phase, Type X, or the ..cap alpha..' phase. Carbide precipitation has a significant effect on the onset of embrittlement of CF-8 and -8M grades of stainless steels aged at 400 or 450/sup 0/C. The existing correlations do not accurately represent the embrittlement behavior over the temperature range 300 to 450/sup 0/C. 18 refs., 13 figs.

  6. Infants' discrimination of shapes from shading and cast shadows.

    PubMed

    Sato, Kazuki; Kanazawa, So; Yamaguchi, Masami K

    2016-07-01

    Shadows are powerful cues in the perception of shapes. We can perceive shading and cast shadow implicitly. We investigated infants' ability to detect a single discrepant figure that was depicted by shading or cast shadow and examined the influence of the contrast polarity of shadows on this process. In Experiment 1, we manipulated the blur direction of a shadow to create stimuli that appeared either to be partially shaded or to cast a shadow and then used a preference to test whether this difference would allow 5- to 8-month-old infants to discriminate the figures that adults were able to perceive as different shapes. Only 7- to-8-month-old infants could differentiate one shading figure from cast shadow figures, and vice versa. In Experiment 2, we reversed the contrast polarity of the figure (dark object with a light shadow) and tested whether discrimination was affected. As has been found with adults, infants exposed to this condition were unable to discriminate the contrast-reversed shading and cast shadow figures. Our results suggested that an age of around 7 months is important for development of the ability to perceive shape differences from shading and cast shadows.

  7. Infants' discrimination of shapes from shading and cast shadows.

    PubMed

    Sato, Kazuki; Kanazawa, So; Yamaguchi, Masami K

    2016-07-01

    Shadows are powerful cues in the perception of shapes. We can perceive shading and cast shadow implicitly. We investigated infants' ability to detect a single discrepant figure that was depicted by shading or cast shadow and examined the influence of the contrast polarity of shadows on this process. In Experiment 1, we manipulated the blur direction of a shadow to create stimuli that appeared either to be partially shaded or to cast a shadow and then used a preference to test whether this difference would allow 5- to 8-month-old infants to discriminate the figures that adults were able to perceive as different shapes. Only 7- to-8-month-old infants could differentiate one shading figure from cast shadow figures, and vice versa. In Experiment 2, we reversed the contrast polarity of the figure (dark object with a light shadow) and tested whether discrimination was affected. As has been found with adults, infants exposed to this condition were unable to discriminate the contrast-reversed shading and cast shadow figures. Our results suggested that an age of around 7 months is important for development of the ability to perceive shape differences from shading and cast shadows. PMID:27150615

  8. Integrated design of castings: effect of porosity on mechanical performance

    NASA Astrophysics Data System (ADS)

    Hardin, R. A.; Beckermann, C.

    2012-07-01

    Porosity can significantly reduce the strength and durability of castings in service. An integrated design approach has been developed where casting simulation is combined with mechanical performance simulations. Predictions of the porosity distribution from the casting process simulation are transferred to and used in stress and fatigue life simulations. Thus, the effect of casting quality on service performance can be evaluated. Results of a study are presented where the measured porosity distribution in cast steel specimens is transferred to an elasto-plastic finite-element stress analysis model. Methods are developed to locally reduce the mechanical properties according to the porosity present, without having to resolve individual pores. Plastic deformation is modeled using porous metal plasticity theory. The predictions are compared to tensile measurements performed on the specimens. The complex deformations and the reductions in the ductility of the specimens due to porosity are predicted well. The predicted stresses are transferred to a fatigue analysis code that takes the porosity distribution into account as well. The measured and predicted fatigue lives are also in good agreement. Finally, the results of a case study are presented that illustrate the utility of the present integrated approach in optimizing the design of a steel casting.

  9. Letter Report: LAW Simulant Development for Cast Stone Screening Test

    SciTech Connect

    Russell, Renee L.; Westsik, Joseph H.; Swanberg, David J.; Eibling, Russell E.; Cozzi, Alex; Lindberg, Michael J.; Josephson, Gary B.; Rinehart, Donald E.

    2013-03-27

    More than 56 million gallons of radioactive and hazardous waste are stored in 177 underground storage tanks at the U.S. Department of Energy’s (DOE’s) Hanford Site in southeastern Washington State. The Hanford Tank Waste Treatment and Immobilization Plant (WTP) is being constructed to treat the wastes and immobilize them in a glass waste form. The WTP includes a pretreatment facility to separate the wastes into a small volume of high-level waste (HLW) containing most of the radioactivity and a larger volume of low-activity waste (LAW) containing most of the nonradioactive chemicals. The HLW will be converted to glass in the HLW vitrification facility for ultimate disposal at an offsite federal repository. At least a portion (~35%) of the LAW will be converted to glass in the LAW vitrification facility and will be disposed of onsite at the Integrated Disposal Facility (IDF). The pretreatment and HLW vitrification facilities will have the capacity to treat and immobilize the wastes destined for each facility. However, a second facility will be needed for the expected volume of additional LAW requiring immobilization. A cementitious waste form known as Cast Stone is being considered to provide the required additional LAW immobilization capacity. The Cast Stone waste form must be acceptable for disposal in the IDF. The Cast Stone waste form and immobilization process must be tested to demonstrate that the final Cast Stone waste form can comply with waste acceptance criteria for the IDF disposal facility and that the immobilization processes can be controlled to consistently provide an acceptable waste form product. Further, the waste form must be tested to provide the technical basis for understanding the long term performance of the waste form in the IDF disposal environment. These waste form performance data are needed to support risk assessment and performance assessment (PA) analyses of the long-term environmental impact of the waste disposal in the IDF. A

  10. [Are investment activity and backlog in investments risks for university medicine in Germany?].

    PubMed

    Amann, I; Heyder, R; Strehl, R

    2009-08-01

    University medicine in Germany requires significantly higher funding and investment because its tasks not only include health care but also research and teaching. However, over recent decades less and less funding compared to the development of the turnover has been available. This trend is due to decreasing public funding. The diminishing funding has caused a major backlog of investment at German university hospitals. The first part of the article summarizes the investments policies at university hospitals and other hospitals. The second part describes the investment needs in university medicine and exposes risk factors for research, education and health care due to the process of investment planning and realization. Goal-oriented solutions are shown to facilitate investments. The third part discusses several risks caused by insufficient investments in university medicine. There are special risks for research, teaching, and the capacity for innovation in university medicine besides economical and medical risks. Some policies and financial strategies to overcome the backlog in investments are presented. After a summary, the article concludes with some practical examples of further measures to ensure sustainable funding.

  11. Tradeoffs in the Evolution of Caste and Body Size in the Hyperdiverse Ant Genus Pheidole

    PubMed Central

    McGlynn, Terrence P.; Diamond, Sarah E.; Dunn, Robert R.

    2012-01-01

    The efficient investment of resources is often the route to ecological success, and the adaptability of resource investment may play a critical role in promoting biodiversity. The ants of the “hyperdiverse” genus Pheidole produce two discrete sterile castes, soldiers and minor workers. Within Pheidole, there is tremendous interspecific variation in proportion of soldiers. The causes and correlates of caste ratio variation among species of Pheidole remain enigmatic. Here we test whether a body size threshold model accounts for interspecific variation in caste ratio in Pheidole, such that species with larger body sizes produce relatively fewer soldiers within their colonies. We evaluated the caste ratio of 26 species of Pheidole and found that the body size of workers accounts for interspecific variation in the production of soldiers as we predicted. Twelve species sampled from one forest in Costa Rica yielded the same relationship as found in previously published data from many localities. We conclude that production of soldiers in the most species-rich group of ants is regulated by a body size threshold mechanism, and that the great variation in body size and caste ratio in Pheidole plays a role in niche divergence in this rapidly evolving taxon. PMID:23133570

  12. Titan Casts Revealing Shadow

    NASA Astrophysics Data System (ADS)

    2004-05-01

    A rare celestial event was captured by NASA's Chandra X-ray Observatory as Titan -- Saturn's largest moon and the only moon in the Solar System with a thick atmosphere -- crossed in front of the X-ray bright Crab Nebula. The X-ray shadow cast by Titan allowed astronomers to make the first X-ray measurement of the extent of its atmosphere. On January 5, 2003, Titan transited the Crab Nebula, the remnant of a supernova explosion that was observed to occur in the year 1054. Although Saturn and Titan pass within a few degrees of the Crab Nebula every 30 years, they rarely pass directly in front of it. "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Koji Mori of Pennsylvania State University in University Park, and lead author on an Astrophysical Journal paper describing these results. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." Animation of Titan's Shadow on Crab Nebula Animation of Titan's Shadow on Crab Nebula Chandra's observation revealed that the diameter of the X-ray shadow cast by Titan was larger than the diameter of its solid surface. The difference in diameters gives a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere. The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. "Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may account for some of this atmospheric expansion," said Hiroshi Tsunemi of Osaka University in Japan, one of the coauthors on the paper. The X-ray brightness and extent of the Crab Nebula made it possible to study the tiny X-ray shadow cast by Titan during its transit. By using Chandra to precisely track Titan's position, astronomers were able to measure a shadow one arcsecond in

  13. The Influence of Cast Shadows on the Detection of Three-Dimensional Curved Contour Structure.

    PubMed

    Khuu, Sieu K; Honson, Vanessa J; Challinor, Kirsten L

    2016-04-01

    Cast shadows have been shown to provide an effective ordinal cue to the depth position of objects. In the present study, two experiments investigated the effectiveness of cast shadows in facilitating the detection of spatial contours embedded in a field of randomly placed elements. In Experiment 1, the separation between the cast shadow and the contour was systematically increased to effectively signal different contour depth positions (relative to background elements), and this was repeated for patterns in which the lighting direction was above and from below. Increasing the shadow separation improved contour detection performance, but the degree to which sensitivity changed was dependent on the lighting direction. Patterns in which the light was from above were better detected than patterns in which the lighting direction was from below. This finding is consistent with the visual system assuming a "light-from-above rule" when processing cast shadows. In Experiment 2, we examined the degree to which changing the shape of the cast shadow (by randomly jittering the position of local cast shadow elements) affected the ability of the visual system to rely on the cast shadow to cue the depth position of the contour. Consistent with a coarse scale analysis, we find that cast shadows remained an effective depth cue even at large degrees of element jitter. Our findings demonstrate that cast shadows provide an effective means of signaling depth, which aids the process of contour integration, and this process is largely tolerant of local variations in lighting direction.

  14. The Influence of Cast Shadows on the Detection of Three-Dimensional Curved Contour Structure.

    PubMed

    Khuu, Sieu K; Honson, Vanessa J; Challinor, Kirsten L

    2016-04-01

    Cast shadows have been shown to provide an effective ordinal cue to the depth position of objects. In the present study, two experiments investigated the effectiveness of cast shadows in facilitating the detection of spatial contours embedded in a field of randomly placed elements. In Experiment 1, the separation between the cast shadow and the contour was systematically increased to effectively signal different contour depth positions (relative to background elements), and this was repeated for patterns in which the lighting direction was above and from below. Increasing the shadow separation improved contour detection performance, but the degree to which sensitivity changed was dependent on the lighting direction. Patterns in which the light was from above were better detected than patterns in which the lighting direction was from below. This finding is consistent with the visual system assuming a "light-from-above rule" when processing cast shadows. In Experiment 2, we examined the degree to which changing the shape of the cast shadow (by randomly jittering the position of local cast shadow elements) affected the ability of the visual system to rely on the cast shadow to cue the depth position of the contour. Consistent with a coarse scale analysis, we find that cast shadows remained an effective depth cue even at large degrees of element jitter. Our findings demonstrate that cast shadows provide an effective means of signaling depth, which aids the process of contour integration, and this process is largely tolerant of local variations in lighting direction. PMID:27107019

  15. Ultra Large Castings to Produce Low Cost Aluminum Vehicle Structures

    SciTech Connect

    T. N. Meyer; M. J. Kinosz; E. M. Bradac; M. Mbaye; J. T. Burg; M. A. Klingensmith

    1999-04-26

    Through a cooperative effort with the U.S. Department of Energy (DOE) Office of Heavy Vehicle Technologies (OHVT), Alcoa is developing a casting process to produce ultra large thin wall components. The casting process is a low pressure, metal mold, multiport injection vertical casting process. The specific system for demonstration of the process is located at Alcoa's Technology Center and will be capable of producing parts extending 3 M long, 1.7 M wide and 0.4 M high. For example, single castings of car floor pan frames or side wall aperture structures are candidates for this installation. This shall provide a major opportunity to reduce the cost of lightweight transportation vehicle structures by (a) reducing the components or part count and (b) reducing the cost of assembly. To develop and demonstrate the process, an inner panel of the Chrysler minivan liftgate will be first produced on this system. Through computer analyses, the cast inner panel design was developed to satisfy both structural performance and casting process requirements. Currently, this is an 11 part assembly of steel components. At the time of this abstract, the numerous system components are in various phases of fabrication and site preparation is fully underway, with system shakedown beginning in the second quarter of 1999. Successful demonstration of caster system operation is anticipated to occur during the third quarter and production of a high quality product during the fourth quarter. Although the process is targeted toward reducing the cost of lightweight trucks, buses and autos, consideration is being given to application in the aircraft industry.

  16. Valuing uncertain cash flows from investments that enhance energy efficiency.

    PubMed

    Abadie, Luis M; Chamorro, José M; González-Eguino, Mikel

    2013-02-15

    There is a broad consensus that investments to enhance energy efficiency quickly pay for themselves in lower energy bills and spared emission allowances. However, investments that at first glance seem worthwhile usually are not undertaken. One of the plausible, non-excluding explanations is the numerous uncertainties that these investments face. This paper deals with the optimal time to invest in an energy efficiency enhancement at a facility already in place that consumes huge amounts of a fossil fuel (coal) and operates under carbon constraints. We follow the Real Options approach. Our model comprises three sources of uncertainty following different stochastic processes which allows for application in a broad range of settings. We assess the investment option by means of a three-dimensional binomial lattice. We compute the trigger investment cost, i.e., the threshold level below which immediate investment would be optimal. We analyze the major drivers of this decision thus aiming at the most promising policies in this regard.

  17. Nuclear-waste encapsulation by metal-matrix casting

    NASA Astrophysics Data System (ADS)

    Nelson, R. G.; Nesbitt, J. F.; Slate, S. C.

    1981-05-01

    Several encapsulation casting processes, developed to embed simulated high-level wastes of two different forms (glass marbles and ceramic pellets) in metal matrices, are described. Preliminary evaluations of these casting processes and the products are presented. Demonstrations hsow that 5- to 10-mm-dia glass marbles can be encapsulated on an engineering scale with lead or lead alloys by gravity or vacuum processes. Marbles approx. 12 mm in dia were successfully encapsulated in a lead alloy on a production scale. Also, 4- to 9-mm-dia ceramic pellets in containers of various sizes were completely penetrated and the individual pellets encased with aluminum-12 wt percent silicon alloy by vacuum 12 wt percent silicon alloy vacuum-cast around ceramic pellets had the highest degree of infiltration or coverage of pellet surfaces.

  18. Aluminum-Based Cast In Situ Composites: A Review

    NASA Astrophysics Data System (ADS)

    Pramod, S. L.; Bakshi, Srinivasa R.; Murty, B. S.

    2015-06-01

    In situ composites are a class of composite materials in which the reinforcement is formed within the matrix by reaction during the processing. In situ method of composite synthesis has been widely followed by researchers because of several advantages over conventional stir casting such as fine particle size, clean interface, and good wettability of the reinforcement with the matrix and homogeneous distribution of the reinforcement compared to other processes. Besides this, in situ processing of composites by casting route is also economical and amenable for large scale production as compared to other methods such as powder metallurgy and spray forming. Commonly used reinforcements for Al and its alloys which can be produced in situ are Al2O3, AlN, TiB2, TiC, ZrB2, and Mg2Si. The aim of this paper is to review the current research and development in aluminum-based in situ composites by casting route.

  19. Energy Saving Melting and Revert Reduction Technology (Energy-SMARRT): Light Metals Permanent Mold Casting

    SciTech Connect

    Fasoyinu, Yemi

    2014-03-31

    Current vehicles use mostly ferrous components for structural applications. It is possible to reduce the weight of the vehicle by substituting these parts with those made from light metals such as aluminum and magnesium. Many alloys and manufacturing processes can be used to produce these light metal components and casting is known to be most economical. One of the high integrity casting processes is permanent mold casting which is the focus of this research report. Many aluminum alloy castings used in automotive applications are produced by the sand casting process. Also, aluminum-silicon (Al-Si) alloys are the most widely used alloy systems for automotive applications. It is possible that by using high strength aluminum alloys based on an aluminum-copper (Al-Cu) system and permanent mold casting, the performance of these components can be enhanced significantly. This will also help to further reduce the weight. However, many technological obstacles need to be overcome before using these alloys in automotive applications in an economical way. There is very limited information in the open literature on gravity and low-pressure permanent mold casting of high strength aluminum alloys. This report summarizes the results and issues encountered during the casting trials of high strength aluminum alloy 206.0 (Al-Cu alloy) and moderate strength alloy 535.0 (Al-Mg alloy). Five engineering components were cast by gravity tilt-pour or low pressure permanent mold casting processes at CanmetMATERIALS (CMAT) and two production foundries. The results of the casting trials show that high integrity engineering components can be produced successfully from both alloys if specific processing parameters are used. It was shown that a combination of melt processing and mold temperature is necessary for the elimination of hot tears in both alloys.

  20. PRKAG3 and CAST genetic polymorphisms and quality traits of dry-cured hams--III. Associations in Slovenian dry-cured ham Kraški pršut and their dependence on processing.

    PubMed

    Škrlep, M; Čandek-Potokar, M; Žlender, B; Robert, N; Santé-Lhoutellier, V; Gou, P

    2012-12-01

    The aim of the present study, the third in a series of three papers, is to show the effects of PRKAG3 and CAST gene polymorphisms on the quality traits of the Slovenian dry-cured ham "Kraški pršut" and their interaction with ham producers. Significant interaction of polymorphisms with producer in the case of salt content, lipid oxidation (PRKAG3 Ile199Val), proteolysis index (CAST Arg249Lys) and pastiness (CAST Ser638Arg) indicated that genotype manifestation was reliant on the manufacturing practice. PRKAG3 Ile199Val polymorphism affected several physico-chemical, rheological and sensory traits. The Ile/Ile genotype yielded less salty and softer hams, indicating beneficial effects on dry-cured ham quality. The effect of CAST polymorphisms was less pronounced, although the observed associations with pastiness, proteolysis index and several free amino acid concentrations indicate its possible influence on proteolysis, with haplotype CAST 249Arg/638Ser being associated with a higher degree of proteolysis. PMID:22770931

  1. Invest in Family*

    PubMed Central

    Shah, Nilesh; De Sousa, Avinash

    2015-01-01

    The family is an integral part of one's life. It is very essential that every individual employed or unemployed invests time therein. The family is a source of support and growth for an individual, and the lack of family support or loneliness may be a causative factor in the genesis of psychiatric disorders, especially depression. In India, family plays a paramount role when it comes to mental health of the individual. Tips on how one should invest time in one's family along with the role of a family in one's personal and social structure are discussed. PMID:25838732

  2. Indirect Fabrication of Lattice Metals with Thin Sections Using Centrifugal Casting.

    PubMed

    Mun, Jiwon; Ju, Jaehyung; Thurman, James

    2016-01-01

    One of the typical methods to manufacture 3D lattice metals is the direct-metal additive manufacturing (AM) process such as Selective Laser Melting (SLM) and Electron Beam Melting (EBM). In spite of its potential processing capability, the direct AM method has several disadvantages such as high cost, poor surface finish of final products, limitation in material selection, high thermal stress, and anisotropic properties of parts. We propose a cost-effective method to manufacture 3D lattice metals. The objective of this study is to provide a detailed protocol on fabrication of 3D lattice metals having a complex shape and a thin wall thickness; e.g., octet truss made of Al and Cu alloys having a unit cell length of 5 mm and a cell wall thickness of 0.5 mm. An overall experimental procedure is divided into eight sections: (a) 3D printing of sacrificial patterns (b) melt-out of support materials (c) removal of residue of support materials (d) pattern assembly (e) investment (f) burn-out of sacrificial patterns (g) centrifugal casting (h) post-processing for final products. The suggested indirect AM technique provides the potential to manufacture ultra-lightweight lattice metals; e.g., lattice structures with Al alloys. It appears that the process parameters should be properly controlled depending on materials and lattice geometry, observing the final products of octet truss metals by the indirect AM technique. PMID:27214495

  3. Indirect Fabrication of Lattice Metals with Thin Sections Using Centrifugal Casting.

    PubMed

    Mun, Jiwon; Ju, Jaehyung; Thurman, James

    2016-05-14

    One of the typical methods to manufacture 3D lattice metals is the direct-metal additive manufacturing (AM) process such as Selective Laser Melting (SLM) and Electron Beam Melting (EBM). In spite of its potential processing capability, the direct AM method has several disadvantages such as high cost, poor surface finish of final products, limitation in material selection, high thermal stress, and anisotropic properties of parts. We propose a cost-effective method to manufacture 3D lattice metals. The objective of this study is to provide a detailed protocol on fabrication of 3D lattice metals having a complex shape and a thin wall thickness; e.g., octet truss made of Al and Cu alloys having a unit cell length of 5 mm and a cell wall thickness of 0.5 mm. An overall experimental procedure is divided into eight sections: (a) 3D printing of sacrificial patterns (b) melt-out of support materials (c) removal of residue of support materials (d) pattern assembly (e) investment (f) burn-out of sacrificial patterns (g) centrifugal casting (h) post-processing for final products. The suggested indirect AM technique provides the potential to manufacture ultra-lightweight lattice metals; e.g., lattice structures with Al alloys. It appears that the process parameters should be properly controlled depending on materials and lattice geometry, observing the final products of octet truss metals by the indirect AM technique.

  4. Expandable pattern casting research. Phase 2, Final report, October 1, 1990--March 31, 1993

    SciTech Connect

    Not Available

    1993-12-01

    The Expandable Pattern Casting (EPC) Process is a developing foundry technology that allows designers the opportunity to consolidate parts, reduce machining, and minimize assembly operations. An air gauging system was developed for measuring foam patterns; exact shrinkage depended on type and density of the foam. Compaction studies showed that maximum sand densities in cavities and under overhangs are achieved with vibrational amplitudes 0.001--0.004 in., and that sand moved most freely within a few inches of the top free surface. Key to complete mold filling while minimizing casting defects lies in removing the foam decomposition products. The most precise iron castings were made by EPC in four commercial EPC foundries, with attention paid to molding and compaction. EP cast 60-45-12 ductile iron had yield strengths, ultimate strengths, and elastic modulus similar to conventionally cast ductile iron cast from the same ladle.

  5. Graphitic corrosion -- Don`t forget about buried cast iron pipes

    SciTech Connect

    Freeman, S.R.

    1999-08-01

    Graphitic corrosion is a form of de-alloying or selective leaching that occurs in cast iron material. This corrosion mechanism is unique to gray cast irons and is caused by the graphitic matrix present. The graphite is cathodic to the iron matrix. Exposure to an electrolyte results in leaching of the iron matrix, leaving behind a porous mass of graphite flakes. Graphite corrosion often occurs in buried gray cast iron pipes, although exposure to an aqueous environment is all that is necessary for the de-alloying to occur. The process of de-alloying in cast iron typically is long-term, taking several years to occur. In fact, many cases of graphitic corrosion-caused failure in cast iron piping occur in piping that has been in service for 50 years or more. Mechanical testing to determine the tensile strength of cast iron can provide information regarding the remaining strength of the pipe.

  6. Quality improvement as an investment.

    PubMed

    Weeks, William B

    2002-01-01

    Health care organizations are experiencing increasing internal and external pressures to improve the quality of care that they provide. However, there is not a framework that can be used to help understand the value of quality improvement projects and to prioritize competing projects. By understanding the current processes, costs and outcomes of care, enumerating the costs and benefits of change, anticipating the timing of the costs and benefits, and performing a financial analysis, quality improvement efforts can be evaluated as investments. Only by understanding and adapting to the financial environments in which health care organizations operate can continuous quality improvement in health care succeed. PMID:12512466

  7. Secondary Waste Cast Stone Waste Form Qualification Testing Plan

    SciTech Connect

    Westsik, Joseph H.; Serne, R. Jeffrey

    2012-09-26

    The Hanford Tank Waste Treatment and Immobilization Plant (WTP) is being constructed to treat the 56 million gallons of radioactive waste stored in 177 underground tanks at the Hanford Site. The WTP includes a pretreatment facility to separate the wastes into high-level waste (HLW) and low-activity waste (LAW) fractions for vitrification and disposal. The LAW will be converted to glass for final disposal at the Integrated Disposal Facility (IDF). Cast Stone – a cementitious waste form, has been selected for solidification of this secondary waste stream after treatment in the ETF. The secondary-waste Cast Stone waste form must be acceptable for disposal in the IDF. This secondary waste Cast Stone waste form qualification testing plan outlines the testing of the waste form and immobilization process to demonstrate that the Cast Stone waste form can comply with the disposal requirements. Specifications for the secondary-waste Cast Stone waste form have not been established. For this testing plan, Cast Stone specifications are derived from specifications for the immobilized LAW glass in the WTP contract, the waste acceptance criteria for the IDF, and the waste acceptance criteria in the IDF Permit issued by the State of Washington. This testing plan outlines the testing needed to demonstrate that the waste form can comply with these waste form specifications and acceptance criteria. The testing program must also demonstrate that the immobilization process can be controlled to consistently provide an acceptable waste form product. This testing plan also outlines the testing needed to provide the technical basis for understanding the long-term performance of the waste form in the disposal environment. These waste form performance data are needed to support performance assessment analyses of the long-term environmental impact of the secondary-waste Cast Stone waste form in the IDF

  8. Mathematical Modeling and Microstructure Analysis of Low Carbon Steel Strips Produced by Horizontal Single Belt Casting (HSBC)

    NASA Astrophysics Data System (ADS)

    Ge, Sa; Chang, Sheng; Wang, Tong; Calzado, Luis E.; Isac, Mihaiela; Kozinski, Janusz; Guthrie, Roderick I. L.

    2016-06-01

    The horizontal single belt casting (HSBC) process has been proposed as an efficient, economical, and environmentally friendly alternative approach to the production of ferrous alloys. Low carbon steel strips were cast using the HSBC simulator apparatus to study the characteristics and properties of the as-cast steel strips. Three-dimensional computational fluid dynamics simulations using ANSYS FLUENT 14.5 were also performed. Numerical predictions were validated against experimental casting results. Microstructural analyses and as-cast surface texture studies were conducted on low carbon steels.

  9. Microstructural characterization of as-cast biocompatible Co-Cr-Mo alloys

    SciTech Connect

    Giacchi, J.V.; Morando, C.N.; Fornaro, O.; Palacio, H.A.

    2011-01-15

    The microstructure of a cobalt-base alloy (Co-Cr-Mo) obtained by the investment casting process was studied. This alloy complies with the ASTM F75 standard and is widely used in the manufacturing of orthopedic implants because of its high strength, good corrosion resistance and excellent biocompatibility properties. This work focuses on the resulting microstructures arising from samples poured under industrial environment conditions, of three different Co-Cr-Mo alloys. For this purpose, we used: 1) an alloy built up from commercial purity constituents, 2) a remelted alloy and 3) a certified alloy for comparison. The characterization of the samples was achieved by using optical microscopy (OM) with a colorant etchant to identify the present phases and scanning electron microscopy (SE-SEM) and energy dispersion spectrometry (EDS) techniques for a better identification. In general the as-cast microstructure is a Co-fcc dendritic matrix with the presence of a secondary phase, such as the M{sub 23}C{sub 6} carbides precipitated at grain boundaries and interdendritic zones. These precipitates are the main strengthening mechanism in this type of alloys. Other minority phases were also reported and their presence could be linked to the cooling rate and the manufacturing process variables and environment. - Research Highlights: {yields}The solidification microstructure of an ASTM-F75 type alloy were studied. {yields}The alloys were poured under an industrial environment. {yields}Carbides and sigma phase identified by color metallography and scanning microscopy (SEM and EDS). {yields}Two carbide morphologies were detected 'blocky type' and 'pearlite type'. {yields}Minority phases were also detected.

  10. The perception of three-dimensional cast-shadow structure is dependent on visual awareness.

    PubMed

    Khuu, Sieu K; Gordon, Jack; Balcomb, Kaleah; Kim, Juno

    2014-03-19

    In the present study we examined whether the perception of depth from cast shadows is dependent on visual awareness using continuous flash suppression (CFS). As a direct measure of how the visual system infers depth from cast shadows, we examined the cast-shadow motion illusion originally reported by Kersten, Knill, Mamassian, and Bulthoff (1996), in which a moving cast shadow induces illusory motion in depth in a physically stationary object. In Experiment 1, we used a disparity defined probe to determine the stereo motion speed required to match the cast-shadow motion illusion for different cast shadow speeds (0°/s-1.6°/s) and different lighting directions. We found that configurations implying light from above produce more compelling illusory effects. We also found that increasing shadow speed monotonically increased the stereo motion speed required to match the illusory motion, which suggests that quantitative depth can be derived from cast shadows when they are in motion. In Experiment 2, we used CFS to suppress the cast shadow from visual awareness. Visual suppression of the cast shadow from awareness greatly diminished the perception of illusory motion in depth. In Experiment 3 we confirmed that while CFS suppresses the cast-shadow motion from awareness, it continues to be processed by the visual system sufficient to generate a significant motion after effect. The results of the present study suggest that cast shadows can greatly contribute to the perception of scene depth structure, through a process that is dependent on the conscious awareness of the cast shadow.

  11. Energy Investment: Beyond Competence

    ERIC Educational Resources Information Center

    Tosti, Donald T.; Amarant, John

    2005-01-01

    People vary considerably in their work performance as well as their overall approach to work. At one extreme are the outstanding performers, who approach work with enthusiasm and energy, and, at the other extreme, are those who seem to do only what is necessary to get by. Organizatins often invest a good deal of energy in trying to improve the…

  12. Beyond the Investment Narrative

    ERIC Educational Resources Information Center

    Moss, Peter

    2013-01-01

    The current policy interest in early childhood education and care is driven by an investment narrative, a story of quality and high returns emerging from a dominant neoliberal political economy. This short note expresses deep reservations about this narrative, and hints at another narrative that foregrounds democracy, experimentation and…

  13. Strategic Investments Overview

    NASA Technical Reports Server (NTRS)

    Comstock, Doug

    2004-01-01

    This viewgraph presentation provides an overview of the organizational hierarchy for strategic management and strategic investments at NASA. The presentation also relates these topics to the budgets it submits to Congress, strategies for space exploration research and development, and systems analysis.

  14. Morphological castes in a vertebrate.

    PubMed

    O'Riain, M J; Jarvis, J U; Alexander, R; Buffenstein, R; Peeters, C

    2000-11-21

    Morphological specialization for a specific role has, until now, been assumed to be restricted to social invertebrates. Herein we show that complete physical dimorphism has evolved between reproductives and helpers in the eusocial naked mole-rat. Dimorphism is a consequence of the lumbar vertebrae lengthening after the onset of reproduction in females. This is the only known example of morphological castes in a vertebrate and is distinct from continuous size variation between breeders and helpers in other species of cooperatively breeding vertebrates. The evolution of castes in a mammal and insects represents a striking example of convergent evolution for enhanced fecundity in societies characterized by high reproductive skew. Similarities in the selective environment between naked mole-rats and eusocial insect species highlight the selective conditions under which queen/worker castes are predicted to evolve in animal societies.

  15. Modeling and Analysis of The Pressure Die Casting Using Response Surface Methodology

    SciTech Connect

    Kittur, Jayant K.; Herwadkar, T. V.; Parappagoudar, M. B.

    2010-10-26

    Pressure die casting is successfully used in the manufacture of Aluminum alloys components for automobile and many other industries. Die casting is a process involving many process parameters having complex relationship with the quality of the cast product. Though various process parameters have influence on the quality of die cast component, major influence is seen by the die casting machine parameters and their proper settings. In the present work, non-linear regression models have been developed for making predictions and analyzing the effect of die casting machine parameters on the performance characteristics of die casting process. Design of Experiments (DOE) with Response Surface Methodology (RSM) has been used to analyze the effect of effect of input parameters and their interaction on the response and further used to develop nonlinear input-output relationships. Die casting machine parameters, namely, fast shot velocity, slow shot to fast shot change over point, intensification pressure and holding time have been considered as the input variables. The quality characteristics of the cast product were determined by porosity, hardness and surface rough roughness (output/responses). Design of experiments has been used to plan the experiments and analyze the impact of variables on the quality of casting. On the other-hand Response Surface Methodology (Central Composite Design) is utilized to develop non-linear input-output relationships (regression models). The developed regression models have been tested for their statistical adequacy through ANOVA test. The practical usefulness of these models has been tested with some test cases. These models can be used to make the predictions about different quality characteristics, for the known set of die casting machine parameters, without conducting the experiments.

  16. Advanced Lost Foam Casting technology: 1997 summary report

    SciTech Connect

    1997-12-31

    Previous research made significant advances in understanding the Lost Foam Casting (LFC) Process and clearly identified areas where additional research was needed to improve the process and make it more functional in an industrial environment. The current project focused on eight tasks listed as follows: Task 1--pyrolysis defects and sand distortion; Task 2--bronze casting technology; Task 3--steel casting technology; Task 4--sand filling and compaction; Task 5--coating technology; Task 6--precision pattern production; Task 7--computational modeling; and Task 8--project management and technology transfer. This report summarizes the work done under the current contract in all eight tasks in the period of October 1, 1995 through December 31, 1997.

  17. Multipurpose Vacuum Induction Processing System

    NASA Astrophysics Data System (ADS)

    Govindaraju, M.; Kulkarni, Deepak; Balasubramanian, K.

    2012-11-01

    Multipurpose vacuum processing systems are cost effective; occupy less space, multiple functional under one roof and user friendly. A multipurpose vacuum induction system was designed, fabricated and installed in a record time of 6 months time at NFTDC Hyderabad. It was designed to function as a) vacuum induction melting/refining of oxygen free electronic copper/pure metals, b) vacuum induction melting furnace for ferrous materials c) vacuum induction melting for non ferrous materials d) large vacuum heat treatment chamber by resistance heating (by detachable coil and hot zone) e) bottom discharge vacuum induction melting system for non ferrous materials f) Induction heat treatment system and g) directional solidification /investment casting. It contains provision for future capacity addition. The attachments require to manufacture multiple shaped castings and continuous rod casting can be added whenever need arises. Present capacity is decided on the requirement for 10years of development path; presently it has 1.2 ton liquid copper handling capacity. It is equipped with provision for capacity addition up to 2 ton liquid copper handling capacity in future. Provision is made to carry out the capacity addition in easy steps quickly. For easy operational maintenance and troubleshooting, design was made in easily detachable sections. High vacuum system is also is detachable, independent and easily movable which is first of its kind in the country. Detailed design parameters, advantages and development history are presented in this paper.

  18. Application of owner technical management in hydraulic machinery and electrical equipment investment target control

    NASA Astrophysics Data System (ADS)

    Luo, H.

    2012-11-01

    Using technical means in investment target control is an effective method to improve investment benefit of a construction project. Take the practice of construction and management in hydropower station as an example, the investment and management need of the owner is put forward through the investment target decision-making process of electromechanical equipment. Owner technical management in the specific application measures and effects of investment target control was discussed in the paper, and the revelation in investment target control application of owner technical management was also summarized. The paper is aimed to provide a useful reference for the investment target control work in the construction of electromechanical equipment.

  19. Casting propellant in rocket engine

    NASA Technical Reports Server (NTRS)

    Roach, J. E.; Froehling, S. C. (Inventor)

    1976-01-01

    A method is described for casting a solid propellant in the casing of a rocket engine having a continuous wall with a single opening which is formed by leaves of a material which melt at a temperature of the propellant and with curved edges concentric to the curvature of the spherical casing. The leaves are inserted into the spherical casing through the opening forming a core having a greater width than the width of the single opening and with curved peripheral edges. The cast propellant forms a solid mass and then heated to melt the leaves and provide a central opening with radial projecting flutes.

  20. Corrosion behavior of cast Ti-6Al-4V alloyed with Cu.

    PubMed

    Koike, Marie; Cai, Zhuo; Oda, Yutaka; Hattori, Masayuki; Fujii, Hiroyuki; Okabe, Toru

    2005-05-01

    It has recently been found that alloying with copper improved the inherently poor grindability and wear resistance of titanium. This study characterized the corrosion behavior of cast Ti-6Al-4V alloyed with copper. Alloys (0.9 or 3.5 mass % Cu) were cast with the use of a magnesia-based investment in a centrifugal casting machine. Three specimen surfaces were tested: ground, sandblasted, and as cast. Commercially pure titanium and Ti-6Al-4V served as controls. Open-circuit potential measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air + 10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was conducted in the same medium deaerated by N(2) + 10% CO(2). Polarization resistance (R(p)), Tafel slopes, and corrosion current density (I(corr)) were determined. A passive region occurred for the alloy specimens with ground and sandblasted surfaces, as for CP Ti. However, no passivation was observed on the as-cast alloys or on CP Ti. There were significant differences among all metals tested for R(p) and I(corr) and significantly higher R(p) and lower I(corr) values for CP Ti compared to Ti-6Al-4V or the alloys with Cu. Alloying up to 3.5 mass % Cu to Ti-6Al-4V did not change the corrosion behavior. Specimens with ground or sandblasted surfaces were superior to specimens with as-cast surfaces. PMID:15744719

  1. The potential of squeeze casting for the production of near net shape uranium parts

    SciTech Connect

    Robertson, E.

    1993-11-01

    This report was written to provide a detailed summary of a literature survey on the near net shape squeeze casting process. Squeeze casting was evaluated as a possible method for achieving the goals of the LANL program titled Near Net Shape Casting of Uranium for Reduced Environmental, Safety, and Health Impact. In this report the squeeze casting process is reviewed and an assessment of its ability to achieve the near net shape and waste minimization goals of the LANL program is made. It is concluded that although squeeze casting is capable of producing near net shaped parts and reducing the amount of subsequent machining (thereby decreasing wastes), to use the process with uranium would require the design of a unique piece of equipment capable of performing the melting, pouring and squeezing operations in close proximity and in a vacuum.

  2. Tuning the properties of polyhydroxybutyrate films using acetic acid via solvent casting

    NASA Astrophysics Data System (ADS)

    Anbukarasu, Preetam; Sauvageau, Dominic; Elias, Anastasia

    2015-12-01

    Biodegradable polyhydroxybutyrate (PHB) films were fabricated using acetic acid as an alternative to common solvents such as chloroform. The PHB films were prepared using a solvent casting process at temperatures ranging from 80 °C to 160 °C. The crystallinity, mechanical properties and surface morphology of the films cast at different temperatures were characterized and compared to PHB films cast using chloroform as a solvent. Results revealed that the properties of the PHB film varied considerably with solvent casting temperature. In general, samples processed with acetic acid at low temperatures had comparable mechanical properties to PHB cast using chloroform. This acetic acid based method is environmentally friendly, cost efficient and allows more flexible processing conditions and broader ranges of polymer properties than traditional methods.

  3. Tuning the properties of polyhydroxybutyrate films using acetic acid via solvent casting

    PubMed Central

    Anbukarasu, Preetam; Sauvageau, Dominic; Elias, Anastasia

    2015-01-01

    Biodegradable polyhydroxybutyrate (PHB) films were fabricated using acetic acid as an alternative to common solvents such as chloroform. The PHB films were prepared using a solvent casting process at temperatures ranging from 80 °C to 160 °C. The crystallinity, mechanical properties and surface morphology of the films cast at different temperatures were characterized and compared to PHB films cast using chloroform as a solvent. Results revealed that the properties of the PHB film varied considerably with solvent casting temperature. In general, samples processed with acetic acid at low temperatures had comparable mechanical properties to PHB cast using chloroform. This acetic acid based method is environmentally friendly, cost efficient and allows more flexible processing conditions and broader ranges of polymer properties than traditional methods. PMID:26640089

  4. Advanced Lost Foam Casting Technology - Phase V

    SciTech Connect

    Wanliang Sun; Harry E. Littleton; Charles E. Bates

    2004-04-29

    Previous research, conducted under DOE Contracts DE-FC07-89ID12869, DE-FC07-93ID12230 and DE-FC07-95ID113358 made significant advances in understanding the Lost Foam Casting (LFC) Process and clearly identified areas where additional developments were needed to improve the process and make it more functional in industrial environments. The current project focused on eight tasks listed as follows: Task 1--Computational Model for the Process and Data Base to Support the Model; Task 2--Casting Dimensional Accuracy; Task 3--Pattern Production; Task 4--Improved Pattern Materials; Task 5--Coating Control; Task 6--In-Plant Case Studies; Task 7--Energy and the Environmental Data; and Task 8--Technology Transfer. This report summarizes the work done on all tasks in the period of October 1, 1999 through September 30, 2004. The results obtained in each task and subtask are summarized in this Executive Summary and details are provided in subsequent sections of the report.

  5. Textures of strip cast Fe16%Cr

    SciTech Connect

    Raabe, D.; Reher, F.; Luecke, K. ); Hoelscher, M. )

    1993-07-01

    Ferritic stainless steels with a Cr content of 16% are mainly manufactured by continuous casting, hot rolling, cold rolling and final recrystallization. The recent development of the strip casting method, which provides sheets with an equivalent geometry, i.e. thickness and width as the hot rolled band, yields significant improvements in comparison to the conventional processing. The weak initial strip texture and the homogeneous microstructure through the sample thickness have shown evidence of avoiding the well known ridging phenomenon of the finally rolled and annealed product. The occurrence of ridging in conventionally processed FeCr steel has been attributed to the collective shear of grains with (hkl)<110>, i.e. [alpha]-fibre orientations, which become oriented and topologically arranged during hot rolling. In the present paper the textures of a stainless ferritic steel with 16% Cr and 0.02% C, strip casted (SC) as well as hot rolled (HR), were thus investigated. The textures were examined by measuring the four incomplete pole figures (110), (200), (112) and (103) in the back reflection mode. The orientation distribution function (ODF) was calculated by the series expansion method (1[sup max]=22). In the case of cubic crystal symmetry and orthorhombic sample symmetry an orientation can then be presented by the three Euler angles [var phi][sub 1], [var phi], [var phi][sub 2] in the reducted Euler space. Since bcc steels tend to develop characteristic fibre textures, it is favorable to present the ODFs as isointensity diagrams in [var phi][sub 1]-sections through the Eulerspace. In this work the [alpha]-fibre and the [gamma]-fibre are of major interest.

  6. INTERIOR VIEW WITH CASTING MACHINE AND A 4' DUCTILE IRON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW WITH CASTING MACHINE AND A 4' DUCTILE IRON PIPE BEING CENTRIFUGALLY CAST, AS OPERATOR WATCHES TO ENSURE QUALITY. - McWane Cast Iron Pipe Company, Pipe Casting Area, 1201 Vanderbilt Road, Birmingham, Jefferson County, AL

  7. INTERIOR VIEW OF CASTING MACHINE WITH 4' DUCTILE IRON PIPE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW OF CASTING MACHINE WITH 4' DUCTILE IRON PIPE BEING WEIGHED ON SCALES AT CASTING MACHINE. - McWane Cast Iron Pipe Company, Pipe Casting Area, 1201 Vanderbilt Road, Birmingham, Jefferson County, AL

  8. INTERIOR VIEW WITH CASTING MACHINE AND A 4" DUCTILE IRON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW WITH CASTING MACHINE AND A 4" DUCTILE IRON PIPE BEING EXTRACTED FROM CASTING MACHINE - McWane Cast Iron Pipe Company, Pipe Casting Area, 1201 Vanderbilt Road, Birmingham, Jefferson County, AL

  9. INTERIOR VIEW WITH CASTING MACHINE COOLING A 20' IRON PIPE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW WITH CASTING MACHINE COOLING A 20' IRON PIPE PRIOR TO EXTRACTION FROM CASTING MACHINE. - McWane Cast Iron Pipe Company, Pipe Casting Area, 1201 Vanderbilt Road, Birmingham, Jefferson County, AL

  10. Advocating investments in information technology

    SciTech Connect

    Nirenberg, L.M. )

    1992-01-01

    Information and communication systems can improve the timeliness and quality of decisions. These benefits are strategically important to the utility industry in an era of increasing competition. Because these systems often do not reduce labor cost, however, they can be difficult to evaluate. This report presents a new process for reaching consensus of the value of capital investment in information and communication systems. The results of this project is A Strategic Advocacy Process (ASAP), a methodology that can be used to evaluate investments in information technology. ASAP uses belief graphs to produce a living business case showing facts, assumptions, goals, and metrics for measuring progress toward those goals; shows how to use option pricing theory to quantify the value of managerial flexibility; ASAP uses an organizational impact assessment tool to identify the potential impact of new information systems and how to realize the benefits of managerial flexibility. The ASAP methodology addresses the critical problem of correctly valuing information and communication systems. The methodology offers a way to account for the intangible'' value of these systems by recognizing the managerial flexibility these systems can provide in addressing risks and uncovering new business opportunities. Metrics for measuring progress toward new goals can be defined, and plans for achieving the goals can be made. As a result, agreement can be reached on the uses, value, and priority of projects based on a metric other than on labor replacement savings.

  11. Development of a New Membrane Casting Apparatus for Studying Macrovoid Defects in Low-G

    NASA Technical Reports Server (NTRS)

    Lee, Hanyong; Hwang, Sun-Tak; Krantz, William B.; Greenberg, Alan R.; Khare, Vivek; Zartman, Jeremiah; Todd, Paul W.

    2002-01-01

    A new membrane-casting apparatus is developed for studying macrovoid defects in polymeric membranes made by the wet- and dry-casting process in low-gravity. Macrovoids are large (10-50 micron), open cavities interspersed among the smaller pores in the substructure under the gelled skin surface layer of the cast membrane. Although their occurrence is considered endemic to the wet- and dry-casting process since they can lead to compaction or skin rupture in the membrane process, recent studies suggest several useful applications such as transdermal and osmotic drug delivery systems, miniature bioreactors, etc. However, lack of knowledge about the macrovoid formation mechanism is an obstacle to further development of applications using them. An on-going debate is the role of the surface-tension-driven solutocapillary convection during macrovoid formation. The rapid growth of macrovoids within 1-5 seconds and the high polymer concentration in and near macrovoids make it difficult to explain the mechanism of macrovoid growth by diffusion alone, which is the widely accepted hypothesis proposed by Reuvers et al. The hypothesis advanced by our research group can explain this rapid growth via a mechanism that involves diffusion from the casting solution in the meta-stable region to the macrovoid enhanced by solutocapillary convection induced by the steep nonsolvent concentration gradient in the vicinity of the macrovoid. Since macrovoid growth is hypothesized to be the interplay of a solutocapillary-induced driving force counteracted by viscous drag and buoyancy, eliminate the latter provides a means for testing this hypothesis. Moreover, free convection mass transfer in the nonsolvent immersion bath used to cause phase-separation in membrane casting complicates developing a model for both the wet-casting process and macrovoid growth. The low-g environment minimizes gravitationally induced free convection thereby permitting a tractable solution to the ternary diffusion

  12. Designing a successful investment program.

    PubMed

    Karpinski, J P

    1997-02-01

    Healthcare organizations have various asset pool funds that can be invested to increase nonoperating revenues. In order to maximize the long-term success of investment efforts, healthcare organizations need to develop comprehensive investment management programs. Such programs identify the assets that can be invested, establish the level of risk each asset type can be exposed to, and match long-term and short-term investment opportunities to the appropriate asset pool. Programs can be managed internally or outsourced to investment management firms with objectives and procedures that are compatible with those of the healthcare organizations' investment policies and guidelines. These policies and guidelines must address asset allocation. Oversight committees must be established to monitor investment performance and reallocate assets, as needed, to take advantage of market movements.

  13. Designing a successful investment program.

    PubMed

    Karpinski, J P

    1997-02-01

    Healthcare organizations have various asset pool funds that can be invested to increase nonoperating revenues. In order to maximize the long-term success of investment efforts, healthcare organizations need to develop comprehensive investment management programs. Such programs identify the assets that can be invested, establish the level of risk each asset type can be exposed to, and match long-term and short-term investment opportunities to the appropriate asset pool. Programs can be managed internally or outsourced to investment management firms with objectives and procedures that are compatible with those of the healthcare organizations' investment policies and guidelines. These policies and guidelines must address asset allocation. Oversight committees must be established to monitor investment performance and reallocate assets, as needed, to take advantage of market movements. PMID:10164878

  14. Investment Vehicles for School Funds.

    ERIC Educational Resources Information Center

    Holman, Paul C.

    1987-01-01

    School administrators are advised to invest school funds for maximum return, coupled with safety and flexibility. The advantages and disadvantages of a variety of investment instruments are explained. (MLF)

  15. The most influential investment.

    PubMed

    Summers, L

    1993-01-01

    Investment in women's education possibly has a greater return than investing in areas such as power generation. Education is an economic issue. When the self-fulfilling prophecy of girls' lack of education yielding lower economic worth is compared with the self-fulfilling prophecy of educated women having healthy children and greater earning ability, there is no doubt which scenario is more beneficial to the individual and society. Wages of educated female workers rise by 20%, and personal hygiene and public health improvements contribute to lower fertility and infant mortality. In Pakistan, educating an additional 1000 girls/year would cost $40,000 in 1990 prices. Each year of schooling would reduce the under-5 year child mortality rate by 10%. 1000 women with an extra year of schooling would prevent 60 infant deaths, which if prevented through health care interventions would cost an estimated $48,000. Female fertility would be reduced by about 10% for an extra year of schooling, and thus would avert 660 births or a saving $43,000. Social improvement alone is worth the extra cost. Investing in female education means establishing scholarship funds, providing more free books and other supplies, adapting curricula to cultural and practical concerns, and hiring female teachers. Increasing female primary school enrollment to equal boys enrollment in low income countries would mean educating an extra 25 million girls every/year at a total cost of about $938 million. Equalizing secondary school enrollment would entail educating an extra 21 million girls at a cost of $1.4 billion. The total cost of $2.4 billion constitutes less than .25% of the gross domestic product of low income countries, less than 1% of investment in new capital goods, and less than 10% of defense spending. Investment statistics on power plants in a sample of 57 developing countries showed a return on physical plant assets of less than 4% over the past 3 years and less than 6% over the past 10 years

  16. Three-dimensional assessment of dental casts' occlusal surfaces using two impression materials.

    PubMed

    Tarawneh, F M; Panos, P G; Athanasiou, A E

    2008-11-01

    The aim of this study was to assess by means of a three-dimensional computed tomography scanning system the occlusal surface characteristics of dental casts made using two different impression materials. Alginate and polyvinyl siloxane impressions were taken of 20 dental students resulting in 40 dental casts. The casts were paired for each student separately so that each pair consisted of an alginate poured cast and a polyvinyl siloxane poured out cast. The casts were scanned using FlashCT scanner and for each cast, a three-dimensional digital image was obtained. The digitized casts were processed using the three-dimensional imaging software Geomagic Studio 9. A total of 464 paired teeth were digitally separated and superimposed. For each tooth, two measurements were obtained corresponding to the two different impression materials used. The two sets of volumes for all digitally separated teeth were compared and analysed using the Wilcoxon signed test. Larger volume measurements were obtained for teeth separated from alginate poured out casts than from their corresponding ones from polyvinyl siloxane casts (P = 0.005). When the teeth were divided into the groups of incisors, canines and premolars/molars, only the last one exhibited significant difference (P = 0.00). The mean difference between the volumes measured for all 464 teeth separated was 0.041 mm(3) (+/-0.33). The occlusal surfaces of teeth appear differently in dental casts depending on the impression materials used. Impressions of dental casts should be utilized with caution in relation to their research application and in reference with dental wear studies.

  17. Materials for Advanced Ultrasupercritical Steam Turbines Task 4: Cast Superalloy Development

    SciTech Connect

    Thangirala, Mani

    2015-09-30

    The Steam Turbine critical stationary structural components are high integrity Large Shell and Valve Casing heavy section Castings, containing high temperature steam under high pressures. Hence to support the development of advanced materials technology for use in an AUSC steam turbine capable of operating with steam conditions of 760°C (1400°F) and 35 Mpa (5000 psia), Casting alloy selection and evaluation of mechanical, metallurgical properties and castability with robust manufacturing methods are mandated. Alloy down select from Phase 1 based on producability criteria and creep rupture properties tested by NETL-Albany and ORNL directed the consortium to investigate cast properties of Haynes 282 and Haynes 263. The goals of Task 4 in Phase 2 are to understand a broader range of mechanical properties, the impact of manufacturing variables on those properties. Scale up the size of heats to production levels to facilitate the understanding of the impact of heat and component weight, on metallurgical and mechanical behavior. GE Power & Water Materials and Processes Engineering for the Phase 2, Task 4.0 Castings work, systematically designed and executed casting material property evaluation, multiple test programs. Starting from 15 lbs. cylinder castings to world’s first 17,000 lbs. poured weight, heavy section large steam turbine partial valve Haynes 282 super alloy casting. This has demonstrated scalability of the material for steam Turbine applications. Activities under Task 4.0, Investigated and characterized various mechanical properties of Cast Haynes 282 and Cast Nimonic 263. The development stages involved were: 1) Small Cast Evaluation: 4 inch diam. Haynes 282 and Nimonic 263 Cylinders. This provided effects of liquidus super heat range and first baseline mechanical data on cast versions of conventional vacuum re-melted and forged Ni based super alloys. 2) Step block castings of 300 lbs. and 600 lbs. Haynes 282 from 2 foundry heats were evaluated which

  18. Casting Freedom, 1860-1862

    ERIC Educational Resources Information Center

    Social Education, 2005

    2005-01-01

    Thomas Crawford, an American Sculptor, created the full-size figure of Freedom in clay. Molds were made, from which a full-size positive plaster model was cast in five main sections. This model is on view today in the basement rotunda of the Russell Senate Office Building. Clark Mills was a self-taught American sculptor with experience in casting…

  19. Tape casting of magnesium oxide.

    SciTech Connect

    Ayala, Alicia; Corral, Erica L.; Loehman, Ronald E.; Bencoe, Denise Nora; Reiterer, Markus; Shah, Raja A.

    2008-02-01

    A tape casting procedure for fabricating ceramic magnesium oxide tapes has been developed as a method to produce flat sheets of sintered MgO that are thin and porous. Thickness of single layer tapes is in the range of 200-400 {micro}m with corresponding surface roughness values in the range of 10-20 {micro}m as measured by laser profilometry. Development of the tape casting technique required optimization of pretreatment for the starting magnesium oxide (MgO) powder as well as a detailed study of the casting slurry preparation and subsequent heat treatments for sintering and final tape flattening. Milling time of the ceramic powder, plasticizer, and binder mixture was identified as a primary factor affecting surface morphology of the tapes. In general, longer milling times resulted in green tapes with a noticeably smoother surface. This work demonstrates that meticulous control of the entire tape casting operation is necessary to obtain high-quality MgO tapes.

  20. Molding A Cast Metals Program

    ERIC Educational Resources Information Center

    Trumble, Dale E.

    1975-01-01

    The cast metals program, a two-year associate degree program, at Muskegon Community College, Musegon, Michigan operates in close cooperation with the local foundry industry to provide a background for entry-level technical jobs and for continued studies toward a four-year degree. (EA)