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Sample records for semi-solid die casting

  1. Numerical simulation on semi-solid die-casting of magnesium matrix composite based on orthogonal experiment

    NASA Astrophysics Data System (ADS)

    Liu, Huihui; He, Xiongwei; Guo, Peng

    2017-04-01

    Three factors (pouring temperature, injection speed and mold temperature) were selected to do three levels L9 (33)orthogonal experiment, then simulate processing of semi-solid die-casting of magnesium matrix composite by Flow-3D software. The stress distribution, temperature field and defect distribution of filling process were analyzed to find the optimized processing parameter with the help of orthogonal experiment. The results showed that semi-solid has some advantages of well-proportioned stress and temperature field, less defect concentrated in the surface. The results of simulation were the same as the experimental results.

  2. Optimization of Casting Design Parameters on Fabrication of Reliable Semi-Solid Aluminum Suspension Control Arm

    NASA Astrophysics Data System (ADS)

    Ragab, Kh. A.; Bouaicha, A.; Bouazara, M.

    2017-09-01

    The semi-solid casting process has the advantage of providing reliable mechanical aluminum parts that work continuously in dynamic as control arm of the suspension system in automotive vehicles. The quality performance of dynamic control arm is related to casting mold and gating system designs that affect the fluidity of semi-solid metal during filling the mold. Therefore, this study focuses on improvement in mechanical performance, depending on material characterization, and casting design optimization, of suspension control arms made of A357 aluminum semi-solid alloys. Mechanical and design analyses, applied on the suspension arm, showed the occurrence of mechanical failures at unexpected weak points. Metallurgical analysis showed that the main reason lies in the difficult flow of semi-solid paste through the thin thicknesses of a complex geometry. A design modification procedure is applied to the geometry of the suspension arm to avoid this problem and to improve its quality performance. The design modification of parts was carried out by using SolidWorks design software, evaluation of constraints with ABAQUS, and simulation of flow with ProCast software. The proposed designs showed that the modified suspension arm, without ribs and with a central canvas designed as Z, is considered as a perfect casting design showing an increase in the structural strength of the component. In this case, maximum von Mises stress is 199 MPa that is below the yield strength of the material. The modified casting mold design shows a high uniformity and minim turbulence of molten metal flow during semi-solid casting process.

  3. Semi-solid Twin-roll Casting Process of Magnesium Alloy Sheets

    NASA Astrophysics Data System (ADS)

    Watari, H.; Davey, K.; Rasgado, M. T. Alonso; Haga, T.; Koga, N.

    2004-06-01

    An experimental approach has been performed to ascertain the effectiveness of semi-solid strip casting using a horizontal twin roll caster. The demand for light-weight products with high strength has grown recently due to the rapid development of automobile and aircraft technology. One key to such development has been utilization of magnesium alloys, which can potentially reduce the total product weight. However, the problems of utilizing magnesium alloys are still mainly related to high manufacturing cost. One of the solutions to this problem is to develop magnesium casting-rolling technology in order to produce magnesium sheet products at competitive cost for commercial applications. In this experiment, magnesium alloy AZ31B was used to ascertain the effectiveness of semi-solid roll strip casting for producing magnesium alloy sheets. The temperature of the molten magnesium, and the roll speeds of the upper and lower rolls, (which could be changed independently), were varied to find an appropriate manufacturing condition. Rolling and heat treatment conditions were changed to examine which condition would be appropriate for producing wrought magnesium alloys with good formability. Microscopic observation of the crystals of the manufactured wrought magnesium alloys was performed. It has been found that a limiting drawing ratio of 2.7 was possible in a warm deep drawing test of the cast magnesium alloy sheets after being hot rolled.

  4. Effect of Casting Defects Distribution on the Beginning of Tensile Fracture in Semi-solid Injected Magnesium AZ91D Alloy

    NASA Astrophysics Data System (ADS)

    Murakami, Yuichiro; Miwa, Kenji; Kanetake, Naoyuki; Tada, Shuji

    Semi-solid process is useful for magnesium alloys because processing temperatures lower than conventional casting processes result in decreased combustibility. Additionally it can decrease casting defects by the increased viscosity and decreased solidification shrinkage. In this study, casting defects of semi-solid injected AZ91D specimens were observed by X-ray CT tomography and tensile test was carried out. Thus, relations between casting defects and fracture starting point were investigated. As a result, the specimens were not always fractured at the site of the largest defect; meanwhile the defects situated near the surface or perpendicularly elongated to the tension axis exerted a potent influence on fracture.

  5. Fatigue Characteristics and Quality Index of A357 Type Semi-Solid Aluminum Castings Used for Automotive Application

    NASA Astrophysics Data System (ADS)

    Bouazara, M.; Bouaicha, A.; Ragab, Kh. A.

    2015-08-01

    The present work aims to investigate the fatigue characteristics of automotive lower suspension arm made of semi-solid A357 aluminum castings using metallurgical and analytical approaches. The fatigue life calculations of analytical model are used to identify and introduce the model parameters based on the suspension arm material followed by analyzing the load-number of cycles fatigue curve. The critical stress areas capable of initiating cracks during fatigue tests are detected using ABAQUS software followed by the installation of strain gages on the suspension arm to calculate maximum stress. The fatigue experiments are carried out to compare the results of the analytical method with the experimental endurance curves traced by lower suspension arm samples. Microstructure characteristics of the semi-solid A357 under T6 heat treatment conditions are examined using scanning electron microscope. The results show that the fatigue life and the quality index of alloys investigated are affected by casting technique, castings design, microstructural characterization, and heat treatment condition.

  6. Sputtered protective coatings for die casting dies

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Nieh, C. Y.; Wallace, J. F.

    1981-01-01

    This investigation determined whether selected ion beam sputtered coatings on H-13 die steel would have the potential of improving the thermal fatigue behavior of the steel used as a die in aluminum die casting. The coatings were selected to test candidate insulators and metals capable of providing protection of the die surface. The studies indicate that 1 micrometer thick W and Pt coatings reduced the thermal fatigue more than any other coating tested and are candidates to be used on a die surface to increase die life.

  7. Production of semi-solid feedstock of A356 alloy and A356-5TiB2 in-situ composite by cooling slope casting

    NASA Astrophysics Data System (ADS)

    Kumar, S. Deepak; Acharya, Mihira; Mandal, A.; Chakraborty, M.

    2015-02-01

    Cooling Slope casting process has gained significant importance for manufacturing of semi-solid feedstock Al alloys and composites which find applications in automotive and aerospace industries. The primary objective of this research is to generate the semi-solid feedstock suitable for thixoforming process. The current work discusses the phenomena involved in the evolution of microstructure of the semi-solid feed stock by Cooling Slope casting process and the effect of various parameters. The process parameters like the angle and length of inclined plate affect the size and morphology of α-Al phase. The Cooling slope process resulted in the formation of fine grain size of about 38 μm of α-Al phase, compared to that of 98 μm processed conventionally. Further, the pouring temperature played a crucial role in the generation of semi-solid microstructures in case of both the alloy and composites. Moreover, fine TiB2 particles of size 0.2-0.5 μm are uniformly distributed in the almost spherical α-Al grains and at the grain boundaries in the composite feed stock. Cooling slope casting route is a suitable and economical route for semi-solid slurry generation by effectively varying the process parameters.

  8. 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.

  9. Die Soldering in Aluminium Die Casting

    SciTech Connect

    Han, Q.; Kenik, E.A.; Viswanathan, S.

    2000-03-15

    Two types of tests, dipping tests and dip-coating tests were carried out on small steel cylinders using pure aluminum and 380 alloy to investigate the mechanism of die soldering during aluminum die casting. Optical and scanning electron microscopy were used to study the morphology and composition of the phases formed during soldering. A soldering mechanism is postulated based on experimental observations. A soldering critical temperature is postulated at which iron begins to react with aluminum to form an aluminum-rich liquid phase and solid intermetallic compounds. When the temperature at the die surface is higher than this critical temperature, the aluminum-rich phase is liquid and joins the die with the casting during the subsequent solidification. The paper discusses the mechanism of soldering for the case of pure aluminum and 380 alloy casting in a steel mold, the factors that promote soldering, and the strength of the bond formed when soldering occurs. conditions, an aluminum-rich soldering layer may also form over the intermetallic layer. Although a significant amount of research has been conducted on the nature of these intermetallics, little is known about the conditions under which soldering occurs.

  10. 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.

  11. 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.

  12. Thermomechanical steels behaviors at semi-solid state

    NASA Astrophysics Data System (ADS)

    Traidi, K.; Favier, V.; Lestriez, P.; Debray, K.; Langlois, L.; Ranc, N.; Saby, M.; Mangin, P.

    2016-10-01

    Semisolid thixoforming is an intermediate process between casting and forging. The combination of the semi-solid state and globular microstructures leads to thixotropic properties of the material [1]. Thixoformingprocess presents several advantages such as energy efficiency, high production rates, smooth die filling, low shrinkage porosity, which together lead to near net shape capability and thus to fewer manufacturing steps than with classical methods. So far, there are only few applications of semisolid processing of highr melting point alloys [2]. Steel is a particularly challenging material to semi-solid process because of about 1400°C temperatures involved. Characterizing and modelling such semi-solid behaviour for steels is still challenging. The aim of the research work was to study the rheological properties of a suitable graded steel (LTT C38) designed for semi-solid processing. An experimental protocol was determined to characterize the thermomechanical behaviors and defect condition. Uniaxial tensile tests were carried out on semi-solid specimen having >0.8 solid fraction for different temperatures. The variation in both ductility and strength with temperature has been identified.

  13. Modeling the Mechanical Performance of Die Casting Dies

    SciTech Connect

    R. Allen Miller

    2004-02-27

    The following report covers work performed at Ohio State on modeling the mechanical performance of dies. The focus of the project was development and particularly verification of finite element techniques used to model and predict displacements and stresses in die casting dies. The work entails a major case study performed with and industrial partner on a production die and laboratory experiments performed at Ohio State.

  14. Investigation on the Mechanical Properties of A356 Alloy Reinforced AlTiB/SiCp Composite by Semi-Solid Stir Casting Method

    NASA Astrophysics Data System (ADS)

    Bhiftime, E. I.; Gueterres, N. F. D. S.

    2017-05-01

    Employing the semi-solid stir casting method to strengthen MMCs by SiCp particle was the simplest way in the casting process. The strength and toughness of a composite material can be obtained through a combination of the A356 / Al7Si composites and SiCp particle. The purpose of this study was to investigate the difference in the mechanical properties of Al7Si1Mg/SiCp and Al7Si1Mg1.5TiB/SiCp composites, as well as the changing effects on the extra level of SiCp particle. Al7Si was used as matrix strengthened by SiCp with the percentage variations of 10, 15, 20 wt%. The additional level of 1.5 wt% AlTiB aimed for increasing the matrix grain refinement. The semi-solid stir casting method was performed to spread the SiCp particles evenly in the liquid matrix. The results of the study were the tensile strength value of as much as 143 MPa or the increase of 22.16%. The biggest yield strength on the Al7Si1Mg1.5TiB/SiCp composite was averagely as much as 106 MPa. The highest impact toughness was averagely amounted to 4.74 J/mm2. The lowest porosity value was averagely 2.10%. The morphology of the composite between the reinforcing particle and the matrix was able to unite and to be dispersed evenly. The present study was conducted through density test, tensile test, impact test, microstructure test, and SEM.

  15. Sputtered protective coatings for die casting dies

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Nieh, C.-Y.; Wallace, J. F.

    1981-01-01

    Three experimental research designs investigating candidate materials and processes involved in protective die surface coating procedures by sputter deposition, using ion beam technologies, are discussed. Various pre-test results show that none of the coatings remained completely intact for 15,000 test cycles. The longest lifetime was observed for coatings such as tungsten, platinum, and molybdenum which reduced thermal fatigue, but exhibited oxidation and suppressed crack initiation only as long as the coating did not fracture. Final test results confirmed earlier findings and coatings with Pt and W proved to be the candidate materials to be used on a die surface to increase die life. In the W-coated specimens, which remained intact on the surface after thermal fatigue testing, no oxidation was found under the coating, although a few cracks formed on the surface where the coating broke down. Further research is planned.

  16. Sputtered protective coatings for die casting dies

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Nieh, C.-Y.; Wallace, J. F.

    1981-01-01

    Three experimental research designs investigating candidate materials and processes involved in protective die surface coating procedures by sputter deposition, using ion beam technologies, are discussed. Various pre-test results show that none of the coatings remained completely intact for 15,000 test cycles. The longest lifetime was observed for coatings such as tungsten, platinum, and molybdenum which reduced thermal fatigue, but exhibited oxidation and suppressed crack initiation only as long as the coating did not fracture. Final test results confirmed earlier findings and coatings with Pt and W proved to be the candidate materials to be used on a die surface to increase die life. In the W-coated specimens, which remained intact on the surface after thermal fatigue testing, no oxidation was found under the coating, although a few cracks formed on the surface where the coating broke down. Further research is planned.

  17. Thermal Modelling In Pressure Die Casting

    NASA Astrophysics Data System (ADS)

    Rasgado, M. T. Alonso; Davey, K.; Watari, H.

    2004-06-01

    The pressure die casting process is cyclic and the temperature levels in the die are principally dictated by the total energy received from the casting. It is thus extremely important that any solidification model for the casting is able to predict energy extraction rates to a high degree of accuracy. In this paper an efficient three dimensional hybrid thermal model for the pressure die casting process is described. The finite element method (FEM) is used for modelling heat transfer in the casting, coupled to a boundary element (BE) model for the die. The FEM can efficiently account for the non-linearity introduced by the release of latent heat on solidification, whereas the BEM is ideally suited for modelling linear heat conduction in the die, as surface temperatures are of principal importance. The FE formulation for the casting is based on a control volume capacitance method, which is shown to provide high accuracy and stability. This method is similar to the apparent and effective heat capacitance methods, which are popular approaches used where conduction predominates over other heat transfer mechanisms. These methods involve the specification of element or nodal capacitances to accommodate for the release of latent heat. Unfortunately they suffer from a major drawback in that energy is not correctly transported through elements and so providing a source of inaccuracy. The control volume capacitance method allows for the transport of mass arising from volumetric shrinkage and ensures that energy is correctly transported. The BE model caters for surface phenomena such as boiling in the cooling channels, which is important, as this effectively controls the manner in which energy is extracted. The die temperature is decomposed into two components, one a steady-state part and the other a time-dependent perturbation. This approach enables the transient die temperatures to be calculated in an efficient way, since only die surfaces close to the die cavity are

  18. Compared production behavior of borax and unborax premixed SiC reinforcement Al7Si-Mg-TiB alloys composites with semi-solid stir casting method

    NASA Astrophysics Data System (ADS)

    Haryono, M. B.; Sulardjaka, Nugroho, Sri

    2016-04-01

    The present study was aimed to investigate the effect of borax additive on physical and mechanical properties of Al7Si-Mg-TiB with the reinforcement of silicon carbide. In this case, the different weight percentage from the reinforcement of SiC (10, 15, and 20% wt), and the borax additive (ratio 1:4) were homogenously added into the matrix by employing the semi-solid stir casting method at the temperature of 590°C. Al7Si-Mg-TiB melted in an electric resistance furnace at 800°C for 25 minutes and the holding time of 5 minutes; SiC was stirred with borax inside the chamber and heated at the temperature of 250°C for 25 minutes. Then, it melted by lowing the temperature into 590°C. The SiC-borax mixture was added into the electric resistance furnace, and automatically stirred by the stirrer at a constant speed (500 rpm for 3 minutes) in the composite A17Si-Mg-TiB. It melted when heated at 750°C for 17minutes,then, casting was performed on the prepared mould. The characterizations of Al7Si-Mg-TiB-SiC/borax were porosity, hardness, and microstructure on the Al7Si-Mg-TiB-SiC/ borax. The porosity of AMC tended to increase along with the increaseof the wt% SiC (1.4%-3.6%); however, borax additive underwent a decrease in porosity (0.14%-1.3%). Further, hardness tended to improve along with the increase of wt% SiC. The unboraxmixture had 79,6 HRB up to 94 HRB. Whereas, the borax additive mixture had 105,8 HRB up to 121 HRB.

  19. Use of RSP Tooling to Manufacture Die Casting Dies

    SciTech Connect

    Kevin McHugh

    2004-07-01

    The technology and art used to construct die casting dies has seen many improvements over the years. However, the time lag from when a design is finalized to the time a tool is in production has remained essentially the same. The two main causes for the bottleneck are the need to qualify a part design by making prototypes (usually from an alternative process), and the production tooling lead time after the prototypes are approved. Production tooling costs are high due to the labor and equipment costs associated with transforming a forged block of tool steel into a finished tool. CNC machining, sink EDM, benching, engraving and heat treatment unit operations are typically involved. As a result, there is increasing interest in rapid tooling (RT) technologies that shorten the design-to-part cycle and reduce the cost of dies. There are currently more than 20 RT methods being developed and refined around the world (1). The "rapid" in rapid tooling suggests time compression for tool delivery, but does not address robustness as nearly all RT approaches are intended for low-volume prototype work, primarily for molding plastics. Few options exist for die casting. An RT technology suitable for production-quality tooling in the time it normally takes for prototype tooling is highly desirable. In fact, there would be no need for a distinction between prototype and production tooling. True prototype parts could be made using the same processing conditions and materials intended for production. Qualification of the prototype part would allow the manufacturer to go directly into production with the same tool. A relatively new RT technology, Rapid Solidification Process (RSP) Tooling, is capable of making production-quality tooling in an RT timeframe for die casting applications. RSP Tooling, was developed at the Idaho National Engineering and Environmental Laboratory (INEEL), and commercialized with the formation of RSP Tooling, LLC (2). This paper describes the process, and

  20. National Metal Casting Research Institute final report. Volume 2, Die casting research

    SciTech Connect

    Jensen, D.

    1994-06-01

    Four subprojects were completed: development and evaluation of die coatings, accelerated die life characterization of die materials, evaluation of fluid flow and solidification modeling programs, selection and characterization of Al-based die casting alloys, and influence of die materials and coatings on die casting quality.

  1. Enhancements in Magnesium Die Casting Impact Properties

    SciTech Connect

    David Schwam; John F. Wallace; Yulong Zhu; Srinath Viswanathan; Shafik Iskander

    2000-06-30

    % in AM50 to over 9% in AZ91, more of the intermetallic Mg17Al12 is formed in the microstructure. For instance, for 15 increase in the aluminum content from AM50 to AM60, the volume fraction of eutectic present in the microstructure increases by 35%! Eventually, the brittle Mg17Al12 compound forms an interconnected network that reduces ductility and impact resistance. The lower aluminum in AM50 and AM60 are therefore a desirable feature in applications that call for higher impact resistance. Further improvement in impact resistance depends on the processing condition of the casting. Sound castings without porosity and impurities will have better mechanical properties. Since magnesium oxidizes readily, good melting and metal transfer practices are essential. The liquid metal has to be protected from oxidation at all times and entrainment of oxide films in the casting needs to be prevented. In this regard, there is evidence that us of vacuum to evacuate air from the die casting cavity can improve the quality of the castings. Fast cooling rates, leading to smaller grain size are beneficial and promote superior mechanical properties. Micro-segregation and banding are two additional defect types often encountered in magnesium alloys, in particular in AZ91D. While difficult to eliminate, segregation can be minimized by careful thermal management of the dies and the shot sleeve. A major source of segregation is the premature solidification in the shot sleeve. The primary solid dendrites are carried into the casting and form a heterogeneous structure. Furthermore, during the shot, segregation banding can occur. The remedies for this kind of defects include a hotter shot sleeve, use of insulating coatings on the shot sleeve and a short lag time between pouring into the shot sleeve and the shot.

  2. Die Casting Part Distortion: Prediction and Attenuation

    SciTech Connect

    Dr, R. Allen Miller

    2002-02-12

    The goal of this research was to predict the part deformation and residual stresses after ejection from the die and cooling to room temperature. A finite element model was built to achieve this goal and several modeling techniques were investigated throughout this research. Die-casting is a very complex process and the researchers are faced with a large number of hard to solve physical problems when modeling the process. Several assumptions are made in our simulation model. The first significant assumption is the instantaneous cavity filling. This means that the cavity filling stage is not considered in our model. Considering the cavity filling stage increases the modeling complexity as a result of different flow patterns. expected in the shot sleeve, gate, runner and different cavity features. The flow of gas from the cavity through the vents is another problem that is ignored in our model as a result of this assumption. Our second assumption is that the cast metal has uniform temperature distribution inside the cavity, at the starting point of simulation. This temperature is assumed to be over liquidus limit, i.e. the solid fraction is 0.0% of the cast metal. The third assumption is due to ABAQUS (commercial software used in this research) limitations. ABAQUS cannot deal with multi-phase models; therefore we use solid elements to define the casting instead of multi-phase (liquid/solid) elements. Liquid elements can carry the hydrostatic pressure from the shot sleeve and apply it on the cavity surfaces, while the solid elements do not have this capability. To compensate for this assumption we add the cavity pressure as a boundary condition and apply it on the cavity surface separately from the part. Another issue with this assumption is that, liquid casting can follow the cavity shape when it distorts. With the use of solid elements to represent the casting during its liquid state, it loses this capability to follow the cavity. Several techniques were tested to

  3. Effect composition of SiCp and TiB to the mechanical properties of composite Al7Si-Mg-SiCp by the method of semi solid stir casting

    NASA Astrophysics Data System (ADS)

    Bhiftime, E. I.; Sulardjaka, Nugroho, Sri

    2016-04-01

    Recently, studies on Aluminum Matrix Composite (AMC) were growing rapidly. AMC reinforced with SiCp particles in the semi solid stir casting method was the most simple way. In particular, the purpose of the present study was to investigate the effect composition of SiCp and TiB to the mechanical properties of the composites Al7Si-Mg-SiCp and Al7Si-Mg-TiB-SiCp. The composites used were Al7Si as the matrix and SiCp as the reinforcement (10, 15, 20 wt%). The casting method used on the study was the semi solid stir casting. The matrix was melted at the temperature of 800 °C. Then, the stirring process started at 590 °C with the speed of 500 rpm for 180 seconds. The composites was heated again until the pouring temperature was at 750 °C. The results of the present study indicated to be successful in which SiCp particles dispersed uniformly in the matrix composites. Further, the hardness value and porosity of the composites Al7Si-Mg-SiCp and Al7Si-Mg-TiB-SiCp increased along with the addition of TiB. Besides, the hardness value increased in the average of 10.5% at the variation of 20% SiCp. Whereas, the porosity value increased in the average of 54.3% at the variation of 20% SiCp.

  4. How process design affects quality of semi-solid metalworking parts

    SciTech Connect

    Khan, P.A.A.; Dax, F.R.

    1996-10-01

    Semi-Solid Metalworking (SSM) incorporates elements of both casting and forging for the manufacture of near-net-shape discrete parts. Parts produced by SSM have higher structural integrity, quality and soundness than castings, yet can be produced at lower cost than parts produced by fully-solid processes. In addition, SSM is capable of producing parts which are essentially free of the porosity associated with high pressure die casting. A carefully designed, systematic experimental approach was used to analyze the SSM process. This paper examines billet structure, induction heating variables, die design, die temperature, die lubricant, venting, ram speed and pressure and correlates these with their effect on improvement in part quality.

  5. Effect of Some Parameters on the Cast Component Properties in Hot Chamber Die Casting

    NASA Astrophysics Data System (ADS)

    Singh, Rupinder; Singh, Harvir

    2016-04-01

    Hot chamber die casting process is designed to achieve high dimensional accuracy for small products by forcing molten metal under high pressure into reusable moulds, called dies. The present research work is aimed at study of some parameters (as a case study of spring adjuster) on cast component properties in hot chamber die casting process. Three controllable factors of the hot chamber die casting process (namely: pressure at second phase, metal pouring temperature and die opening time) were studied at three levels each by Taguchi's parametric approach and single-response optimization was conducted to identify the main factors controlling surface hardness, dimensional accuracy and weight of the casting. Castings were produced using aluminium alloy, at recommended parameters through hot chamber die casting process. Analysis shows that in hot chamber die casting process the percentage contribution of second phase pressure, die opening time, metal pouring temperature for surface hardness is 82.48, 9.24 and 6.78 % respectively. While in the case of weight of cast component the contribution of second phase pressure is 94.03 %, followed by metal pouring temperature and die opening time (4.58 and 0.35 % respectively). Further for dimensional accuracy contribution of die opening time is 76.97 %, metal pouring temperature is 20.05 % and second phase pressure is 1.56 %. Confirmation experiments were conducted at an optimal condition showed that the surface hardness, dimensional accuracy and weight of the castings were improved significantly.

  6. Influence wt.% of SiC and borax on the mechanical properties of AlSi-Mg-TiB-SiC composite by the method of semi solid stir casting

    NASA Astrophysics Data System (ADS)

    Bhiftime, E. I.; Guterres, Natalino F. D. S.; Haryono, M. B.; Sulardjaka, Nugroho, Sri

    2017-04-01

    SiC particle reinforced metal matrix composites (MMCs) with solid semi stir casting method is becoming popular in recent application (automotive, aerospace). Stirring the semi solid condition is proven to enhance the bond between matrix and reinforcement. The purpose of this study is to investigate the effect of the SiC wt.% and the addition of borax on mechanical properties of composite AlSi-Mg-TiB-SiC and AlSi-Mg-TiB-SiC/Borax. Specimens was tested focusing on the density, porosity, tensile test, impact test microstructure and SEM. AlSi is used as a matrix reinforced by SiC with percentage variations (10, 15, 20 wt.%). Giving wt.% Borax which is the ratio of 1: 4 between wt.% SiC. The addition of 1.5% of TiB gives grain refinement. The use of semi-solid stir casting method is able to increase the absorption of SiC particles into a matrix AlSi evenly. The improved composite presented here can be used as a guideline to make a new composite.

  7. Method and apparatus for semi-solid material processing

    DOEpatents

    Han, Qingyou [Knoxville, TN; Jian, Xiaogang [Knoxville, TN; Xu, Hanbing [Knoxville, TN; Meek, Thomas T [Knoxville, TN

    2009-11-24

    A method of forming a material includes the steps of: vibrating a molten material at an ultrasonic frequency while cooling the material to a semi-solid state to form non-dendritic grains therein; forming the semi-solid material into a desired shape; and cooling the material to a solid state. The method makes semi-solid castings directly from molten materials (usually a metal), produces grain size usually in the range of smaller than 50 .mu.m, and can be easily retrofitted into existing conventional forming maching.

  8. Method and apparatus for semi-solid material processing

    DOEpatents

    Han, Qingyou [Knoxville, TN; Jian, Xiaogang [Knoxville, TN; Xu, Hanbing [Knoxville, TN; Meek, Thomas T [Knoxville, TN

    2009-02-24

    A method of forming a material includes the steps of: vibrating a molten material at an ultrasonic frequency while cooling the material to a semi-solid state to form non-dendritic grains therein; forming the semi-solid material into a desired shape; and cooling the material to a solid state. The method makes semi-solid castings directly from molten materials (usually a metal), produces grain size usually in the range of smaller than 50 .mu.m, and can be easily retrofitted into existing conventional forming machine.

  9. Method and apparatus for semi-solid material processing

    DOEpatents

    Han, Qingyou; Jian, Xiaogang; Xu, Hanbing; Meek, Thomas T.

    2007-05-15

    A method of forming a material includes the steps of: vibrating a molten material at an ultrasonic frequency while cooling the material to a semi-solid state to form non-dendritic grains therein; forming the semi-solid material into a desired shape; and cooling the material to a solid state. The method makes semi-solid castings directly from molten materials (usually a metal), produces grain size usually in the range of smaller than 50 .mu.m, and can be easily retrofitted into existing conventional forming machine.

  10. Microstructures and properties of aluminum die casting alloys

    SciTech Connect

    M. M. Makhlouf; D. Apelian; L. Wang

    1998-10-01

    This document provides descriptions of the microstructure of different aluminum die casting alloys and to relate the various microstructures to the alloy chemistry. It relates the microstructures of the alloys to their main engineering properties such as ultimate tensile strength, yield strength, elongation, fatigue life, impact resistance, wear resistance, hardness, thermal conductivity and electrical conductivity. Finally, it serves as a reference source for aluminum die casting alloys.

  11. The thermal fatigue resistance of H-13 Die Steel for aluminum die casting dies

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The effects of welding, five selected surface coatings, and stress relieving on the thermal fatigue resistance of H-13 Die Steel for aluminum die casting dies were studied using eleven thermal fatigue specimens. Stress relieving was conducted after each 5,000 cycle interval at 1050 F for three hours. Four thermal fatigue specimens were welded with H-13 or maraging steel welding rods at ambient and elevated temperatures and subsequently, subjected to different post-weld heat treatments. Crack patterns were examined at 5,000, 10,000, and 15,000 cycles. The thermal fatigue resistance is expressed by two crack parameters which are the average maximum crack and the average cracked area. The results indicate that a significant improvement in thermal fatigue resistance over the control was obtained from the stress-relieving treatment. Small improvements were obtained from the H-13 welded specimens and from a salt bath nitrogen and carbon-surface treatment. The other surface treatments and welded specimens either did not affect or had a detrimental influence on the thermal fatigue properties of the H-13 die steel.

  12. The rheological behavior of semi-solid A356 alloy

    NASA Astrophysics Data System (ADS)

    Lashkari, Omid

    The semi-solid-metal, SSM, processing deals with semi solid slurries, in which non dendritic solid particles are dispersed in a liquid matrix with apparent viscosity values near to that of liquid. It is able to flow easily under pressure and fills complicated die cavities to manufacture sound as-cast products with high integrity. The SSM slurry is prepared through different methods. In the current study conventional casting and the SEED process were employed to produce SSM billets with different morphologies of primary alpha-Al phase in A356 Al-Si alloy. For conventional casting, a range of solid particle morphologies, microstructure, were realized through variation of pouring temperature while for the SEED billets, as a new patent of ALCAN international for semi solid casting, changes in the morphology were achieved by control of process parameters during solidification of the melt. In order to investigate the morphological evolution due to the effect of different process parameters, pouring temperature and swirling intensities, the SSM billets prepared by both methods were studied using quantitative metallography. The microstructure of SSM A356 alloy has also been characterized using an innovative method, parallel plate compression viscometry, where a correlation was made between the morphology and viscosity. The main objective of the current research was the implication of rheological principles to study the deformation behavior of A356 alloy at different morphologies and fraction of solid, while treating the SSM billets as Newtonian and Non-Newtonian fluids respectively. Furthermore, two empirical relationships were proposed to underline the correlation among the viscosity, and fraction solid and its morphology. In order to further confirm the reliability of the tests results in this research and to highlight that the sample size has no effect on the final deformation and viscosity values, a new series of tests were performed using two sets of specimens with

  13. A review of semi-solid aluminium-steel joining processes

    NASA Astrophysics Data System (ADS)

    Obeidi, Muhannad; McCarthy, Éanna; Brabazon, Dermot

    2016-10-01

    The semi-solid metal (SSM) forming process can be applied to achieve near net shape forming of metal alloys, and provides superior component properties compared to those achievable with conventional casting methods. The technique, also commonly called thixoforming, relies on achieving a spheroidal microstructure within the metal alloy so that its fluidity can be adjusted to achieve a controlled laminar filling of the die. Despite the better quality and the higher mechanical properties of an SSM product, thixoforming still represents only 1% of the total aluminium production, which can be explained by the higher premium cost of the processing equipment compared to conventional die casting. The method has also proven successful as a joining method, for joining similar and dissimilar materials. This paper reviews semisolid forming as a forming method and as a joining method, in particular the joining of dissimilar materials such as stainless steel to aluminium.

  14. 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.

  15. Evaluation of permanent die coatings to improve the wear resistance of die casting dies. Final project report, January 1, 1995--April 30, 1997

    SciTech Connect

    Shivpuri, R.

    1997-09-18

    Die Casting dies are subject to severe service conditions during the die casting operation. While these severe conditions are necessary to achieve high production rates, they cause the dies which are commonly made of H13 die steel, to suffer frequent failures. The major die failure mechanisms are erosion or washout, Heat checking, soldering and corrosion. Due to their geometrical complexity, die casting dies are very expensive (some dies cost over a million dollars), and thus a large number of parts have to be produced by a die, to justify this cost and leverage the advantages of the die casting process (high production rates, low manpower costs). A potential increase in the die service life, thus has a significant impact on the economics of the die; casting operation. There are many ways to extend die life: developing new wear resistant die materials, developing new surface treatments including coatings, improving heat treatment of existing H13 dies, using better lubricants that can protect the die material, or modifying the die geometry and process parameters to reduce the intensity of wear. Of these the use of coatings to improve the wear resistance of the die surface has shown a lot of promise. Consequently, use of coatings in the die casting industry and their wide use to decrease die wear can improve significantly the productivity of shop operations resulting in large savings in material and energy usage.

  16. Manufacture of die casting dies by hot isostatic pressing. CRADA final report

    SciTech Connect

    Viswanathan, S.; Ren, W.; Luk, K.; Brucher, H.G.

    1998-09-01

    The reason for this Cooperative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory (ORNL) and Doehler-Jarvis was to investigate the manufacture die-casting dies with internal water-cooling lines by hot-isostatic pressing (HIPing) of H13 tool steel powder. The use of HIPing will allow the near-net-shape manufacture of dies and the strategic placement of water-cooling lines during manufacture. The production of near-net-shape dies by HIPing involves the generation of HIPing diagrams, the design of the can that can be used for HIPing a die with complex details, strategic placement of water-cooling lines in the die, computer modeling to predict movement of the water lines during HIPing, and the development of strategies for placing water lines in the appropriate locations. The results presented include a literature review, particle analysis and characterization of H13 tool steel powder, and modeling of the HIPing process.

  17. Deburring die-castings by wet vibratory plant

    NASA Technical Reports Server (NTRS)

    Loeschbart, H. M.

    1980-01-01

    A wet vibratory procedure for the removal of burrs from die castings is described. In this process synthetic abrasive chips and detergent solutions are agitated with the work in such a way as to produce a spiral circulatory movement. Details of various forms of vibrator basin and shapes of abrasive are illustrated. The automation of deburring is illustrated through the application of vibrators of spiral design in combination with transport and drying devices.

  18. Energy Saving Melting and Revert Reduction Technology: Innovative Semi-Solid Metal (SSM) Processing

    SciTech Connect

    Diran Apelian

    2012-08-15

    Semi-solid metal (SSM) processing has emerged as an attractive method for near-net-shape manufacturing due to the distinct advantages it holds over conventional near-net-shape forming technologies. These advantages include lower cycle time, increased die life, reduced porosity, reduced solidification shrinkage, improved mechanical properties, etc. SSM processing techniques can not only produce the complex dimensional details (e.g. thin-walled sections) associated with conventional high-pressure die castings, but also can produce high integrity castings currently attainable only with squeeze and low-pressure permanent mold casting processes. There are two primary semi-solid processing routes, (a) thixocasting and (b) rheocasting. In the thixocasting route, one starts from a non-dendritic solid precursor material that is specially prepared by a primary aluminum manufacturer, using continuous casting methods. Upon reheating this material into the mushy (a.k.a. "two-phase") zone, a thixotropic slurry is formed, which becomes the feed for the casting operation. In the rheocasting route (a.k.a. "slurry-on-demand" or "SoD"), one starts from the liquid state, and the thixotropic slurry is formed directly from the melt via careful thermal management of the system; the slurry is subsequently fed into the die cavity. Of these two routes, rheocasting is favored in that there is no premium added to the billet cost, and the scrap recycling issues are alleviated. The CRP (Trade Marked) is a process where the molten metal flows through a reactor prior to casting. The role of the reactor is to ensure that copious nucleation takes place and that the nuclei are well distributed throughout the system prior to entering the casting cavity. The CRP (Trade Marked) has been successfully applied in hyper-eutectic Al-Si alloys (i.e., 390 alloy) where two liquids of equal or different compositions and temperatures are mixed in the reactor and creating a SSM slurry. The process has been mostly

  19. Effects of silicon, copper and iron on static and dynamic properties of alloy 206 (aluminum-copper) in semi-solids produced by the SEED process

    NASA Astrophysics Data System (ADS)

    Lemieux, Alain

    The advantages of producing metal parts by rheocasting are generally recognised for common foundry alloys of Al-Si. However, other more performing alloys in terms of mechanical properties could have a great interest in specialized applications in the automotive industry, while remaining competitive in the forming. Indeed, the growing demand for more competitive products requires the development of new alloys better suited to semi-solid processes. Among others, Al-Cu alloys of the 2XX series are known for their superior mechanical strength. However, in the past, 2XX alloys were never candidates for pressure die casting. The main reason is their propensity to hot tearing. Semi-solid processes provide better conditions for molding with the rheological behavior of dough and molding temperatures lower reducing this type of defect. In the initial phase, this research has studied factors that reduce hot tearing susceptibility of castings produced by semi-solid SEED of alloy 206. Subsequently, a comparative study on the tensile properties and fatigue was performed on four variants of the alloy 206. The results of tensile strength and fatigue were compared with the specifications for applications in the automotive industry and also to other competing processes and alloys. During this study, several metallurgical aspects were analyzed. The following main points have been validated: i) the main effects of compositional variations of silicon, iron and copper alloy Al-Cu (206) on the mechanical properties, and ii) certain relationships between the mechanism of hot cracking and the solidification rate in semi-solid. Parts produced from the semi-solid paste coming from the SEED process combined with modified 206 alloys have been successfully molded and achieved superior mechanical properties than the requirements of the automotive industry. The fatigue properties of the two best modified 206 alloys were higher than those of A357 alloy castings and are close to those of the

  20. High pressure die casting of Fe-based metallic glass

    NASA Astrophysics Data System (ADS)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-10-01

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

  1. High pressure die casting of Fe-based metallic glass.

    PubMed

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-10-11

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

  2. High pressure die casting of Fe-based metallic glass

    PubMed Central

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-01-01

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications. PMID:27725780

  3. Vacuum Die Casting of Silicon Sheet for Photovoltaic Applications

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The development of a vacuum die-casting process for producing silicon sheet suitable for photovoltaic cells with a terrestrial efficiency greater than 12 percent and having the potential to be scaled for large quantity production is considered. The initial approach includes: (1) obtaining mechanical design parameters by using boron nitride, which has been shown to non-wetting to silicon; (2) optimizing silicon nitride material composition and coatings by sessile drop experiments; (3) testing effectiveness of fluoride salt interfacial media with a graphite mold; and (4) testing the effect of surface finish using both boron nitride and graphite. When the material and mechanical boundary conditions are established, a finalized version of the prototype assembly will be constructed and the casting variables determined.

  4. Development of Thin Section Zinc Die Casting Technology

    SciTech Connect

    Goodwin, Frank

    2013-10-31

    A new high fluidity zinc high pressure die casting alloy, termed the HF alloy, was developed during laboratory trials and proven in industrial production. The HF alloy permits castings to be achieved with section thicknesses of 0.3 mm or less. Technology transfer activities were conducted to develop usage of the HF high fluidity alloy. These included production of a brochure and a one-hour webinar on the HF alloy. The brochure was then sent to 1,184 product designers in the Interzinc database. There was excellent reception to this mailing, and from this initial contact 5 technology transfer seminars were conducted for 81 participants from 30 companies across a wide range of business sectors. Many of the successful applications to date involve high quality surface finishes. Design and manufacturing assistance was given for development of selected applications.

  5. Notched bar Izod impact properties of zinc die castings

    SciTech Connect

    Schrems, K.K.; Dogan, O.N.; Goodwin, F.E.

    2007-03-01

    Notched bar Izod impact testing of zinc die cast Alloy 3, Alloy 5, ZA-8, and AcuZinc 5 was performed at five temperatures between -40\\mDC and room temperature in accordance with ASTM E23 for impact testing of metallic materials. A direct comparison between ASTM D256 for impact testing of plastics and ASTM E23 was performed using continuously cast zinc specimens of Alloy 5 and ZA-8 at -40\\mDC and room temperature. There are differences in sample sizes, impact velocity, and striker geometry between the two tests. Bulk zinc tested according to ASTM E23 resulted in higher impact energies at -40\\mDC and lower impact energies at room temperature then did the same alloys when tested according to ASTM D256.

  6. 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.

  7. Die casting die deflections: Prediction and attenuation. Final report, July 1, 1995--September 30, 1997

    SciTech Connect

    Miller, R.Allen; Ahuett-Garza, Horacio; Choudhury, Aswin K.; Dedhia, Sanjay

    1998-05-01

    The objective of this work was to develop and test die casting design evaluation techniques based on the visualization of geometric data that is related to potential defects or problems. Specifically, thickness information is used to provide insight into potential thermal problems in the part and die. Distance from the gate and a special type of animation of the fill pattern is used to provide an assessment of gate, vent and overflow locations. Techniques have been developed to convert part design information in the form of STL files to a volume-based representation called a voxel model. The use of STL files makes the process CAD system independent. Once in voxel form, methods that were developed in this work are used to identify thick regions in the part, thin regions in the part and/or die, distance from user specified entry locations (gates), and the qualitative depiction of the fill pattern. The methods were tested with a prototype implementation on the UNIX platform. The results of comparisons with numerical simulation and field reported defects were surprisingly good. The fill-related methods were also compared against short-shots and a water analog study using high speed video. The report contains the results of the testing plus detailed background material on the construction of voxel models, the methods used for displaying results, and the computational geometric reasoning methods used to create die casting-related information from the voxel model for display to the user.

  8. Modelling the Cast Component Weight in Hot Chamber Die Casting using Combined Taguchi and Buckingham's π Approach

    NASA Astrophysics Data System (ADS)

    Singh, Rupinder

    2017-03-01

    Hot chamber (HC) die casting process is one of the most widely used commercial processes for the casting of low temperature metals and alloys. This process gives near-net shape product with high dimensional accuracy. However in actual field environment the best settings of input parameters is often conflicting as the shape and size of the casting changes and one have to trade off among various output parameters like hardness, dimensional accuracy, casting defects, microstructure etc. So for online inspection of the cast components properties (without affecting the production line) the weight measurement has been established as one of the cost effective method (as the difference in weight of sound and unsound casting reflects the possible casting defects) in field environment. In the present work at first stage the effect of three input process parameters (namely: pressure at 2nd phase in HC die casting; metal pouring temperature and die opening time) has been studied for optimizing the cast component weight `W' as output parameter in form of macro model based upon Taguchi L9 OA. After this Buckingham's π approach has been applied on Taguchi based macro model for the development of micro model. This study highlights the Taguchi-Buckingham based combined approach as a case study (for conversion of macro model into micro model) by identification of optimum levels of input parameters (based on Taguchi approach) and development of mathematical model (based on Buckingham's π approach). Finally developed mathematical model can be used for predicting W in HC die casting process with more flexibility. The results of study highlights second degree polynomial equation for predicting cast component weight in HC die casting and suggest that pressure at 2nd stage is one of the most contributing factors for controlling the casting defect/weight of casting.

  9. WARM WATER SCALE MODEL EXPERIMENTS FOR MAGNESIUM DIE CASTING

    SciTech Connect

    Sabau, Adrian S

    2006-01-01

    High-pressure die casting (HPDC) involves the filling of a cavity with the molten metal through a thin gate. High gate velocities yield jet break-up and atomization phenomena. In order to improve the quality of magnesium parts, the mold filling pattern, including atomization phenomena, needs to be understood. The goal of this study was to obtain experimental data on jet break-up characteristics for conditions similar to that of magnesium HPDC, and measure the droplet velocity and size distribution. A scale analysis is first presented in order to identify appropriate analogue for liquid magnesium alloys. Based on the scale analysis warm water was chosen as a suitable analogue and different nozzles were manufactured. A 2-D component phase Doppler particle analyzer (PDPA) and 2-D component particle image velocimetry (PIV) were then used to obtain fine particle diameter and velocity distributions in 2-D plane.

  10. Feeding Mechanisms in High-Pressure Die Castings

    NASA Astrophysics Data System (ADS)

    Otarawanna, S.; Laukli, H. I.; Gourlay, C. M.; Dahle, A. K.

    2010-07-01

    This work focuses on understanding the feeding behavior during high-pressure die casting (HPDC). The effects of intensification pressure (IP) and gate thickness on the transport of material through the gate during the latter stages of HPDC were investigated using an AlSi3MgMn alloy. Microstructural characterization of the gate region indicated a marked change in feeding mechanism with increasing IP and gate size. Castings produced with a high IP or thick gate contained a relatively low fraction of total porosity, and shear band-like features existed through the gate, suggesting that semisolid strain localization in the gate is involved in feeding during the pressure intensification stage. When a low IP is combined with a thin gate, no shear band is observed in the gate and feeding is less effective, resulting in a higher level of porosity in the HPDC component. Although shear banding through the gate was found to reduce porosity in HPDC parts, if gates are not properly designed, deformation of the mushy zone through the gate can cause severe macrosegregation, large pores, and large cracks, which could severely reduce the performance of the component.

  11. A comparison of the accuracy of two removable die systems with intact working casts.

    PubMed

    Aramouni, P; Millstein, P

    1993-01-01

    This study evaluated the reproducibility of die position using two removable die systems and two die stones. Poly(vinyl siloxane) impressions were made of a stainless steel, U-shaped arch with four evenly spaced abutments. Six groups were evaluated: Zeiser system/Fuji Rock; Zeiser system/Die Keen; solid cast/Fuji Rock; solid cast/Die Keen; Fuji Rock/Pindex; and Die Keen/Pindex. An optical comparator was used to measure the height of each abutment, the distance between the anterior abutments, and the distance between the posterior abutments. The Zeiser system with either Fuji Rock or Die Keen yielded the greatest accuracy. Die Keen exhibited more linear expansion than Fuji Rock, and solid casts had less distortion than the Pindex system.

  12. 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.

  13. Modeling and Analysis of The Pressure Die Casting Using Response Surface Methodology

    NASA Astrophysics Data System (ADS)

    Kittur, Jayant K.; Herwadkar, T. V.; Parappagoudar, M. B.

    2010-10-01

    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.

  14. Understanding the Relationship Between Filling Pattern and Part Quality in Die Casting

    SciTech Connect

    Jerald Brevick; R. Allen Miller

    2004-03-15

    The overall objective of this research project was to investigate phenomena involved in the filling of die cavities with molten alloy in the cold chamber die-casting process. It has long been recognized that the filling pattern of molten metal entering a die cavity influences the quality of die-cast parts. Filling pattern may be described as the progression of molten metal filling the die cavity geometry as a function of time. The location, size and geometric configuration of points of metal entry (gates), as well as the geometry of the casting cavity itself, have great influence on filling patterns. Knowledge of the anticipated filling patterns in die-castings is important for designers. Locating gates to avoid undesirable flow patterns that may entrap air in the casting is critical to casting quality - as locating vents to allow air to escape from the cavity (last places to fill). Casting quality attributes that are commonly flow related are non-fills, poor surface finish, internal porosity due to trapped air, cold shuts, cold laps, flow lines, casting skin delamination (flaking), and blistering during thermal treatment.

  15. Application of High-Temperature Mold Materials to Die Cast Copper Motor Rotor for Improved Efficiency

    SciTech Connect

    John G. Cowie; Edwin F. Brush, Jr.; Dale T. Peters; Stephen P. Midson; Darryl J. Van Son

    2003-05-01

    The objective of the study, Application of High-Temperature Mold Materials to Die Cast Copper Motor Rotor for Improved Efficiency, was to support the Copper Development Association (CDA) in its effort to design, fabricate and demonstrate mold technologies designed to withstand the copper motor rotor die casting environment for an economically acceptable life. The anticipated result from the compiled data and tests were to: (1) identify materials suitable for die casting copper, (2) fabricate motor rotor molds and (3) supply copper rotor motors for testing in actual compressor systems. Compressor manufacturers can apply the results to assess the technical and economical viability of copper rotor motors.

  16. Analytical and numerical study of the pressure die casting processes

    NASA Astrophysics Data System (ADS)

    Lopez Rodriguez, Joaquin

    In pressure die casting, the most common defect in manufactured parts is porosity, one of the major causes of which is air entrapment in the molten metal during the injection process. Among other factors, the correct design of the gating and venting systems and an appropriate selection of the operating conditions during the injection phase can contribute to minimizing casting porosity. In the present work, a systematic study of the operating conditions and the characteristics of the injection and venting systems (plunger motion law, initial filling fraction, shot sleeve dimensions, dimension and location of the vents, atmospheric and vacuum venting conditions, etc.) that reduce air entrapment while keeping the injection filling time as low as possible is carried out. Limiting values of the initial filling fraction required for appropriate operating conditions are also determined for wide ranges of acceleration parameters and pouring hole locations. The flow of molten metal inside the injection chamber is analyzed using a two-dimensional finite-element model and a simpler model based on the shallow-water approximation. Two commonly used types of plunger movements are considered, for which results for wave profiles, the volume (area) of entrapped air in the injection chamber, and optimum values of the parameters characterizing the law of plunger motion are presented. A new law of plunger acceleration which would completely eliminate the air from the shot sleeve at the end of the slow phase of injection and minimizes the filling time is derived. The flow through venting systems is analyzed using an unsteady model for both atmospheric and vacuum venting conditions. The model is solved numerically using the method of characteristics. The numerical results of the model agree very well with the results of previous quasi-steady models for conditions for which unsteady effects are negligible, as could be expected. The results presented in this work show that, for broad

  17. Fabrication of Porous Aluminum Using Gases Intrinsically Contained in Aluminum Alloy Die Castings

    NASA Astrophysics Data System (ADS)

    Hangai, Yoshihiko; Utsunomiya, Takao

    2009-06-01

    Closed-cell porous aluminum was fabricated using gases intrinsically contained in aluminum alloy die castings without using a blowing agent. By incorporating the friction stir processing technique, porous aluminum with a porosity of more than 50 pct was successfully obtained at a holding temperature of 923 to 948 K and a holding time of 10 minutes. This proposed die-casting route has high potential for fabricating porous aluminum at a low cost by a higher productivity process.

  18. Effect of Process Parameters, Casting Thickness, and Alloys on the Interfacial Heat-Transfer Coefficient in the High-Pressure Die-Casting Process

    NASA Astrophysics Data System (ADS)

    Guo, Zhi-Peng; Xiong, Shou-Mei; Liu, Bai-Cheng; Li, Mei; Allison, John

    2008-12-01

    The heat transfer at the metal-die interface is believed to have great influence on the solidification process and cast structure of the high-pressure die-casting (HPDC) process. The present article focused on the effects of process parameters, casting thickness, and alloys on the metal-die interfacial heat-transfer coefficient (IHTC) in the HPDC process. Experiment was carried out on a cold-chamber die-casting machine with two casting alloys AM50 and ADC12. A special casting, namely, “step-shape” casting, was used and cast against a H13 steel die. The IHTC was determined using an inverse approach based on the temperature measurements inside the die. Results show that the IHTC is different at different steps and changes as the solidification of the casting proceeds. Process parameters only influence the IHTC in its peak value, and for both AM50 and ADC12 alloys, a greater fast shot velocity leads to a greater IHTC peak value at steps 1 and 2. The initial die surface temperature has a more prominent influence on the IHTC peak values at the thicker steps, especially step 5. Results also show that a closer contact between the casting and die could be achieved when the casting alloy is ADC12 instead of AM50, which consequently leads to a higher IHTC.

  19. Evaluation of a Heat Flux Sensor for Spray Cooling for the Die Casting Processes

    SciTech Connect

    Sabau, Adrian S; Wu, Zhuoxi

    2007-02-01

    During the die casting process, lubricants are sprayed in order to cool the dies and facilitate the ejection of the casting. In this paper, a new technique for measuring the heat flux during lubricant application is evaluated. Data from experiments conducted using water spray are first presented. Water spray experiments were conducted for different initial plate temperatures. Measurements were conducted for the application of two different lubricants, of dilution ratios of 1/15 and 1/50 of lubricant in water. The measurement uncertainties were documented. The results show that the surface temperature decreases initially very fast. Numerical simulation results confirmed that the abrupt temperature drop is not an artifact but illustrates the thermal shock experienced by the dies during the initial stages of lubricant application. The lubricant experiments show that the sensor can be successfully used for testing die lubricants with typical dilution ratios encountered in the die casting process.

  20. Energy Saving Melting and Revert Reduction Technology (E-SMARRT): Development of Surface Engineered Coating Systems for Aluminum Pressure Die Casting Dies: Towards a 'Smart' Die Coating

    SciTech Connect

    Dr. John J. Moore; Dr. Jianliang Lin,

    2012-07-31

    The main objective of this research program was to design and develop an optimal coating system that extends die life by minimizing premature die failure. In high-pressure aluminum die-casting, the die, core pins and inserts must withstand severe processing conditions. Many of the dies and tools in the industry are being coated to improve wear-resistance and decrease down-time for maintenance. However, thermal fatigue in metal itself can still be a major problem, especially since it often leads to catastrophic failure (i.e. die breakage) as opposed to a wear-based failure (parts begin to go out of tolerance). Tooling costs remain the largest portion of production costs for many of these parts, so the ability prevent catastrophic failures would be transformative for the manufacturing industry.The technology offers energy savings through reduced energy use in the die casting process from several factors, including increased life of the tools and dies, reuse of the dies and die components, reduction/elimination of lubricants, and reduced machine down time, and reduction of Al solder sticking on the die. The use of the optimized die coating system will also reduce environmental wastes and scrap parts. Current (2012) annual energy saving estimates, based on initial dissemination to the casting industry in 2010 and market penetration of 80% by 2020, is 3.1 trillion BTU's/year. The average annual estimate of CO2 reduction per year through 2020 is 0.63 Million Metric Tons of Carbon Equivalent (MM TCE).

  1. Analysis of in-cavity thermal and pressure characteristics in aluminum alloy die casting

    SciTech Connect

    Venkatasamy, Vasanth Kumar

    1996-01-01

    The lack of effective control of the die casting process is the primary reason for the occurrence of defective die cast products. A reliable process control system must be capable of measuring the process variables, comparing them to the standard or ideal values and making suitable alterations in the process to eliminate any deviation from the ideal. This study attempted to facilitate the development of such a process control system. A two pronged approach was used to achieve this objective. The experimental approach addressed some of the problems in the measurement of process variables. The analytical approach addressed some of the problems in the design of the process and subsequent identification of the ideal process variable values. The experimental approach concentrated on the measurement of in-cavity pressure and thermal characteristics of the die casting process. Kistler direct pressure sensors were evaluated and utilized for cavity pressure measurement during the die casting campaign. Thermal probes using staggered thermocouples were developed and utilized for the simultaneous measurement of die surface temperatures and heat flow rate through the die. The measured thermal and pressure characteristics were related to the injection characteristics measured using the shot control equipment of the Buhler H-250SC die casting machine used in the campaign. The analytical approach concentrated on the verification of the predictions of a computer numerical solidification analysis by comparison with the experimental data obtained as an output of the die casting campaign. Particular attention was paid to the predictions of thermal characteristics like freezing time and die surface temperature. A sensitivity analysis was also performed to determine the effect of changes in individual variables on the predictions of BINORM.

  2. Application of a tungsten/tungsten-carbide film to H-13 casting dies by plasma assisted deposition

    SciTech Connect

    Horswill, N.; Jetzer, W.; Fetherston, P.; Conrad, J.R.

    1995-12-31

    Die casting is used extensively to produce Al, Mg and Zn alloy parts. H-13, a widely used die material, is a medium carbon steel alloy with Cr, Mo, and Si. A problem with die casting is soldering, thermal fatigue cracking, and carbon buildup which cause degradation of the casting. Application of a metallic coating to the die has been shown to increase the resistance to thermal fatigue cracking. In this study, a tungsten/tungsten carbide thin film was deposited on a casting die of H-13 die steel by a two step Plasma Source Ion Enhanced Deposition process using an argon and methane plasmas. The film was characterized using Auger Electron Spectroscopy, Scanning Electron Microscopy and Electron Dispersive Spectroscopy. The die and representative castings (from regular intervals during the lifetime of the die) were examined for evidence of soldering, thermal fatigue cracking and carbon buildup.

  3. Effect of mold designs on molten metal behaviour in high-pressure die casting

    NASA Astrophysics Data System (ADS)

    Ibrahim, M. D.; Rahman, M. R. A.; Khan, A. A.; Mohamad, M. R.; Suffian, M. S. Z. M.; Yunos, Y. S.; Wong, L. K.; Mohtar, M. Z.

    2017-04-01

    This paper presents a research study conducted in a local automotive component manufacturer that produces aluminium alloy steering housing local and global markets. This study is to investigate the effect of design modification of mold in die casting as to improve the production rate. Design modification is carried out on the casting shot of the mold. Computer flow simulation was carried out to study the flow of molten metal in the mold with respect to the mold design modification. The design parameters of injection speed, die temperature and clamping force has been included in the study. The result of the simulation showed that modifications of casting shot give significant impact towards the molten flow behaviour in casting process. The capabilities and limitations of die casting process simulation to conduct defect analysis had been optimized. This research will enhance the efficiency of the mass production of the industry of die casting with the understanding of defect analysis, which lies on the modification of the mold design, a way early in its stages of production.

  4. High Density Die Casting (HDDC): new frontiers in the manufacturing of heat sinks

    NASA Astrophysics Data System (ADS)

    Sce, Andrea; Caporale, Lorenzo

    2014-07-01

    Finding a good solution for thermal management problems is every day more complex. due to the power density and the required performances. When a solution suitable for high volumes is needed. die-casting and extrusion are the most convenient technologies. However designers have to face the well-known limitations for those processes. High Density Die Casting (HDDC) is a process under advanced development. in order to overcome the extrusion and traditional die casting limits by working with alloys having much better thermal performances than the traditional die-casting process. while keeping the advantages of a flexible 3D design and a low cost for high volumes. HDDC offers the opportunity to design combining different materials (aluminium and copper. aluminium and stainless steel) obtaining a structure with zero porosity and overcoming some of die-casting limits. as shown in this paper. A dedicated process involving embedded heat pipes is currently under development in order to offer the possibility to dramatically improve the heat spreading.

  5. 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.

  6. Recycling of Al-Si die casting scraps for solar Si feedstock

    NASA Astrophysics Data System (ADS)

    Seo, Kum-Hee; Jeon, Je-Beom; Youn, Ji-Won; Kim, Suk Jun; Kim, Ki-Young

    2016-05-01

    Recycling of aluminum die-casting scraps for solar-grade silicon (SOG-Si) feedstock was performed successfully. 3 N purity Si was extracted from A383 die-casting scrap by using the combined process of solvent refining and an advanced centrifugal separation technique. The efficiency of separating Si from scrap alloys depended on both impurity level of scraps and the starting temperature of centrifugation. Impurities in melt and processing temperature governed the microstructure of the primary Si. The purity of Si extracted from the scrap melt was 99.963%, which was comparable to that of Si extracted from a commercial Al-30 wt% Si alloy, 99.980%. The initial purity of the scrap was 2.2% lower than that of the commercial alloy. This result confirmed that die-casting scrap is a potential source of high-purity Si for solar cells.

  7. Improving the strength and ductility of magnesium die-casting alloys via rare-earth addition

    NASA Astrophysics Data System (ADS)

    Bakke, Per; Pettersen, Ketil; Westengen, Hakon

    2003-11-01

    The development of new die-casting alloys is a multifaceted task, where success depends upon the ability to control a chain of properties, and where the weakest link determines the outcome. Optimizing one property by alloying often comes at the expense of one or more other properties. A typical example is yield strength vs. ductility. In developing alloys for high-pressure die casting, the peculiar aspects of the process must be considered. High injection speeds, high metal pressures, and the lack of efficient thermal barriers lead to extremely high cooling rates. This makes high-pressure die casting unique since the resulting refined microstructure provides excellent mechanical properties. In this article, the influence of alloy composition on mechanical properties is investigated, with special emphasis on strength and ductility.

  8. Laser beam welding of aluminum die casting with reduced pore formation

    SciTech Connect

    Rehbein, D.H.; Decker, I.; Wohlfahrt, H.

    1994-12-31

    Laser beam welding is already well treated within the laboratory, but there is still a minor industrial application because of the lack of reliability of the process due to violent fluctuations of the plasma formation above and melt flow turbulence around the welding key-hole. An even greater challenge is the welding of die cast aluminum since the high hydrogen content dissolved within the material during the casting process is responsible for a strong pore formation of the weld and a rather unsteady welding process. During the last 10 years, intensive research work has been executed by the research institute of the authors in order to increase the weldability of die-case aluminum by optimization of the casting process. The casting process has been optimized in such a way that as few gases as possible can penetrate into the castings. The porosity of the welds has been reduced to a level comparable to that of high-quality joints of wrought material. The weld quality achieved by electron beam welding is excellent. The range of possible welding speeds and the necessary laser power depending on the wall thickness and the chosen optical arrangement are quantified. Die casting of aluminum is a manufacturing operation of high productivity. However, it s not suited for production of hollow structures. A combination with a highly productive welding technique such as laser beam welding is now available, and one may expect it to be of reasonable economic benefit in the future.

  9. Semi-solid Processing of Alloys

    NASA Astrophysics Data System (ADS)

    Kirkwood, David H.; Suéry, Michel; Kapranos, Plato; Atkinson, Helen V.; Young, Kenneth P.

    The original semisolid forming process, developed at MIT in 1972, involved stirring an alloy during solidification to produce a slurry of spheroidal primary particles in a liquid matrix, which was then injected directly into a die to produce a solid component. This was termed "rheocasting." Subsequently, it was found more convenient to solidify the slurry completely during the continuous casting of an electromag netically stirred strand, which was then cut into slugs for partial remelting back into semisolid billets on demand. These could be loaded into a diecasting machine in this state for injection into the die. This alternative process route is called "thixoforming," and until recently, it was the preferred industrial process. For this reason, the microstructure developed during the reheating and melting for thixo forming will be considered first. Experimentally, it has been found that the most effective fraction solid f s for thixoforming, lies between 0.5 and 0.6. Below this range, the semisolid slug becomes too soft to support its own weight and sags during remelting; above this range, it is too stiff to flow readily and fill the die. However, the slurry technologies used in rheocasting typically operate at lower fraction solids and rely on the ability to pour the semisolid alloy much like a liquid (see Chap. 4). It has been observed in practice that the fraction solid is in fact a critical factor for effective thixoforming, and therefore, both good temperature control and lack of sensitivity of f s to small temperature variations of the alloy are essential to efficient manufacturing.

  10. Simple visualization techniques for die casting part and die design. Final report, July 1, 1995--September 30, 1997

    SciTech Connect

    Miller, R.A.; Lu, S.C.; Rebello, A.B.

    1998-05-01

    The objective of this work was to develop and test die casting design evaluation techniques based on the visualization of geometric data that is related to potential defects of problems. Specifically, thickness information is used to provide insight into potential thermal problems in the part and die. Distance from the gate and a special type of animation of the fill pattern is used to provide an assessment of gate, vent and overflow locations. Techniques have been developed to convert part design information in the form of STL files to a volume-based representation called a voxel model. The use of STL files makes the process CAD system independent. Once in voxel form, methods that were developed in this work are used to identify thick regions in the part, thin regions in the part and/or die, distance from user specified entry locations (gates), and the qualitative depiction of the fill pattern. The methods were tested with a prototype implementation on the UNIX platform. The results of comparisons with numerical simulation and field reported defects were surprisingly good. The fill-related methods were also compared against short-shots and a water analog study using high speed video. The report contains the results of the testing plus detailed background material on the construction of voxel models, the methods used for displaying results, and the computational geometric reasoning methods used to create die casting-related information form the voxel model for display to the user.

  11. Simple visualization techniques for die casting part and die design. Final report, July 1, 1995--September 30, 1997

    SciTech Connect

    Miller, R.A.; Lu, S.C.; Rebello, A.B.

    1998-05-01

    The objective of this work was to develop and test die casting design evaluation techniques based on the visualization of geometric data that is related to potential defects of problems. Specifically, thickness information is used to provide insight into potential thermal problems in the part and die. Distance from the gate and a special type of animation of the fill pattern is used to provide an assessment of gate, vent and overflow locations. Techniques have been developed to convert part design information in the form of STL files to a volume-based representation called a voxel model. The use of STL files makes the process CAD system independent. Once in voxel form, methods that were developed in this work are used to identify thick regions in the part, thin regions in the part and/or die, distance from user specified entry locations (gates), and the qualitative depiction of the fill pattern. The methods were tested with a prototype implementation on the UNIX platform. The results of comparisons with numerical simulation and field reported defects were surprisingly good. The fill-related methods were also compared against short-shots and a water analog study using high speed video. The report contains the results of the testing plus detailed background material on the construction of voxel models, the methods used for displaying results, and the computational geometric reasoning methods used to create die casting-related information from the voxel model for display to the user.

  12. Metallic Reinforcement of Direct Squeeze Die Casting Aluminum Alloys for Improved Strength and Fracture Resistance

    SciTech Connect

    D. Schwam: J.F. Wallace: Y. Zhu: J.W. Ki

    2004-10-01

    The utilization of aluminum die casting as enclosures where internal equipment is rotating inside of the casting and could fracture requires a strong housing to restrain the fractured parts. A typical example would be a supercharger. In case of a failure, unless adequately contained, fractured parts could injure people operating the equipment. A number of potential reinforcement materials were investigated. The initial work was conducted in sand molds to create experimental conditions that promote prolonged contact of the reinforcing material with molten aluminum. Bonding of Aluminum bronze, Cast iron, and Ni-resist inserts with various electroplated coatings and surface treatments were analyzed. Also toughening of A354 aluminum cast alloy by steel and stainless steel wire mesh with various conditions was analyzed. A practical approach to reinforcement of die cast aluminum components is to use a reinforcing steel preform. Such performs can be fabricated from steel wire mesh or perforated metal sheet by stamping or deep drawing. A hemispherical, dome shaped casting was selected in this investigation. A deep drawing die was used to fabricate the reinforcing performs. The tendency of aluminum cast enclosures to fracture could be significantly reduced by installing a wire mesh of austenitic stainless steel or a punched austenitic stainless steel sheet within the casting. The use of reinforcements made of austenitic stainless steel wire mesh or punched austenitic stainless steel sheet provided marked improvement in reducing the fragmentation of the casting. The best strengthening was obtained with austenitic stainless steel wire and with a punched stainless steel sheet without annealing this material. Somewhat lower results were obtained with the annealed punched stainless steel sheet. When the annealed 1020 steel wire mesh was used, the results were only slightly improved because of the lower mechanical properties of this unalloyed steel. The lowest results were

  13. 77 FR 6587 - PHB Die Casting a Subsidiary of PHB, Inc., Including On-Site Leased Workers From Career Concepts...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-08

    ... Employment and Training Administration PHB Die Casting a Subsidiary of PHB, Inc., Including On-Site Leased... Alternative Trade Adjustment Assistance on December 19, 2008, applicable to workers of PHB Die Casting, a subsidiary of PHB, Inc., including on-site leased workers from Career Concepts and Volt Services,...

  14. The Simulation of Magnesium Wheel Low Pressure Die Casting Based on PAM-CAST™

    NASA Astrophysics Data System (ADS)

    Peng, Yinghong; Wang, Yingchun; Li, Dayong; Zeng, Xiaoqin

    2004-06-01

    Magnesium is the lightest metal commonly used in engineering, with various excellent characteristics such as high strength and electromagnetic interference shielding capability. Particularly, the usage of magnesium in automotive industry can meet better the need to reduce fuel consumption and CO2 emissions. Nowadays, most current magnesium components in automobiles are made by die casting. In this paper, commercial software for die casting, PAM-CAST™, was utilized to simulate the low pressure die casting process of magnesium wheel. Through calculating temperature field and velocity field during filling and solidification stages, the evolution of temperature distribution and liquid fraction was analyzed. Then, the potential defects including the gas entrapments in the middle of the spokes, shrinkages between the rim and the spokes were forecasted. The analytical results revealed that the mold geometry and die casting parameters should be improved in order to get the sound magnesium wheel. The reasons leading to these defects were also analyzed and the solutions to eliminate them were put forward. Furthermore, through reducing the pouring velocity, the air gas entrapments and partial shrinkages were eliminated effectively.

  15. Influence of Sludge Particles on the Tensile Properties of Die-Cast Secondary Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Ferraro, Stefano; Timelli, Giulio

    2015-04-01

    The effects of sludge intermetallic particles on the mechanical properties of a secondary AlSi9Cu3(Fe) die-casting alloy have been studied. Different alloys have been produced by systematically varying the Fe, Mn, and Cr contents within the composition tolerance limits of the standard EN AC-46000 alloy. The microstructure shows primary α-Al x (Fe,Mn,Cr) y Si z sludge particles, with polyhedral and star-like morphologies, although the presence of primary β-Al5FeSi phase is also observed at the highest Fe:Mn ratio. The volume fraction of primary compounds increases as the Fe, Mn, and Cr contents increase and this can be accurately predicts from the Sludge Factor by a linear relationship. The sludge amount seems to not influence the size and the content of porosity in the die-cast material. Furthermore, the sludge factor is not a reliable parameter to describe the mechanical properties of the die-cast AlSi9Cu3(Fe) alloy, because this value does not consider the mutual interaction between the elements. In the analyzed range of composition, the design of experiment methodology and the analysis of variance have been used in order to develop a semi-empirical model that accurately predicts the mechanical properties of the die-cast AlSi9Cu3(Fe) alloys as function of Fe, Mn, and Cr concentrations.

  16. 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.

  17. Experimental Damage Criterion for Static and Fatigue Life Assessment of Commercial Aluminum Alloy Die Castings

    NASA Astrophysics Data System (ADS)

    Battaglia, Eleonora; Bonollo, Franco; Ferro, Paolo

    2017-05-01

    Defects, particularly porosity and oxides, in high-pressure die casting can seriously compromise the in-service behavior and durability of products subjected to static or cyclic loadings. In this study, the influence of dimension, orientation, and position of casting defects on the mechanical properties of an AlSi12(b) (EN-AC 44100) aluminum alloy commercial component has been studied. A finite element model has been carried out in order to calculate the stress distribution induced by service loads and identify the crack initiation zones. Castings were qualitatively classified on the basis of porosities distribution detected by X-ray technique and oxides observed on fracture surfaces of specimens coming from fatigue and tensile tests. A damage criterion has been formulated which considers the influence of defects position and orientation on the mechanical strength of the components. Using the proposed damage criterion, it was possible to describe the mechanical behavior of the castings with good accuracy.

  18. Study on objective functions for the slow shot phase in high-pressure die casting

    NASA Astrophysics Data System (ADS)

    Frings, Markus; Behr, Marek; Elgeti, Stefanie

    2016-10-01

    High-pressure die casting is an important process in the field of aluminum processing. Especially during the slow shot phase, the process parameters immensely influence the cast part quality. At the current state of the art, the appropriate process parameters are identified based on running-in trials and significant experience. To translate this experience into a mathematical framework is the aim of this work. The idea is to shift the running-in trials to the computer—now in the form of a numerical optimization. In view of the optimization, this paper presents a selection of objective functions. These are assessed with the respect to (1) their suitability as an overall quality measure of the casting process and (2) the extent to which they reflect the goals of the casting process.

  19. Experimental Damage Criterion for Static and Fatigue Life Assessment of Commercial Aluminum Alloy Die Castings

    NASA Astrophysics Data System (ADS)

    Battaglia, Eleonora; Bonollo, Franco; Ferro, Paolo

    2017-03-01

    Defects, particularly porosity and oxides, in high-pressure die casting can seriously compromise the in-service behavior and durability of products subjected to static or cyclic loadings. In this study, the influence of dimension, orientation, and position of casting defects on the mechanical properties of an AlSi12(b) (EN-AC 44100) aluminum alloy commercial component has been studied. A finite element model has been carried out in order to calculate the stress distribution induced by service loads and identify the crack initiation zones. Castings were qualitatively classified on the basis of porosities distribution detected by X-ray technique and oxides observed on fracture surfaces of specimens coming from fatigue and tensile tests. A damage criterion has been formulated which considers the influence of defects position and orientation on the mechanical strength of the components. Using the proposed damage criterion, it was possible to describe the mechanical behavior of the castings with good accuracy.

  20. Energy Saving Melting and Revert Reduction Technology: Melting Efficiency in Die Casting Operations

    SciTech Connect

    David Schwam

    2012-12-15

    This project addressed multiple aspects of the aluminum melting and handling in die casting operations, with the objective of increasing the energy efficiency while improving the quality of the molten metal. The efficiency of melting has always played an important role in the profitability of aluminum die casting operations. Consequently, die casters need to make careful choices in selecting and operating melting equipment and procedures. The capital cost of new melting equipment with higher efficiency can sometimes be recovered relatively fast when it replaces old melting equipment with lower efficiency. Upgrades designed to improve energy efficiency of existing equipment may be well justified. Energy efficiency is however not the only factor in optimizing melting operations. Melt losses and metal quality are also very important. Selection of melting equipment has to take into consideration the specific conditions at the die casting shop such as availability of floor space, average quantity of metal used as well as the ability to supply more metal during peaks in demand. In all these cases, it is essential to make informed decisions based on the best available data.

  1. 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.

  2. Characterization of pores in high pressure die cast aluminum using active thermography and computed tomography

    NASA Astrophysics Data System (ADS)

    Maierhofer, Christiane; Myrach, Philipp; Röllig, Mathias; Jonietz, Florian; Illerhaus, Bernhard; Meinel, Dietmar; Richter, Uwe; Miksche, Ronald

    2016-02-01

    Larger high pressure die castings (HPDC) and decreasing wall thicknesses are raising the issue of casting defects like pores in aluminum structures. Properties of components are often strongly influenced by inner porosity. As these products are being established more and more in lightweight construction (e.g. automotive and other transport areas), non-destructive testing methods, which can be applied fast and on-site, are required for quality assurance. In this contribution, the application of active thermography for the direct detection of larger pores is demonstrated. The analysis of limits and accuracy of the method are completed by numerical simulation and the method is validated using computed tomography.

  3. Low Cost and Energy Efficient Methods for the Manufacture of Semi-Solid (SSM) Feedstock

    SciTech Connect

    Diran Apelian; Qingyue Pan; Makhlouf Makhlouf

    2005-11-07

    The SSM Consortium (now ACRC) at WPI has been carrying out fundamental, pre-competitive research in SSM for several years. Current and past research (at WPI) has generated many results of fundamental and applied nature, which are available to the SSM community. These include materials characterization, yield stress effects, alloy development, rheological properties, process modeling/simulation, semi-solid slurry formation, etc. Alternative method to produce SSM slurries at lower processing costs and with reduced energy consumption is a critical need. The production of low cost SSM feedstock will certainly lead to a dramatic increase in the tonnage of castings produced by SSM, and will provide end users such as the transportation industry, with lighter, cheaper and high performance materials. In this program, the research team has addressed three critical issues in semi-solid processing. They are: (1) Development of low cost, reliable slurry-on-demand approaches for semi-solid processing; (2) Application of the novel permanent grain refining technology-SiBloy for the manufacture of high-quality SSM feedstock, and (3) Development of computational and modeling tools for semi-solid processing to enhance SSM process control. Salient results from these studies are summarized and detailed in our final technical report.

  4. Extrusion of AlSi/SiCp composite alloys in the semi-solid state

    SciTech Connect

    Laplante, S.; Ajersch, F.; Legros, N.

    1995-10-01

    Semi-solid A356 alloys with 15 vol % SiC particles (10--15{micro}m) were extruded through cylindrical dies of variable dimension in order to evaluate the resistance to extrusion of these composites. The samples were first prepared by isothermal mixing in the semi-solid state for controlled periods of time and shear rates in order to obtain 20, 30 and 40 vol% primary fraction of the alloy ({alpha}-aluminum) generating a consistent globular-agglomerated structure. The quenched samples were introduced into the die chamber of a computer controlled extrusion press where the temperature was again raised to the semi-solid state and then extruded at a constant rate. Extrusions were carried out to evaluate the effect of extrusion rate, die length and diameter and variable solid fraction. All examples exhibited a sharp rise in extrusion force, and then reaching a plateau for the duration of the extrusion. Die entrance resistance was found to be the predominant force measured. Analysis of sections of the extruded material showed that the primary phase particles are deformed axially along the extrusion direction resulting in a non-isotropic structure with increased tensile strength and ductility.

  5. Defect Band Characteristics in Mg-Al and Al-Si High-Pressure Die Castings

    NASA Astrophysics Data System (ADS)

    Gourlay, C. M.; Laukli, H. I.; Dahle, A. K.

    2007-08-01

    Bands of positive macrosegregation and porosity commonly follow the surface contour of components produced by high-pressure die casting (HPDC). In this article, Al alloy AlSi7Mg and Mg alloys AZ91 and AM60 were cast into tensile test bars using cold-chamber (cc) HPDC. Microstructural characterization revealed that externally solidified crystals (ESCs) are not necessary for defect band formation, and that defect bands can form both near to and relatively far from any surface layer of different microstructure. The defect bands were 140 to 240 μm thick. In addition to defect-band-related macrosegregation, the castings also contained inverse segregation and surface segregation. Defect bands are shown to have the characteristics of the dilatant shear bands reported in past rheology studies, indicating that defect bands form due to strain localization in partially solid material during the HPDC process.

  6. Characterization of Flow Behavior of Semi-Solid Slurries with Low Solid Fractions

    NASA Astrophysics Data System (ADS)

    Chucheep, Thiensak; Wannasin, Jessada; Canyook, Rungsinee; Rattanochaikul, Tanate; Janudom, Somjai; Wisutmethangoon, Sirikul; Flemings, Merton C.

    2013-10-01

    Semi-solid slurry casting is a metal-forming process that involves transforming liquid metal into slurry having a low solid fraction and then forming the slurry into solid parts. To successfully apply this slurry-forming process, it is necessary to fully understand the flow behavior of semi-solid slurries. This present work applied the rapid quenching method and the modified gravity fluidity casting to investigate the flow behavior, which involves characterizations of the initial solid fraction, fluidity, and microstructure of semi-solid slurries. Three commercial aluminum alloys were used in this study: 383 (Al-Si11Cu), 356 (Al-Si7MgFe), and 7075 (Al-Zn6MgCu) alloys. The results show that the initial solid fractions can be controlled by varying the rheocasting time. The rapid quenching mold can be used to determine the initial solid fractions. In this method, it is important to apply the correcting procedure to account for growth during quenching and to include all the solid phases. Results from the fluidity study of semi-solid slurries show that the fluidity decreases as the initial solid fraction increases. The decrease is relatively rapid near the low end of the initial solid fraction curves, but is quite slow near the high end of the curves. All the three alloys follow this trend. The results also demonstrate that the slurries that contain high solid fractions of up to 30 pct can still flow well. The microstructure characterization results show that the solid particles in the slurries flow uniformly in the channel. A uniform and fine microstructure with limited phase segregation is observed in the slurry cast samples.

  7. Fabrication of glass photonic crystal fibers with a die-cast process.

    PubMed

    Guiyao, Zhou; Zhiyun, Hou; Shuguang, Li; Lantian, Hou

    2006-06-20

    We demonstrate a novel method for the fabrication of glass photonic crystal fibers (PCFs) with a die-cast process. SF6 glass is used as the material for PCFs, and the die is made of heat-resisting alloy steel, whose inner structure matches the PCF's structure. The die is put vertically in the vessel with SF6 glass, and the vacuum hose is attached to the top of the die. The die and glass are put in the furnace to heat at 870 K. The die is slowly filled with the softening glass under vacuum conduction until it is full. It is kept in the furnace to anneal at a rate of 20 K/h to remove the thermal stress that could lead to cracks. The outer tube of the die is taken apart when its temperature is close to room temperature, and the fused glass bundle is etched in an acidic solution to remove the heat-resisting alloy steel rods. Thus, the etched bundle is ready to use as a PCF preform. The PCF is observed in the generation of a supercontinuum, with the flat plateau in the spectrum of the output emission stretching from 400 to 1400 nm by experimental measurement. The transmission loss is 0.2-0.3 dB/m at wavelengths of 420-900 nm.

  8. Fabrication of glass photonic crystal fibers with a die-cast process

    NASA Astrophysics Data System (ADS)

    Guiyao, Zhou; Zhiyun, Hou; Shuguang, Li; Lantian, Hou

    2006-06-01

    We demonstrate a novel method for the fabrication of glass photonic crystal fibers (PCFs) with a die-cast process. SF6 glass is used as the material for PCFs, and the die is made of heat-resisting alloy steel, whose inner structure matches the PCF's structure. The die is put vertically in the vessel with SF6 glass, and the vacuum hose is attached to the top of the die. The die and glass are put in the furnace to heat at 870 K. The die is slowly filled with the softening glass under vacuum conduction until it is full. It is kept in the furnace to anneal at a rate of 20 K/h to remove the thermal stress that could lead to cracks. The outer tube of the die is taken apart when its temperature is close to room temperature, and the fused glass bundle is etched in an acidic solution to remove the heat-resisting alloy steel rods. Thus, the etched bundle is ready to use as a PCF preform. The PCF is observed in the generation of a supercontinuum, with the flat plateau in the spectrum of the output emission stretching from 400 to 1400 nm by experimental measurement. The transmission loss is 0.2-0.3 dB/m at wavelengths of 420-900 nm.

  9. Microstructure and Elevated Temperature Properties of Die-cast AZ91- xNd Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Wang, Limin; An, Jian; Liu, Yongbing

    2008-10-01

    The effect of Nd addition on the microstructure and mechanical properties of a die-cast AZ91 alloy was investigated in the present work. The results show that the die-cast AZ91 alloy is composed of α-Mg matrix and γ-Mg17Al12 phase. Nd addition into the AZ91 alloy leads to the formation of rare earth containing intermetallic phase. Al4Nd phase forms when Nd content is less than or equal to 1.0 wt.%. Al2Nd phase appears simultaneously when Nd content reaches to 3.0 wt.%. The size and volume fraction of γ-Mg17Al12 phase decrease, because of the newly formed Al-Nd phase. And the γ-Mg17Al12 phase distributes from reticular to dispersive. Nd addition has a little effect on the room temperature properties of the die-cast AZ91 alloy, but greatly improves the elevated temperature properties. The tensile strength of AZ91-0.5Nd and AZ91-1.0Nd alloy tested at 150 °C is even close to the room temperature strength. The AZ91-1.0Nd alloy has the optimal properties.

  10. 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

  11. Analog Studies of Thermomechanical Fatigue and Abrasive Wear of Cast and Forged Steels for "Autoforge" Dies

    NASA Astrophysics Data System (ADS)

    Kolesnikov, M. S.; Mironova, Yu. S.; Mukhametzyanova, G. F.; Novikova, I. E.; Novikov, V. Yu.

    2014-07-01

    Processes of thermomechanical fatigue and abrasive wear of suspension-cast precipitation-hardening ferrite-carbide steel 30T6NTiC-1.5 and standard steel 4Kh5MFS are studied. The dominant kinds of fracture typical for dies for semisolid stamping are determined. The factors and parameters of cyclic temperature and force loading are shown to produce a selective action on the competing kinds of damage of the die steels. A comparative analysis of the properties of the steels is performed. Steel 30T6NTiC-1.5 is shown to have substantial advantages over steel 4Kh5FMS traditionally used for making "Autoforge" dies.

  12. Casting Technology.

    ERIC Educational Resources Information Center

    Wright, Michael D.; And Others

    1992-01-01

    Three articles discuss (1) casting technology as it relates to industry, with comparisons of shell casting, shell molding, and die casting; (2) evaporative pattern casting for metals; and (3) high technological casting with silicone rubber. (JOW)

  13. Development of Advanced Coating Techniques for Highly-durable Casting Dies

    NASA Astrophysics Data System (ADS)

    Tanaka, S.; Takagi, M.; Mano, T.

    2013-03-01

    In order to improve the durability of aluminum die-casting molds, we applied microstructure-controlled PVD coating techniques. Single-layer and multilayer films consisting of chromium nitride (CrN) or titanium aluminum nitride (TiAlN) were prepared using an ion plating process. Structures of multilayer films were observed using transmission electron microscopy. Pin-shaped mold steel specimens coated with each of the films were soaked in the molten aluminum alloy at 953 K different periods of time, and the amount of weight loss due to erosion was evaluated. The weight losses for the multilayer CrN and TiAlN specimens were found to be less than those for the single-layer specimens. As a practical test, five specimens of core pins used in aluminum die casting of automobile parts were coated with multilayer films, and the number of maintenance operations required to remove aluminum alloy remaining on the specimen surfaces after several thousand castings was counted and compared with six control specimens (core pins treated using a commercial salt bath diffusion process). The number of maintenance operations for CrN- and TiAlN-based multilayer-coated core pins was found to be lower than for the control specimens.

  14. Fatigue Life Prediction in Rapid Die Casting — Preliminary Work in View of Current Research

    NASA Astrophysics Data System (ADS)

    Ng, Chuan Huat; Grote, Karl-Heinrich; Bähr, Rüdiger

    2007-05-01

    Numerical simulation technique as a prediction tool is slowly adopted in metal casting industry for predicting design modelling solidification analysis. The reasons for this activity is found in the need to further enhance the geometrical design and mechanical properties of the tool design and the correct prediction methodology to fulfil industrial needs. The present state of numerical simulation capabilities in rapid die casting technologies is reviewed and the failure mode mechanisms of thermal fatigue, aimed at developing a numerical simulation with a systematic design guidance for predicting the thermal cyclic loading analysis and improvement is presented along with several other methods. The economic benefits of a numerical simulation technique in die casting are limited to tool life time, mechanical properties and design guidance. The extensive computer capabilities of a numerical simulation with a systematic design guidance methodology are exploited to provide a solution for flexible design, mechanical properties and mould life time. Related research carried out worldwide by different organisations and academic institutions are discussed.

  15. Sand, die and investment cast parts via the SLS selective laser sintering process

    NASA Astrophysics Data System (ADS)

    van de Crommert, Simon; Seitz, Sandra; Esser, Klaus K.; McAlea, Kevin

    1997-09-01

    Complex three-dimensional parts can be manufactured directly from CAD data using rapid prototyping processes. SLS selective laser sintering is a rapid prototyping process developed at the University of Texas at Austin and commercialized by DTM Corporation. SLS parts are constructed layer by layer from powdered materials using laser energy to melt CAD specified cross sections. Polymer, metal, and ceramic powders are all potential candidate materials for this process. In this paper the fabrication of complex metal parts rapidly using the investment, die and sand casting technologies in conjunction with the selective laser sintering process are being explained and discussed. TrueForm and polycarbonate were used for investment casting, while RapidSteel metal mould inserts were used for the die casting trials. Two different SandForm materials, zircon and silica sand, are currently available for the direct production of sand moulds and cores. The flexible and versatile selective laser sintering process all these materials on one single sinterstation. Material can be changed fast and easily between two different builds.

  16. Fatigue Life Prediction in Rapid Die Casting - Preliminary Work in View of Current Research

    SciTech Connect

    Chuan Huat Ng; Grote, Karl-Heinrich; Baehr, Ruediger

    2007-05-17

    Numerical simulation technique as a prediction tool is slowly adopted in metal casting industry for predicting design modelling solidification analysis. The reasons for this activity is found in the need to further enhance the geometrical design and mechanical properties of the tool design and the correct prediction methodology to fulfil industrial needs. The present state of numerical simulation capabilities in rapid die casting technologies is reviewed and the failure mode mechanisms of thermal fatigue, aimed at developing a numerical simulation with a systematic design guidance for predicting the thermal cyclic loading analysis and improvement is presented along with several other methods. The economic benefits of a numerical simulation technique in die casting are limited to tool life time, mechanical properties and design guidance. The extensive computer capabilities of a numerical simulation with a systematic design guidance methodology are exploited to provide a solution for flexible design, mechanical properties and mould life time. Related research carried out worldwide by different organisations and academic institutions are discussed.

  17. 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)

  18. Low-strain plasticity in a high pressure die cast Mg-Al alloy

    NASA Astrophysics Data System (ADS)

    Vanna Yang, K.; Cáceres, C. H.; Nagasekhar, A. V.; Easton, M. A.

    2012-03-01

    The Kocks-Mecking method was used to compare the strain-hardening behavior at low strains of high pressure die cast Mg-9 mass% Al alloy and gravity cast fine grained pure Mg specimens. The alloy specimens exhibited a rounded flow curve in contrast with the pure metal's for which macroscopic yielding occurred at a well-defined stress. Microhardness mapping of the cross-section of an alloy specimen showed a surface layer, or skin, with hardness values ˜20 HV above those of the centre or core region. On the assumption that the core strain hardens at the same rate as the pure Mg specimen, it was estimated that ˜20% of the alloy specimen's cross-section was still elastic when the core reached full plasticity. The micromechanics of the elasto-plastic transition in the alloy specimens are discussed.

  19. Microstructure and homogeneity of semi-solid 7075 aluminum tubes processed by parallel tubular channel angular pressing

    NASA Astrophysics Data System (ADS)

    Meshkabadi, Ramin; Faraji, Ghader; Javdani, Akbar; Fata, Ali; Pouyafar, Vahid

    2017-09-01

    Semi-solid processing is a new developing technology for the fabrication of intricate parts at low temperatures in comparison with conventional casting routes. In this research, a parallel tubular channel angular pressing (PTCAP) was used as a pre strain-inducing process, and the influence of the number of PTCAP passes and semi-solid heating parameters on the microstructural characteristics of Al7075 tubes was investigated. The results demonstrated that PTCAP process could successfully be used as a best pre-straining method for tubular samples showing semi-solid microstructures. As the temperature is increased, the solid particle size first decreased, then increased, and gradually became more spherical. The appropriate condition for the subsequent semi-solid forming process was gained at reheating temperature of 620 oC. The suitability of this temperature was confirmed by the uniform distribution of grains. The grain size and shape factor both increased along with increasing the holding time. The distribution of the solid particles was strongly dependent upon the holding time and became uniform as the holding time increased. Comparison of the grain size and shape factor between ECAPed and PTCAPed samples revealed a high capacity of the PTCAP process as a strain-inducing stage. Also the two-pass PTCAP samples exhibited higher hardness than one-pass treated samples in the semi-solid state.

  20. Secondary Al-Si-Mg High-pressure Die Casting Alloys with Enhanced Ductility

    NASA Astrophysics Data System (ADS)

    Bösch, Dominik; Pogatscher, Stefan; Hummel, Marc; Fragner, Werner; Uggowitzer, Peter J.; Göken, Mathias; Höppel, Heinz Werner

    2015-03-01

    Al-Si-Mg-based secondary cast alloys are attractive candidates for thin-walled high-pressure die castings for applications in the transport industry. The present study investigates the effect of manganese additions at high cooling rates on microstructure, mechanical properties, and on the dominating fracture mechanisms of alloy AlSi10Mg with an elevated iron concentration. Systematic variations of the Mn content from 0.20 to 0.85 wt pct at a constant Fe content of 0.55 wt pct illustrate the key changes in type, phase fraction, and shape of the Fe-containing intermetallic phases, and the corresponding influence on the alloy's ductility. For high-pressure die casting (HPDC), an optimal range of the Mn content between 0.40 and 0.60 wt pct, equivalent to a Mn/Fe ratio of approximately 1, has been identified. At these Mn and Fe contents, the high cooling rates obtained in HPDC result in the formation of fine and homogeneously distributed α-Al15(Fe,Mn)3Si2 phase, and crack initiation is transferred from AlFeSi intermetallics to eutectic silicon. The study interprets the microstructure-property relationship in the light of thermodynamic calculations which reveal a significant increase in undercooling of the α-Al15(Fe,Mn)3Si2 phase with increased Mn content. It concludes that the interdependence of the well-defined Mn/Fe ratio and the high cooling rate in HPDC can generate superior ductility in secondary AlSi10Mg cast alloys.

  1. 2D and 3D characterization of pore defects in die cast AM60

    SciTech Connect

    Yang, Zhuofei; Maurey, Alexandre; Kang, Jidong; Wilkinson, David S.

    2016-04-15

    The widespread application of die castings can be hampered due to the potential of large scale porosity to act as nucleation sites for fracture and fatigue. It is therefore important to develop robust approaches to the characterization of porosity providing parameters that can be linked to the material's mechanical properties. We have tackled this problem in a study of the AM60 die cast Mg alloy, using samples extracted from a prototype shock tower. A quantitative characterization of porosity has been undertaken, analyzing porosity in both 2D (using classical metallographic methods) and in 3D (using X-ray computed tomography (XCT)). Metallographic characterization results show that shrinkage pores and small gas pores can be distinguished based on their distinct geometrical features. Shrinkage pores are irregular with multiple arms, resulting in a form factor less than 0.4. In contrast, gas pores are generally more circular in shape yielding form factors larger than 0.6. XCT provides deeper insight into the shape of pores, although this understanding is limited by the resolution obtainable by laboratory based XCT. It also shows how 2D sectioning can produce artefacts as single complex pores are sectioned into multiple small pores. - Highlights: • Mg (e.g. AM60) die castings may contain large scale porosity that act as nucleation sites for fracture and fatigue • Quantitative characterization of porosity metallography (2D) and X-ray tomography (3D) is used • Shrinkage pores and small gas pores can be distinguished based on their distinct geometrical features. • Shrinkage pores are irregular giving a form factor < 0.4; gas pores are rounder with form factors > 0.6 • XCT enables pore visualization, although limited by the resolution obtainable by laboratory based XCT.

  2. Polymer melt rheology and flow simulations applied to cast film extrusion die design: An industrial perspective

    NASA Astrophysics Data System (ADS)

    Catherine, Olivier

    2017-05-01

    This article is an overview of the techniques used today in the area of rheology and flow simulation, on the industrial level, for cast film extrusion die design. This industry has made significant progress over the past three decades and die and feedblock design and optimization certainly have been instrumental in the overall improvement. Dies and coextrusion feedblocks are a critical aspect of the process due to the layering and forming function, which drive the final product economics and properties. Polymer melt rheology is a key aspect to consider when optimizing the flow patterns in the extrusion equipment. Not only is rheology critical for the flow channel design when aiming at obtaining a uniform flow distribution at the die exit, but also it is playing a major role in the thermal aspect of the flow due to the strong mechanical and thermal coupling. This coupling comes, on one hand, from the occurrence of viscous dissipation in the flow and on the other hand from the significant temperature dependency of melt viscosity. Viscous dissipation is due to relatively high melt viscosities and strain rates, especially with today's processes which involve formidable extrusion speeds. The third aspect discussed in this paper is the complexity of residence time distribution in modern flow channels, which is evaluated with advanced three-dimensional flow simulation and particle tracking.

  3. Stationary semi-solid battery module and method of manufacture

    DOEpatents

    Slocum, Alexander; Doherty, Tristan; Bazzarella, Ricardo; Cross, III, James C.; Limthongkul, Pimpa; Duduta, Mihai; Disko, Jeffry; Yang, Allen; Wilder, Throop; Carter, William Craig; Chiang, Yet-Ming

    2015-12-01

    A method of manufacturing an electrochemical cell includes transferring an anode semi-solid suspension to an anode compartment defined at least in part by an anode current collector and an separator spaced apart from the anode collector. The method also includes transferring a cathode semi-solid suspension to a cathode compartment defined at least in part by a cathode current collector and the separator spaced apart from the cathode collector. The transferring of the anode semi-solid suspension to the anode compartment and the cathode semi-solid to the cathode compartment is such that a difference between a minimum distance and a maximum distance between the anode current collector and the separator is maintained within a predetermined tolerance. The method includes sealing the anode compartment and the cathode compartment.

  4. Transgranular liquation cracking of grains in the semi-solid state

    NASA Astrophysics Data System (ADS)

    Karagadde, S.; Lee, P. D.; Cai, B.; Fife, J. L.; Azeem, M. A.; Kareh, K. M.; Puncreobutr, C.; Tsivoulas, D.; Connolley, T.; Atwood, R. C.

    2015-09-01

    Grain refinement via semi-solid deformation is desired to obtain superior mechanical properties of cast components. Using quantitative in situ synchrotron X-ray tomographic microscopy, we show an additional mechanism for the reduction of grain size, via liquation assisted transgranular cracking of semi-solid globular microstructures. Here we perform localized indentation of Al-15wt.%Cu globular microstructures, with an average grain size of ~480 μm, at 555 °C (74% solid fraction). Although transgranular fracture has been observed in brittle materials, our results show transgranular fracture can also occur in metallic alloys in semi-solid state. This transgranular liquation cracking (TLC) occurs at very low contact stresses (between 1.1 and 38 MPa). With increasing strain, TLC continues to refine the size of the microstructure until the grain distribution reaches log-normal packing. The results demonstrate that this refinement, previously attributed to fragmentation of secondary arms by melt-shearing, is also controlled by an additional TLC mechanism.

  5. Transgranular liquation cracking of grains in the semi-solid state

    PubMed Central

    Karagadde, S.; Lee, P. D.; Cai, B.; Fife, J. L.; Azeem, M. A.; Kareh, K. M.; Puncreobutr, C.; Tsivoulas, D.; Connolley, T.; Atwood, R. C.

    2015-01-01

    Grain refinement via semi-solid deformation is desired to obtain superior mechanical properties of cast components. Using quantitative in situ synchrotron X-ray tomographic microscopy, we show an additional mechanism for the reduction of grain size, via liquation assisted transgranular cracking of semi-solid globular microstructures. Here we perform localized indentation of Al-15wt.%Cu globular microstructures, with an average grain size of ∼480 μm, at 555 °C (74% solid fraction). Although transgranular fracture has been observed in brittle materials, our results show transgranular fracture can also occur in metallic alloys in semi-solid state. This transgranular liquation cracking (TLC) occurs at very low contact stresses (between 1.1 and 38 MPa). With increasing strain, TLC continues to refine the size of the microstructure until the grain distribution reaches log-normal packing. The results demonstrate that this refinement, previously attributed to fragmentation of secondary arms by melt-shearing, is also controlled by an additional TLC mechanism. PMID:26353994

  6. Strategies to reduce the environmental impact of an aluminium pressure die casting plant: a scenario analysis.

    PubMed

    Neto, Belmira; Kroeze, Carolien; Hordijk, Leen; Costa, Carlos; Pulles, Tinus

    2009-02-01

    This study explores a model (MIKADO) to analyse scenarios for the reduction of the environmental impact of an aluminium die casting plant. Our model calculates the potential to reduce emissions, and the costs associated with implementation of reduction options. In an earlier paper [Neto, B., Kroeze, C., Hordijk, L., Costa, C., 2008. Modelling the environmental impact of an aluminium pressure die casting company and options for control. Environmental Modelling & Software 23 (2) 147-168] we included the model description and explored the model by applying it to a plant in which no reduction options are assumed to be implemented (so-called zero case, reflecting the current practice in the plant). Here, we perform a systematic analysis of reduction options. We analysed seven types of reduction strategies, assuming the simultaneous implementation of different reduction options. These strategies are analysed with respect to their potential to reduce emissions, environmental impact and costs associated with the implementation of options. These strategies were found to differ largely in their potential to reduce the environmental impact of the plant (10-87%), as well as in the costs associated with the implementation of options (-268 to +277keuro/year). We were able to define 11 strategies, reducing the overall environmental impact by more than 50%. Of these, two have net negative costs, indicating that the company may in fact earn money through their implementation.

  7. 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).

  8. Semi-solid electrodes having high rate capability

    DOEpatents

    Chiang, Yet-Ming; Duduta, Mihai; Holman, Richard; Limthongkul, Pimpa; Tan, Taison

    2016-06-07

    Embodiments described herein relate generally to electrochemical cells having high rate capability, and more particularly to devices, systems and methods of producing high capacity and high rate capability batteries having relatively thick semi-solid electrodes. In some embodiments, an electrochemical cell includes an anode and a semi-solid cathode. The semi-solid cathode includes a suspension of an active material of about 35% to about 75% by volume of an active material and about 0.5% to about 8% by volume of a conductive material in a non-aqueous liquid electrolyte. An ion-permeable membrane is disposed between the anode and the semi-solid cathode. The semi-solid cathode has a thickness of about 250 .mu.m to about 2,000 .mu.m, and the electrochemical cell has an area specific capacity of at least about 7 mAh/cm.sup.2 at a C-rate of C/4. In some embodiments, the semi-solid cathode slurry has a mixing index of at least about 0.9.

  9. A process chain for integrating piezoelectric transducers into aluminum die castings to generate smart lightweight structures

    NASA Astrophysics Data System (ADS)

    Stein, Stefan; Wedler, Jonathan; Rhein, Sebastian; Schmidt, Michael; Körner, Carolin; Michaelis, Alexander; Gebhardt, Sylvia

    The application of piezoelectric transducers to structural body parts of machines or vehicles enables the combination of passive mechanical components with sensor and actuator functions in one single structure. According to Herold et al. [1] and Staeves [2] this approach indicates significant potential regarding smart lightweight construction. To obtain the highest yield, the piezoelectric transducers need to be integrated into the flux of forces (load path) of load bearing structures. Application in a downstream process reduces yield and process efficiency during manufacturing and operation, due to the necessity of a subsequent process step of sensor/actuator application. The die casting process offers the possibility for integration of piezoelectric transducers into metal structures. Aluminum castings are particularly favorable due to their high quality and feasibility for high unit production at low cost (Brunhuber [3], Nogowizin [4]). Such molded aluminum parts with integrated piezoelectric transducers enable functions like active vibration damping, structural health monitoring or energy harvesting resulting in significant possibilities of weight reduction, which is an increasingly important driving force of automotive and aerospace industry (Klein [5], Siebenpfeiffer [6]) due to increasingly stringent environmental protection laws. In the scope of those developments, this paper focuses on the entire process chain enabling the generation of lightweight metal structures with sensor and actuator function, starting from the manufacturing of piezoelectric modules over electrical and mechanical bonding to the integration of such modules into aluminum (Al) matrices by die casting. To achieve this challenging goal, piezoceramic sensors/actuator modules, so-called LTCC/PZT modules (LPM) were developed, since ceramic based piezoelectric modules are more likely to withstand the thermal stress of about 700 °C introduced by the casting process (Flössel et al., [7]). The

  10. Repeatability of tensile properties in high pressure die-castings of an Al-Mg-Si-Mn alloy

    NASA Astrophysics Data System (ADS)

    Yang, Hailin; Ji, Shouxun; Watson, Douglas; Fan, Zhongyun

    2015-09-01

    High pressure die-castings of an Al-Mg-Si-Mn alloy have been assessed in terms of the repeatability of the mechanical properties including yield strength, ultimate tensile strength and elongation by the normal standard deviations method and by the Weibull statistical model with three parameters. It was found that the round samples had the maximum Weibull modulus, indicating the best repeatability. The machined samples exhibited the second best of Weibull modulus. Among the square samples, the 2 mm and 5 mm thick samples had the lowest and the highest Weibull modulus respectively, indicating that the repeatability for the castings was influenced by the wall thickness. The microstructural uniformity and porosity levels are critical factors in determining the repeatability of the high pressure die-castings. A less segregation in the microstructure could uniform the stress distribution in the die-castings and a less porosity in the casting could reduce the sources for brittle fracture. These improved the repeatability in casting production.

  11. Improved design and durability of aluminum die casting horizontal shot sleeves

    NASA Astrophysics Data System (ADS)

    Birceanu, Sebastian

    The design and performance of shot sleeves is critical in meeting the engineering requirements of aluminum die cast parts. Improvement in shot sleeve materials have a major impact on dimensional stability, reproducibility and quality of the product. This investigation was undertaken in order to improve the life of aluminum die casting horizontal shot sleeves. Preliminary pin tests were run to evaluate the soldering, wash-out and thermal fatigue behavior of commercially available materials and coatings. An experimental rig was designed and constructed for shot sleeve configuration evaluation. Fabrication and testing of experimental shot sleeves was based upon preliminary results and manufacturing costs. Three shot sleeve designs and materials were compared to a reference nitrided H13 sleeve. Nitrided H13 is the preferred material for aluminum die casting shot sleeves because of wear resistance, strength and relative good soldering and wash-out resistance. The study was directed towards damage evaluation on the area under the pouring hole. This area is the most susceptible to damage because of high temperatures and impingement of molten aluminum. The results of this study showed that tungsten and molybdenum had the least amount of soldering and wash-out damage, and the best thermal fatigue resistance. Low solubility in molten aluminum and stability of intermetallic layers are main factors that determine the soldering and wash-out behavior. Thermal conductivity and thermal expansion coefficient directly influence thermal fatigue behavior. TiAlN nanolayered coating was chosen as the material with the best damage resistance among several commercial PVD coatings, because of relatively large thickness and simple deposition conditions. The results show that molybdenum thermal sprayed coating provided the best protection against damage under the pouring hole. Improved bonding is however required for life extension of the coating. TiAlN PVD coating applied on H13 nitrided

  12. The Effect of Porosity on Fatigue of Die Cast AM60

    NASA Astrophysics Data System (ADS)

    Yang, Zhuofei; Kang, Jidong; Wilkinson, David S.

    2016-07-01

    AM60 high-pressure die castings are known to contain significant porosity which can affect fatigue life. We have studied this using samples drawn from prototype AM60 shock towers by conducting strain-controlled fatigue tests accompanied by X-ray computed tomography analysis. The results show that the machined surface is the preferential location for fatigue crack development, with pores close to these surfaces serving as initiation sites. Fatigue life shows a strong inverse correlation with the size of the fatigue-crack-initiating pore. Pore shape and pore orientation also influence the response. A supplemental study on surface roughness shows that porosity is the dominant factor in fatigue. Tomography enables the link between porosity and fatigue crack initiation to be clearly identified. These data are complemented by SEM observations of the fracture surfaces which are generally flat and full of randomly oriented serration patterns but without long-range fatigue striations.

  13. Case study of lean manufacturing application in a die casting manufacturing company

    NASA Astrophysics Data System (ADS)

    Ching, Ng Tan; Hoe, Clarence Chan Kok; Hong, Tang Sai; Ghobakhloo, Morteza; Pin, Chen Kah

    2015-05-01

    The case study of lean manufacturing aims to study the application of lean manufacturing in a die casting manufacturing company located in Pulau Penang, Malaysia. This case study describes mainly about the important concepts and applications of lean manufacturing which could gradually help the company in increasing the profit by studying and analyzing their current manufacturing process and company culture. Many approaches of lean manufacturing are studied in this project which includes: 5S housekeeping, Kaizen, and Takt Time. Besides, the lean tools mentioned, quality tool such as the House of Quality is being used as an analysis tool to continuously improve the product quality. In short, the existing lean culture in the company is studied and analyzed, with recommendations written at the end of this paper.

  14. A summary of special coatings projects conducted in support of the Die Casting Program

    SciTech Connect

    Selle, J.E.

    1988-09-12

    The usefulness of various kinds of coatings to the die casting program has been studied. This work includes heat transfer and fluid flow calculations, as well as experimental work, to examine the feasibility and characteristics of various types of coatings. Calculations include the effect of surface roughness on fluid flow, conductance as a function of coating thickness, conductivity as a function of coating porosity, and solidification and possible remelting of microspheres of metal. In each case, the model is described and the results are presented. Experimental work involved evaluating the relative insulating value of various coatings and an analysis of commercial flame-sprayed coatings, low-density coatings, and release coatings. In each case, description of the experimental arrangement is given and the results are described. 5 refs., 28 figs., 6 tabs.

  15. A Numerical and Experimental Study of Flow Behavior in High Pressure Die Casting

    NASA Astrophysics Data System (ADS)

    Saeedipour, Mahdi; Schneiderbauer, Simon; Pirker, Stefan; Bozorgi, Salar

    High pressure die casting (HPDC) is one of the most important and yet little known manufacturing methods especially during liquid metal injection and filling phase. During its application different problems can arise: on the one hand, wavy disintegration of the jet might result in cold shut defect in the final product, on the other hand a high degree of atomization may strongly increase the porosity defect. A numerical simulation using volume of fluid approach (VOF), is carried out to model the global spreading of liquid metal jet. The formation of droplets, which are usually smaller than the grid spacing in computational domain, is determined by a surface energy-based criterion. An Eulerian-Lagrangian framework is introduced to track and model the droplets after formation. Since liquid metal is hardly to access, we performed experiments based on water analogy to capture the flow regime changes and drop formation. The comparison between numerical results and experiments shows a very good agreement.

  16. Adhesive Bonding and Corrosion Protection of a Die Cast Magnesium Automotive Door

    NASA Astrophysics Data System (ADS)

    Bretz, G. T.; Lazarz, K. A.; Hill, D. J.; Blanchard, P. J.

    It is well known that magnesium alloys, in close proximity to other alloys, are susceptible to galvanic corrosion. Combined with this fact, in automotive applications, it is rare that magnesium will be present in the absence of other alloys such as steel or aluminum. Therefore, in wet applications, where the galvanic cell is completed, it is necessary to isolate the magnesium in order to prevent accelerated corrosion. There are numerous commercial pre-treatments available for magnesium, however this paper focuses on conversion coatings in conjunction with a spray powder coat. By means of example, results for a hem flange joint on an AM50 die cast magnesium door structure will be presented. The outer door skin is an aluminum alloy hemmed around a cast magnesium flange. An adhesive is used between the inner and outer to help with stiffness and NVH (Noise, Vibration and Harshness). Results from bonded lap-shear coupon tests that have been exposed to accelerated corrosion cycles are presented. A second phase of this work considered a surrogate hem flange coupon, which was similarly exposed to the same accelerated corrosion cycle. Results from both of these tests are presented within this paper along with a discussion as to their suitability for use within automotive applications.

  17. Effects of Pore Distributions on Ductility of Thin-Walled High Pressure Die-Cast Magnesium

    SciTech Connect

    Choi, Kyoo Sil; Li, Dongsheng; Sun, Xin; Li, Mei; Allison, John

    2013-06-01

    In this paper, a microstructure-based three-dimensional (3D) finite element modeling method is adopted to investigate the effects of porosity in thin-walled high pressure die-cast (HPDC) Magnesium alloys on their ductility. For this purpose, the cross-sections of AM60 casting samples are first examined using optical microscope and X-ray tomography to obtain the general information on the pore distribution features. The experimentally observed pore distribution features are then used to generate a series of synthetic microstructure-based 3D finite element models with different pore volume fractions and pore distribution features. Shear and ductile damage models are adopted in the finite element analyses to induce the fracture by element removal, leading to the prediction of ductility. The results in this study show that the ductility monotonically decreases as the pore volume fraction increases and that the effect of ‘skin region’ on the ductility is noticeable under the condition of same local pore volume fraction in the center region of the sample and its existence can be beneficial for the improvement of ductility. The further synthetic microstructure-based 3D finite element analyses are planned to investigate the effects of pore size and pore size distribution.

  18. Experimental Investigations And Numerical Modelling of 210CR12 Steel in Semi-Solid State

    SciTech Connect

    Maciol, Piotr; Jakubowicz, Aleksandra; Wladislaw, Stanislaw; Zalecki, Wladyslaw; Kuziak, Roman

    2011-05-04

    Experimental investigation, including hot compression and simple closed die filling was performed. Temperature range of tests was between 1225 deg. C and 1320 deg. C. Temperature selection was adequate with liquid fraction between 20 and 60%, which is typical for thixoforming processes. In the die filling test, steel dies with ceramic layer was used (highly refractory air-setting mortar JM 3300 manufactured by Thermal Ceramics). Experiments were carried out on the Gleeble 3800 physical simulator with MCU unit. In the paper, methodology of experimental investigation is described. Dependency of forming forces on temperature and forming velocities is analysed. Obtained results are discussed. The second part of the paper concerns numerical modelling of semi-solid forming. Numerical models for both sets of test were developed. Structural and Computational Fluid Dynamics models are compared. Initial works in microstructural modelling of 210CR12 steel behaviour are described. Lattice Boltzman Method model for thixotropic flows is introduced. Microscale and macroscale models were integrated into multiscale simulation of semi-solid forming. Some fundamental issues related to multiscale modelling of thixoforming are discussed.

  19. Experimental Investigations And Numerical Modelling of 210CR12 Steel in Semi-Solid State

    NASA Astrophysics Data System (ADS)

    Macioł, Piotr; Zalecki, Władysław; Kuziak, Roman; Jakubowicz, Aleksandra; Weglarczyk, Stanisław

    2011-05-01

    Experimental investigation, including hot compression and simple closed die filling was performed. Temperature range of tests was between 1225 °C and 1320 °C. Temperature selection was adequate with liquid fraction between 20 and 60%, which is typical for thixoforming processes. In the die filling test, steel dies with ceramic layer was used (highly refractory air-setting mortar JM 3300 manufactured by Thermal Ceramics). Experiments were carried out on the Gleeble 3800 physical simulator with MCU unit. In the paper, methodology of experimental investigation is described. Dependency of forming forces on temperature and forming velocities is analysed. Obtained results are discussed. The second part of the paper concerns numerical modelling of semi-solid forming. Numerical models for both sets of test were developed. Structural and Computational Fluid Dynamics models are compared. Initial works in microstructural modelling of 210CR12 steel behaviour are described. Lattice Boltzman Method model for thixotropic flows is introduced. Microscale and macroscale models were integrated into multiscale simulation of semi-solid forming. Some fundamental issues related to multiscale modelling of thixoforming are discussed.

  20. Semi-solid electrodes having high rate capability

    DOEpatents

    Chiang, Yet-Ming; Duduta, Mihai; Holman, Richard; Limthongkul, Pimpa; Tan, Taison

    2015-11-10

    Embodiments described herein relate generally to electrochemical cells having high rate capability, and more particularly to devices, systems and methods of producing high capacity and high rate capability batteries having relatively thick semi-solid electrodes. In some embodiments, an electrochemical cell includes an anode, a semi-solid cathode that includes a suspension of an active material and a conductive material in a liquid electrolyte, and an ion permeable membrane disposed between the anode and the cathode. The semi-solid cathode has a thickness in the range of about 250 .mu.m-2,500 .mu.m, and the electrochemical cell has an area specific capacity of at least 5 mAh/cm.sup.2 at a C-rate of C/2.

  1. Modeling and Design of Semi-Solid Flow Batteries

    NASA Astrophysics Data System (ADS)

    Brunini, Victor Eric

    A three-dimensional dynamic model of the recently introduced semi-solid flow battery system is developed and applied to address issues with important design and operation implications. Because of the high viscosity of semi-solid flow battery suspensions, alternative modes of operation not typically used in conventional redox flow battery systems must be explored to reduce pumping energy losses. Modeling results are presented .and compared to experimental observations to address important considerations for both stoichiometric and intermittent flow operation. The importance of active material selection, and its impact on efficient stoichiometric flow operation is discussed. Electrochemically active zone considerations relevant to intermittent flow operation of semi-solid flow batteries (or other potential electronically conductive flow battery systems) are addressed. Finally, the use of the model as a design tool for optimizing flow channel design to improve system level performance is demonstrated.(Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs@mit.edu)

  2. Semi-solid electrodes having high rate capability

    SciTech Connect

    Chiang, Yet-Ming; Duduta, Mihai; Holman, Richard; Limthongkul, Pimpa; Tan, Taison

    2016-07-05

    Embodiments described herein relate generally to electrochemical cells having high rate capability, and more particularly to devices, systems and methods of producing high capacity and high rate capability batteries having relatively thick semi-solid electrodes. In some embodiments, an electrochemical cell includes an anode, a semi-solid cathode that includes a suspension of an active material and a conductive material in a liquid electrolyte, and an ion permeable membrane disposed between the anode and the cathode. The semi-solid cathode has a thickness in the range of about 250 .mu.m-2,500 .mu.m, and the electrochemical cell has an area specific capacity of at least 5 mAh/cm.sup.2 at a C-rate of C/2.

  3. 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.

  4. Final report to USAMP on the use of EBPVD in the light metal die casting industry

    SciTech Connect

    Heestand, G.M.

    1996-02-02

    This is the final report to the United States Automotive Materials Partnership (USAMP) on the use of Electron Beam Physical Vapor Deposition (EBPVD) to make rapid tooling for functional prototyping of metal mold processes. Historically this process has been successfully applied to the production of mold inserts for the plastics injection mold industry. Our approach for this project was to use the same technique to produce dies which could be used to make a few thousand light metal (aluminum and magnesium) prototype parts. The difficulty encountered in this project was that the requirements for the die casting industry, both in size and material requirements, were considerably more stringent than those encountered in the plastics injection industry. Consequently our technique, within the allotted time and budget constraints, was not able to meet the requirements set forth by USAMP. The remainder of this report is organized into five sections. The first discusses the technique in some detail while the second discusses a successful application. The third section discusses issues with this process while the fourth specifically discusses the work done in this project. The last is a short summary and conclusion section.

  5. 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.

  6. Casting dimensional control and fatigue life prediction for permanent mold casting dies. Technical progress report, September 29, 1993-- September 30, 1994

    SciTech Connect

    1994-11-01

    First year 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 castings. The influence of process variation and casting geometry variables on dimensional tolerances have been investigated. Preliminary results have shown that these factors have a significant influence on dimensional variability, although this variability is considerably less than the variability indicated in current tolerance standards. Gage repeatability and reproducibility testing must precede dimensional studies to insure that measurement system errors are acceptably small. Also initial efforts leading to the development 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. Initial validation trials have indicated the validity of the temperature distribution model developed.

  7. The effect of processing on the mechanical and fatigue properties of semi-solid formed A357 aluminum

    NASA Astrophysics Data System (ADS)

    Basner, Timothy Glen

    2001-11-01

    The fundamental relationship between semi-solid processing and microstructure and their effect on the flow characteristics of semisolid metals have been studied for several years. However, how the process related microstructure influences mechanical and fatigue properties has not been given the same attention. This study examines the influence of process-related microstructures on the mechanical and fatigue properties of semi-solid formed A357 alloys. Low solid fraction (<40% solid) and high solid fraction (>50% solid) semi-solid A357 aluminum were formed by two different processes, rheocasting and thixocasting. Solid fraction, globule size, globule shape factor, globule density, and the eutectic particle size and aspect ratio after T6 heat treatment were evaluated to determine their effect on the as-cast, T5, and T6 properties. The mechanical properties of low solid fraction (LSF) and high solid fraction (HSF) semi-solid formed A357 vary considerably with solid fraction, microstructure, chemistry, and heat treatment. In spite of these differences, common traits were identified that influence the mechanical properties, regardless of the process or the heat treatment condition. Increasing globule size, porosity, and iron content have a detrimental effect on strength and ductility in the as-cast, T5, and T6 conditions. Low solid fraction semi-solid formed A357 alloys apparently have lower strength in the as-cast and T5 conditions than high solid fraction semi-solid formed A357 alloys. This is attributed to the higher processing temperature and its adverse affect on the solid solubility of magnesium in the primary alpha-aluminum globules. Fatigue life was found to be a function of material strength, increasing with increasing ultimate tensile strength. Extrinsic fatigue initiation features, such as pores, were found to reduce the axial fatigue life by 25% or more, as compared to fatigue initiation features associated with the microstructure. Linear elastic fracture

  8. Low-Cycle Fatigue Behavior of Die-Cast Mg Alloys AZ91 and AM60

    NASA Astrophysics Data System (ADS)

    Rettberg, Luke H.; Jordon, J. Brian; Horstemeyer, Mark F.; Jones, J. Wayne

    2012-07-01

    The influence of microstructure and artificial aging response (T6) on the low-cycle fatigue behavior of super vacuum die-cast (SVDC) AZ91 and AM60 has been investigated. Fatigue lifetimes were determined from the total strain-controlled fatigue tests for strain amplitudes of 0.2 pct, 0.4 pct, 0.6 pct, 0.8 pct, and 1.0 pct under fully reversed loading at a frequency of 5 Hz. Cyclic stress-strain behavior was determined using an incremental step test (IST) and compared with the more traditional constant amplitude test. Two locations in a prototype casting were investigated to examine the role of microstructure and porosity on fatigue behavior. At all total strain amplitudes microstructure refinement had a negligible impact on fatigue life because of significant levels of porosity. AM60 showed an improvement in fatigue life at higher strain amplitudes when compared with AZ91 because of higher ductility. T6 heat treatment had no impact on fatigue life. Cyclic stress-strain behavior obtained via the incremental step test varied from constant amplitude test results due to load history effects. The constant amplitude test is believed to be the more accurate test method. In general, larger initiation pores led to shorter fatigue life. The fatigue life of AZ91 was more sensitive to initiation pore size and pore location than AM60 at the lowest tested strain amplitude of 0.2 pct. Fatigue crack paths did not favor any specific phase, interdentritic structure or eutectic structure. A multistage fatigue (MSF) model showed good correlation to the experimental strain-life results. The MSF model reinforced the dominant role of inclusion (pore) size on the scatter in fatigue life.

  9. Improved Life of Die Casting Dies of H13 Steel by Attaining Improved Mechanical Properties and Distortion Control During Heat Treatment

    SciTech Connect

    J. F. Wallace; D. Schwam

    1998-10-01

    The ultimate goal of this project is to increase die casting die life by using fast enough quenching rates to obtain good toughness and fatigue resistance in premium grade H-13 steel dies. The main tasks of the project were to compile a database on physical and mechanical properties of H-13; conduct gas quenching experiments to determine cooling rates of dies in difference vacuum furnaces; measure the as-quenched distortion of dies and the residual stresses; generate finite element analysis models to predict cooling rates, distortion, and residual stress of gas quenched dies; and establish rules and create PC-based expert system for prediction of cooling rates, distortion, and residual stress in vacuum/gas quenched H-13 dies. Cooling curves during gas quenching of H-13 blocks and die shapes have been measured under a variety of gas pressure. Dimensional changes caused by the gas quenching processes have been determined by accurate mapping of all surfaces with coordinate measuring machines before and after the quench. Residual stresses were determined by the ASTM E837 hole-drilling strain gage method. To facilitate the computer modeling work, a comprehensive database of H-13 mechanical and physical properties has been compiled. Finite element analysis of the heat treated shapes has been conducted using the TRAST/ABAQUS codes. There is a good fit between the predicted and measured distortion contours. However, the magnitude of the predicted distortion and residual stresses does not match well the measured values. Further fine tuning of the model is required before it can be used to predict distortion and residual stress in a quantitative manner. This last step is a prerequisite to generating rules for a reliable expert system.

  10. Mechanical Properties of Carbon Fiber-Reinforced Aluminum Manufactured by High-Pressure Die Casting

    NASA Astrophysics Data System (ADS)

    Kachold, Franziska; Singer, Robert

    2016-08-01

    Carbon fiber reinforced aluminum was produced by a specially adapted high-pressure die casting process. The MMC has a fiber volume fraction of 27%. Complete infiltration was achieved by preheating the bidirectional, PAN-based carbon fiber body with IR-emitters to temperatures of around 750 °C. The degradation of the fibers, due to attack of atmospheric oxygen at temperatures above 600 °C, was limited by heating them in argon-rich atmosphere. Additionally, the optimization of heating time and temperature prevented fiber degradation. Only the strength of the outer fibers is reduced by 40% at the most. The fibers in core of fiber body are nearly undamaged. In spite of successful manufacturing, the tensile strength of the MMC is below strength of the matrix material. Also unidirectional MMCs with a fiber volume fraction of 8% produced under the same conditions, lack of the reinforcing effect. Two main reasons for the unsatisfactory mechanical properties were identified: First, the fiber-free matrix, which covers the reinforced core, prevents effective load transfer from the matrix to the fibers. And second, the residual stresses in the fiber-free zones are as high as 100 MPa. This causes premature failure in the matrix. From this, it follows that the local reinforcement of an actual part is limited. The stress distribution caused by residual stresses and by loading needs to be known. In this way, the reinforcing phase can be placed and aligned accordingly. Otherwise delamination and premature failure might occur.

  11. Microstructure and Creep Behavior of High-Pressure Die-Cast Magnesium Alloy AE44

    NASA Astrophysics Data System (ADS)

    Zhu, S. M.; Nie, J. F.; Gibson, M. A.; Easton, M. A.; Bakke, P.

    2012-11-01

    The microstructure and creep behavior of a high-pressure die-cast AE44 (Mg-4Al-4RE) alloy have been studied. The creep properties were evaluated at 423 K and 448 K (150 °C and 175 °C) under stresses in the range 90 to 110 MPa. The microstructures before and after creep were examined by transmission electron microscopy (TEM). After creep, AE44 exhibits anomalously high stress exponents ( n = 67 at 423 K [150 °C] and n = 41 at 448 K [175 °C]) and stress-dependant activation energies ranging from 221 to 286 kJ/mol. The dislocation substructure developed during creep is characterized by extensive nonbasal slip and isolated but well-defined subgrain boundaries. It is shown that the anomalously high stress exponents cannot be rationalized by the threshold stress approach that is commonly adopted in analyzing the creep behavior of dispersion-strengthened alloys or metal matrix composites. A comparison in creep resistance is also made between AE44 and AE42 (Mg-4Al-2RE).

  12. Cradle-to-Gate Impact Assessment of a High-Pressure Die-Casting Safety-Relevant Automotive Component

    NASA Astrophysics Data System (ADS)

    Cecchel, Silvia; Cornacchia, Giovanna; Panvini, Andrea

    2016-09-01

    The mass of automotive components has a direct influence on several aspects of vehicle performance, including both fuel consumption and tailpipe emissions, but the real environmental benefit has to be evaluated considering the entire life of the products with a proper life cycle assessment. In this context, the present paper analyzes the environmental burden connected to the production of a safety-relevant aluminum high-pressure die-casting component for commercial vehicles (a suspension cross-beam) considering all the phases connected to its manufacture. The focus on aluminum high-pressure die casting reflects the current trend of the industry and its high energy consumption. This work shows a new method that deeply analyzes every single step of the component's production through the implementation of a wide database of primary data collected thanks to collaborations of some automotive supplier companies. This energy analysis shows significant environmental benefits of aluminum recycling.

  13. The fuzzy algorithm in the die casting mould for the application of multi-channel temperature control

    NASA Astrophysics Data System (ADS)

    Sun, Jin-gen; Chen, Yi; Zhang, Jia-nan

    2017-01-01

    Mould manufacturing is one of the most basic elements in the production chain of China. The mould manufacturing technology has become an important symbol to measure the level of a country's manufacturing industry. The die-casting mould multichannel intelligent temperature control method is studied by cooling water circulation, which uses fuzzy control to realize, aiming at solving the shortcomings of slow speed and big energy consumption during the cooling process of current die-casting mould. At present, the traditional PID control method is used to control the temperature, but it is difficult to ensure the control precision. While , the fuzzy algorithm is used to realize precise control of mould temperature in cooling process. The design is simple, fast response, strong anti-interference ability and good robustness. Simulation results show that the control method is completely feasible, which has higher control precision.

  14. A generic approach to improved semi-solid forming of metals

    SciTech Connect

    Klier, E. M.

    2002-06-05

    Lack of technology for the production of large inexpensive feedstock, with uniform spherical primary phase throughout as required for semi-solid forming, has restricted realization of the full potential for the semi-solid forming process. Furthermore, narrow process windows and alloy chemistry restrictions increase process costs and limit performance attributes possible with existing semi-solid metal systems. Successful semi-solid forming trials utilizing Chesapeake Composites Corporation's DSC trademark Metals for feedstock indicate that this represents a generic approach to providing a permanent highly uniform, spherical solid phase, without electromagnetic or mechanical shearing. This approach also provides for further growth of semi-solid forming by providing for: low cost large diameter billet stock, reduced semi-solid forming costs, extension of semi-solid forming to new alloy systems, and semi-solid formed components with substantially enhanced physical and mechanical proper ties.

  15. Semi-solid processing and its as yet unexplored potential

    NASA Astrophysics Data System (ADS)

    Aisman, D.; Rubesova, K.; Masek, B.

    2016-03-01

    Thanks to the available advanced control technology, manufacturing processes which have been described in the past but their hidden potential remained untapped are now continuing to be developed. As a result, even conventional materials which have been around for years can be manipulated to obtain unusual microstructures with specific mechanical and physical properties. Semi-solid processing belongs to the above-described group: it had been studied in the past but, due to complicated process control, it gradually lost its appeal. However, advanced techniques of temperature field control enable engineers to control this complex process accurately. One of the innovative methods of semi-solid processing is mini- thixoforming. As it focuses on very small-size products, it offers very steep heating curves and extremely high solidification and cooling rates, when compared to conventional thixoforming. The capabilities of this process were tested on X210Cr12 ledeburitic tool steel. After the optimum processing conditions were found, additional materials were tried, ranging from low- carbon microalloyed steels through medium-alloy steels to high-alloy tool steels. The microstructure evolution upon the mini-thixoforming process is an issue of its own. The final microstructure of X210Cr12 consisted of more than 90% of austenite and chromium carbides. Semi-solid processing of a steel with a high vanadium content led to a microstructure comprising MA matrix and globular vanadium carbides. In a low-alloy steel, martensitic microstructure was obtained.

  16. Evolution of Fragmented Fe-Intermetallic Compounds in the Semi-Solid State of Al-Mg-Si-Fe Alloys by Deformation Semi-Solid Forming Process

    NASA Astrophysics Data System (ADS)

    Phongphisutthinan, Chakkrist; Tezuka, Hiroyasu; Kobayashi, Equo; Sato, Tatsuo

    Fe-intermetallic compounds are commonly considered as a harmful phase in the recycled aluminum alloys. The Deformation Semi-Solid Forming (D-SSF) process has advantages to modify these harmful compounds into more favorable particles by thermo-mechanical deformation and subsequently heating to the semi-solid state. The evolution of fragmented Fe-intermetallic compounds of the Al-Mg-Si-Fe alloy was investigated during heating to various semi-solid temperatures. The fragmented Fe-intermetallic compound was transformed into the polyhedral shape in the initial stage and subsequently spheroidized shape at the low semi-solid temperatures between 580-610°C. At temperatures higher than 613°C, fragmented Fe-intermetallic compounds completely melt into the liquid phase with long holding time. The Fe-intermetallic compounds are stable as solid phase at low semi-solid temperature and metastable at high semi-solid temperature.

  17. Semi-Solid Flowable Battery Electrodes: Semi-Solid Flow Cells for Automotive and Grid-Level Energy Storage

    SciTech Connect

    2010-09-01

    BEEST Project: Scientists at 24M are crossing a Li-Ion battery with a fuel cell to develop a semi-solid flow battery. This system relies on some of the same basic chemistry as a standard Li-Ion battery, but in a flow battery the energy storage material is held in external tanks, so storage capacity is not limited by the size of the battery itself. The design makes it easier to add storage capacity by simply increasing the size of the tanks and adding more paste. In addition, 24M's design also is able to extract more energy from the semi-solid paste than conventional Li-Ion batteries. This creates a cost-effective, energy-dense battery that can improve the driving range of EVs or be used to store energy on the electric grid.

  18. Development of a 3D Filling Model of Low-Pressure Die-Cast Aluminum Alloy Wheels

    NASA Astrophysics Data System (ADS)

    Duan, Jianglan; Maijer, Daan; Cockcroft, Steve; Reilly, Carl

    2013-12-01

    A two-phase computational fluid dynamics model of the low-pressure die-cast process for the production of A356 aluminum alloy wheels has been developed to predict the flow conditions during die filling. The filling model represents a 36-deg section of a production wheel, and was developed within the commercial finite-volume package, ANSYS CFX, assuming isothermal conditions. To fully understand the behavior of the free surface, a novel technique was developed to approximate the vent resistances as they impact on the development of a backpressure within the die cavity. The filling model was first validated against experimental data, and then was used to investigate the effects of venting conditions and pressure curves during die filling. It was found that vent resistance and vent location strongly affected die filling time, free surface topography, and air entrainment for a given pressure fill-curve. With regard to the pressure curve, the model revealed a strong relation between the pressure curve and the flow behavior in the hub, which is an area prone to defect formation.

  19. Evaluation of Magnesium Die-Casting Alloys for Elevated Temperature Applications: Microstructure, Tensile Properties, and Creep Resistance

    NASA Astrophysics Data System (ADS)

    Zhu, Suming; Easton, Mark A.; Abbott, Trevor B.; Nie, Jian-Feng; Dargusch, Matthew S.; Hort, Norbert; Gibson, Mark A.

    2015-08-01

    Several families of magnesium die-casting alloys have been developed to operate at the elevated temperatures experienced in automotive powertrain applications. Most alloys are based on the Mg-Al system with alloying additions such as silicon, strontium, calcium, and rare earth elements (RE), although alloys with RE as the primary alloying constituent are also considered. This work presents an evaluation of the tensile properties and creep resistance of the most common magnesium die-casting alloys, in conjunction with the analysis of microstructure. The alloys investigated include AS31 (Mg-3Al-1Si), AJ52 (Mg-5Al-2Sr), MRI153A (Mg-9Al-1Ca-0.1Sr), MRI153M (Mg-8Al-1Ca-0.3Sr), MRI230D (Mg-6.5Al-2Ca-1Sn-0.3Sr), AXJ530 (Mg-5Al-3Ca-0.2Sr), AE42 (Mg-4Al-2RE), AE44 (Mg-4Al-4RE), and AM-HP2+ (Mg-3.5RE-0.4Zn). It is shown that, among the various alloys evaluated, MRI230D, AXJ530, and AM-HP2+ have higher yield strength than the Al alloy A380, but the ductility is relatively low at room temperature for these alloys. In contrast, AS31 and the AE series alloys have very good room temperature ductility, but their yield strength is lower than that of A380. In terms of creep resistance, MRI230D, AXJ530, AE44, and AM-HP2+ are all comparable to the Al alloy counterpart at 423 K and 448 K (150 °C and 175 °C). Microstructural factors that are most important to the strength and creep resistance of the Mg die-casting alloys are discussed.

  20. Thermal fatigue behavior of H-13 die steel for aluminum die casting with various ion sputtered coatings

    NASA Technical Reports Server (NTRS)

    Nieh, C. Y.; Wallace, J. F.

    1981-01-01

    Sputtered coatings of Mo, W, Pt, Ag, Au, Co, Cr, Ni, Ag + Cu, Mo + Pt, Si3N4, A1N, Cr3C2, Ta5Si3, and ZrO2 were applied to a 2-inch-square, 7-inch-long thermal fatigue test specimen which was then internally water cooled and alternately immersed in molten aluminum and cooled in air. After 15,000 cycles the thermal fatigue cracks at the specimen corners were measured. Results indicate that a significant improvement in thermal fatigue resistance was obtained with platinum, molybdenum, and tungsten coatings. Metallographic examination indicates that the improvement in thermal fatigue resistance resulted from protection of the surface of the die steel from oxidation. The high yield strength and ductility of molybdenum and tungsten contributed to the better thermal fatigue resistance.

  1. Process Modeling of Low-Pressure Die Casting of Aluminum Alloy Automotive Wheels

    NASA Astrophysics Data System (ADS)

    Reilly, C.; Duan, J.; Yao, L.; Maijer, D. M.; Cockcroft, S. L.

    2013-09-01

    Although on initial inspection, the aluminum alloy automotive wheel seems to be a relatively simple component to cast based on its shape, further insight reveals that this is not the case. Automotive wheels are in a select group of cast components that have strict specifications for both mechanical and aesthetic characteristics due to their important structural requirements and their visibility on a vehicle. The modern aluminum alloy automotive wheel continues to experience tightened tolerances relating to defects to improve mechanical performance and/or the physical appearance. Automotive aluminum alloy wheels are assessed against three main criteria: wheel cosmetics, mechanical performance, and air tightness. Failure to achieve the required standards in any one of these categories will lead to the wheel either requiring costly repair or being rejected and remelted. Manufacturers are becoming more reliant on computational process modeling as a design tool for the wheel casting process. This article discusses and details examples of the use of computational process modeling as a predictive tool to optimize the casting process from the standpoint of defect minimization with the emphasis on those defects that lead to failure of aluminum automotive wheels, namely, macroporosity, microporosity, and oxide films. The current state of applied computational process modeling and its limitations with regard to wheel casting are discussed.

  2. Characterization of Pore Defects and Fatigue Cracks in Die Cast AM60 Using 3D X-ray Computed Tomography

    NASA Astrophysics Data System (ADS)

    Yang, Zhuofei; Kang, Jidong; Wilkinson, David S.

    2015-08-01

    AM60 high pressure die castings have been used in automobile applications to reduce the weight of vehicles. However, the pore defects that are inherent in die casting may negatively affect mechanical properties, especially the fatigue properties. Here we have studied damage ( e.g., pore defects, fatigue cracks) during strained-controlled fatigue using 3-dimensional X-ray computed tomography (XCT). The fatigue test was interrupted every 2000 cycles and the specimen was removed to be scanned using a desktop micro-CT system. XCT reveals pore defects, cracks, and fracture surfaces. The results show that pores can be accurately measured and modeled in 3D. Defect bands are found to be made of pores under 50 µm (based on volume-equivalent sphere diameter). Larger pores are randomly distributed in the region between the defect bands. Observation of fatigue cracks by XCT is performed in three ways such that the 3D model gives the best illustration of crack-porosity interaction while the other two methods, with the cracks being viewed on transverse or longitudinal cross sections, have better detectability on crack initiation and crack tip observation. XCT is also of value in failure analysis on fracture surfaces. By assessing XCT data during fatigue testing and observing fracture surfaces on a 3D model, a better understanding on the crack initiation, crack-porosity interaction, and the morphology of fracture surface is achieved.

  3. Application of TPM indicators for analyzing work time of machines used in the pressure die casting

    NASA Astrophysics Data System (ADS)

    Borkowski, Stanisław; Czajkowska, Agnieszka; Stasiak-Betlejewska, Renata; Borade, Atul B.

    2014-05-01

    The article presents the application of total productive maintenance (TPM) to analyze the working time indicators of casting machines with particular emphasis on failures and unplanned downtime to reduce the proportion of emergency operation for preventive maintenance and diagnostics. The article presents that the influence of individual factors of complex machinery maintenance (TPM) is different and depends on the machines' modernity level. In an original way, by using correlation graphs, research findings on the impact of individual TPM factors on the castings quality were presented and interpreted. The examination results conducted for machines with varying modernity degrees allowed to determine changes within the impact of individual TPM factors depending on machine parameters. These results provide a rich source of information for the improvement processes on casting quality of the foundry industry that satisfies the automotive industry demand.

  4. Predicting Stress vs. Strain Behaviors of Thin-Walled High Pressure Die Cast Magnesium Alloy with Actual Pore Distribution

    SciTech Connect

    Choi, Kyoo Sil; Barker, Erin; Cheng, Guang; Sun, Xin; Forsmark, Joy; Li, Mei

    2016-01-06

    In this paper, a three-dimensional (3D) microstructure-based finite element modeling method (i.e., extrinsic modeling method) is developed, which can be used in examining the effects of porosity on the ductility/fracture of Mg castings. For this purpose, AM60 Mg tensile samples were generated under high-pressure die-casting in a specially-designed mold. Before the tensile test, the samples were CT-scanned to obtain the pore distributions within the samples. 3D microstructure-based finite element models were then developed based on the obtained actual pore distributions of the gauge area. The input properties for the matrix material were determined by fitting the simulation result to the experimental result of a selected sample, and then used for all the other samples’ simulation. The results show that the ductility and fracture locations predicted from simulations agree well with the experimental results. This indicates that the developed 3D extrinsic modeling method may be used to examine the influence of various aspects of pore sizes/distributions as well as intrinsic properties (i.e., matrix properties) on the ductility/fracture of Mg castings.

  5. Analysis of Dendritic Primary Al Grain Ripening and Solid Fraction Measurement in A356 Alloy Semi-Solid Slurry Using Segregation Sensitive Reagent

    NASA Astrophysics Data System (ADS)

    Gao, Li; Harada, Yohei; Kumai, Shinji

    Ripening of dendritic primary Al grain in semi-solid state has been paid much attention to since it is the most economical way to produce semi-solid slurry containing spheroidal Al grains for thixocasting. Also, solid fraction is the key factor in all the semi-solid processes. A segregation sensitive reagent (Weck's reagent) can help to study both the two topics, revealing the inner-primary Al grain's optical microstructure evolution during semi-solid heat treatments (partial re-melting) of small A356 alloy samples cut from both as-DC cast and compressed ingots (Recrystallization and partial re-melting process). With the help of this etching technique, the influence of induced strain on the ripening mechanism of primary Al grains was investigated precisely. Furthermore, the peripheral part of the primary Al grain grown during water quenching was distinguished by the reagent. Therefore we could exclude this area when measuring the solid fraction and avoid overestimation by image analysis.

  6. Fabrication of ZnO Nanowires Arrays by Anodization and High-Vacuum Die Casting Technique, and Their Piezoelectric Properties.

    PubMed

    Kuo, Chin-Guo; Chang, Ho; Wang, Jian-Hao

    2016-03-24

    In this investigation, anodic aluminum oxide (AAO) with arrayed and regularly arranged nanopores is used as a template in the high-vacuum die casting of molten zinc metal (Zn) into the nanopores. The proposed technique yields arrayed Zn nanowires with an aspect ratio of over 600. After annealing, arrayed zinc oxide (ZnO) nanowires are obtained. Varying the anodizing time yields AAO templates with thicknesses of approximately 50 μm, 60 μm, and 70 μm that can be used in the fabrication of nanowires of three lengths with high aspect ratios. Experimental results reveal that a longer nanowire generates a greater measured piezoelectric current. The ZnO nanowires that are fabricated using an alumina template are anodized for 7 h and produce higher piezoelectric current of up to 69 pA.

  7. Self-sealing anodization approach to enhance micro-Vickers hardness and corrosion protection of a die cast Al alloy

    NASA Astrophysics Data System (ADS)

    Lee, Chulho; Oh, Kiseok; Lee, Dongeun; Kim, Yelim; Yoon, Hyungsop; Park, Dong-Wha; Gab Kim, Moon; Lee, Kiyoung; Choi, Jinsub

    2017-04-01

    Die cast, high-Si content ADC12 Al alloy samples were successfully anodized without surface cracks. This was accomplished with a 0.3 M sulfuric acid electrolyte with a high concentration of sodium aluminate. During anodization, the AlO2- anions were attracted to the positively-charged Al substrate and deposited in the cracks formed by un-oxidized Si islands within the ADC12. Anodic films prepared in electrolytes with a high concentration of AlO2- drastically enhanced surface morphology, thickness uniformity, Vickers hardness, and corrosion behavior in comparison with anodic film prepared without AlO2- concentration. The simultaneous sealing mechanism by AlO2- anions during anodization is reported in detail.

  8. Effect of Gas Pores on Mechanical Properties of High-Pressure Die-Casting AM50 Magnesium Alloy.

    PubMed

    Jiang, Wei; Cao, Zhanyi; Liu, Liping; Jiang, Bo

    2016-08-01

    High-pressure die-casting (HPDC) AM50 tensile specimens were used to investigate characteristics of gas pores and its effect on mechanical properties of HPDC AM50 magnesium alloy. Combining microstructure morphology gained from optical microscopy, scanning electron microscopy (SEM), and three-dimensional (3D) reconstruction with the experimental data from uniaxial tensile testing, we pursued the relationship between gas pores and the mechanical properties of HPDC AM50 Mg alloy. Results indicate that comparing with 3D reconstruction models, 2D images like optical metallography images and SEM images have one-sidedness. Furthermore, the size and maximum areal fraction of gas pores have negative effects on the mechanical properties of HPDC AM50 Mg alloy. With increase of the maximum size of gas pores in the specimen, the ultimate tensile strength (UTS) and elongation decrease. In addition, with the maximum areal fraction becoming larger, both the UTS and elongation decrease linearly.

  9. Fabrication of ZnO Nanowires Arrays by Anodization and High-Vacuum Die Casting Technique, and Their Piezoelectric Properties

    PubMed Central

    Kuo, Chin-Guo; Chang, Ho; Wang, Jian-Hao

    2016-01-01

    In this investigation, anodic aluminum oxide (AAO) with arrayed and regularly arranged nanopores is used as a template in the high-vacuum die casting of molten zinc metal (Zn) into the nanopores. The proposed technique yields arrayed Zn nanowires with an aspect ratio of over 600. After annealing, arrayed zinc oxide (ZnO) nanowires are obtained. Varying the anodizing time yields AAO templates with thicknesses of approximately 50 μm, 60 μm, and 70 μm that can be used in the fabrication of nanowires of three lengths with high aspect ratios. Experimental results reveal that a longer nanowire generates a greater measured piezoelectric current. The ZnO nanowires that are fabricated using an alumina template are anodized for 7 h and produce higher piezoelectric current of up to 69 pA. PMID:27023546

  10. A high temperature EMAT sensor for semi-solid metalworking

    SciTech Connect

    Maxfield, B.; Yu, C.J.; Dax, F.R.

    1995-12-31

    The relationship between solid fraction and temperature for aluminum alloys A356 and A357 were developed by Backerud et al. In the material`s semi-solid state, there are five distinct chemical reactions within the microstructure which change the amount of solid fraction. Reference 1 gives tables that summarize these reactions in the microstructure, the corresponding temperature and the resulting solid fraction. For these two SSM alloys (A356 and A357), approximately 50% of the solid is the primary alpha phase and the rest is the eutectic phase with different constituents. The characteristic temperatures represent the formation of each reaction. These temperatures are observed and confirmed for the SSM material during the laboratory heat tests, these reaction temperatures are 550 C, 555 C, 567 C and 575 C. The corresponding solid fraction for each reaction is 95--100%, 90--95%, 70--90% and 50--70%. A rapid change in solid fraction takes place between 567 to 575 C. Above 575 C, melting of the primary {alpha} phase occurs. It is necessary to monitor the SSM material temperature during heating which is done via an induction coil that surrounds the material. One good means of accomplishing this task is to generate a burst of ultrasound at the top of the cylindrical material using a pulsed laser and detecting the resulting ultrasonic pulse at the bottom surface using an EMAT receiver. This talk describes the EMAT receiver that was used and presents some of the result that they obtained.

  11. Ultrasonic evaluation of semi-solid metals during processing

    NASA Astrophysics Data System (ADS)

    Jen, C.-K.; Liaw, J.-W.; Chen, T.-F.; Moreau, A.; Monchalin, J.-P.; Yang, C.-C.

    2000-11-01

    Ultrasonic velocity and attenuation measurements for three different semi-solid (SS) aluminum (Al) alloy billets (A356, A357 and 86S) and one dendritic sample (A356) were performed in the temperature range between room temperature and ~575 °C using a non-contact laser-ultrasonic technique. It was found that there are measurable differences in ultrasonic velocity and attenuation between SS and dendritic samples and these differences are larger as the temperature becomes closer to the complete melt state. In a laboratory setup simulating the barrel section of a thixomoulding or a rheomoulding machine, a clad buffer rod (high temperature probe) was used to perform real time ultrasonic monitoring. We have observed 10 MHz ultrasonic signals of 30 dB signal-to-noise ratio reflected from a rotating screw with a distance of 5.5 mm between the probe end and the root of the screw in a viscous liquid Al alloy (A356) at 610 °C. This information should enable us to determine whether the processed part has the desired thixotropic structure or not, and then to properly adjust heating and other process parameters.

  12. Oral movements and the perception of semi-solid foods.

    PubMed

    de Wijk, René A; Janssen, Anke M; Prinz, Jon F

    2011-09-01

    Here we review the role of oral movements in the perception of food attributes, particularly for semi-solid and liquid foods ingested almost in ready-to-swallow form. An overview of a series of instrumental and sensory studies suggests clear links between the type of sensation and the time point of processing in the mouth. Some commonly-reported sensations, such as thickness, are relatively immediate and reflect the bulk properties of food bolus when the food is relatively intact. Others, such as fattiness and melting, reflect both bulk and surface properties and follow considerable oral processing when the food is relatively degraded. Yet others, such as fatty after-feel, are only fully developed after swallowing is complete. In addition, oral processing also plays an important role in the generation of aroma and taste sensations. Most of these in prior vivo studies have now been confirmed by in vitro work using a modified rheometer, dubbed the Structure Breakdown Cell (SBC), wherein the mechanical and enzymatic break-down of food can be monitored directly and related to sensory profiles generated by trained panelists. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Heat transfer during quenching of modified and unmodified gravity die-cast A357 cylindrical bars

    NASA Astrophysics Data System (ADS)

    Prabhu, K. N.; Hemanna, P.

    2006-06-01

    Heat transfer during quenching of chill-cast modified and unmodified A357 Al-Si alloy was examined using a computer-aided cooling curve analysis. Water at 60 °C and a vegetable oil (palm oil) were used as quench media. The measured temperatures inside cylindrical probes of the A357 alloy were used as inputs in an inverse heat-conduction model to estimate heat flux transients at the probe/quenchant interface and the surface temperature of the probe in contact with the quench medium. It was observed that modified alloy probes yielded higher cooling rates and heat flux transients. The investigation clearly showed that the heat transfer during quenching depends on the casting history. The increase in the cooling rate and peak heat flux was attributed to the increase in the thermal conductivity of the material on modification melt treatment owing to the change in silicon morphology. Fine and fibrous silicon particles in modified A357 probes increase the conductance of the probe resulting in higher heat transfer rates. This was confirmed by measuring the electrical conductivity of modified samples, which were found to be higher than those of unmodified samples. The ultrasound velocity in the probes decreased on modification.

  14. Elasto-Plastic-Creep Constitutive Equation of an Al-Si-Cu High-Pressure Die Casting Alloy for Thermal Stress Analysis

    NASA Astrophysics Data System (ADS)

    Motoyama, Yuichi; Shiga, Hidetoshi; Sato, Takeshi; Kambe, Hiroshi; Yoshida, Makoto

    2016-11-01

    Accurate simulation of residual stress and deformation is necessary to optimize the design and lifetime of casting components. Therefore, the recovery and strain-rate dependence of the stress-strain curve have been incorporated into empirical constitutive equations to improve the thermal stress analysis accuracy. Nevertheless, these equations present several difficulties related to the determination of material constants and their physical bases. This study suggested an empirical elasto-plastic-creep constitutive equation incorporating these phenomena. To determine the material parameters used in this constitutive equation, this study investigated tensile test methods to obtain stress-strain curves that most closely resemble those during or immediately after casting for the Al-Si-Cu high-pressure die-casting alloy JIS ADC 12 (A383.0), which exhibits natural aging. Results show that solution heat treatment with subsequent cooling to the test temperature should be applied to obtain stress-strain curves used for the thermal stress analysis of high-pressure die casting process of this alloy. The yield stresses obtained using the conventional heating method were 50-64 pct higher than those of the method described above. Therefore, the conventional method is expected to overestimate the overestimation of the predicted residual stress in die castings. Evaluation of the developed equation revealed that it can represent alloy recovery and strain-rate dependence.

  15. On the performance of low pressure die-cast Al-Cu based automotive alloys: Role of additives

    NASA Astrophysics Data System (ADS)

    Zaki, Gergis Adel

    The present study focuses on the effect of alloying elements, namely, strontium (Sr), titanium (Ti), zirconium (Zr), scandium (Sc) and silver(Ag) individually or in combination, on the performance of a newly developed Al-2%Cu based alloy. A total of thirteen alloy compositions were used in the study. Tensile test bar castings were prepared employing the low pressure die casting (LPDC) technique. The test bars were solution heat treated at 495°C for 8 hours, followed by quenching in warm water, and then subjected to different isochronal aging treatments using an aging time of 5 hours and aging temperatures of 155°C, 180°C, 200°C, 240°C and 300°C. Tensile testing of as-cast and heat-treated test bars was carried out at room temperature using a strain rate of 4 x 10-4s-1. Five test bars were used per alloy composition/condition. Hardness measurements were also carried out on these alloys using a Brinell hardness tester. The microstructures of selected samples were examined using optical microscopy and electron probe microanalysis (EPMA). The results showed that adding Ti in the amount of 0.15 wt% in the form of Al-5%Ti-1%B master alloy is sufficient to refine the grains in the cast structure in the presence of 200 ppm Sr (0.02 wt%). Addition of Zr and Sc did not contribute further to the grain refining effect. The main role of addition of these two elements appeared in the formation of complex compounds with Al and Ti. Their presence resulted in extending the aging temperature range before the onset of softening. Mathematical analysis of the hardness and tensile data was carried out using the Minitab statistical software program. It was determined that the alloy containing (0.5wt% Zr + 0.15wt% Ti) is the most effective in maximizing the alloy tensile strength over the range of aging temperatures, from 155°C to 300°C. Addition of Ag is beneficial at high aging temperatures, in the range of 240°C-300°C. However, it is less effective compared to the (Zr + Ti

  16. Spray-formed tooling for injection molding and die casting applications

    SciTech Connect

    K. M. McHugh; B. R. Wickham

    2000-06-26

    Rapid Solidification Process (RSP) Tooling{trademark} is a spray forming technology tailored for producing molds and dies. The approach combines rapid solidification processing and net-shape materials processing in a single step. The ability of the sprayed deposit to capture features of the tool pattern eliminates costly machining operations in conventional mold making and reduces turnaround time. Moreover, rapid solidification suppresses carbide precipitation and growth, allowing many ferritic tool steels to be artificially aged, an alternative to conventional heat treatment that offers unique benefits. Material properties and microstructure transformation during heat treatment of spray-formed H13 tool steel are described.

  17. Spray-formed Tooling for Injection Molding and Die Casting Applications

    SciTech Connect

    Mc Hugh, Kevin Matthew

    2000-06-01

    Rapid Solidification Process (RSP) ToolingTM is a spray forming technology tailored for producing molds and dies. The approach combines rapid solidification processing and net-shape materials processing in a single step. The ability of the sprayed deposit to capture features of the tool pattern eliminates costly machining operations in conventional mold making and reduces turnaround time. Moreover, rapid solidification suppresses carbide precipitation and growth, allowing many ferritic tool steels to be artificially aged, an alternative to conventional heat treatment that offers unique benefits. Material properties and microstructure transformation during heat treatment of spray-formed H13 tool steel are described.

  18. Microstructure Formation in AlSi4MgMn and AlMg5Si2Mn High-Pressure Die Castings

    NASA Astrophysics Data System (ADS)

    Otarawanna, S.; Gourlay, C. M.; Laukli, H. I.; Dahle, A. K.

    2009-07-01

    Understanding microstructure formation during high-pressure die casting (HPDC) is important for the effective quality control of high-pressure diecast aluminum-alloy components for high-integrity applications. In this study, two HPDC-specific aluminum alloys, AlSi4MgMn and AlMg5Si2Mn, were cast into tensile test bars by cold-chamber (CC) HPDC. The microstructures of the tensile bar specimens were characterized at different length scales, from the scale of the casting to the scale of the eutectic interlamellar spacing. The results show that the salient as-cast microstructural features, e.g., externally solidified crystals (ESCs), defect bands, the surface layer, grain size distribution, porosity, and hot tears were similar for both alloys. The formation of these features can be understood by considering the influence of flow and solidification during each stage of the HPDC process.

  19. Strengthening Micromechanisms in Cold-Chamber High-Pressure Die-Cast Mg-Al Alloys

    NASA Astrophysics Data System (ADS)

    Yang, Kun V.; Cáceres, Carlos H.; Easton, Mark A.

    2014-08-01

    The contributions from grain boundary, solid solution, and dispersion strengthening to the yield strength of cast-to-shape specimens were calculated for seven binary alloys with compositions ranging from very dilute (0.5 mass pct Al) to concentrated (12 mass pct Al). Experimentally and theoretically determined parameters were used to explicitly account for the different microstructures at the skin and core regions of specimens' cross sections. Microhardness maps were used to identify the specimens' skin. The specimens' strength was calculated as the weighted addition of the respective strengths of skin and core. The calculated strengths reproduced well the experimental values for the dilute alloys but underestimated the strength of the most concentrated alloys by as much as ~35 MPa. It is argued that the presence of the percolating network of Mg17Al12 eutectic intermetallic, particularly in the skin region, in conjunction with highly efficient dispersion hardening due to the convoluted shape of the intermetallics, accounts for the shortfall in the calculated strength.

  20. 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.

  1. Revealing the micromechanisms behind semi-solid metal deformation with time-resolved X-ray tomography

    NASA Astrophysics Data System (ADS)

    Kareh, K. M.; Lee, P. D.; Atwood, R. C.; Connolley, T.; Gourlay, C. M.

    2014-07-01

    The behaviour of granular solid-liquid mixtures is key when deforming a wide range of materials from cornstarch slurries to soils, rock and magma flows. Here we demonstrate that treating semi-solid alloys as a granular fluid is critical to understanding flow behaviour and defect formation during casting. Using synchrotron X-ray tomography, we directly measure the discrete grain response during uniaxial compression. We show that the stress-strain response at 64-93% solid is due to the shear-induced dilation of discrete rearranging grains. This leads to the counter-intuitive result that, in unfed samples, compression can open internal pores and draw the free surface into the liquid, resulting in cracking. A soil mechanics approach shows that, irrespective of initial solid fraction, the solid packing density moves towards a constant value during deformation, consistent with the existence of a critical state in mushy alloys analogous to soils.

  2. Revealing the micromechanisms behind semi-solid metal deformation with time-resolved X-ray tomography.

    PubMed

    Kareh, K M; Lee, P D; Atwood, R C; Connolley, T; Gourlay, C M

    2014-07-18

    The behaviour of granular solid-liquid mixtures is key when deforming a wide range of materials from cornstarch slurries to soils, rock and magma flows. Here we demonstrate that treating semi-solid alloys as a granular fluid is critical to understanding flow behaviour and defect formation during casting. Using synchrotron X-ray tomography, we directly measure the discrete grain response during uniaxial compression. We show that the stress-strain response at 64-93% solid is due to the shear-induced dilation of discrete rearranging grains. This leads to the counter-intuitive result that, in unfed samples, compression can open internal pores and draw the free surface into the liquid, resulting in cracking. A soil mechanics approach shows that, irrespective of initial solid fraction, the solid packing density moves towards a constant value during deformation, consistent with the existence of a critical state in mushy alloys analogous to soils.

  3. Predicting the Influence of Pore Characteristics on Ductility of Thin-Walled High Pressure Die Casting Magnesium

    SciTech Connect

    Sun, Xin; Choi, Kyoo Sil; Li, Dongsheng

    2013-06-10

    In this paper, a two-dimensional microstructure-based finite element modeling method is adopted to investigate the effects of porosity in thin-walled high pressure die casting Mg materials on their ductility. For this purpose, the cross-sections of AM50 and AM60 casting samples are first examined using optical microscope to obtain the overall information on the pore characteristics. The experimentally quantified pore characteristics are then used to generate a series of synthetic microstructures with different pore sizes, pore volume fractions and pore size distributions. Pores are explicitly represented in the synthetic microstructures and meshed out for the subsequent finite element analysis. In the finite element analysis, an intrinsic critical strain value is used for the Mg matrix material, beyond which work-hardening is no longer permissible. With no artificial failure criterion prescribed, ductility levels are predicted for the various microstructures in the form of strain localization. Mesh size effect study is also conducted, from which a mesh size dependent critical strain curve is determined. A concept of scalability of pore size effects is then presented and examined with the use of the mesh size dependent critical strain curve. The results in this study show that, for the regions with lower pore size and lower volume fraction, the ductility generally decreases as the pore size and pore volume fraction increase whereas, for the regions with larger pore size and larger pore volume fraction, other factors such as the mean distance between the pores begin to have some substantial influence on the ductility. The results also indicate that the pore size effects may be scalable for the models with good-representative pore shape and distribution with the use of the mesh size dependent critical strain curve.

  4. Simultaneous Effect of Plunger Motion Profile, Pressure, and Temperature on the Quality of High-Pressure Die-Cast Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Fiorese, Elena; Bonollo, Franco

    2016-12-01

    High-pressure die casting has been used widely to manufacture a large variety of products with high dimensional accuracy and productivity. Although this process has a considerably lower cycle time than the other metal forming processes, it is not yet optimized, due to the complexity of the process and the number of parameters to be controlled. Hence, the identification of the parameters affecting quality of castings is the current challenge toward efficient and effective production. In their previous work, the authors proposed and validated some novel kinematic parameters of the plunger, which explain and forecast both the static mechanical properties and the internal quality of castings. The present work extends such an approach by including two other meaningful parameters, which describe the effect of upset pressure and temperature on the final outcome. These parameters are here formulated and have been validated by means of a statistically significant sample manufactured with different plunger motion profiles, upset pressures, and temperatures of the melt and die. The quality of the castings was assessed through static mechanical properties and density measurements. As further proof, internal defects were analyzed on the fracture surfaces of some meaningful castings.

  5. Effects of Solid-Liquid Mixing on Microstructure of Semi-Solid A356 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Guo, H. M.; Wang, L. J.; Wang, Q.; Yang, X. J.

    2014-08-01

    The desired starting material for semi-solid processing is the semi-solid slurry in which the solid phase is present as fine and globular particles. A modified solid-liquid mixing (SLM) is reported wherein semi-solid slurry can be produced by mixing a solid alloy block into a liquid alloy, and mechanical vibration is utilized to enhance the mixing. Effects such as liquid alloy temperature, mass ratio, and mixing intensity on the microstructure and the cooling curves during SLM were evaluated. 2D and 3D microstructure analysis of treated A356 aluminum alloy shows that microstructure can be refined significantly with a considerable morphology change in primary Al phase. It is critical that the temperature of mixture after mixing is lower than its liquidus temperature to obtain a valid SLM process. Specially, mixing intensity is identified as a primary factor for a favorable microstructure of semi-solid slurry.

  6. In situ, time-resolved tomography for validating models of deformation in semi-solid alloys

    NASA Astrophysics Data System (ADS)

    Kareh, K. M.; Lee, P. D.; Gourlay, C. M.

    2012-07-01

    The development and validation of physically-based models of semi-solid alloy deformation requires experimental data on the microstructural response to load. In this work we present three-dimensional in situ synchrotron results of the indirect extrusion of semi-solid aluminium-copper alloys. Globular Al-15wt.% Cu specimens were deformed at solid fractions of approximately 0.7 during time-resolved x-ray tomography. Key phenomena of the response to load were observed and quantified, with a focus on particle translations and rotations, and the resulting displacement field. This example shows that crystal displacements can be quantified during semi-solid deformation of bulk specimens, allowing for datasets to be produced suitable for validating models of complex phenomena during semi-solid flow.

  7. Comparison of Microstructure and Mechanical Properties of AZ91D Alloy Formed by Rheomolding and High-Pressure Die Casting

    NASA Astrophysics Data System (ADS)

    Qi, M. F.; Kang, Y. L.; Yan, Y.; Zhu, G. M.; Liao, W. N.

    2015-10-01

    The microstructure and mechanical properties of AZ91D alloy thin-wall parts produced by the rheomolding (RM) process were investigated and compared with the same alloy formed by conventional high-pressure die casting (HPDC). The results indicate that the RM process is able to get such AZ91D parts in which α 1 -Mg with average size of 27.36 μm are spherical and uniformly distributed in the matrix, and the matrix is a mixture of numerous fine α 2 -Mg and intermetallic β-Mg17Al12. High mechanical properties including ultimate tensile strength (UTS) of 270 MPa, yield strength (YS) of 169 MPa, elongation of 7.1%, and Vickers hardness of 102 are obtained in parts formed by RM due to the fine and uniform microstructure and less porosities. Compared with HPDC, the UTS, YS, elongation, and hardness of RM AZ91D are increased by 14.4, 9.7, 86.8, and 21.4%, respectively. The solidified grains in RM AZ91D alloy show a smaller aluminum gradient than that in HPDC. This indicates that the solidification of the RM AZ91D is closer to equilibrium.

  8. Neurobehavioral testing of subjects exposed residentially to groundwater contaminated from an aluminum die-casting plant and local referents

    SciTech Connect

    Kilburn, K.H.; Warshaw, R.H. )

    1993-08-01

    Residents adjoining a die-casting plant had excessive headaches, numbness of hands and feet, dizziness, blurred vision, staggering, sweating, abnormal heart rhythm, and depression, which led to measurements of neurobehavioral performance, affective status, and the frequency of symptoms. They had all been exposed via well water and proximity to the plant to volatile organic chemicals (VOC) and to polychlorinated biphenyls (PCBs). The 117 exposed women and men and 46 unexposed referents were studied together for simple and choice visual reaction time, body sway speed, blink reflex latency, color discrimination, Culture Fair (a nonverbal nonarithmetic intelligence test), recall of stories, figures, and numbers, cognitive and psychomotor control (slotted pegboard and trail making A and B), long-term memory, profile of mood states (POMS), and scores and frequencies of 34 symptoms. Choice reaction time, sway speed, and blink latency were impaired in both sexes of the exposed group and trail making B was impaired in exposed women. The POMS scores and frequencies of 30 of 34 symptoms were elevated in both sexes, compared to referents. Recall, long-term memory, psychomotor speed, and other cognitive function tests were reduced in exposed subjects and in the referents as compared to national referents. Neurophysiological impairment, and cognitive and psychomotor dysfunction and affective disorders, especially depression and excessive frequency of symptoms, were associated with the use of wells contaminated with VOCs, TCE and PCBs.

  9. Fatigue characterization of high pressure die-cast magnesium AM60B alloy using experimental and computational investigations

    NASA Astrophysics Data System (ADS)

    Lu, You

    The object of the current dissertation is to foster fundamental advances in microstructure-fatigue characteristics of a high pressure die cast magnesium AM60B alloy. First, high cycle fatigue staircase experiments were conducted on specimens extracted from automobile instrument panels. The resulting fracture surfaces were then examined with scanning electron microscopic imaging to elucidate the fatigue crack initiation sites and propagation paths at different stages of the fatigue life. Due to the fact that the qualification of the crack initiation and propagation mechanisms through experiment alone is difficult, complementary micromechanical finite element simulations were conducted. Particularly, the effects of different applied loading conditions and the porosity morphology (e.g. pore shape, pore size, pore spacing, proximity to the free surface) on the maximum plastic shear strain range, as a driving force for crack initiation, were analyzed. Moreover, at the microstructually small crack (MSC) propagation stage, the shielding effects of beta-phase Mg17Al12 particles were systematically studied. Based on the distribution of the maximum principal stress within the particles and the maximum hydrostatic stress along the particle/matrix interfaces, the relative influence of the pre-damaged (fractured or debonded) particles and various particle cluster morphologies were carefully investigated. In the finite element simulations, the constitutive behaviours of AM60B alloy and the alpha-matrix were simulated by the advanced kinematic hardening law tuned with experimentally determined material parameters under cyclic loading.

  10. Microstructure and corrosion behavior of die-cast AM60B magnesium alloys in a complex salt solution. A slow positron beam study

    SciTech Connect

    Liu, Y. F.; Yang, W.; Qin, Q. L.; Wen, W.; Zhai, T.; Yu, B.; Liu, D. Y.; Luo, A.; Song, GuangLing

    2013-12-15

    The microstructure and corrosion behavior of high pressure die-cast (HPDC) and super vacuum die-cast (SVDC) AM60B magnesium alloys were investigated in a complex salt solution using slow positron beam technique and potentiodynamic polarization tests. The experiments revealed that a CaCO3 film was formed on the surface of the alloys and that the rate of CaCO3 formation for the SVDC alloy with immersion time was slower than that of the HPDC alloy. The larger volume fraction of b-phase in the skin layer of the SVDC alloy than that of the HPDC alloy was responsible for the better corrosion resistance.

  11. Effects of Dy, Sr and Die Casting on Microstructure, Mechanical and Corrosion Properties of Mg-Dy-Sr-Nd-Zr Alloys

    NASA Astrophysics Data System (ADS)

    Liu, Dexue; Yin, Xunyan; Pang, Xin; Hu, Shiwen; Ding, Yutian

    2017-08-01

    By adding 2, 6 and 10 wt.% Dy and 0.5, 1.5 and 2 wt.% Sr elements to Mg-2.4Nd-0.5Zr alloys and adopting die-casting process for biomedical Mg-10Dy-0.5Sr-2.4Nd-0.5Zr alloys, the effects of Dy and Sr elements and die-casting process on the microstructure, mechanical properties and corrosion resistance of Mg-Dy-Sr-Nd-Zr alloys were investigated. The new biomedical Mg-10Dy-0.5Sr-2.4Nd-0.5Zr alloys were designed, and the grain size of the as-cast new alloy was refined to 70 μm and distributed equably. The ultimate tensile strength increased with increasing Dy content and decreasing Sr content. The corrosion rate decreased firstly and then increased with increasing Dy content and decreased with increasing Sr content. By adjusting the content of Sr and Dy, the ultimate tensile strength of as-cast new Mg-10Dy-0.5Sr-2.4Nd-0.5Zr alloys increased to 203 MPa, elongation was 7.4%, and the corrosion rate decreased to 0.48 mm/a. The elongation rate increased to 10.2% after the new biomedical alloys were processed by die casting with an refine-grained microstructure of 18 μm, meanwhile the ultimate tensile strength decreased to 180 MPa, and the corrosion rate was 1.29 mm/a.

  12. The Effect of Aluminum Content and Processing on the Tensile Behavior of High Pressure Die Cast Mg Alloys

    NASA Astrophysics Data System (ADS)

    Deda, Erin M.

    Due to their high specific strength and good castability, magnesium alloys are desirable for use in weight reduction strategies in automotive applications. However, the mechanical properties of high pressure die cast (HPDC) magnesium can be highly variable and dependent on location in the casting. To better understand the relationship between microstructure and tensile properties, the influence of alloying and section thickness on the microstructural features and tensile properties of Mg-Al and Mg-Al-Mn alloys is quantified. This investigation provides experimental input to modeling activities for the development of an Integrated Computational Materials Engineering capability, to assess and quantify the impact of microstructure on the tensile behavior of HPDC Mg AM series (magnesium-aluminum-manganese) alloys. As a result of this work, it is found that with increasing aluminum content, the yield strength increases and the ductility decreases. Increasing the plate thickness results in a decrease in both the yield strength and ductility. HPDC components have varying microstructural features through the plate thickness, developing a "skin" and "core". The grain size, beta-Mg 17Al12 phase, and solute content are all quantified through the thickness of the plates. By quantifying microstructural variations, a physics-based model has been developed which is able to predict the effects of alloying and plate thickness on yield strength. The primary factors affecting strengthening are accounted for using a linear superposition model of solid solution, grain size, and dispersion hardening. This model takes into account through-thickness microstructure gradients that exist in HPDC components by using a composite model to incorporate the skin and core changes. The yield strength in these alloys is dominated by grain boundary strengthening and solute hardening effects. In order to isolate the effects of eutectic phases, shrinkage porosity and oxide films on strength and

  13. Effects of grain refinement on the microstructure, mechanical properties and reliability of AlSi7Cu3Mg gravity die cast cylinder heads

    NASA Astrophysics Data System (ADS)

    Timelli, Giulio; Camicia, Giordano; Ferraro, Stefano; Molina, Roberto

    2014-07-01

    The effects of grain refinement on the microstructure and mechanical properties of a secondary AlSi7-Cu3Mg gravity die cast cylinder head are reported. Metallographic and image analysis techniques have been used to quantitatively examine the macro- and microstructural changes occurring with the addition of grain-refining agent. The results indicate that the AlTi5B1 addition produces a fine and uniform grain structure throughout the casting; this effect is more pronounced in the slowly solidified regions. The initial contents of Ti and B, which are present as impurity elements in the supplied secondary alloy ingots, are not sufficient to produce effective grain refinement. Under the present casting conditions, the combined addition of AlTi5B1 and Sr does not produce any reciprocal interaction or effect on primary α-Al and eutectic solidification. Grain refinement improves the mechanical properties of the as-cast AlSi7Cu3Mg alloy and produces higher Weibull moduli, thus increasing the reliability of the casting. For automotive structural components, this could be considered an increase in safety.

  14. Zinc Base Die Castings

    DTIC Science & Technology

    1935-01-31

    183 B86- 33T SAE N.J .zn Co. B86-33T 1934 SAE N.J.Zn Cc,. Zamak 3N AllO;E Cl C2 Allo~ XXI 221 Zarnak 2 .A.llo;z XXIII .Allol XXIII 202 Zamak 2 O...2 includ.es Pb ,Fe, Cd, C:’. 3 special high gra1e ?:inc. • t • • ; -J TABLE II Chemical Composition for Zinc Alloy Nuuber Zam.ak 2 Zamak 3...was alco given regarding the aging of the alloys. The a1loy3 Aupplied were: Zamak 2, Zamak 3, Zamak 3-S (Stabilized to hasten contraction which

  15. Relationship Between the 3D Porosity and β-Phase Distributions and the Mechanical Properties of a High Pressure Die Cast AZ91 Mg Alloy

    NASA Astrophysics Data System (ADS)

    Biswas, Somjeet; Sket, Federico; Chiumenti, Michele; Gutiérrez-Urrutia, Iván; Molina-Aldareguía, Jon M.; Pérez-Prado, Maria Teresa

    2013-09-01

    Currently, most magnesium lightweight components are fabricated by casting as this process is cost effective and allows forming parts with complex geometries and weak textures. However, cast microstructures are known to be heterogeneous and contain unpredictable porosity distributions, which give rise to a large variability in the mechanical properties. This work constitutes an attempt to correlate the microstructure and the mechanical behavior of a high pressure die cast (HPDC) Mg AZ91 alloy, aimed at facilitating process optimization. We have built a stairway-shaped die to fabricate alloy sections with different thicknesses and, thus, with a range of microstructures. The grain size distributions and the content of β-phase (Mg17Al12) were characterized by optical and electron microscopy techniques as well as by electron backscatter diffraction (EBSD). The bulk porosity distribution was measured by 3D computed X-ray microtomography. It was found that the through-thickness microhardness distribution is mostly related to the local area fraction of the β-phase and to the local area fraction of the pores. We correlate the tensile yield strength to the average pore size and the fracture strength and elongation to the bulk porosity volume fraction. We propose that this empirical approach might be extended to the estimation of mechanical properties in other HPDC Mg alloys.

  16. Experimental Investigation and Numerical Simulation During Backward Extrusion of a Semi-Solid Al-Si Hypoeutectic Alloy

    SciTech Connect

    Neag, Adriana; Favier, Veronique; Bigot, Regis; Canta, Traian; Frunza, Dan

    2007-04-07

    This work has been performed along two main directions. First of all we present the experimental results and effects obtained by backward extrusion tests on semi-solid aluminum alloy at three different forming temperatures and different holding times in isothermal conditions. The semi-solid billets were fabricated by the re-melting heat treatment method. Semi-solid extrusion tests were carried out to investigate the load-displacement curves and the deformation behaviour at different temperatures. The load level clearly decreases with increasing temperature and increasing holding time. Numerical simulations of semi-solid extrusion has been made too, using Forge 2005,. Experimental and simulated results are compared and discussed.

  17. Improved life of die casting dies of H13 steel by attaining improved mechanical properties and distortion control during heat treatment. Year 1 report, October 1994--September 1995

    SciTech Connect

    Wallace, J.F.; Schwam, D.

    1995-03-01

    Optimum heat treatment of dies (quenching) is critical in ensuring satisfactory service performance: rapid cooling rates increase the thermal fatigue/heat checking resistance of the steel, although very fast cooling rates can also lead to distortion and lower fracture toughness, increasing the danger of catastrophic fracture. Goal of this project is to increase die life by using fast enough quenching rates (> 30 F/min ave cooling rate from 1750 to 550 F, 1/2 in. below working surfaces) to obtain good toughness and fatigue resistance in Premium grade H-13 steel dies. An iterative approach of computer modeling validated by experiment was taken. Cooling curves during gas quenching of H-13 blocks and die shapes were measured under 2, 5, and 7.5 bar N2 and 4 bar Ar. Resulting dimensional changes and residual stresses were determined. To facilitate the computer modeling work, a database of H-13 mechanical and physical properties was compiled. Finite element analysis of the heat treated shapes was conducted. Good fit of modeled vs measured quenched rates was demonstrated for simple die shapes. The models predict well the phase transformation products from the quench. There is good fit between predicted and measured distortion contours; however magnitude of predicted distortion and residual stresses does not match well the measured values. Further fine tuning of the model is required.

  18. Semi-Solid Forming of A356 Alloy by Rapid Slurry Forming Process

    NASA Astrophysics Data System (ADS)

    Sharma, S.; Sharma, A.; Kumar, S.

    Rapid Slurry Forming (RSF) is a relatively new technique of semi-solid forming. RSF process has been used for A356, A356+Ti+B (grain refiner) and A356+Ti+B+Sr (grain refiner and modifier) Al alloys in the present investigation. All the three alloys were held at 597°C, at which about 30% solid fraction is obtained in the semi-solid slurry, for 0, 5, 10 and 15 minutes. After each holding time, the slurry was quenched in water to preserve the semi-solid microstructure. Microstructure of all the three alloys at each stage was examined and hardness was measured. A globular microstructure was obtained for the RSF-processed alloys. The globularity of a-grains increased but grain size also increased and hardness decreased with increase in holding time. The optimum hold time appeared to be 5 minutes. The grain refiner and modifier did not seem to have any effect on the formation of semi solid slurry. The coarsening kinetics of the globular a-grains was found to be faster than that predicted by the LSW theory.

  19. A combined analytical solution for Chemical Exchange Saturation Transfer and semi-solid Magnetization Transfer

    PubMed Central

    Zaiss, Moritz; Zu, Zhongliang; Xu, Junzhong; Schuenke, Patrick; Gochberg, Daniel F.; Gore, John C.; Ladd, Mark E.; Bachert, Peter

    2015-01-01

    Off-resonant radiofrequency irradiation in tissue indirectly lowers the water signal by saturation transfer processes: On the one hand, there are selective chemical exchange saturation transfer (CEST) effects originating from exchanging endogenous protons resonating a few ppm from water; on the other hand, there is the broad semi-solid magnetization transfer (MT) originating from immobile protons associated with the tissue matrix with kHz line-widths. Recently it was shown that endogenous CEST contrasts can be strongly affected by the MT background so that corrections are needed to derive accurate estimates of CEST effects. Herein we show that a full analytical solution of the underlying Bloch-McConnell equations for both MT and CEST provides insights into their interaction and suggests a simple means to isolate their effects. The presented analytical solution, based on the eigenspace solution of the Bloch-McConnell equations, extends previous treatments by allowing arbitrary line-shapes for the semi-solid MT effects and simultaneously describing multiple CEST pools in the presence of a large MT pool for arbitrary irradiation. The structure of the model indicates that semi-solid MT and CEST effects basically add up inversely in determining the steady-state Z-spectrum, as previously shown for direct saturation and CEST effects. Implications for existing previous CEST analyses in the presence of a semi-solid MT are studied and discussed. It turns out that to accurately quantify CEST contrast, a good reference Z-value, the observed longitudinal relaxation rate of water, and the semi-solid MT pool size fraction, must all be known. PMID:25504828

  20. Advances in aluminum casting technology

    SciTech Connect

    Tiryakioglu, M.; Campbell, J.

    1998-01-01

    This symposium focuses on the improvements of aluminum casting quality and reliability through a better understanding of processes and process variables, and explores the latest innovations in casting-process design that allow increasing use of the castings to replace complex assemblies and heavy steel and cast-iron components in aerospace and automotive applications. Presented are 35 papers by international experts in the various aspects of the subject. The contents include: Semisolid casting; Computer-aided designing of molds and castings; Casting-process modeling; Aluminum-matrix composite castings; HIPing of castings; Progress in the US car project; Die casting and die design; and Solidification and properties.

  1. Microstructure, Mechanical and Surface Morphological Properties of Al5Ti5Cr Master Alloy as Friction Material Prepared by Stir Die Casting

    NASA Astrophysics Data System (ADS)

    Ahmed, Syed Faisal; Srivastava, Sanjay; Agarwal, Alka Bani

    2017-06-01

    Metal matrix composite offers outstanding properties for better performance of disc brakes. In the present study, the composite of AlTiCr master alloy was prepared by stir die casting method. The developed material was reinforced with (0-10 wt%) silicon carbide (SiC) and boron carbide (B4C). The effects of SiC reinforcement from 0 to 10 wt% on mechanical, microstructure and surface morphological properties of Al MMC was investigated and compared with B4C reinforcement. Physical properties like density and micro Vickers hardness number show an increasing trend with an increase in the percentage of SiC and B4C reinforcement. Mechanical properties viz. UTS, yield strength and percentage of elongation are improved with increasing the fraction of reinforcement. The surface morphology and phase were identified from scanning electron microscopy (SEM) and X-ray diffraction analysis and the oxidized product formed during the casting was investigated by Fourier transformation infrared spectroscopy. This confirms the presence of crystallization of corundum (α-Al2O3) in small traces as one of the alumina phases, within casting sample. Micro-structural characterization by SEM depicted that the particles tend to be more agglomerated more and more with the percentage of the reinforcement. The AFM results reveal that the surface roughness value shows a decreasing trend with SiC reinforcement while roughness increases with increase the percentage of B4C.

  2. The Optimizing Conditions by Taguchi Method for Fabricating Semi-Solid Al-Zn-Mg Alloy Slurry by Cooling Plate Method

    NASA Astrophysics Data System (ADS)

    Shim, Sung-Yong; Park, Hyung-Won; Jeong, In-Sang; Lim, Su-Gun

    In order to optimize the condition for the semi-solid Al-Zn-Mg aluminium alloy fabricated by cooling plate method, the Taguchi design was used. The cooling plate method effectively separating the grains formed from the mold wall can be used to form a semi-solid material by flowing molten metal over an inclined Cu plate and casting in a mold for the near-net shape component. In Taguchi's design method, the higher signal vs noise (S/N) ratio the better. Therefore, the manufacturing conditions were arranged as a table of orthogonal arrays (L9(34)), and the influence of two factors, pouring temperature and cooling plate angle, was examined. From the observed microstructures, the grain size and aspect ratio were measured by image analyzer. The results indicated that the pouring temperature exerts the main effect on the spherical microstructures since the S/N ratio, which is the sensibility of the surrounding environment, was the highest. The optimum condition for the Al-Zn-Mg alloy was a cooling plate angle of 40° and a pouring temperature of 680°C. The grain size and aspect ratio were 70 μm and 1.3, respectively.

  3. Ultrasonic semi-solid coating soldering 6061 aluminum alloys with Sn-Pb-Zn alloys.

    PubMed

    Yu, Xin-ye; Xing, Wen-qing; Ding, Min

    2016-07-01

    In this paper, 6061 aluminum alloys were soldered without a flux by the ultrasonic semi-solid coating soldering at a low temperature. According to the analyses, it could be obtained that the following results. The effect of ultrasound on the coating which promoted processes of metallurgical reaction between the components of the solder and 6061 aluminum alloys due to the thermal effect. Al2Zn3 was obtained near the interface. When the solder was in semi-solid state, the connection was completed. Ultimately, the interlayer mainly composed of three kinds of microstructure zones: α-Pb solid solution phases, β-Sn phases and Sn-Pb eutectic phases. The strength of the joints was improved significantly with the minimum shear strength approaching 101MPa.

  4. Asymmetric battery having a semi-solid cathode and high energy density anode

    DOEpatents

    Tan, Taison; Chiang, Yet-Ming; Ota, Naoki; Wilder, Throop; Duduta, Mihai

    2016-09-06

    Embodiments described herein relate generally to devices, systems and methods of producing high energy density batteries having a semi-solid cathode that is thicker than the anode. An electrochemical cell can include a positive electrode current collector, a negative electrode current collector and an ion-permeable membrane disposed between the positive electrode current collector and the negative electrode current collector. The ion-permeable membrane is spaced a first distance from the positive electrode current collector and at least partially defines a positive electroactive zone. The ion-permeable membrane is spaced a second distance from the negative electrode current collector and at least partially defines a negative electroactive zone. The second distance is less than the first distance. A semi-solid cathode that includes a suspension of an active material and a conductive material in a non-aqueous liquid electrolyte is disposed in the positive electroactive zone, and an anode is disposed in the negative electroactive zone.

  5. Modeling of oleaginous fungal biofilm developed on semi-solid media.

    PubMed

    Economou, Ch N; Vasiliadou, I A; Aggelis, G; Pavlou, S; Vayenas, D V

    2011-10-01

    An oleaginous fungus, Mortierella isabellina, able to transform efficiently sugar to storage lipid, was used as a model microorganism which develops a biofilm structure during the semi-solid fermentation process for the production of biodiesel from sweet sorghum. A mathematical model was developed to describe the fungal oil production in M. isabellina biofilm. The model describes diffusion and consumption of sugars and nitrogen of sweet sorghum and single cell oil production in a biofilm, which grows according to the kinetics of double-substrate limitation (sugars and nitrogen) with sugar inhibition. Experimental data from a previous experimental study were used to determine the kinetic parameters of the model. Maximum biofilm thickness and the percentage of lipid inside the biofilm were estimated using the model at 1892 μm and 15%, respectively. The proposed mathematical model could prove a useful tool for designing semi-solid fermentation processes. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Semi-solid processing of high-chromium tool steel to obtain microstructures without carbide network

    NASA Astrophysics Data System (ADS)

    Jirková, H.; Aišman, D.; Rubešová, K.; Opatová, K.; Mašek, B.

    2017-02-01

    Treatment of high-alloy tool steels that involves transition to the semi-solid state can transform the sharp-edged primary carbides which usually form during solidification. These carbides severely impair toughness and are virtually impossible to eliminate by conventional treatment routes. Upon classical semi-solid processing which dissolves these carbides, the resulting microstructure consists of polyhedral and super-saturated austenite embedded in lamellar austenite-carbide network. This type of microstructure reflects in the mechanical properties, predominantly in material behaviour under tensile loading. Such a network, however, can be removed by appropriate thermomechanical treatment. In the present experiment, various procedures involving heating to the semi-solid state were tested on X210Cr12 tool steel. The feedstock was heated to the temperature range of 1220 – 1280 °C. The heating was followed by procedures involving either water quenching to the forming temperature, room temperature or temperature from the range from 500 °C to 1000 °C followed by reheating to the forming temperature. It was found that the development of the lamellar network strongly depends on the temperature of heating to semi-solid state. Thermomechanical treatment produced microstructures in which the matrix consisted of a mixture of polyhedral austenite grains and the M-A constituent. In addition, the initial lamellar eutectic network was partially or even completely melted and substituted with a mixture of very fine recrystallized austenite grains and precipitates of chromium carbides. Some fine M7C3 carbides were present in the austenitic-martensitic matrix as well. When appropriate processing parameters were chosen, very good mechanical properties were obtained, among them a hardness of 860 HV10.

  7. Corrosion Behaviour of A380 Aluminiun Alloy by Semi-Solid Rheocasting

    NASA Astrophysics Data System (ADS)

    Forn, A.; Rupérez, E.; Baile, M. T.; Campillo, M.; Menargues, S.; Espinosa, I.

    2007-04-01

    A comparative study was performed on the corrosion behavior of a component of A380 aluminium alloy obtained by Semi-Solid Rheocasting (SSR). The effect of heat treatments T5 and T6 on corrosion resistance was compared with components without heat treatment by SSR processes. Corrosion studies were performed using an acetic acid salt spray test, impedance measurements and polarization curves using a 3,5%Na Cl test solution. The corrosion progress is described by micrographic analysis.

  8. Corrosion Behaviour of A380 Aluminiun Alloy by Semi-Solid Rheocasting

    SciTech Connect

    Forn, A.; Ruperez, E.; Baile, M. T.; Campillo, M.; Menargues, S.; Espinosa, I.

    2007-04-07

    A comparative study was performed on the corrosion behavior of a component of A380 aluminium alloy obtained by Semi-Solid Rheocasting (SSR). The effect of heat treatments T5 and T6 on corrosion resistance was compared with components without heat treatment by SSR processes. Corrosion studies were performed using an acetic acid salt spray test, impedance measurements and polarization curves using a 3,5%Na Cl test solution. The corrosion progress is described by micrographic analysis.

  9. Contamination of semi-solid dosage forms by leachables from aluminium tubes.

    PubMed

    Haverkamp, Jan Boris; Lipke, Uwe; Zapf, Thomas; Galensa, Rudolf; Lipperheide, Cornelia

    2008-11-01

    The objective of this study was to determine to what extent bisphenol A (BPA), bisphenol A diglycidyl ether (BADGE) and its derivatives are extractable from epoxy-based coatings of aluminium tubes for pharmaceutical use and to monitor their leaching into different kinds of semi-solid dosage forms. Migration increasing factors should be evaluated. Extraction tests using acetonitrile for 10 days at 40 degrees C turned out to be suitable to estimate the maximum amount of extractables. A plain variability in the nature and amount of extractables among tubes of different vendors (n=7) could be demonstrated. Leaching of the remnants into various semi-solid drug products (ointment, cream, gel) during storage (30 degrees C/40 degrees C) was verifiable. Leachable profiles were, apart from storage time and temperature, decisively influenced by the matrix. In particular, matrix polarity seemed to play a crucial role. Thus, the highest amount of leachables was found in isopropanol-based carbomer gel. Furthermore, in-use conditions (mechanical stress) enhanced migration significantly. In order to ensure quality and safety of semi-solid formulae, interactions between the coating material and the drug product should be thoroughly evaluated.

  10. Tailorable Burning Behavior of Ti14 Alloy by Controlling Semi-Solid Forging Temperature

    PubMed Central

    Chen, Yongnan; Yang, Wenqing; Zhan, Haifei; Zhang, Fengying; Huo, Yazhou; Zhao, Yongqing; Song, Xuding; Gu, Yuantong

    2016-01-01

    Semi-solid processing (SSP) is a popular near-net-shape forming technology for metals, while its application is still limited in titanium alloy mainly due to its low formability. Recent works showed that SSP could effectively enhance the formability and mechanical properties of titanium alloys. The processing parameters such as temperature and forging rate/ratio, are directly correlated with the microstructure, which endow the alloy with different chemical and physical properties. Specifically, as a key structural material for the advanced aero-engine, the burn resistant performance is a crucial requirement for the burn resistant titanium alloy. Thus, this work aims to assess the burning behavior of Ti14, a kind of burn resistant alloy, as forged at different semi-solid forging temperatures. The burning characteristics of the alloy are analyzed by a series of burning tests with different burning durations, velocities, and microstructures of burned sample. The results showed that the burning process is highly dependent on the forging temperature, due to the fact that higher temperatures would result in more Ti2Cu precipitate within grain and along grain boundaries. Such a microstructure hinders the transport of oxygen in the stable burning stage through the formation of a kind of oxygen isolation Cu-enriched layer under the burn product zone. This work suggests that the burning resistance of the alloy can be effectively tuned by controlling the temperature during the semi-solid forging process. PMID:28773820

  11. Microstructure Evolution of Semi-Solid 7075 Aluminum Alloy During Reheating Process

    NASA Astrophysics Data System (ADS)

    Mohammadi, H.; Ketabchi, M.; Kalaki, A.

    2011-10-01

    Microstructural evolution of semi-solid 7075 Al alloy manufactured by strain-induced melt activation (SIMA) process was investigated. The effects of different processing parameters, such as isothermal temperature and holding time on the semi-solid microstructures (the liquid volume fraction, average grain size, and degree of spheroidization of the solid particles) during partial remelting have been investigated on 7075 Al alloy that was extruded by an extrusion ratio of 20 before remelting. Experiments of remelting were carried out in the range of 560-610 °C for 10, 20, and 30 min holding time and then the specimens were quenched in cold water. Microstructure of quenched samples were observed under optical microscope and then analyzed via image analysis. The results showed that high semi-solid isothermal temperature would increase the liquid volume fraction and accelerate the spherical processing of the solid particles. Furthermore at long holding time, the globular grains coarsened slightly and the average grains size are increased. The experimental results showed that the optimum process parameters, should be chosen at isothermal temperature of 580 °C with the holding time, <30 min.

  12. Effect of Hydrostatic Pressure on the 3D Porosity Distribution and Mechanical Behavior of a High Pressure Die Cast Mg AZ91 Alloy

    NASA Astrophysics Data System (ADS)

    Sket, Federico; Fernández, Ana; Jérusalem, Antoine; Molina-Aldareguía, Jon M.; Pérez-Prado, María Teresa

    2015-09-01

    A limiting factor of high pressure die cast (HPDC) Mg alloys is the presence of porosity, which has a detrimental effect on the mechanical strength and gives rise to a large variability in the ductility. The application of hydrostatic pressure after casting is known to be beneficial to improve the mechanical response of HPDC Mg alloys. In this study, a combined experimental and simulation approach has been developed in order to investigate the influence of pressurization on the 3D porosity distribution and on the mechanical behavior of an HPDC Mg AZ91 alloy. Examination of about 10,000 pores by X-ray computed microtomography allowed determining the effect of hydrostatic pressure on the bulk porosity volume fraction, as well as the change in volume and geometry of each individual pore. The evolution of the 3D porosity distribution and mechanical behavior of a sub-volume containing 200 pores was also simulated by finite element analysis. Both experiments and simulations consistently revealed a decrease in the bulk porosity fraction and a bimodal distribution of the individual volume changes after the application of the pressure. This observation is associated with pores containing internal pressure as a result of the HPDC process. Furthermore, a decrease in the complexity factor with increasing volume change is observed experimentally and predicted by simulations. The pressure-treated samples have consistently higher plastic flow strengths.

  13. Numerical simulation of mechanical deformation of semi-solid material using a level-set based finite element method

    NASA Astrophysics Data System (ADS)

    Sun, Zhidan; Bernacki, Marc; Logé, Roland; Gu, Guochao

    2017-09-01

    In this work, a level-set based finite element method was used to numerically evaluate the mechanical behavior in a small deformation range of semi-solid materials with different microstructure configurations. For this purpose, a finite element model of the semi-solid phase was built based on Voronoï diagram. Interfaces between the solid and the liquid phases were implicitly described by level-set functions coupled to an anisotropic meshing technique. The liquid phase was considered as a Newtonian fluid, whereas the behavior of the solid phase was described by a viscoplastic law. Simulations were performed to study the effect of different parameters such as solid phase fraction and solid bridging. Results show that the macroscopic mechanical behavior of semi-solid material strongly depends on the solid fraction and the local microstructure which play important roles in the formation of hot tearing. These results could provide valuable information for the processing of semi-solid materials.

  14. Research on the Microstructure and Mechanical Property of Ti-7Cu Alloy after Semi-Solid Forging

    NASA Astrophysics Data System (ADS)

    Chen, Yongnan; Huo, Yazhou; Zhao, Yongqing; Sun, Zhiping; Bai, Fan

    2016-06-01

    The present work is focused on the development of microstructure of Ti-7Cu alloy as a function of forging temperature and forging ratio in semi-solid state and the influence of resulting microstructure on the mechanical properties. The experimental results showed that the dynamic recrystallization occurred during semi-solid forging and the grain refinement was attained which is considered to be favorable for improving the semi-solid formability. The grain size increased with forging temperature and decreased with forging ratio. Forging temperature has a significant effect on the precipitation behavior in grain boundary regions during the semi-solid processing. More acicular-Ti2Cu tended to precipitate in grain boundary regions with higher forging temperature and finally formed precipitates zones adjacent to grain boundaries after forged at 1,100°C. High ultimate tensile strengths and low elongation have been achieved after semi-solid forging. The strength and hardness decreased with increase of forging temperature, while the ductility increased with increase of forging ratio. The relative contributions of tensile properties were attributed to the varieties of grain size and the distribution of Ti2Cu precipitates obtained by semi-solid forging.

  15. A genetic approach to improved semi-solid forming of metals. Final report for period September 4, 1999 - March 4, 2000

    SciTech Connect

    Klier, Eric M.

    2000-05-04

    Lack of technology for the production of large inexpensive feedstock, with uniform spherical primary phase throughout as required for semi-solid forming, has restricted realization of the full potential for the semi-solid forming process. Furthermore narrow process windows and alloy chemistry restrictions increase process costs and limit performance attributes possible with existing semi-metal systems. Successful semi-solid forming trials utilizing Chesapeake Composites Corporation's DSC{sup TM} Metals for feedstock indicate that this represents a generic approach to providing a permanent highly uniform, spherical solid phase, without electromagnetic or mechanical shearing. This approach also provides for further growth of semi-solid forming by providing for: low cost large diameter billet stock, reduced semi-solid forming costs, extension of semi-solid forming to new alloy systems, and semi-solid formed components with substantially enhanced physical and mechanical properties.

  16. Development of microstructure in high-alloy steel K390 using semi-solid forming

    NASA Astrophysics Data System (ADS)

    Opatova, K.; Aisman, D.; Rubesova, K.; Ibrahim, K.; Jenicek, S.

    2016-03-01

    Semi-solid processing of light alloys, namely aluminium and magnesium alloys, is a widely known and well-established process. By contrast, processing of powder steels which have high levels of alloying elements is a rather new subject of research. Thixoforming of high-alloy steels entails a number of technical difficulties. If these are overcome, the method can offer a variety of benefits. First of all, the final product shape and the desired mechanical properties can be obtained using a single forming operation. Semi-solid forming can produce unusual powder steel microstructures unattainable by any other route. Generally, the microstructures, which are normally found in thixoformed steels, consist of large fractions of globular or polygonal particles of metastable austenite embedded in a carbide network. An example is the X210Cr12 steel which is often used for semi-solid processing experiments. A disadvantage of the normal microstructure configuration is the brittleness of the carbide network, in which cracks initiate and propagate, causing low energy fractures. However, there is a newly-developed mini-thixoforming route which produces microstructures with an inverted configuration. Here, the material chosen for this purpose was K390 steel, in which the content of alloying elements is up to 24%. Its microstructure which was obtained by mini- thixoforming did not contain polyhedral austenite grains but hard carbides embedded in a ductile austenitic matrix. This provided the material with improved toughness. The spaces between the austenite grains were filled with a eutectic in which chromium, molybdenum and cobalt were distributed uniformly. After the processing parameters were optimized, complexshaped demonstration products were manufactured by this route. These products showed an extraordinary compressive strength and high wear resistance, thanks to the hardness of their microstructure constituents, predominantly the carbides.

  17. Semi-solid Sucrose Stearate-Based Emulsions as Dermal Drug Delivery Systems

    PubMed Central

    Klang, Victoria; Schwarz, Julia C.; Matsko, Nadejda; Rezvani, Elham; El-Hagin, Nivine; Wirth, Michael; Valenta, Claudia

    2011-01-01

    Mild non-ionic sucrose ester surfactants can be employed to produce lipid-based drug delivery systems for dermal application. Moreover, sucrose esters of intermediate lipophilicity such as sucrose stearate S-970 possess a peculiar rheological behavior which can be employed to create highly viscous semi-solid formulations without any further additives. Interestingly, it was possible to develop both viscous macroemulsions and fluid nanoemulsions with the same chemical composition merely by slight alteration of the production process. Optical light microscopy and cryo transmission electron microscopy (TEM) revealed that the sucrose ester led to the formation of an astonishing hydrophilic network at a concentration of only 5% w/w in the macroemulsion system. A small number of more finely structured aggregates composed of surplus surfactant were likewise detected in the nanoemulsions. These discoveries offer interesting possibilities to adapt the low viscosity of fluid O/W nanoemulsions for a more convenient application. Moreover, a simple and rapid production method for skin-friendly creamy O/W emulsions with excellent visual long-term stability is presented. It could be shown by franz-cell diffusion studies and in vitro tape stripping that the microviscosity within the semi-solid formulations was apparently not influenced by their increased macroviscosity: the release of three model drugs was not impaired by the complex network-like internal structure of the macroemulsions. These results indicate that the developed semi-solid emulsions with advantageous application properties are highly suitable for the unhindered delivery of lipophilic drugs despite their comparatively large particle size and high viscosity. PMID:24310496

  18. Determination of Material Properties in the Semi-Solid State Using Gleeble Simulator

    SciTech Connect

    Solek, Krzysztof; Kuziak, Roman; Kapranos, Plato

    2007-04-07

    This work shows that the Gleeble thermomechanical simulator can be used to carry out controlled material tests. Although originally the simulator was not designed for testing materials in the semi-solid state, it could be adapted to such tests with only minor changes based on the construction of a special chamber for material heating and moulds for material shaping. To achieve this, a special resistance heating system was developed and installed in the Gleeble simulator. The design of a heating chamber that allows uniform heating of the material was achieved by computer simulations. The numerical model of the resistance heating developed and the results of calculations are described in detail.

  19. Microstructure evolution in hot worked steel after heating to semi-solid state.

    PubMed

    Sołek, K; Mitura, Z; Karbowniczek, M; Dutkiewicz, J; Faryna, M; Rogal, Ł

    2010-03-01

    Metal alloys can be formed successfully in a partially liquid state if they display a particular globular microstructure. The article presents an analysis of a study carried out of the development, by means of the strain-induced melt-activated method, of such a microstructure for an X210CrW12 steel. Hot rolled samples, with subsequent cooling, were heated to the temperature range at which the liquid and solid phases coexist in the material. The spheroidal shapes for solid particles, required for semi-solid processing, were found. The investigations were carried out using scanning electron microscopy in combination with energy dispersive spectroscopy.

  20. Crystallization of semi-solid magnesium alloys and composites in the presence of magnetohydrodynamic shear flows

    NASA Astrophysics Data System (ADS)

    Vivès, Charles

    1994-04-01

    The working principle of a new electromagnetic rheocaster, which is based on the use of rotating permanent magnets and which allows the production of intense three-dimensional multiphase flows in solidifying semi-solid alloy slurries and metal matrix composites, is described. Local measurement techniques are applied to the study of the evolution of non-newtonian magnetohydrodynamic multiphase flow phenomena with the rotational speed of the inductor, the solid fraction of the magnesium alloy matrix and the size and volume percent of SiC particles. A discussion is presented relating the metallurgical findings to the heat and three-phase flow measurements.

  1. Modelling and optimization of semi-solid processing of 7075 Al alloy

    NASA Astrophysics Data System (ADS)

    Binesh, B.; Aghaie-Khafri, M.

    2017-09-01

    The new modified strain-induced melt activation (SIMA) process presented by Binesh and Aghaie-Khafri was optimized using a response surface methodology to improve the thixotropic characteristics of semi-solid 7075 alloy. The responses, namely the average grain size and the shape factor, were considered as functions of three independent input variables: effective strain, isothermal holding temperature and time. Mathematical models for the responses were developed using the regression analysis technique, and the adequacy of the models was validated by the analysis of variance method. The calculated results correlated fairly well with the experiments. It was found that all the first- and second-order terms of the independent parameters and the interactive terms of the effective strain and holding time were statistically significant for the responses. In order to simultaneously optimize the responses, the desirable values for the effective strain, holding temperature and time were predicted to be 5.1, 609 °C and 14 min, respectively, when employing the desirability function approach. Based on the optimization results, a significant improvement in the average grain size and shape factor of the semi-solid slurry prepared by the new modified SIMA process was observed.

  2. Gender difference in the gastric emptying measured by magnetogastrography using a semi-solid test meal.

    PubMed

    Córdova-Fraga, Teodoro; De la Roca-Chiapas, José María; Solís, Silvia; Sosa, Modesto; Bernal-Alvarado, Jesús; Hernández, Enedino; Hernández-González, Martha

    2008-12-01

    evidence of gender-related differences in gastric emptying have been reported in the literature. Usually, those researches have focusing only with solid or liquid meal and invasive techniques. The objective of this study was to know the differences in the half time of gastric emptying and frequency of peristaltic contractions measured with magnetogastrography (MGG) on healthy subjects, using a semi-solid test meal. the study was carried out in 16 healthy subjects without gastrointestinal disease history they were divided in two groups, 8 male and 8 female. A test meal composed by 250 ml of yogurt and 3 grs of magnetite (Fe3O4), was employed. the gastric emptying half times were found to be 32.3 +/- 10.8 and 36.0 +/- 6.7 minutes, for men and women, respectively. Magnetogastrography modality presented in this study is a useful technique to measure the gastric emptying and the peristaltic contractions frequency. The studies were performed in healthy subjects without side effects. Using this technique a significant statistical difference (p<0.05) on gastric emptying from healthy volunteers was obtained between men and women. a contribution of this study was to demonstrate the feasibility of magnetogastrography to analyze gender differences in the gastric emptying half time using a semi-solid test meal.

  3. Enhancement of Gleditsia sinensis gum rheological properties with pressure cell treatment in semi-solid state.

    PubMed

    Zhou, Zi-yuan; Zhang, Wei-an; Duan, Jiu-fang; Zhang, Wei-ming; Sun, Da-feng; Jiang, Jian-xin

    2016-03-01

    The apparent viscosity, molecular weight, and molecular weight distribution are important physical properties that determine the functional properties of galactomannan gum. Gleditsia sinensis gum (GSG) in semi-solid state was pressure cell treated over a range of temperature (30-110 °C) under nitrogen maintained at a pressure of 1.0-4.0 MPa. Physicochemical properties of GSG samples both before and after the pressure cell treatment were characterized. These include measurements of rheological properties by LVDV-III Ultra Rheometer, molecular weight and radius of gyration by light scattering, and changes in surface morphology by scanning electron microscopy. GSG had the highest apparent viscosity at a treatment temperature of 30 °C; further increase in temperature led to decrease in apparent viscosity. The apparent viscosity of GSG can be efficiently improved at room temperature and low pressure. The process of pressure cell treatment of GSG in semi-solid state could be industrialized for enhancement of rheological properties of galactomannan gum.

  4. Modeling the hydrodynamic and electrochemical efficiency of semi-solid flow batteries

    SciTech Connect

    Brunini, VE; Chiang, YM; Carter, WC

    2012-05-01

    A mathematical model of flow cell operation incorporating hydrodynamic and electrochemical effects in three dimensions is developed. The model and resulting simulations apply to recently demonstrated high energy-density semi-solid flow cells. In particular, state of charge gradients that develop during low flow rate operation and their effects on the spatial non-uniformity of current density within flow cells are quantified. A one-dimensional scaling model is also developed and compared to the full three-dimensional simulation. The models are used to demonstrate the impact of the choice of electrochemical couple on flow cell performance. For semi-solid flow electrodes, which can use solid active materials with a wide variety of voltage-capacity responses, we find that cell efficiency is maximized for electrochemical couples that have a relatively flat voltage vs. capacity curve, operated under slow flow conditions. For example, in flow electrodes limited by macroscopic charge transport, an LiFePO4-based system requires one-third the polarization to reach the same cycling rate as an LiCoO2-based system, all else being equal. Our conclusions are generally applicable to high energy density flow battery systems, in which flow rates can be comparatively low for a given required power. (C) 2012 Elsevier Ltd. All rights reserved.

  5. The effect of saliva composition on texture perception of semi-solids.

    PubMed

    Engelen, Lina; van den Keybus, Petra A M; de Wijk, René A; Veerman, Enno C I; Amerongen, Arie V Nieuw; Bosman, Frits; Prinz, Jon F; van der Bilt, Andries

    2007-06-01

    Saliva is expected to be of significance for the perception of food stimuli in the mouth. Mixing the food with saliva, including breakdown and dilution, is considered to be of large importance for semi-solids as these products are masticated without chewing. It is known that there are large variations in composition of saliva originating from different glands and different subjects. In this study we investigated how variations in salivary characteristics affect sensory perception. Eighteen trained subjects participated in the study. Saliva was collected at rest and during three types of stimulation (odour, parafilm chewing and citric acid), and flow rates were determined. The collected saliva was analyzed for protein concentration, buffer capacity, mucin level and alpha-amylase activity. The salivary components measured in this study varied considerably among subjects, but also within subjects as a result of different means of stimulation. Variations in salivary components were correlated with sensory perception of a number of flavour, mouth feel and after feel attributes in the semi-solids mayonnaise and custard dessert. Total protein concentration and alpha-amylase activity were observed to correlate most strongly with texture perception.

  6. Three-Dimensional Microstructure Reconstruction and Finite Element Simulation of Gas Pores in the High-Pressure Die-Casting AZ91 Mg Alloy.

    PubMed

    Jiang, Wei; Cao, Zhanyi; Sun, Xu; Liu, Haifeng

    2015-12-01

    High-pressure die-casting (HPDC) AZ91 tensile specimens were used to investigate characteristics of gas pores and their effects on mechanical properties of HPDC AZ91 magnesium (Mg) alloy. Combining the stereoscopic morphology of gas pores obtained from a three-dimensional (3D) reconstruction technique with the experimental data from uniaxial tensile testing, we worked on finite element simulation to find the relationship between gas pores and the mechanical properties of HPDC AZ91 Mg alloy. Results indicate that the 2D metallography images have one-sidedness. Moreover, gas pores >100 µm in the center region have a remarkable negative influence on the ultimate tensile strength (UTS) and elongation. With an increase in the size of large gas pores in the center region, the UTS and elongation of the material decreases. In addition, the distribution of gas pores in the specimens and the areal fraction of gas pores >100 µm on cross sections can also affect the UTS and elongation to some extent.

  7. The Influence of Al Content and Thickness on the Microstructure and Tensile Properties in High-Pressure Die Cast Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Deda, Erin; Berman, Tracy D.; Allison, John E.

    2017-04-01

    The influence of Al content and section thickness on the microstructural features and tensile properties of high-pressure die cast AM series magnesium alloys is quantified in order to better understand the relationship between microstructure and tensile properties. It is found that with increasing aluminum content, the yield strength increases and the ductility decreases. Increasing the plate thickness results in a decrease in both the yield strength and ductility. The grain size, β-Mg17Al12 phase volume fraction, and solute content are all quantified through the thickness of the plates. It is found that the plates have a skin with increased hardness, due to a fine grain structure. The primary factors affecting strengthening in these alloys, including microstructural variations through the thickness, are accounted for using a linear superposition model. We conclude that yield strength is dominated by grain boundary strengthening and solid solution strengthening effects. The through-thickness grain size and solute concentration were quantified and these variations were found to play an important role in controlling the yield strength of these alloys.

  8. The Influence of Al Content and Thickness on the Microstructure and Tensile Properties in High-Pressure Die Cast Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Deda, Erin; Berman, Tracy D.; Allison, John E.

    2017-01-01

    The influence of Al content and section thickness on the microstructural features and tensile properties of high-pressure die cast AM series magnesium alloys is quantified in order to better understand the relationship between microstructure and tensile properties. It is found that with increasing aluminum content, the yield strength increases and the ductility decreases. Increasing the plate thickness results in a decrease in both the yield strength and ductility. The grain size, β-Mg17Al12 phase volume fraction, and solute content are all quantified through the thickness of the plates. It is found that the plates have a skin with increased hardness, due to a fine grain structure. The primary factors affecting strengthening in these alloys, including microstructural variations through the thickness, are accounted for using a linear superposition model. We conclude that yield strength is dominated by grain boundary strengthening and solid solution strengthening effects. The through-thickness grain size and solute concentration were quantified and these variations were found to play an important role in controlling the yield strength of these alloys.

  9. Fabrication of metal matrix composite by semi-solid powder processing

    SciTech Connect

    Wu, Yufeng

    2011-01-01

    Various metal matrix composites (MMCs) are widely used in the automotive, aerospace and electrical industries due to their capability and flexibility in improving the mechanical, thermal and electrical properties of a component. However, current manufacturing technologies may suffer from insufficient process stability and reliability and inadequate economic efficiency and may not be able to satisfy the increasing demands placed on MMCs. Semi-solid powder processing (SPP), a technology that combines traditional powder metallurgy and semi-solid forming methods, has potential to produce MMCs with low cost and high efficiency. In this work, the analytical study and experimental investigation of SPP on the fabrication of MMCs were explored. An analytical model was developed to understand the deformation mechanism of the powder compact in the semi-solid state. The densification behavior of the Al6061 and SiC powder mixtures was investigated with different liquid fractions and SiC volume fractions. The limits of SPP were analyzed in terms of reinforcement phase loading and its impact on the composite microstructure. To explore adoption of new materials, carbon nanotube (CNT) was investigated as a reinforcing material in aluminum matrix using SPP. The process was successfully modeled for the mono-phase powder (Al6061) compaction and the density and density distribution were predicted. The deformation mechanism at low and high liquid fractions was discussed. In addition, the compaction behavior of the ceramic-metal powder mixture was understood, and the SiC loading limit was identified by parametric study. For the fabrication of CNT reinforced Al6061 composite, the mechanical alloying of Al6061-CNT powders was first investigated. A mathematical model was developed to predict the CNT length change during the mechanical alloying process. The effects of mechanical alloying time and processing temperature during SPP were studied on the mechanical, microstructural and

  10. An Enhanced Steady-State Constitutive Model for Semi-solid Forming of Al7075 Based on Cross Model

    NASA Astrophysics Data System (ADS)

    Meshkabadi, Ramin; Pouyafar, Vahid; Javdani, Akbar; Faraji, Ghader

    2017-09-01

    The parameters of the Cross model were determined in a wide range of shear rates close to industrial conditions using rapid compression tests and backward extrusion experiments. The Cross model fitted well with experimental results at low shear rates, but it almost broke down at high shear rates. In this paper, a new steady-state model was proposed for semi-solid forming of Al7075 considering the effects of the yield stress, entrapped liquid, and shear rate using the Cross model. The yield stress of the alloy was estimated in the semi-solid state by extrapolating the viscosity at the least applicable shear rates. The results showed that the new model eliminated the Cross model's deviations, and it can be used for accurate prediction of the steady-state flow behavior of the semi-solid alloy in a wide range of shear rates.

  11. An Enhanced Steady-State Constitutive Model for Semi-solid Forming of Al7075 Based on Cross Model

    NASA Astrophysics Data System (ADS)

    Meshkabadi, Ramin; Pouyafar, Vahid; Javdani, Akbar; Faraji, Ghader

    2017-07-01

    The parameters of the Cross model were determined in a wide range of shear rates close to industrial conditions using rapid compression tests and backward extrusion experiments. The Cross model fitted well with experimental results at low shear rates, but it almost broke down at high shear rates. In this paper, a new steady-state model was proposed for semi-solid forming of Al7075 considering the effects of the yield stress, entrapped liquid, and shear rate using the Cross model. The yield stress of the alloy was estimated in the semi-solid state by extrapolating the viscosity at the least applicable shear rates. The results showed that the new model eliminated the Cross model's deviations, and it can be used for accurate prediction of the steady-state flow behavior of the semi-solid alloy in a wide range of shear rates.

  12. Detection of inhomogeneities in semi-solid materials using pulsed digital holography

    NASA Astrophysics Data System (ADS)

    Hernandez-Montes, Maria del Socorro; Mendoza Santoyo, Fernando; Perez-Lopez, Carlos

    2004-08-01

    An out of plane optical sensitive configuration for pulsed digital holography was used to detect inhomogeneities inside semi solid organic materials. A loud speaker was employed to produce a mechanical wave that propagates through the material in such a way that it generates vibrational resonant modes and transient events on the material surface. Surface micro displacements were observed between the firing of two consecutive laser pulses, both for a steady resonant mode and for different times during the transient event. Two kinds of inhomogeneities were inserted approximately 2 cm inside the material diffracting the original mechanical wave and thus changing the resonant mode pattern or the transient wave on the surface. Comparison of phase unwrapped patterns, with and without inhomogeneities allows the rapid identification of their existence. The results for the resonant and transient conditions show that the method may be reliably used to study, compare and distinguish data from inside homogeneous and in-homogeneous organic materials.

  13. Synchrotron radiography of direct-shear in semi-solid alloys

    NASA Astrophysics Data System (ADS)

    Gourlay, C. M.; Nagira, T.; Dahle, A. K.; Nakatsuka, N.; Uesugi, K.; Yasuda, H.

    2012-01-01

    Understanding phenomena occurring at the scale of the crystals during the deformation of semi-solid alloys is important for the development of physically-based rheological models. A range of deformation mechanisms have been proposed including agglomeration and disagglomeration, viscoplastic deformation of the solid skeleton, and granular phenomena such as jamming and dilatancy. This paper overviews in-situ experiments that directly image crystal-scale deformation mechanisms in equiaxed Al alloys at solid fractions shortly after the crystals have impinged to form a loose crystal network. Direct evidence is presented for granular deformation mechanisms including shear-induced dilation in both equiaxed-dendritic and globular microstructures. Modelling approaches suitable for capturing this behaviour are then discussed.

  14. Material efficient production of complex (hybrid) components using semi solid forming processes

    NASA Astrophysics Data System (ADS)

    Riedmüller, Kim Rouven; Liewald, Mathias

    2016-10-01

    By means of lightweight design and lightweight material structures, weight of single components and of resulting component assemblies should be reduced and, additionally, existing functionalities, reliabilities and material properties should be preserved. Therefore, on the one hand novel materials and hybrid material combinations are investigated and on the other hand weight reduction is realized by material efficient component designs. With regard to the manufacturing of such complex component geometries with high dimensional accuracy and relating to the realization of hybrid material concepts, semi solid forming technology offers promising prospects. This paper deals with two research projects recently conducted at the Institute for Metal Forming Technology (IFU, University of Stuttgart) in the field of this forming technology. First project is concerned with the manufacturing of hybrid components with integrated sensor and/or actuator functions and second project is in the field of material efficient manufacturing.

  15. Tensile Properties and Fracture Behavior of Aluminum Alloy Foam Fabricated from Die Castings without Using Blowing Agent by Friction Stir Processing Route

    PubMed Central

    Hangai, Yoshihiko; Kamada, Hiroto; Utsunomiya, Takao; Kitahara, Soichiro; Kuwazuru, Osamu; Yoshikawa, Nobuhiro

    2014-01-01

    Al foam has been used in a wide range of applications owing to its light weight, high energy absorption and high sound insulation. One of the promising processes for fabricating Al foam involves the use of a foamable precursor. In this study, ADC12 Al foams with porosities of 67%–78% were fabricated from Al alloy die castings without using a blowing agent by the friction stir processing route. The pore structure and tensile properties of the ADC12 foams were investigated and compared with those of commercially available ALPORAS. From X-ray computed tomography (X-ray CT) observations of the pore structure of ADC12 foams, it was found that they have smaller pores with a narrower distribution than those in ALPORAS. Tensile tests on the ADC12 foams indicated that as their porosity increased, the tensile strength and tensile strain decreased, with strong relation between the porosity, tensile strength, and tensile strain. ADC12 foams exhibited brittle fracture, whereas ALPORAS exhibited ductile fracture, which is due to the nature of the Al alloy used as the base material of the foams. By image-based finite element (FE) analysis using X-ray CT images corresponding to the tensile tests on ADC12 foams, it was shown that the fracture path of ADC12 foams observed in tensile tests and the regions of high stress obtained from FE analysis correspond to each other. Therefore, it is considered that the fracture behavior of ADC12 foams in relation to their pore structure distribution can be investigated by image-based FE analysis. PMID:28788573

  16. Tensile Properties and Fracture Behavior of Aluminum Alloy Foam Fabricated from Die Castings without Using Blowing Agent by Friction Stir Processing Route.

    PubMed

    Hangai, Yoshihiko; Kamada, Hiroto; Utsunomiya, Takao; Kitahara, Soichiro; Kuwazuru, Osamu; Yoshikawa, Nobuhiro

    2014-03-21

    Al foam has been used in a wide range of applications owing to its light weight, high energy absorption and high sound insulation. One of the promising processes for fabricating Al foam involves the use of a foamable precursor. In this study, ADC12 Al foams with porosities of 67%-78% were fabricated from Al alloy die castings without using a blowing agent by the friction stir processing route. The pore structure and tensile properties of the ADC12 foams were investigated and compared with those of commercially available ALPORAS. From X-ray computed tomography (X-ray CT) observations of the pore structure of ADC12 foams, it was found that they have smaller pores with a narrower distribution than those in ALPORAS. Tensile tests on the ADC12 foams indicated that as their porosity increased, the tensile strength and tensile strain decreased, with strong relation between the porosity, tensile strength, and tensile strain. ADC12 foams exhibited brittle fracture, whereas ALPORAS exhibited ductile fracture, which is due to the nature of the Al alloy used as the base material of the foams. By image-based finite element (FE) analysis using X-ray CT images corresponding to the tensile tests on ADC12 foams, it was shown that the fracture path of ADC12 foams observed in tensile tests and the regions of high stress obtained from FE analysis correspond to each other. Therefore, it is considered that the fracture behavior of ADC12 foams in relation to their pore structure distribution can be investigated by image-based FE analysis.

  17. Experimental investigations on monitoring and control of induction heating process for semi-solid alloys using the heating coil as sensor

    NASA Astrophysics Data System (ADS)

    Ono, Yuu; Zheng, Cheng-Qing; Hamel, François G.; Charron, Rémi; Ang Loong, Chee

    2002-08-01

    A method of monitoring the state of metal alloys during induction heating and control of the heating process utilizing the heating coil itself as a sensor is proposed, and its usefulness and effectiveness were experimentally investigated using aluminium A357 billets for the semi-solid metal (SSM) casting processes. The impedance of the coil containing the billet was continuously measured by the proposed method in the temperature range between room temperature and 700 °C. It was found that the reactance component of the impedance varied distinctively according to the billet state and could clearly monitor the deformation of the billet, while the resistance component increased with temperature, reflecting the variation of the resistivity of the billet which has strong correlation to the solid/liquid fraction of the billets. The measured impedance is very sensitive to the billet states such as temperature, deformation and solid/liquid fraction and could be used as a parameter to monitor and control the heating process for SSMs.

  18. Semi solid matrix formulations of meloxicam and tenoxicam: an in vitro and in vivo evaluation.

    PubMed

    Alladi, Saritha; Shastri, Nalini R

    2015-01-01

    The objective of this study was to improve the dissolution and subsequently the therapeutic efficacy of poorly water soluble BCS class-II drugs meloxicam and tenoxicam, by lipid semi solid matrix (SSM) systems filled in hard gelatin capsules by liquid fill technology. The present research involved preparation of SSM formulations using Gelucire 44/14 as a carrier due to its self emulsifying, wetting and hydrophilic properties. The SSM capsules were characterized by assay, in vitro dissolution studies, moisture uptake, FTIR and DSC. The optimized formulations were also evaluated for their in vivo anti inflammatory activity in rat model. Six to ten fold enhancement in vitro drug release, in both acidic and basic media, was obtained with formulations containing drug to carrier in 1:6 ratio. The absence of drug peak in DSC scans indicated complete dissolution of the drug in carrier, while IR revealed no chemical interaction of pure drug and Gelucire 44/14. The optimized SSM formulations of meloxicam and tenoxicam showed a rapid decrease in paw edema with a significant increase in anti-inflammatory activity. The SSM formulations were successful in providing rapid release of drugs with improved dissolution and in vivo anti-inflammatory activity by liquid fill technology in hard gelatin capsules.

  19. Materials for suspension (semi-solid) electrodes for energy and water technologies

    SciTech Connect

    Hatzell, Kelsey B.; Boota, Muhammad; Gogotsi, Yury

    2015-01-01

    Suspension or semi-solid electrodes have recently gained increased attention for large-scale applications such as grid energy storage, capacitive water deionization, and wastewater treatment. A suspension electrode is a multiphase material system comprised of an active (charge storing) material suspended in ionic solution (electrolyte). Gravimetrically, the electrolyte is the majority component and aids in physical transport of the active material. For the first time, this principle enables, scalability of electrochemical energy storage devices (supercapacitors and batteries) previously limited to small and medium scale applications. This critical review describes the ongoing material challenges encompassing suspension-based systems. The research described here combines classical aspects of electrochemistry, colloidal science, material science, fluid mechanics, and rheology to describe ion and charge percolation, adsorption of ions, and redox charge storage processes in suspension electrodes. Our review summarizes the growing inventory of material systems, methods and practices used to characterize suspension electrodes, and describes universal material system properties (rheological, electrical, and electrochemical) that are pivotal in the design of high performing systems. We include a discussion of the primary challenges and future research directions.

  20. A Process for Semi-Solid Moulding of High Viscosity Thermoplastic Polymers

    NASA Astrophysics Data System (ADS)

    Frick, Achim; Rochman, Arif; Martin, Peter

    2011-05-01

    A new moulding process for manufacturing micro parts made from high viscosity polymers has been developed as a result of a feasibility study. The process basically involves compression moulding of a polymeric preform by heating it up to its semi-solid state, i.e. between its glass transition temperature and melting temperature. The apparatus is made up of three main parts: a forming device, a single cavity micro mould and an induction heating system. The processing technique was successfully tested in the manufacturing of 10 mm round discs with a flange and inner bore using high viscosity polymers such as polyphenylene sulfide (PPS), polyetheretherketone (PEEK), ultra-high molecular weight polyethylene (UHMW PE) and polytetrafluoroethylene (PTFE). In a further miniaturization study, U-shaped micro seals with an outer diameter up to 2.5 mm were also successfully manufactured from non-injection mouldable PTFE. Thus, the new process is a realistic alternative technique to the existing micro moulding processes with respect to its capability to process a huge variety of polymers, even ultra high viscosity materials and the possibility to create micro parts with non-uniform wall thickness distributions.

  1. Transporting Cells in Semi-Solid Gel Condition and at Ambient Temperature

    PubMed Central

    Wang, Junjian; Chen, Peng; Xu, Jianzhen; Zou, June.X; Wang, Haibin; Chen, Hong-Wu

    2015-01-01

    Mammalian cells including human cancer cells are usually transported in cryovials on dry ice or in a liquid nitrogen vapor shipping vessel between different places at long distance. The hazardous nature of dry ice and liquid nitrogen, and the associated high shipping cost strongly limit their routine use. In this study, we tested the viability and properties of cells after being preserved or shipped over long distance in Matrigel mixture for different days. Our results showed that cells mixed with Matrigel at suitable ratios maintained excellent viability (>90%) for one week at room temperature and preserved the properties such as morphology, drug sensitivity and metabolism well, which was comparable to cells cryopreserved in liquid nitrogen. We also sent cells in the Matrigel mixture via FedEx service to different places at ambient temperature. Upon arrival, it was found that over 90% of the cells were viable and grew well after replating. These data collectively suggested that our Matrigel-based method was highly convenient for shipping live cells for long distances in semi-solid gel condition and at ambient temperature. PMID:26098554

  2. Materials for suspension (semi-solid) electrodes for energy and water technologies.

    PubMed

    Hatzell, Kelsey B; Boota, Muhammad; Gogotsi, Yury

    2015-12-07

    Suspension or semi-solid electrodes have recently gained increased attention for large-scale applications such as grid energy storage, capacitive water deionization, and wastewater treatment. A suspension electrode is a multiphase material system comprised of an active (charge storing) material suspended in ionic solution (electrolyte). Gravimetrically, the electrolyte is the majority component and aids in physical transport of the active material. This principle enables, for the first time, scalability of electrochemical energy storage devices (supercapacitors and batteries) previously limited to small and medium scale applications. This critical review describes the ongoing material challenges encompassing suspension-based systems. The research described here combines classical aspects of electrochemistry, colloidal science, material science, fluid mechanics, and rheology to describe ion and charge percolation, adsorption of ions, and redox charge storage processes in suspension electrodes. This review summarizes the growing inventory of material systems, methods and practices used to characterize suspension electrodes, and describes universal material system properties (rheological, electrical, and electrochemical) that are pivotal in the design of high performing systems. A discussion of the primary challenges and future research directions is included.

  3. The Formulation of Bacteriophage in a Semi Solid Preparation for Control of Propionibacterium acnes Growth

    PubMed Central

    Brown, Teagan L.; Petrovski, Steve; Dyson, Zoe A.; Seviour, Robert; Tucci, Joseph

    2016-01-01

    Aims To isolate and characterise phage which could lyse P. acnes and to formulate the phage into a delivery form for potential application in topical treatment of acne infection. Methods and Results Using standard phage isolation techniques, ten phage capable of lysing P. acnes were isolated from human skin microflora. Their genomes showed high homology to previously reported P. acnes phage. These phage were formulated into cetomacrogol cream aqueous at a concentration of 2.5x108 PFU per gram, and shown to lyse underlying P. acnes cells grown as lawn cultures. These phage formulations remained active for at least 90 days when stored at four degrees Celsius in a light protected container. Conclusions P. acnes phage formulated into cetomacrogol cream aqueous will lyse surrounding and underlying P. acnes bacteria, and are effective for at least 90 days if stored appropriately. Significance and Impact of the Study There are few reports of phage formulation into semi solid preparations for application as phage therapy. The formulation method described here could potentially be applied topically to treat human acne infections. The potential exists for this model to be extended to other phage applied to treat other bacterial skin infections. PMID:26964063

  4. Urinary casts

    MedlinePlus

    ... Waxy casts; Casts in the urine; Fatty casts; Red blood cell casts; White blood cell casts ... a sign of many types of kidney diseases. Red blood cell casts mean there is a microscopic amount of ...

  5. Microstructure evolution and thixoforming behavior of 7075 aluminum alloy in the semi-solid state prepared by RAP method

    NASA Astrophysics Data System (ADS)

    Fu, Jin-long; Wang, Kai-kun; Li, Xiao-wei; Zhang, Hai-kuan

    2016-12-01

    The effects of isothermal treatments on the microstructural evolution and coarsening rate of semi-solid 7075 aluminum alloy produced via the recrystallization and partial remelting (RAP) process were investigated. Samples of 7075 aluminum alloy were subjected to cold extrusion, and semi-solid treatment was carried out for 5-30 min at temperatures ranging from 580 to 605°C. A backward-extrusion experiment was conducted to investigate liquid segregation during the thixoforming process. The results revealed that obvious grain coarsening and spheroidization occurred during prolonged isothermal treatments. In addition, higher soaking temperatures promoted the spheroidization and coarsening process because of the increased liquid fraction and the melting of second phases. Segregation of the liquid phase caused by the difference in fluidity between the liquid and the solid phases was observed in different regions of the thixoformed specimens.

  6. Semi-solid Gels Function as Physical Barriers to Human Immunodeficiency Virus Transport In Vitro

    PubMed Central

    Lai, Bonnie E.; Geonnotti, Anthony R.; DeSoto, Michael G.; Montefiori, David C.; Katz, David F.

    2010-01-01

    Vaginal gels may act as physical barriers to HIV following semen deposition. However, the extent and significance of this effect are not well understood. During male-to-female sexual transmission of HIV, semen containing infectious HIV is present within the lower female reproductive tract. In cases where a topical gel has previously been applied to the vaginal epithelium, virions must move through gel layers before reaching vulnerable tissue. This additional barrier could affect the functioning of anti-HIV microbicide gels and placebos. To better understand HIV transport in gels, we: (1) quantified diffusion coefficients of HIV virions within semi-solid delivery vehicles; and (2) tested the barrier functioning of thin gel layers in a Transwell system. Two gels used as placebos in microbicides clinical trials, hydroxyethyl cellulose (HEC) and methylcellulose (MC), were found to hinder HIV transport in vitro. The diffusion coefficients for HIV virions in undiluted HEC and MC were 4 ± 2 × 10−12 cm2/s and 7 ± 1 × 10−12 cm2/s respectively. These are almost 10,000 times lower than the diffusion coefficient for HIV in water. Substantial gel dilution (80%: diluent/gel, v/v) was required before diffusion coefficients rose to even two orders of magnitude lower than those in water. In the Transwell system, gel layers of approximately 150-μm thickness reduced HIV transport. There was a log reduction in the amount of HIV that had breached the Transwell membrane after 0-, 4-, and 8- hour incubations. The ability of a gel to function as a physical barrier to HIV transport from semen to tissue will also depend on its distribution over the epithelium and effects of dilution by vaginal fluids or semen. Results here can serve as a baseline for future design of products that act as barriers to HIV transmission. The potential barrier function of placebo gels should be considered in the design and interpretation of microbicides clinical trials. PMID:20709109

  7. Learning about the energy density of liquid and semi-solid foods.

    PubMed

    Hogenkamp, P S; Stafleu, A; Mars, M; de Graaf, C

    2012-09-01

    People learn about a food's satiating capacity by exposure and consequently adjust their energy intake. To investigate the effect of energy density and texture on subsequent energy intake adjustments during repeated consumption. In a randomized crossover design, participants (n=27, age: 21±2.4 years, body mass index: 22.2±1.6 kg m(-2)) repeatedly consumed highly novel foods that were either low-energy-dense (LE: 30 kcal per 100 g) or high-energy-dense (HE: 130 kcal per 100 g), and either liquid or semi-solid, resulting in four product conditions. In each condition, a fixed portion of test food was consumed nine times as an obligatory part of breakfast, lunch and dinner on 3 consecutive days. All meals continued with an ad libitum buffet; food items for evening consumption were provided and the intake (kcal per day) was measured. Buffet intake depended on energy density and day of consumption of the test foods (day*energy interaction: P=0.02); daily buffet intake increased from day 1 (1745±577 kcal) to day 3 (1979±567 kcal) in the LE conditions; intake did not change in the HE conditions (day 1: 1523±429 kcal, day 3: 1589±424 kcal). Food texture did not affect the intake (P=0.56). Intake did depend on energy density of the test foods; participants increased their buffet intake over days in response to learning about the satiating capacity of the LE foods, but did not change buffet intake over days when repeatedly consuming a HE food as part of their meal. The adjustments in intake were made irrespective of the food texture.

  8. Stability, clinical efficacy, and antioxidant properties of Honeybush extracts in semi-solid formulations

    PubMed Central

    Gerber, Gezina S. F. W.; Fox, Lizelle T.; Gerber, Minja; du Preez, Jan L.; van Zyl, Sterna; Boneschans, Banie; du Plessis, Jeanetta

    2015-01-01

    Background: Honeybush extracts (Cyclopia spp.) can be incorporated into skin care products to treat conditions such as skin dryness and can function as an anti-oxidant. Objective: To formulate Honeybush formulations and test it for antioxidant activity, skin penetration, and skin hydrating effects. Materials and Methods: Semi-solid formulations containing either Cyclopia maculata (2%) or Cyclopia genistoides (2%) underwent accelerated stability studies. Membrane release studies, Franz cell skin diffusion and tape stripping studies were performed. Antioxidant potential was determined with the 2-thiobarbituric acid-assay and clinical efficacy studies were performed to determine the formulations' effect on skin hydration, scaliness, and smoothness after 2 weeks of treatment on the volar forearm. Results: The formulations were unstable over 3 months. Membrane release, skin diffusion studies, and tape stripping showed that both formulations had inconclusive results due to extremely low concentrations mangiferin and hesperidin present in the Franz cell receptor compartments, stratum corneum-epidermis, and epidermis-dermis layers of the skin. Honeybush extracts showed antioxidant activity with concentrations above 0.6250 mg/ml when compared to the toxin; whereas mangiferin and hesperidin did not show any antioxidant activity on their own. The semisolid formulations showed the potential to emit their own antioxidant activity. Both formulations improved skin smoothness, although they did not improve skin hydration compared to the placebos. C. maculata reduced the skin scaliness to a larger extent than the placebos and C. genistoides. Conclusion: Honeybush formulations did not penetrate the skin but did, however, show antioxidant activity and the potential to be used to improve skin scaliness and smoothness. PMID:26664024

  9. Acoustic-resonance spectrometry as a process analytical technology for the quantification of active pharmaceutical ingredient in semi-solids.

    PubMed

    Medendorp, Joseph; Buice, Robert G; Lodder, Robert A

    2006-09-01

    The purpose of this study was to demonstrate acoustic resonance spectrometry (ARS) as an alternative process analytical technology to near infrared (NIR) spectroscopy for the quantification of active pharmaceutical ingradient (API) in semi-solids such as creams, gels, ointments, and lotions. The ARS used for this research was an inexpensive instrument constructed from readily available parts. Acoustic-resonance spectra were collected with a frequency spectrum from 0 to 22.05 KHz. NIR data were collected from 1100 to 2500 nm. Using 1-point net analyte signal (NAS) calibration, NIR for the API (colloidal oatmeal [CO]) gave anr (2) prediction accuracy of 0.971, and a standard error of performance (SEP) of 0.517%CO. ARS for the API resulted in anr (2) of 0.983 and SEP of 0.317%CO. NAS calibration is compared with principal component regression. This research demonstrates that ARS can sometimes outperform NIR spectrometry and can be an effective analytical method for the quantification of API in semi-solids. ARS requires no sample preparation, provides larger penetration depths into lotions than optical techniques, and measures API concentrations faster and more accurately. These results suggest that ARS is a useful process analytical technology (PAT).

  10. Depth position measurement of inhomogeneities in semi-solid organic materials using 3D pulsed digital holography

    NASA Astrophysics Data System (ADS)

    del Socorro Hernández-Montes, María; Mendoza Santoyo, Fernando; Pérez-López, C.

    2006-02-01

    We show experimental results to determine the depth of inhomogeneities such as glass spheres and biological human tumors, in semi-solids organic materials, like gels (phantom), using the non invasive optical technique called 3D Pulsed Digital Holography (PDH). We reported previously that this technique may be used for the detection of biological tissues1. 3D Pulsed Digital Holography allowed us to make a quantitative analysis of the changes that the phantom suffers when it contains inhomogeneities as compared to a phantom that does not have one. The results obtained there showed quite remarkably the internal fault in semi-solids. In here we report early results obtained from three different object illumination positions that gave 3 wrapped phase maps that allowed the calculation of the depth position of the inhomogeneity within the phantom. The optical technique used looks at the phantom surface micro displacement, where measurements are correlated to the z position of the inhomogeneity inside the phantom. Likewise, the technique is able to show the deformation that the material undergoes in x, y, and z.

  11. Semi-solid feeds may reduce the risk of aspiration pneumonia and shorten postoperative length of stay after percutaneous endoscopic gastrostomy (PEG).

    PubMed

    Toh Yoon, Ezekiel Wong; Yoneda, Kaori; Nishihara, Kazuki

    2016-12-01

    Background and study aims: Feeding-related adverse events after percutaneous endoscopic gastrostomy (PEG) such as aspiration pneumonia may result in prolonged hospitalization and postoperative mortality. This study evaluated the efficacy of using semi-solid feeds to reduce feeding-related adverse events and improve clinical outcomes. Patients and methods: Patients who received PEG for enteral nutrition at our hospital between January 2014 and December 2015 were allocated to a postoperative feeding protocol that used either liquid feed or semi-solid feed. Baseline characteristics, postoperative feeding-related adverse events and clinical outcomes in the 2 groups were prospectively analysed and compared. Results: One hundred and seventeen PEG patients (age range: 59 - 97 years, male: 53) were enrolled with 72 patients given liquid feed and 45 patients receiving semi-solid feed. Baseline characteristics were similar in both groups. The semi-solid feed group experienced fewer incidence of feeding-related aspiration pneumonia (2.2 % vs. 22.2 %, P < 0.005) and shorter postoperative hospital length of stay (12.7 days vs. 18.8 days, P < 0.01). Significant differences were not observed in the frequency of peristomal infection (11.1 % vs. 12.5 %, P = 0.82), feeding-related diarrhea (2.2 % vs. 12.5 %, P = 0.09) and 30-day mortality rates (2.2 % vs. 8.3 %, P = 0.25). Conclusions: Semi-solid feeding may reduce the risk of aspiration pneumonia and shorten postoperative hospital length of stay after PEG. Semi-solid feeds are safe to use and can be employed either as a first line feeding protocol or an alternative when liquid feeding is unsuccessful.

  12. Semi-solid feeds may reduce the risk of aspiration pneumonia and shorten postoperative length of stay after percutaneous endoscopic gastrostomy (PEG)

    PubMed Central

    Toh Yoon, Ezekiel Wong; Yoneda, Kaori; Nishihara, Kazuki

    2016-01-01

    Background and study aims: Feeding-related adverse events after percutaneous endoscopic gastrostomy (PEG) such as aspiration pneumonia may result in prolonged hospitalization and postoperative mortality. This study evaluated the efficacy of using semi-solid feeds to reduce feeding-related adverse events and improve clinical outcomes. Patients and methods: Patients who received PEG for enteral nutrition at our hospital between January 2014 and December 2015 were allocated to a postoperative feeding protocol that used either liquid feed or semi-solid feed. Baseline characteristics, postoperative feeding-related adverse events and clinical outcomes in the 2 groups were prospectively analysed and compared. Results: One hundred and seventeen PEG patients (age range: 59 – 97 years, male: 53) were enrolled with 72 patients given liquid feed and 45 patients receiving semi-solid feed. Baseline characteristics were similar in both groups. The semi-solid feed group experienced fewer incidence of feeding-related aspiration pneumonia (2.2 % vs. 22.2 %, P < 0.005) and shorter postoperative hospital length of stay (12.7 days vs. 18.8 days, P < 0.01). Significant differences were not observed in the frequency of peristomal infection (11.1 % vs. 12.5 %, P = 0.82), feeding-related diarrhea (2.2 % vs. 12.5 %, P = 0.09) and 30-day mortality rates (2.2 % vs. 8.3 %, P = 0.25). Conclusions: Semi-solid feeding may reduce the risk of aspiration pneumonia and shorten postoperative hospital length of stay after PEG. Semi-solid feeds are safe to use and can be employed either as a first line feeding protocol or an alternative when liquid feeding is unsuccessful. PMID:27995184

  13. Effect of Particle Size on the Mechanical Properties of Semi-Solid, Powder-Rolled AA7050 Strips

    NASA Astrophysics Data System (ADS)

    Luo, Xia; Liu, Yunzhong

    2016-12-01

    The AA7050 alloy strips can be successfully prepared by semi-solid powder rolling. The effect and factors of particle size on the microstructure, relative density, and mechanical properties were discussed. The results show that coarse starting powders require less liquid to achieve high relative density, and the formed strips have lower elongation compared with that prepared with the fine starting powders. The strength is more related to defects, whereas elongation partially depends on the grain size. Additionally, the fracture mechanism of strips prepared with fine powders is the ductile fracture because many dimples are observed. For relative density, when the initial liquid fraction is lower than 10%, the difference of deformation degree is the main factor. When the liquid fraction is higher than 10-20%, premature solidification and more particle interfaces are the two main factors.

  14. In Situ Observation of Deformation in Semi-solid Fe-C Alloys at High Shear Rate

    NASA Astrophysics Data System (ADS)

    Nagira, Tomoya; Morita, Shugo; Yokota, Hiroyoshi; Yasuda, Hideyuki; Gourlay, Christopher M.; Yoshiya, Masato; Sugiyama, Akira; Uesugi, Kentaro; Takeuchi, Akihisa; Suzuki, Yoshio

    2014-11-01

    Synchrotron X-ray radiography at 125 frames per second was used to study deformation mechanisms in semi-solid Fe-C alloys at high solid fraction and shear strain rates of 10-1/s. An image correlation approach was also used to quantify the shear strain fields and study shear-induced dilation and the origin of shear cracking. It was shown that, at high solid fraction (90 to 93 pct solid), rearrangement including rotation and translation of solid particles became restricted and shear strain localized into narrow liquid-filled channels/fissures. Shear cracking was shown to originate from inadequate liquid flow into the expanding spaces between solid particles caused by shear-induced dilation. At lower solid fraction (~85 pct solid), solid particles rearranged with a significantly higher component of rotation leading to more shear-induced dilation and a wider shear band.

  15. The development of a nanostructured, graded multilayer Cr-CrxNy-Cr1-xAlxN coating produced by pulsed closed field unbalanced magnetron sputtering (P-CFUBMS) for use in aluminum pressure die casting dies.

    PubMed

    Lin, Jianliang; Mishra, Brajendra; Myers, Sterling; Ried, Peter; Moore, John J

    2009-06-01

    The main objective of this research is to design an optimized 'coating system' that extends die life by minimizing premature die failure. The concept of the multilayer coating system with desired combinations of different kinds of single-layer coatings was introduced. A pulsed closed field unbalanced magnetron sputtering (P-CFUBMS) deposition system has been used to deposit Cr-CrxNy-Cr1-xAlxN compositionally graded multilayer coating structures. In this study, three power law scenarios have been adopted to vary the aluminum concentration in the graded Cr1-xAlxN layer: (i) p = 1, the aluminum concentration was increased linearly in the Cr1-xAlxN layer. (ii) p = 0.2, the Cr1-xAlxN layer is an aluminum-rich graded layer, and (iii) p = 2, the Cr1-xAlxN layer is a chromium-rich graded layer. It was found that all the graded coatings exhibit lower residual stress and higher adhesion strength than the homogeneous Cr1-xAlxN (x = 0.585) film. However, different power law grading architectures have significant influence on the hardness and wear resistance of the films. When p = 2 and p = 1, the graded films exhibited relatively low hardness values (24 and 26 GPa respectively) and high COF (0.55 to 0.60). When p = 0.2 the graded film exhibited both high hardness (34 GPa) and good wear resistance (COF = 0.45) due to the structural consistency in the graded zone. The paper discusses the correlation between the pulsing parameters and coating architecture with the resulting nanostructure and tribological properties of this Cr-CrxNy-Cr1-xAlxN coating system.

  16. Effect of hydration status and fluid availability on ad-libitum energy intake of a semi-solid breakfast.

    PubMed

    Corney, Robert A; Horina, Anja; Sunderland, Caroline; James, Lewis J

    2015-08-01

    This study investigated the effects of hydration status and fluid availability on appetite and energy intake. Sixteen males completed four 24 h trials, visiting the laboratory overnight fasted on two consecutive days. Standardised foods were provided during the 24 h and on day two an ad-libitum semi-solid porridge breakfast was provided. Water intake during the 24 h (0 or 40 mL⋅kg(-1)) and fluid provision during the ad-libitum breakfast were manipulated so subjects were euhydrated with (EU-F) and without fluid (EU-NF) available at breakfast; and hypohydrated with (HYPO-F) and without fluid (HYPO-NF) available at breakfast. Blood samples (0 and 24 h), urine samples (0-24 h) and subjective responses (0, 24 and 24.5 h) were collected. HYPO trials decreased body mass by ~1.8%. Serum and urine osmolality increased and plasma volume decreased during HYPO trials (P <0.001). Total urine output was greater during EU than HYPO trials (P <0.001). Ad-libitum energy intake was not different between trials: 2658 (938) kJ (EU-F), 2353 (643) kJ (EU-NF), 2295 (529) kJ (HYPO-F), 2414 (954) kJ (HYPO-NF), (P = 0.131). Fluid intake was ~200 mL greater during HYPO-F than EU-F (P <0.01). There was an interaction effect for thirst (P < 0.001), but not hunger or fullness. These results demonstrate that mild hypohydration produced by inadequate fluid intake and fluid availability during eating does not influence ad-libitum energy intake of a semi-solid breakfast, at least in healthy young males. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Study on the rheoformability of semi-solid 7075 wrought aluminum alloy using seed process =

    NASA Astrophysics Data System (ADS)

    Zhao, Qinfu

    Semisolid metal forming is becoming more and more attractive in the foundry industry due to its low cost and easy operation to produce high quality near-net-shape components. Over the past years, semisolid forming technique is mainly applied on the casting aluminum alloys due to their superior castability because of low melting temperature and viscosity. In semisolid forming field, thixoforming has been majorly used which involves of reheating the billet into semisolid state followed by casting process. Rheocasting is a more economic semisolid processing compared to thixoforming, which the semisolid billet is produced directly from liquid phase. The SEED process is one of reliable rheocasting techniques to produce high quality semisolid billets. To produce high quality semisolid billets, their unique rheological properties have been the most important issue need to be fully investigated. The aim of present project is to produce high quality semisolid AA7075 billets by SEED process and analyze their rheological properties under various process conditions. The effect of the SEED processing parameters and grain refiners on the semisolid microstructure and rheoformability were investigated. The deformation and rheological behavior of the semisolid billets of AA7075 base and its grain-refined alloys were studied using parallel-plate viscometer. In the first part, the evolution of liquid fraction to temperature of semisolid AA7075 alloy was investigated using Differential Scanning Calorimetry (DSC). It was found that the liquidus and solidus temperature of AA7075 alloy were 631 °C and 490°C respectively. And the corresponding temperatures of solid fraction of 40% and 60% were 622°C and 610°C, which was recognized as the temperature window for semisolid forming of this alloy. In the second part, the semisolid slurries were rheocasted using SEED technology and the effect of the SEED process parameters like swirling frequency and demolding temperature on evolution of

  18. Rheological behavior and microstructural evolution of semi-solid hypereutectic aluminum-silicon-magnesium-copper alloys using rheoforming process

    NASA Astrophysics Data System (ADS)

    Tebib, Mehand

    The aim of the current study was to investigate the rheological behavior and microstructural evolution of hypereutectic Al-Si-Cu and Al-Si-Mg-Cu alloys using conventional and modified SEED process (Swirled Enthalpy Equilibration Device). In the first part; the feasibility of semi-solid processing of hypereutectic Al-Si-Cu A390 alloys using a novel rheoforming process was investigated. A combination of the SEED process, isothermal holding using insulation and addition of solid alloy during swirling was introduced as a novel method to improve the processability of semi-solid A390 slurries. The effects of isothermal holding and the addition of solid alloy on the temperature gradient between the centre and the wall and on the formation of alpha-Al particles were examined. In addition, phosphorus and strontium were added to the molten metal to refine the primary and eutectic silicon structure to facilitate semi-solid processing. It was found that the combination of the SEED process with two additional processing steps can produce semisolid 390 alloys that can be rheoformed. In the second part, the effects of Mg additions ranging from 6 to 15% on the solidification behaviour of hypereutectic Al-155i-xMg-4Cu alloys was investigated using thermodynamic calculations, thermal analysis and extensive microstructural examination. The Mg level strongly influenced the microstructural evolution of the primary Mg2Si phase as well as the solidification behaviour. Thermodynamic predictions using ThermoCalc software reported the occurrence of six reactions, comprising the formation of primary Mg2 Si, two pre-eutectic binary reactions, forming either Mg2Si + Si or Mg2Si + alpha-Al phases, the main ternary eutectic reaction forming Mg2Si + Si + alpha-Al, and two post-eutectic reactions resulting in the precipitation of the Q-Al5Mg8Cu 2Si6 and theta-Al2Cu phases, respectively. Microstructures of the four alloys studied confirmed the presence of these phases, in addition to that of the pi

  19. 75 FR 20387 - Contech Castings, LLC, Including Workers Whose Unemployment Insurance (UI) Wages Are Reported...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-19

    ... workers are engaged in activities related to the production of aluminum and magnesium die casted component... who were adversely affected by increased imports of aluminum and magnesium die casted component parts...

  20. Modeling and control of casting and welding processes

    SciTech Connect

    Kou, S.; Mehrabian, R.

    1986-01-01

    This book contains papers divided among the following sections: process monitor and control in welding; plasma processing and refining; strip casting; modelling of welding processes; CAD/CAM in casting; investment and die casting; ingot, continuous and other shape casting; and rapid solidification and microstructural evolution.

  1. 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.

  2. Production of Trametes pubescens laccase under submerged and semi-solid culture conditions on agro-industrial wastes.

    PubMed

    Gonzalez, Juan C; Medina, Sandra C; Rodriguez, Alexander; Osma, Johann F; Alméciga-Díaz, Carlos J; Sánchez, Oscar F

    2013-01-01

    Laccases are copper-containing enzymes involved in the degradation of lignocellulosic materials and used in the treatment of phenol-containing wastewater. In this study we investigated the effect of culture conditions, i.e. submerged or semi-solid, and copper supplementation on laccase production by Trametespubescens grown on coffee husk, soybean pod husk, or cedar sawdust. The highest specific laccase activity was achieved when the culture was conducted under submerged conditions supplemented with copper (5 mM), and using coffee husk as substrate. The crude extracts presented two laccase isoforms with molecular mass of 120 (Lac1) and 60 kDa (Lac2). Regardless of the substrate, enzymatic crude extract and purified fractions behaved similarly at different temperatures and pHs, most of them presented the maximum activity at 55 °C and a pH range between 2 and 3. In addition, they showed similar stability and electro-chemical properties. At optimal culture conditions laccase activity was 7.69 ± 0.28 U mg(-1) of protein for the crude extract, and 0.08 ± 0.001 and 2.86 ± 0.05 U mg(-1) of protein for Lac1 and Lac2, respectively. In summary, these results show the potential of coffee husk as an important and economical growth medium to produce laccase, offering a new alternative use for this common agro-industrial byproduct.

  3. Physicochemical characterization and in vitro release studies of ascorbyl palmitate-loaded semi-solid nanostructured lipid carriers (NLC gels).

    PubMed

    Teeranachaideekul, Veerawat; Souto, Eliana B; Müller, Rainer H; Junyaprasert, Varaporn B

    2008-03-01

    The aim of this study was to characterize the physicochemical properties and to study in vitro release of ascorbyl palmitate from semi-solid lipid nanoparticles based on nanostructured lipid carriers (NLC gels) systems with the desired viscosity for dermal delivery. NLC gels were obtained by a one-step production procedure employing a high pressure homogenization technique using different solid lipid matrices. Ascorbyl palmitate (AP) was selected as a lipophilic active ingredient due to its range of cosmetic applications. After the production, particles within the size range 170-250 nm having polydispersity index lower than 0.3 were obtained from all formulations. After the AP incorporation into the NLC gels, the zeta potential increased to values higher than |30 mV|. Almost 100% encapsulation efficiency was observed. The obtained SEM and AFM data revealed non-spherical shaped nanoparticles. From DSC and X-ray diffraction studies, it was shown that the lipid recrystallized in the solid state possessing a less ordered structure as compared to the bulk material. The release study of active-loaded NLC gel formulations using Franz diffusion cells revealed that the type of lipid matrix affects both the rate and the release pattern. The viscoelastic measurements revealed a more elastic than viscous behaviour of NLC formulations indicating a typical gel-like structure.

  4. Production of Trametes pubescens Laccase under Submerged and Semi-Solid Culture Conditions on Agro-Industrial Wastes

    PubMed Central

    Rodriguez, Alexander; Osma, Johann F.; Alméciga-Díaz, Carlos J.; Sánchez, Oscar F.

    2013-01-01

    Laccases are copper-containing enzymes involved in the degradation of lignocellulosic materials and used in the treatment of phenol-containing wastewater. In this study we investigated the effect of culture conditions, i.e. submerged or semi-solid, and copper supplementation on laccase production by Trametespubescens grown on coffee husk, soybean pod husk, or cedar sawdust. The highest specific laccase activity was achieved when the culture was conducted under submerged conditions supplemented with copper (5 mM), and using coffee husk as substrate. The crude extracts presented two laccase isoforms with molecular mass of 120 (Lac1) and 60 kDa (Lac2). Regardless of the substrate, enzymatic crude extract and purified fractions behaved similarly at different temperatures and pHs, most of them presented the maximum activity at 55 °C and a pH range between 2 and 3. In addition, they showed similar stability and electro-chemical properties. At optimal culture conditions laccase activity was 7.69±0.28 U mg-1 of protein for the crude extract, and 0.08±0.001 and 2.86±0.05 U mg-1 of protein for Lac1 and Lac2, respectively. In summary, these results show the potential of coffee husk as an important and economical growth medium to produce laccase, offering a new alternative use for this common agro-industrial byproduct. PMID:24019936

  5. Exploratory study on H13 steel dies

    SciTech Connect

    Sunwoo, A.J.

    1994-04-01

    Ultrahigh-strength H13 steel is a recommended die material for aluminum die casting; dies made from H13 steel can be safely water- cooled during hot working operations without cracking. However, after time the dies exhibited surface cracking and excessive wear. Erosive wear also occurs owing to high pressure injection of molten Al. An exploratory study was made of the causes for surface cracking of H13 dies. Results suggest that surface cracking is caused by interrelated factors, internal to the die material as well as externally induced conditions.

  6. Indication of metal homeostasis disturbance in earthworm Eisenia fetida after exposure to semi-solid depot sludge.

    PubMed

    Babić, Sanja; Dragun, Zrinka; Sauerborn Klobučar, Roberta; Ivanković, Dušica; Bačić, Niko; Fiket, Željka; Barišić, Josip; Krasnići, Nesrete; Strunjak-Perović, Ivančica; Topić Popović, Natalija; Čož-Rakovac, Rozelindra

    2015-09-01

    Treated sewage sludge is commonly used in agriculture as fertilizer. It is, therefore, necessary to determine possible detrimental influences of sludge application on soil contamination and accumulation of contaminants in tissues of terrestrial animals, which in the long run could also have undesirable effects on humans. With that aim, the study was performed using earthworm Eisenia fetida as test organism and semi-solid depot sludge from a wastewater treatment plant as exposure media. The concentrations of 26 metals/metalloids were determined in depot sludge, and their bioaccumulation was estimated in whole tissue of E. fetida, and for the first time in the soluble tissue fraction, which represents metal fraction available for metabolic requirements and toxic effects. Obtained results have revealed acceptable levels of several elements (Cd, Cr, Cu, Ni, Pb, Zn) in depot sludge, when compared to currently valid regulations, and only moderate accumulation of some elements (e.g. As, Ba, Cd, Co, Fe, Tl, V, and Zn) in earthworms, as a consequence of exposure to depot sludge. However, a concentration increase after exposure to depot sludge was observed in E. fetida for several elements (Cd, Mo, and Zn), which were present in lower concentrations in the exposure mixtures than in soil. Contrary, a concentration decrease was observed for Cs, Mn, and Rb, although they were present in higher concentrations in depot sludge than in soil. It was an indication of disturbance in metal homeostasis in earthworms, possibly caused by exposure to complex mixture of contaminants present in depot sludge. The cumulative effect of exposure to a number of various contaminants (inorganic, organic, microbiological and pharmaceutical), even if each of them was not present in very high concentrations, could have caused distress in earthworms exposed to depot sludge. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Qualitative Reasoning for Additional Die Casting Applications

    SciTech Connect

    R. Allen Miller; Dehua Cui; Yuming Ma

    2003-05-28

    If manufacturing incompatibility of a product can be evaluated at the early product design stage, the designers can modify their design to reduce the effect of potential manufacturing problems. This will result in fewer manufacturing problems, less redsign, less expensive tooling, lower cost, better quality, and shorter development time. For a given design, geometric reasoning can predict qualitatively the behaviors of a physical manufacturing process by representing and reasoning with incomplete knowledge of the physical phenomena. It integrates a design with manufacturing processes to help designers simultaneously consider design goals and manufacturing constraints during the early design stage. The geometric reasoning approach can encourage design engineers to qualitatively evaluate the compatibility of their design with manufacturing limitations and requirements.

  8. Computer prediction of hot tears in castings

    SciTech Connect

    Cheng, S.; Sundarraj, S.; Jo, J.; Chandra, U.

    1996-12-31

    Hot tears occur frequently in parts made by a process involving solidification such as casting, welding or semi-solid metalworking. This paper presents an attempt to predict hot tears in castings utilizing Pellini`s strain theory and the finite element method. The proposed methodology involves two key steps: (1) the prediction of the thickness of liquid film surrounding the solid grains, and (2) the calculation of the accumulated strain in the liquid film; both of these quantities are computed as the solidification progresses. Then, by comparing the computed strain at each time step with the critical fracture or hot tear strain, the possibility of hot tears may be predicted. The critical fracture strain is a function of solid fraction and is predetermined experimentally. The thickness of the liquid film is predicted with the help of a microscopic solidification model. Also, a new constitutive model is proposed to compute the strain in liquid film. The two models are implemented in a commercial general purpose transient nonlinear thermo-mechanical finite element analysis software. The proposed methodology is applied to a two-dimensional casting made of a short freezing range alloy since an experimentally obtained set of necessary material constants is available for such an alloy. The extension of the proposed methodology to three-dimensional castings does not require any additional development.

  9. Optimization of Composition and Heat Treating of Die Steels for Extended Lifetime

    SciTech Connect

    David Schwam; John F. Wallace; Quanyou Zhou

    2002-01-30

    An ''average'' die casting die costs fifty thousand dollars. A die used in making die cast aluminum engine blocks can cost well over one million dollars. These costs provide a strong incentive for extension of die life. While vacuum quenched Premium Grade H13 dies have become the most widely used in the United States, tool makers and die casters are constantly searching for new steels and heat treating procedures to extend die life. This project was undertaken to investigate the effects of composition and heat treating on die life and optimize these parameters.

  10. SPHERICAL DIE

    DOEpatents

    Livingston, J.P.

    1959-01-27

    A die is presented for pressing powdered materials into a hemispherical shape of uniforin density and wall thickness comprising a fcmale and male die element held in a stationary spaced relation with the space being equivalent to the wall thickness and defining the hemispherical shape, a pressing ring linearly moveable along the male die element, an inlet to fill the space with powdered materials, a guiding system for moving the pressing ring along the male die element so as to press the powdered material and a heating system for heating the male element so that the powdered material is heated while being pressed.

  11. Solidification science in cast MMCs: The influence of merton flemings

    NASA Astrophysics Data System (ADS)

    Rohatgi, Pradeep; Asthana, Rajiv

    2001-09-01

    The solidification science of cast metalmatrix composites (MMC) evolved as a subset of the broad field of solidification of monolithic alloys pioneered by Merton Flemings and his students. As a result of advances in solidification, the cast MMC field has evolved from its early incarnation—employing empirical research to engineer novel materials using versatile and cost-effective casting techniques—to using solidification-science-based approaches to tailor advanced materials for application-specific needs. The current and emerging applications of cast MMCs in a variety of automotive, aerospace, electronic packaging, and consumer-good industries exemplify the maturity of the field and the materials. Innovations in composite-forming techniques and efforts at wider industrial acceptance of MMCs will undoubtedly continue. However, the scientific principles underlying the solidification microstructure evolution that governs the composite properties have become well established, to a great extent, due to Flemings’ early, pioneering work on monolithic alloys and some of his more recent studies on solidification of reinforced metals. This paper reviews some aspects of solidification of discontinuously reinforced cast metals that owe their current understanding to Flemings’ contributions, in particular, the scientific understanding of macro- and microsegregation, fluidity and rheology of multiphase slurries, and stircasting, semi-solid casting, and preform infiltration. Current research to develop and test prototype components made from cast composites, including Al-flyash, Cu-graphite, Al-graphite, Al-alumina, and SiC-Al, is also presented, along with directions for future research.

  12. Factors Associated with Early Introduction of Formula and/or Solid, Semi-Solid or Soft Foods in Seven Francophone West African Countries

    PubMed Central

    Issaka, Abukari I.; Agho, Kingsley E.; Page, Andrew N.; Burns, Penelope L.; Stevens, Garry J.; Dibley, Michael J.

    2015-01-01

    The aim of this study was to identify factors associated with early introduction of formula and/or solid, semi-solid or soft foods to infants aged three to five months in seven Francophone West African countries. The sources of data for the analyses were the most recent Demographic and Health Survey datasets of the seven countries, namely Benin (BDHS, 2012), Burkina Faso (BFDHS, 2010), Cote d’Ivoire (CIDHS, 2011–2012), Guinea (GDHS, 2012), Mali (MDHS, 2012–2013), Niger (NDHS, 2012) and Senegal (SDHS, 2010). The study used multiple logistic regression methods to analyse the factors associated with early introduction of complementary feeding using individual-, household- and community-level determinants. The sample was composed of 4158 infants aged between three and five months with: 671 from Benin, 811 from Burkina Faso, 362 from Cote d’Ivoire, 398 from Guinea, 519 from Mali, 767 from Niger and 630 from Senegal. Multiple analyses indicated that in three of the seven countries (Benin, Guinea and Senegal), infants who suffered illnesses, such as diarrhoea and acute respiratory infection, were significantly more likely to be introduced to formula and/or solid, semi-solid or soft foods between the age of three and five months. Other significant factors included infants who: were born in second to fourth position (Benin), whose mothers did not attend any antenatal clinics (Burkina Faso and Niger), were male (Cote d’Ivoire and Senegal), lived in an urban areas (Senegal), or were delivered by traditional birth attendants (Guinea, Niger and Senegal). Programmes to discourage early introduction of formula and/or solid, semi-solid or soft foods in these countries should target the most vulnerable segments of the population in order to improve exclusive breastfeeding practices and reduce infant mortality. PMID:25647663

  13. Squeeze Casting of Steel Weapon Components

    DTIC Science & Technology

    1976-09-01

    nd 45 percent alloy steel is ver- d flat-walled pport. Auxiliary eeze casting the ssure, effectively last-to-freeze chine weight com...Castings 132 49 Local Deformatnion of the 1045 Steel Punch. . 133 50 End Facing of the Inconel 713C Punch Showing Heat Checking 135 51 Higher...December 1971, 14 ff. (10) R. Mehrabian and M. C, Flemings, "Die Casting of Parti- ally Solidified Alloys ," Trans-AFS, Vol. 80, 1972, pp. 173-183; Die

  14. Bacterial plasmid conjugation on semi-solid surfaces monitored with the green fluorescent protein (GFP) from Aequorea victoria as a marker.

    PubMed

    Christensen, B B; Sternberg, C; Molin, S

    1996-01-01

    Horizontal transfer of the TOL plasmid was examined in Pseudomonas putida (Pp) KT2442 micro-colonies on semi-solid agar surfaces. Horizontal gene transfer is usually studied in large populations where all information is based on average estimates of the transfer events in the entire population. We have used the green fluorescent protein (GFP) from the jellyfish Aequorea victoria as a plasmid marker, in combination with single-cell observations. This provided hitherto unknown details on the distribution of cells active in conjugation. In the present study, donor cells containing the gfp gene expressed from the bacteriophage T7 phi 10 promoter on the TOL plasmid, and recipient cells expressing the corresponding phage RNA polymerase allowed us to monitor the occurrence of ex-conjugants as green fluorescent cells upon illumination with blue light (470-490 nm). Further, the recipients were labeled with the luxAB genes to distinguish micro-colonies of donor cells from recipient cells. We conclude that conjugal plasmid transfer in Pp KT2442 cells on semi-solid surfaces occurs mainly during a short period of time after the initial contact of donors and recipients, indicating that spread of the TOL plasmid is limited in static, but viable cultures.

  15. Flow simulation and solidification phenomena of AC4CH aluminum alloy in semi-solid forging process by explicit MPS method

    NASA Astrophysics Data System (ADS)

    Regmi, Amit; Shintaku, Hiroki; Sasaki, Tsutomu; Koshizuka, Seiichi

    2015-09-01

    Semi-solid forging (SSF) is a powerful manufacturing technology to fabricate near-net shaped products in automotive industries. During SSF process, the filling behavior and solidification process of AC4CH aluminum alloy is presented in this paper. The explicit MPS method program solving Navier-Stokes equation is coupled with heat transfer and solidification has been used to predict the filling pattern and temperature distribution of semi-solid material (SSM). The non-Newtonian rheological model was used as the constitutive equation of SSM. In this study, numerical analysis of SSF was carried out in box cavity with various flange thickness (4, 8, 12 and 16 mm) and corresponding experiments were undertaken for AC4CH aluminum alloy with solid fraction less than 0.5. The numerical results of SSM filling pattern and solidification phenomena in flange were validated with the experimental results. During solidification process, flow calculation was stopped and only thermal calculation was carried out. The shrinkage defect was well predicted near the lower mid area of the box cavity with flange thickness 16 mm.

  16. Quantitative assessment of amide proton transfer (APT) and nuclear overhauser enhancement (NOE) imaging with extrapolated semi-solid magnetization transfer reference (EMR) signals: Application to a rat glioma model at 4.7 Tesla.

    PubMed

    Heo, Hye-Young; Zhang, Yi; Lee, Dong-Hoon; Hong, Xiaohua; Zhou, Jinyuan

    2016-01-01

    To quantify amide proton transfer (APT) and nuclear Overhauser enhancement (NOE) contributions to in vivo chemical exchange saturation transfer MRI signals in tumors. Two-pool (free water and semi-solid protons) and four-pool (free water, semi-solid, amide, and upfield NOE-related protons) tissue models combined with the super-Lorentzian lineshape for semi-solid protons were used to fit wide and narrow frequency-offset magnetization-transfer (MT) data, respectively. Extrapolated semi-solid MT signals at 3.5 and -3.5 ppm from water were used as reference signals to quantify APT and NOE, respectively. Six glioma-bearing rats were scanned at 4.7 Tesla. Quantitative APT and NOE signals were compared at three saturation power levels. The observed APT signals were significantly higher in the tumor (center and rim) than in the contralateral normal brain tissue at all saturation powers, and were the major contributor to the APT-weighted image contrast (based on MT asymmetry analysis) between the tumor and the normal brain tissue. The NOE (a positive confounding factor) enhanced this APT-weighted image contrast. The fitted amide pool sizes were significantly larger, while the NOE-related pool sizes were significantly smaller in the tumor than in the normal brain tissue. The extrapolated semi-solid magnetization transfer reference provides a relatively accurate approach for quantitatively measuring pure APT and NOE signals. © 2015 Wiley Periodicals, Inc.

  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. Influence of unmodified and β-glycerophosphate cross-linked chitosan on anti-Candida activity of clotrimazole in semi-solid delivery systems.

    PubMed

    Szymańska, Emilia; Winnicka, Katarzyna; Wieczorek, Piotr; Sacha, Paweł Tomasz; Tryniszewska, Elżbieta Anna

    2014-09-30

    The combination of an antifungal agent and drug carrier with adjunctive antimicrobial properties represents novel strategy of complex therapy in pharmaceutical technology. The goal of this study was to investigate the unmodified and ion cross-linked chitosan's influence on anti-Candida activity of clotrimazole used as a model drug in hydrogels. It was particularly crucial to explore whether the chitosans' structure modification by β-glycerophosphate altered its antifungal properties. Antifungal studies (performed by plate diffusion method according to CLSI reference protocol) revealed that hydrogels obtained with chitosan/β-glycerophosphate displayed lower anti-Candida effect, probably as a result of weakened polycationic properties of chitosan in the presence of ion cross-linker. Designed chitosan hydrogels with clotrimazole were found to be more efficient against tested Candida strains and showed more favorable drug release profile compared to commercially available product. These observations indicate that novel chitosan formulations may be considered as promising semi-solid delivery system of clotrimazole.

  19. Evaluation of master cast techniques for multiple abutment implant prostheses.

    PubMed

    Vigolo, P; Millstein, P L

    1993-01-01

    This study compared the accuracy of three techniques used to fabricate master casts for implant prostheses. A metal model with six implants and standard abutments and a matching template were fabricated. Impressions of the model were made in Impregum and cast in Die Keen. The casts were divided into three groups of 15 casts: group A--solid casts; group B--Pindex; and group C--Zeiser system. Each cast was visually evaluated for fit of the template. Positional accuracy of the abutments was numerically assessed using an optical comparator. Visual analysis showed that only casts sectioned with the Zeiser system allowed a passive fit of the template. Statistical analysis of numerical findings indicated that casts made with the Zeiser system were significantly more accurate than solid casts, which in turn were more accurate than those made with the Pindex system.

  20. Mechanical properties and constitutive behaviors of as-cast 7050 aluminum alloy from room temperature to above the solidus temperature

    NASA Astrophysics Data System (ADS)

    Bai, Qing-ling; Li, Hong-xiang; Du, Qiang; Zhang, Ji-shan; Zhuang, Lin-zhong

    2016-08-01

    The mechanical properties and constitutive behaviors of as-cast AA7050 in both the solid and semi-solid states were determined using the on-cooling and in situ solidification approaches, respectively. The results show that the strength in the solid state tends to increase with decreasing temperature. The strain rate plays an important role in the stress-strain behaviors at higher temperatures, whereas the influence becomes less pronounced and irregular when the temperature is less than 250°C. The experimental data were fitted to the extended Ludwik equation, which is suitable to describe the mechanical behavior of the materials in the as-cast state. In the semi-solid state, both the strength and ductility of the alloy are high near the solidus temperature and decrease drastically with decreasing solid fraction. As the solid fraction is less than 0.97, the maximum strength only slightly decreases, whereas the post-peak ductility begins to increase. The experimental data were fitted to the modified creep law, which is used to describe the mechanical behavior of semi-solid materials, to determine the equivalent parameter f GBWL, i.e., the fraction of grain boundaries covered by liquid phase.

  1. Method and Apparatus for Die Forming Metal Sheets and Extrusions.

    DTIC Science & Technology

    of a variety of die blocks for introducing a variety of angled joggles in the metal sheets and extrusions. Relatively low melting temperature material is used for the castings. Keywords: Patents; Aircraft parts. (kt)

  2. Cool Cast Facts

    MedlinePlus

    ... moving. The outer layer is usually made of plaster or fiberglass. Fiberglass casts are made of fiberglass, ... color! These casts are lighter and stronger than plaster casts. Plaster casts are usually white and made ...

  3. Titanium Aluminide Casting Technology Development

    NASA Astrophysics Data System (ADS)

    Bünck, Matthias; Stoyanov, Todor; Schievenbusch, Jan; Michels, Heiner; Gußfeld, Alexander

    2017-08-01

    Titanium aluminide alloys have been successfully introduced into civil aircraft engine technology in recent years, and a significant order volume increase is expected in the near future. Due to its beneficial buy-to-fly ratio, investment casting bears the highest potential for cost reduction of all competing production technologies for TiAl-LPTB. However, highest mechanical properties can be achieved by TiAl forging. In view of this, Access e.V. has developed technologies for the production of TiAl investment cast parts and TiAl die cast billets for forging purposes. While these parts meet the highest requirements, establishing series production and further optimizing resource and economic efficiency are present challenges. In order to meet these goals, Access has recently been certified according to aircraft standards, aiming at qualifying parts for production on technology readiness level 6. The present work gives an overview of the phases of development and certification.

  4. A comparative study of the centrifugal and vacuum-pressure techniques of casting removable partial denture frameworks.

    PubMed

    Shanley, J J; Ancowitz, S J; Fenster, R K; Pelleu, G B

    1981-01-01

    A study was undertaken to evaluate two techniques for casting accuracy on removable partial denture frameworks: centrifugal casting and vacuum-pressure casting. A standard metal die with predetermined reference points in a horizontal plane was duplicated in refractory investment. The casts were waxed, and castings of nickel-chrome alloy were fabricated by the two techniques. Both the casts and the castings were measured between the reference points with a measuring microscope. With both casting methods, the differences between the casts and the castings were significant, but no significant differences were found between castings produced by the two techniques. Vertical measurements at three designated points also showed no significant differences between the castings. Our findings indicate that dental laboratories should be able to use the vacuum-pressure method of casting removable partial denture frameworks and achieve accuracy similar to that obtained by the centrifugal method of casting.

  5. CASTING FURNACES

    DOEpatents

    Ruppel, R.H.; Winters, C.E.

    1961-01-01

    A device is described for casting uranium which comprises a crucible, a rotatable table holding a plurality of molds, and a shell around both the crucible and the table. The bottom of the crucible has an eccentrically arranged pouring hole aligned with one of the molds at a time. The shell can be connected with a vacuum.

  6. 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…

  7. Paper Casting.

    ERIC Educational Resources Information Center

    Arrasjid, Dorine A.

    1980-01-01

    Describes an art project, based on the work of artist Chew Teng Beng, in the molding of wet paper on a plaster cast to create embossed paper designs. The values of such a project are outlined, including a note that its tactile approach makes it suitable to visually handicapped students. (SJL)

  8. Paper Casting.

    ERIC Educational Resources Information Center

    Arrasjid, Dorine A.

    1980-01-01

    Describes an art project, based on the work of artist Chew Teng Beng, in the molding of wet paper on a plaster cast to create embossed paper designs. The values of such a project are outlined, including a note that its tactile approach makes it suitable to visually handicapped students. (SJL)

  9. A new insight into high-strength Ti62Nb12.2Fe13.6Co6.4Al5.8 alloys with bimodal microstructure fabricated by semi-solid sintering

    PubMed Central

    Liu, L. H.; Yang, C.; Kang, L. M.; Qu, S. G.; Li, X. Q.; Zhang, W. W.; Chen, W. P.; Li, Y. Y.; Li, P. J.; Zhang, L. C.

    2016-01-01

    It is well known that semi-solid forming could only obtain coarse-grained microstructure in a few alloy systems with a low melting point, such as aluminum and magnesium alloys. This work presents that semi-solid forming could also produce novel bimodal microstructure composed of nanostructured matrix and micro-sized (CoFe)Ti2 twins in a titanium alloy, Ti62Nb12.2Fe13.6Co6.4Al5.8. The semi-solid sintering induced by eutectic transformation to form a bimodal microstructure in Ti62Nb12.2Fe13.6Co6.4Al5.8 alloy is a fundamentally different approach from other known methods. The fabricated alloy exhibits high yield strength of 1790 MPa and plastic strain of 15.5%. The novel idea provides a new insight into obtaining nano-grain or bimodal microstructure in alloy systems with high melting point by semi-solid forming and into fabricating high-performance metallic alloys in structural applications. PMID:27029858

  10. A new insight into high-strength Ti62Nb12.2Fe13.6Co6.4Al5.8 alloys with bimodal microstructure fabricated by semi-solid sintering

    NASA Astrophysics Data System (ADS)

    Liu, L. H.; Yang, C.; Kang, L. M.; Qu, S. G.; Li, X. Q.; Zhang, W. W.; Chen, W. P.; Li, Y. Y.; Li, P. J.; Zhang, L. C.

    2016-03-01

    It is well known that semi-solid forming could only obtain coarse-grained microstructure in a few alloy systems with a low melting point, such as aluminum and magnesium alloys. This work presents that semi-solid forming could also produce novel bimodal microstructure composed of nanostructured matrix and micro-sized (CoFe)Ti2 twins in a titanium alloy, Ti62Nb12.2Fe13.6Co6.4Al5.8. The semi-solid sintering induced by eutectic transformation to form a bimodal microstructure in Ti62Nb12.2Fe13.6Co6.4Al5.8 alloy is a fundamentally different approach from other known methods. The fabricated alloy exhibits high yield strength of 1790 MPa and plastic strain of 15.5%. The novel idea provides a new insight into obtaining nano-grain or bimodal microstructure in alloy systems with high melting point by semi-solid forming and into fabricating high-performance metallic alloys in structural applications.

  11. A comparison of the accuracy of three removable die systems and two die materials.

    PubMed

    Sivakumar, I; Mohan, J; Arunachalam, K S; Zankari, V

    2013-09-01

    The purpose of this study was to evaluate the dimensional shift of three commonly used die systems (Conventional system, Pindex system, Di-Lok tray system) with two commercially available type IV die stones (Ultra rock and Pearl stone). Under controlled conditions, ten casts, each with two removable dies, were constructed for each system for a total of 30 casts and 60 removable dies. Before and after sectioning measurements to within 0.01 mm in horizontal and vertical planes were recorded and differences calculated. Data were analyzed with 't' tests, one way analysis of variance and post hoc Tukey test. The results demonstrated that among the die systems compared, no single system was superior to the others in all respects. But among the die materials, dies poured in Pearl stone exhibited more dimensional changes than Ultra rock (p<0.05). Selection of die material is as critical as selection of any particular die system for successful fabrication of fixed partial denture and implant prosthesis.

  12. Energy and Technolgy Assessment of Zinc and Magnesium Casting Plants, Technical Report Close-out, August 25,2006

    SciTech Connect

    Twin City Die Castings Company; Tom Heider; North American Die Castings Association

    2006-08-25

    Twin City Die Castings Company of Minneapolis, Minnesota, Twin City Die Castings Company was awarded project No. DE-FG36-05GO15097 to perform plant wide assessments of ten (10) die casting facilities that produce zinc and magnesium alloy castings in order to determine improvements and potential cost savings in energy use. Mr. Heider filled the role of team leader for the project and utilized the North American Die Casting Association (NADCA) to conduct audits at team participant plants so as to hold findings specific to each plant proprietary. The intended benefits of the project were to improve energy use through higher operational and process efficiency for the plants assessed. An improvement in energy efficiency of 5 – 15% was targeted. The primary objectives of the project was to: 1) Expand an energy and technology tool developed by the NADCA under a previous DOE project titled, “Energy and Technology Assessment for Die Casting Plants” for assessing aluminum die casting plants to be more specifically applicable to zinc and magnesium die casting facilities. 2) Conduct ten (10) assessments of zinc and magnesium die casting plants, within eight (8) companies, utilizing the assessment tool to identify, evaluate and recommend opportunities to enhance energy efficiency, minimize waste, and improve productivity. 3) Transfer the assessment tool to the die casting industry at large.

  13. Casting alloys.

    PubMed

    Wataha, John C; Messer, Regina L

    2004-04-01

    Although the role of dental casting alloys has changed in recent years with the development of improved all-ceramic materials and resin-based composites, alloys will likely continue to be critical assets in the treatment of missing and severely damaged teeth. Alloy shave physical, chemical, and biologic properties that exceed other classes of materials. The selection of the appropriate dental casting alloy is paramount to the long-term success of dental prostheses,and the selection process has become complex with the development of many new alloys. However, this selection process is manageable if the practitioner focuses on the appropriate physical and biologic properties, such as tensile strength, modulus of elasticity,corrosion, and biocompatibility, and avoids dwelling on the less important properties of alloy color and short-term cost. The appropriate selection of an alloy helps to ensure a longer-lasting restoration and better oral health for the patient.

  14. 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.

  15. 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.

  16. 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.

  17. Matrix effect on leaching of Bisphenol A diglycidyl ether (BADGE) from epoxy resin based inner lacquer of aluminium tubes into semi-solid dosage forms.

    PubMed

    Lipke, Uwe; Haverkamp, Jan Boris; Zapf, Thomas; Lipperheide, Cornelia

    2016-04-01

    To study the impact of different semi-solid dosage form components on the leaching of Bisphenol A (BPA) and Bisphenol A diglycidyl ether (BADGE) from the epoxy resin-based inner lacquer of aluminium tubes, the tubes were filled with different matrix preparations and stored at an elevated temperature. Despite compliance with the European Standards EN 15348 and EN 15766 on porosity and polymerisation of internal coatings of aluminium tubes, the commercially available tubes used in the study contained an increased amount of polymerisation residues, such as unbound BPA, BADGE and BADGE derivatives in the lacquer, as determined by acetonitrile extraction. Storage of Macrogol ointments in these tubes resulted in an almost quantitative migration of the unbound polymerisation residues from the coating into the ointment. In addition, due to alterations observed in the RP-HPLC chromatograms of the matrix spiked with BADGE and BADGE derivatives it is supposed that the leachates can react with formulation components. The contamination of the medicinal product by BPA, BADGE and BADGE derivatives can be precluded by using aluminium tubes with an internal lacquer with a low degree of unbound polymerisation residues. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  18. Solid fraction evolution characteristics of semi-solid A356 alloy and in-situ A356-TiB2 composites investigated by differential thermal analysis

    NASA Astrophysics Data System (ADS)

    Deepak Kumar, S.; Mandal, A.; Chakraborty, M.

    2015-04-01

    The key factor in semi-solid metal processing is the solid fraction at the forming temperature because it affects the microstructure and mechanical properties of the thixoformed components. Though an enormous amount of data exists on the solid fraction-temperature relationship in A356 alloy, information regarding the solid fraction evolution characteristics of A356-TiB2 composites is scarce. The present article establishes the temperature-solid fraction correlation in A356 alloy and A356- xTiB2 ( x = 2.5wt% and 5wt%) composites using differential thermal analysis (DTA). The DTA results indicate that the solidification characteristics of the composites exhibited a variation of 2°C and 3°C in liquidus temperatures and a variation of 3°C and 5°C in solidus temperatures with respect to the base alloy. Moreover, the eutectic growth temperature and the solid fraction ( f s) vs. temperature characteristics of the composites were found to be higher than those of the base alloy. The investigation revealed that in-situ formed TiB2 particles in the molten metal introduced more nucleation sites and reduced undercooling.

  19. Study of the degradation of methylene blue by semi-solid-state fermentation of agricultural residues with Phanerochaete chrysosporium and reutilization of fermented residues.

    PubMed

    Zeng, Guangming; Cheng, Min; Huang, Danlian; Lai, Cui; Xu, Piao; Wei, Zhen; Li, Ningjie; Zhang, Chen; He, Xiaoxiao; He, Yan

    2015-04-01

    The degradation of methylene blue (MB) by semi-solid-state fermentation of agricultural residues rice straw with Phanerochaete chrysosporium and the reutilization of fermented residues was investigated. A maximum decolorization of 84.8% for an initial dye concentration of 0.4 g/L was observed at the optimal operating conditions (temperature 35 °C, pH 5). As compared to the previous results obtained using synthetic materials as substrate, the results in the present study revealed an excellent performance of the bioreactor in decolorizing the wastewater containing MB, which is due to this type of cultivation reproducing the natural living conditions of the white rot fungi. Among the two ligninolytic enzymes that are responsible to the decolorization, manganese peroxidase (MnP) activity was found better correlated with decoloration percentage. Our results also provide a first step to recycling the fermented residues for the removal of MB from aqueous solutions, the maximum adsorption capacity of the fermented residues reached 51.4 mg/g.

  20. Method and apparatus for die forming metal sheets and extrusions

    NASA Astrophysics Data System (ADS)

    Darter, John L.

    1986-06-01

    The invention comprises an apparatus for die forming metal sheets and extrusions which utilizes die blocks of low melting temperature metallic material. The die blocks are formed in an adjustable mold which comprises a mold box, a pivotable dam within the mold box and blocking means for locking the pivotable dam member in a desired angular position. Once a desired die block angle is ascertained for a particular joggle, the pivotable member of the mold box is adjusted to produce the desired angle in the die casting made in the mold box.

  1. 76 FR 5840 - The Basic Aluminum Castings Co., Cleveland, OH; Notice of Revised Determination on Reconsideration

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-02

    ... Employment and Training Administration The Basic Aluminum Castings Co., Cleveland, OH; Notice of Revised... Assistance (TAA) applicable to workers and former workers of The Basic Aluminum Castings Co., Cleveland, Ohio... are engaged in employment related to the production of aluminum die castings. New information revealed...

  2. 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.

  3. Casting the Spirit: A Handmade Legacy

    ERIC Educational Resources Information Center

    Rutenberg, Mona

    2008-01-01

    This article discusses how an art therapist working in a hospital palliative care unit has incorporated a ritual of hand casting to help bring closure to dying patients and family members who are grieving as death approaches. The finished hand sculptures depict the hands of the patients and, sometimes, of their loved ones. They are faithful and…

  4. Die Materials for Critical Applications and Increased Production Rates

    SciTech Connect

    David Schwam; John Wallace; Sebastian Birceanu

    2002-11-30

    Die materials for aluminum die-casting need to be resistant to heat checking, and have good resistance to washout and to soldering in a fast flow of molten aluminum. To resist heat checking, die materials should have a low coefficient of thermal expansion, high thermal conductivity, high hot yield strength, good temper softening resistance, high creep strength, and adequate ductility. To resist the washout and soldering, die materials should have high hot hardness, good temper resistance, low solubility in molten aluminum and good oxidation resistance. It is difficult for one material to satisfy with all above requirements. In practice, H13 steel is the most popular material for aluminum die casting dies. While it is not an ideal choice, it is substantially less expensive to use than alternative materials. However, in very demanding applications, it is sometimes necessary to use alternative materials to ensure a reasonable die life. Copper-base, nickel-base alloys and superalloys, titanium-,molybdenum-, tungsten-base alloys, and to some extent yttrium and niobium alloys, have all been considered as potential materials for demanding die casting applications. Most of these alloys exhibit superior thermal fatigue resistance, but suffer from other shortcomings.

  5. Wege in die Zukunft

    NASA Astrophysics Data System (ADS)

    Kauermann, Göran; Mosler, Karl

    Die Zukunft stellt große Herausforderungen an die Arbeit der Deutschen Statistischen Gesellschaft. Sie betreffen die gestiegenen Anforderungen der Nutzer von Statistik, die Kommunikationsmöglichkeiten des Internets sowie die Dynamik der statistischen Wissenschaften und ihrer Anwendungsgebiete. Das Kapitel 5 beschreibt, wie sich die Gesellschaft diesen Herausforderungen stellt und welche Ziele sie sich in der wissenschaftlichen Zusammenarbeit und im Kampf gegen das Innumeratentum gesetzt hat.

  6. Wettability of elastomeric impression materials and voids in gypsum casts.

    PubMed

    Cullen, D R; Mikesell, J W; Sandrik, J L

    1991-08-01

    Numerous factors are involved in making an accurate void-free dental artificial stone cast or die. The relationship of the wettability of an elastomeric impression material and its interaction with the gypsum slurry is an important factor. This study examined the relative "pourability" of several impression materials by counting the number of resultant voids in artificial stone casts containing 48 point angles. Those elastomers that exhibited the lowest contact angle with water produced artificial stone casts with the fewest voids. Surfactants applied to the impression material significantly reduced the number of voids in artificial stone casts, as did modified elastomers designated by the manufacturer as hydrophilic.

  7. 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.

  8. Evaluation of Heat Checking and Washout of Heat Resistant Superalloys and Coatings for Die inserts

    SciTech Connect

    David Schwam; John F. Wallace; Yulong Zhu; Edward Courtright; Harold Adkins

    2005-01-30

    This project had two main objectives: (1) To design, fabricate and run a full size test for evaluating soldering and washout in die insert materials. This test utilizes the unique capabilities of the 350 Ton Squeeze Casting machine available in the Case Meal Casting Laboratory. Apply the test to evaluate resistance of die materials and coating, including heat resistant alloys to soldering and washout damage. (2) To evaluate materials and coatings, including heat resistant superalloys, for use as inserts in die casting of aluminum alloys.

  9. DIE Deflection Modeling: Empirical Validation and Tech Transfer

    SciTech Connect

    R. Allen Miller

    2003-05-28

    This report summarizes computer modeling work that was designed to help understand how the die casting die and machine contribute to parting plane separation during operation. Techniques developed in earlier research (8) were applied to complete a large computational experiment that systematically explored the relationship between the stiffness of the machine platens and key dimensional and structural variables (platen area covered, die thickness, platen thickness, thickness of insert and the location of the die with respect to the platen) describing the die/machine system. The results consistently show that there are many significant interactions among the variables and it is the interactions, more than the individual variables themselves, which determine the performance of the machine/die system. That said, the results consistently show that it is the stiffness of the machine platens that has the largest single impact on die separation.

  10. Optimization of an efficient semi-solid culture protocol for sterilization and plant regeneration of Centella asiatica (L.) as a medicinal herb.

    PubMed

    Moghaddam, Sina Siavash; Jaafar, Hawa Binti; Aziz, Maheran Abdul; Ibrahim, Rusli; Rahmat, Asmah Bt; Philip, Elizabeth

    2011-01-01

    The present study investigates the effects of different concentrations, as well as type of plant growth regulators (PGRs) and medium (MS, Duchefa) on the growth and development of Centella asiatica in semi-solid culture. In addition, a protocol for successful sterilization of C.asiatica explants prepared from field-grown plants highly exposed to fungal and bacterial contamination was determined. Results for sterilization treatments revealed that applying HgCl₂ and Plant Preservative Mixture (PPM) with cetrimide, bavistin and trimethoprim which were included after washing with tap water, followed by the addition of PPM in the medium, produced a very satisfactory result (clean culture 90 ± 1.33%) and TS5 (decon + cetrimide 1% + bavistin 150 mg/L + trimethoprim 50 mg/L + HgCl₂0.1% + PPM 2% soak and 2 mL/L in medium) was hence chosen as the best method of sterilization for C.asiatica. The synergistic combination of 6 benzylaminopurine (BAP) and 1-naphthaleneacetic acid (NAA) in concentrations of 2 mg/L and 0.1 mg/L, respectively, in Duchefa medium compared with MS induced the most optimal percentage of sprouted shoots (93 ± 0.667), number of shoots (5.2 ± 0.079) and nodes (4 ± 0.067) per explant, leaf per explant (14 ± 0.107) and shoot length (4.1 ± 0.67 cm). Furthermore, optimum rooting frequency (95.2 ± 0.81%), the number of roots/shoot (7.5 ± 0.107) and the mean root length (4.5 ± 0.133 cm) occurred for shoots that were cultured on full-strength MS medium containing 0.5 mg/L indole-3-butyric acid (IBA). In this study, the acclimatized plantlets were successfully established with almost 85% survival. The findings of this study have proven an efficient medium and PGR concentration for the mass propagation of C.asiatica. These findings would be useful in micropropagation and ex situ conservation of this plant.

  11. Task 7: Die soldering during host site testing. Final report, January1--December 31, 1997

    SciTech Connect

    Goodwin, F.E.; Walkington, W.G.

    1998-01-31

    To provide industrial confirmation of laboratory results produced in Task 6 of this project, five industrial trials were organized with cooperative die casters in the USA. Components cast during these trials ranged from functional electronic heat sinks to decorative household plumbing components. Whereas laboratory work indicated that die temperature and draft angle were the most important process factors influencing solder accumulation, it was not possible to vary draft angle on the established production dies used for these trials. Substantial variations in die temperature were realized however and also die surface conditions were varied, confirming the influence of a secondary variable in the laboratory investigation. Substantial evidence from the trials indicated that die surface temperature is the most important factor for controlling solder build up. The surface roughness of the die casting die greatly influenced the number of castings that could be run before solder initially appeared. Development of careful thermal management techniques, now judged to be beyond the capabilities of most US die casters, will be necessary to control incidences of die soldering found in typical production. Thermal control will involve both control of the bulk die temperature through use of thermally controlled cooling lines, and also regulation of surface temperature by well controlled cooling lines, and also regulation of surface temperature by well controlled die spraying (lubrication) techniques. Further research, development and technology transfer to enhance thermal control capabilities of US die casters is recommended.

  12. 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

  13. Fiberglass cast application.

    PubMed

    Smith, Gillian D; Hart, Raymond G; Tsai, Tsu-Min

    2005-05-01

    Plaster of Paris has been largely superceded for casting in orthopedic departments by synthetic cast materials. Despite its weight, its relative brittleness, its unpopularity with patients, and its messiness in application, plaster of Paris remains the mainstay of casting in the emergency department. This is due to a combination of economic reasons, the belief that synthetic casts leave less room for swelling and its relative ease of application compared to synthetic materials. We present a technique for synthetic cast application that avoids the problems of the rapidly setting cast and therefore allows the time for less experienced hands to produce a well-fitting cast or splint. We believe that this option, which allows the patient to have a lighter synthetic cast, rather than the traditional plaster of Paris cast, will be welcomed by both the patient and physician.

  14. INTERIOR VIEW WITH CASTING MACHINE AND CASTING FOREMAN OBSERVING OPERATION ...

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

    INTERIOR VIEW WITH CASTING MACHINE AND CASTING FOREMAN OBSERVING OPERATION TO ENSURE MAXIMUM PRODUCTION AND QUALITY. - McWane Cast Iron Pipe Company, Pipe Casting Area, 1201 Vanderbilt Road, Birmingham, Jefferson County, AL

  15. Numerical Simulation on the Die Filling Process of the Thixo-Forging of Al-7 wt pct Si/Al-22 wt pct Si Bimetal Composite

    NASA Astrophysics Data System (ADS)

    Wang, Guangxu; Huang, Honghua; Yang, Zhao; Shi, Xiaocheng; He, Xiaolong

    2015-10-01

    A bimetal semi-solid fluid has more complicated flow behaviors than a normal semi-solid fluid during thixo-forging. In order to clarify the detailed properties of the bimetal thixo-forging, the effects of billet temperatures and frictions on flow behaviors of the Al-7 wt pct Si/Al-22 wt pct Si bimetal thixo-forging were investigated by commercial software DEFORM-3D. The simulation results show that shear force was unable to be transferred from the upper billet on the drop die side to the bottom billet on the counter die side efficiently in the initial stage of die filling. Only when the upper billet severely deformed, did the shear force deform the bottom billet. A stiffer upper billet can enhance the efficiency of shear force transfer. The processing temperature, the relative stiffness between the upper billet and bottom billet, and frictions between dies and billets, as well as friction between billets, were important factors to control the interface outline of the bimetal parts. The experimental results are consistent with the simulation results.

  16. 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.

  17. 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' ...

  18. Displaced capillary dies

    DOEpatents

    Kalejs, Juris P.; Chalmers, Bruce; Surek, Thomas

    1982-01-01

    An asymmetrical shaped capillary die made exclusively of graphite is used to grow silicon ribbon which is capable of being made into solar cells that are more efficient than cells produced from ribbon made using a symmetrically shaped die.

  19. Displaced capillary dies

    DOEpatents

    Kalejs, Juris P.; Chalmers, Bruce; Surek, Thomas

    1984-01-01

    An asymmetrical shaped capillary die made exclusively of graphite is used to grow silicon ribbon which is capable of being made into solar cells that are more efficient than cells produced from ribbon made using a symmetrically shaped die.

  20. Packaged die heater

    DOEpatents

    Spielberger, Richard; Ohme, Bruce Walker; Jensen, Ronald J.

    2011-06-21

    A heater for heating packaged die for burn-in and heat testing is described. The heater may be a ceramic-type heater with a metal filament. The heater may be incorporated into the integrated circuit package as an additional ceramic layer of the package, or may be an external heater placed in contact with the package to heat the die. Many different types of integrated circuit packages may be accommodated. The method provides increased energy efficiency for heating the die while reducing temperature stresses on testing equipment. The method allows the use of multiple heaters to heat die to different temperatures. Faulty die may be heated to weaken die attach material to facilitate removal of the die. The heater filament or a separate temperature thermistor located in the package may be used to accurately measure die temperature.

  1. Interfacial heat transfer in squeeze casting of magnesium alloy AM60 with variation of applied pressures and casting wall-thicknesses

    NASA Astrophysics Data System (ADS)

    Zhang, Xuezhi; Fang, Li; Sun, Zhizhong; Hu, Henry; Nie, Xueyuan; Tjong, Jimi

    2016-10-01

    The heat transfer coefficient at the casting-die interface is the most important factor on the solidification process. With the 75-ton hydraulic press machine and P20 steel die mold, 5-step castings of magnesium alloy AM60 with different wall-thicknesses (3, 5, 8, 12, 20 mm) were poured under various hydraulic pressures (30, 60, and 90 MPa) using an indirect squeeze casting process. Thermal histories throughout the die wall and the casting surface have been recorded by fine type-K thermocouples. The in-cavity local pressures measured by pressure transducers were explored at the casting-die interfaces of 5 steps. The casting-die interfacial heat transfer coefficients (IHTC) initially reached a maximum peak value followed by a gradually decline to the lower level. Similar characteristics of IHTC peak values can be observed at the applied pressures of 30, 60 and 90 MPa. With the applied pressure of 90 MPa, the peak IHTC values from steps 1 to 5 varied from 5623 to 10,649 W/m2 K. As the applied hydraulic pressure increased, the IHTC peak value of each step was increased accordingly. The wall thickness also affected IHTC peak values significantly. The peak IHTC value and heat flux increased as the step became thicker. The empirical equations relating the IHTCs to the local pressures and the solidification temperature at the casting surface were developed based on the multivariate linear and polynomial regression.

  2. 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.

  3. The Ambiguous Dying Syndrome

    ERIC Educational Resources Information Center

    Bern-Klug, Mercedes

    2004-01-01

    More than one-half of the 2.4 million deaths that will occur in the United States in 2004 will be immediately preceded by a time in which the likelihood of dying can best be described as "ambiguous." Many people die without ever being considered "dying" or "at the end of life." These people may miss out on the…

  4. The Ambiguous Dying Syndrome

    ERIC Educational Resources Information Center

    Bern-Klug, Mercedes

    2004-01-01

    More than one-half of the 2.4 million deaths that will occur in the United States in 2004 will be immediately preceded by a time in which the likelihood of dying can best be described as "ambiguous." Many people die without ever being considered "dying" or "at the end of life." These people may miss out on the…

  5. Cast articulation accuracy using rigid cast stabilization.

    PubMed

    Gunderson, Ronald Bruce; Siegel, Sharon Crane

    2002-06-01

    This study evaluated the positional accuracy of casts articulated on a semi-adjustable articulator, with and without rigid cast stabilization using either laboratory plaster or mounting plaster. A reference articulation of melamine casts in maximum articulation was established and recorded in the horizontal and vertical dimensions using a verification device. The same casts were subsequently remounted 24 times using either laboratory plaster or mounting plaster. Half of the articulations from each group were stabilized using detachable mounting rods and sticky wax, and half were hand-articulated without stabilization, for a total of 6 articulations in each of 4 test groups. The resulting spatial positions established on the articulator were compared to the initial reference position on the verification device grid. Means and standard deviations of the absolute values of the horizontal and vertical displacement for each group were determined separately and compared using a one-way anaylsis of variance. Significant differences (p <0.05) were identified using Tukey's honestly significant difference multiple comparison test. Mean vertical mandibular cast displacement ranged from 0.26 +/-0.21mm for stabilized casts mounted with laboratory plaster to 1.58 +/-0.32 mm for unstabilized casts mounted with mounting plaster. For each mounting material, significantly less vertical displacement (p <0.001) was observed with the mandibular cast stabilized before mounting. The cast mounted with laboratory plaster exhibited horizontal displacement (0.87 +/-0.29 mm) that was significantly greater than the remaining groups (p <0.001), which did not differ from each other. Rigid stabilization of the mandibular to maxillary cast during mounting with laboratory and mounting plaster improved articulation accuracy. Copyright 2002 by The American College of Prosthodontists.

  6. 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.

  7. HIGH PRESSURE DIES

    DOEpatents

    Wilson, W.B.

    1960-05-31

    A press was invented for subjecting specimens of bismuth, urania, yttria, or thoria to high pressures and temperatures. The press comprises die parts enclosing a space in which is placed an electric heater thermally insulated from the die parts so as not to damage them by heat. The die parts comprise two opposed inner frustoconical parts and an outer part having a double frustoconical recess receiving the inner parts. The die space decreases in size as the inner die parts move toward one another against the outer part and the inner parts, though very hard, do not fracture because of the mode of support provided by the outer part.

  8. A comparative evaluation of linear dimensional accuracy of the dies obtained using three conceptually different die systems in the fabrication of implant prosthesis: an in vitro study.

    PubMed

    Ahmad, Manawar; Balakrishnan, Dhanasekar; Narayan, Aparna Ichangod

    2014-01-01

    Given that meticulous implant prosthodontic procedures are recommended to obtain the best possible intraoral fit, the die systems used for multi implant casts warrant further investigation. Die stone expansion and errors introduced by removable die casts may exceed the accuracy required for the passive fit of implant prosthesis. The purpose of the study was to evaluate the linear dimensional accuracy between the implant master die and three conceptually different die systems such as Pindex system, Accu-trac precision die system, and Conventional brass dowel pin system. Thirty impressions of implant master die were made with polyether impression material. Ten experimental implant casts were fabricated for each of the three different die systems tested: Accu-trac precision die tray system, Pindex system, and conventional brass dowel pin system. The solid experimental casts were sectioned and then removed from the die system 30 times. Linear distances between all six possible distances were measured from one centre of the transfer coping to the other, using a co-ordinate measuring machine in millimeters up to accuracy of 0.5 microns. Data were tabulated and statistically analyzed by Binomial non parametric test using SPSS version 15. Significant differences were found for distance A-B (P = 0.002), A-C ( P = 0.002), A-D (P value = 0.002), and B-D ( P = 0.021) in Conventional Dowel pin system however for Accu-trac precision die tray system, it was significant only for distance A-D (P = 0.002) but for Pindex system it was non-significant for all the distances measured. Within the limitations of this study, use of Pindex system is recommended when sectioned dies are needed for a multi implant retained prosthesis.

  9. Cast erosion from the cleaning of debris after the use of a cast trimmer.

    PubMed

    Hansen, Paul A; Beatty, Mark W

    2017-02-01

    Whether using tap water to rinse off debris will make a clinical difference to the surface detail of a gypsum cast is unknown. In addition, how best to remove debris from the cast is unknown. The purpose of this in vitro study was to evaluate the efficiency of different methods of cleaning a gypsum cast after trimming and the effect of short-term exposure to tap water on the surface quality of the cast. A die fitting American National Standards Institute/American Dental Association specification 25 (International Standards Organization specification 6873) for dental gypsum products was embedded in a Dentoform with the machined lines positioned at the same level as the occlusal surface of the posterior teeth. A flat plate was used to ensure that the plane of occlusion for the die was at the same position as the posterior teeth. Forty polyvinyl siloxane impressions of the Dentoform were made and poured with vacuum-mixed improved Type IV dental stone. Each cast was inspected for the accurate reproduction of the lines. The base of the 2-stage pour was trimmed with a cast trimmer with water, and surface debris was removed by rinsing by hand under tap water for 10 seconds, by brushing the cast with a soft toothbrush for 10 seconds, or by resoaking the cast and using a soft camel hair brush in slurry water for 10 seconds. The amount of debris was evaluated on a scale of 1 to 4, and the quality of the 20-μm line was evaluated on a scale of 1 to 4 under ×15 magnification. The nonparametric Kruskal-Wallis ranks test was used to identify significant differences among the different cleaning methods (α=.05). Results of the Kruskal-Wallis and Kruskal-Wallis Z-value tests demonstrated that all cleaning methods produced cleaner casts than were observed for uncleansed controls (P<.001), but no differences in debris removal were found among the different cleaning methods (.065≤P≤.901). The ability to see the quality of a 20-μm line (P=.974) was not statistically different

  10. 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.

  11. Evaluating the Tensile Properties of Aluminum Foundry Alloys through Reference Castings-A Review.

    PubMed

    Anilchandra, A R; Arnberg, Lars; Bonollo, Franco; Fiorese, Elena; Timelli, Giulio

    2017-08-30

    The tensile properties of an alloy can be exploited if detrimental defects and imperfections of the casting are minimized and the microstructural characteristics are optimized through several strategies that involve die design, process management and metal treatments. This paper presents an analysis and comparison of the salient characteristics of the reference dies proposed in the literature, both in the field of pressure and gravity die-casting. The specimens produced with these reference dies, called separately poured specimens, are effective tools for the evaluation and comparison of the tensile and physical behaviors of Al-Si casting alloys. Some of the findings of the present paper have been recently developed in the frame of the European StaCast project whose results are complemented here with some more recent outcomes and a comprehensive analysis and discussion.

  12. 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.

  13. Study of protective coatings for aluminum die casting molds

    NASA Astrophysics Data System (ADS)

    Peter, Ildiko; Rosso, Mario; Gobber, Federico Simone

    2015-12-01

    In this paper, the development and characterization of some protective coatings on steel substrate are presented. The coatings are realized by plasma spray techniques. The substrate material used is a Cr-Mo-V based hot work tool steel, initially submitted to vacuum heat treatment to achieve homogeneous hardness. The main attention is focused on the study of wear and on the characterization of the interface between the substrate material and the coating layer, because of their key role in determining the resistance of the coating layer. Simulation of friction and wear processes is performed by pin-on-disk test and the tested samples are observed by scanning electron microscopy.

  14. The Effect of Thermal Cycling on the Surface Roughness of Dental Casting Investments.

    DTIC Science & Technology

    1991-05-01

    ceramometal alloys, cast into the various dental investment samples, was also evaluated. Finally, the roughness average measurement method was evaluated for...adaptability to dental casting investments. Ten epoxy resin dies were fabricated from the surface of six dental investment products after they were set...against a smooth reference surface. Ten additional epoxy resin dies were fabricated from the six dental investment samples after they were set

  15. Castings, Steel, Homogenization of Steel Castings

    DTIC Science & Technology

    1942-12-05

    diffraction pattern of quenched and tempered steel castings. 2. Calculations based upon known diffusion rates show: A. Practical homogenizing heat ...will be largely eliminated by either the usual heating for nuenching or a homo- genizing treatment. C. Interdendritic segregation of sulfur will...26 Appendix A - History of the Heat Treatment and Composition of Centrifugal Gun Castings at W-tertown Ar- sen-.l. ..... ..................... 2

  16. Glovebox Advanced Casting System Casting Optimization

    SciTech Connect

    Fielding, Randall Sidney

    2016-03-01

    Casting optimization in the GACS included three broad areas; casting of U-10Zr pins, incorporation of an integral FCCI barrier, and development of a permanent crucible coating. U-10Zr casting was improved over last year’s results by modifying the crucible design to minimize contact with the colder mold. Through these modifications casting of a three pin batch was successful. Incorporation of an integral FCCI barrier also was optimized through furnace chamber pressure changes during the casting cycle to reduce gas pressures in the mold cavities which led to three full length pins being cast which incorporated FCCI barriers of three different thicknesses. Permanent crucible coatings were tested against a base case; 1500°C for 10 minutes in a U-20Pu-10Zr molten alloy. None of the candidate coating materials showed evidence of failure upon initial visual examination. In all areas of work a large amount of characterization will be needed to fully determine the effects of the optimization activities. The characterization activities and future work will occur next year.

  17. Die singulation method

    DOEpatents

    Swiler, Thomas P [Albuquerque, NM; Garcia, Ernest J [Albuquerque, NM; Francis, Kathryn M [Rio Rancho, NM

    2014-01-07

    A method is disclosed for singulating die from a semiconductor substrate (e.g. a semiconductor-on-insulator substrate or a bulk silicon substrate) containing an oxide layer (e.g. silicon dioxide or a silicate glass) and one or more semiconductor layers (e.g. monocrystalline or polycrystalline silicon) located above the oxide layer. The method etches trenches through the substrate and through each semiconductor layer about the die being singulated, with the trenches being offset from each other around at least a part of the die so that the oxide layer between the trenches holds the substrate and die together. The trenches can be anisotropically etched using a Deep Reactive Ion Etching (DRIE) process. After the trenches are etched, the oxide layer between the trenches can be etched away with a HF etchant to singulate the die. A release fixture can be located near one side of the substrate to receive the singulated die.

  18. Die singulation method

    DOEpatents

    Swiler, Thomas P.; Garcia, Ernest J.; Francis, Kathryn M.

    2013-06-11

    A method is disclosed for singulating die from a semiconductor substrate (e.g. a semiconductor-on-insulator substrate or a bulk silicon substrate) containing an oxide layer (e.g. silicon dioxide or a silicate glass) and one or more semiconductor layers (e.g. monocrystalline or polycrystalline silicon) located above the oxide layer. The method etches trenches through the substrate and through each semiconductor layer about the die being singulated, with the trenches being offset from each other around at least a part of the die so that the oxide layer between the trenches holds the substrate and die together. The trenches can be anisotropically etched using a Deep Reactive Ion Etching (DRIE) process. After the trenches are etched, the oxide layer between the trenches can be etched away with an HF etchant to singulate the die. A release fixture can be located near one side of the substrate to receive the singulated die.

  19. Casting the Die before the Die Is Cast: The Importance of the Home Numeracy Environment for Preschool Children

    ERIC Educational Resources Information Center

    Niklas, Frank; Schneider, Wolfgang

    2014-01-01

    Mathematical competencies are important not only for academic achievement at school but also for professional success later in life. Although we know a lot about the impact of "Home Literacy Environment" on the development of early linguistic competencies, research on "Home Numeracy Environment" (HNE) and the assessment of its…

  20. Casting the Die before the Die Is Cast: The Importance of the Home Numeracy Environment for Preschool Children

    ERIC Educational Resources Information Center

    Niklas, Frank; Schneider, Wolfgang

    2014-01-01

    Mathematical competencies are important not only for academic achievement at school but also for professional success later in life. Although we know a lot about the impact of "Home Literacy Environment" on the development of early linguistic competencies, research on "Home Numeracy Environment" (HNE) and the assessment of its…

  1. Extrusion die and method

    DOEpatents

    Lipp, G. Daniel

    1994-04-26

    A method and die apparatus for manufacturing a honeycomb body of rhombic cell cross-section by extrusion through an extrusion die of triangular cell discharge slot configuration, the die incorporating feedholes at selected slot intersections only, such that slot segments communicating directly with the feedholes discharge web material and slot segments not so connected do not discharge web material, whereby a rhombic cell cross-section in the extruded body is provided.

  2. The Angry Dying Patient.

    PubMed

    Houston, Robert E.

    1999-02-01

    Over 25 years ago, Kubler-Ross identified anger as a predictable part of the dying process. When the dying patient becomes angry in the clinical setting, all types of communication become strained. Physicians can help the angry dying patient through this difficult time by using 10 rules of engagement. When physicians engage and empathize with these patients, they improve the patient's response to pain and they reduce patient suffering. When physicians educate patients on their normal responses to dying and enlist them in the process of family reconciliation, they can impact the end-of-life experience in a positive way.

  3. Effect of Casting Material on the Cast Pressure After Sequential Cast Splitting.

    PubMed

    Roberts, Aaron; Shaw, K Aaron; Boomsma, Shawn E; Cameron, Craig D

    2017-01-01

    Circumferential casting is a vital component of nonoperative fracture management. These casts are commonly valved to release pressure and decrease the risk of complications from swelling. However, little information exists regarding the effect of different casting supplies on the pressure within the cast. Seventy-five long-arm casts were performed on human volunteers, divided between 5 experimental groups with 15 casts in each groups. Testing groups consisted of 2 groups with a plaster short-arm cast overwrapped with fiberglass to a long arm with either cotton or synthetic cast padding. The 3 remaining groups included fiberglass long-arm casts with cotton, synthetic, or waterproof cast padding. A pediatric blood pressure cuff bladder was placed within the cast and inflated to 100 mm Hg. After inflation, the cast was sequentially released with pressure reading preformed after each stage. Order of release consisted of cast bivalve, cast padding release, and cotton stockinet release. After release, the cast was overwrapped with a loose elastic bandage. Difference in pressure readings were compared based upon the cast material. Pressures within the cast were found to decrease with sequential release of cast. The cast type had no effect of change in pressure. Post hoc testing demonstrated that the type of cast padding significantly affected the cast pressures with waterproof padding demonstrating the highest pressure readings at all time-points in the study, followed by synthetic padding. Cotton padding had the lowest pressure readings at all time-points. Type of cast padding significantly influences the amount of pressure within a long-arm cast, even after bivalving the cast and cutting the cast padding. Cotton cast padding allows for the greatest change in pressure. Cotton padding demonstrates the greatest change in pressure within a long-arm cast after undergoing bivalve. Synthetic and waterproof cast padding should not be used in the setting of an acute fracture to

  4. Improving Metal Casting Process

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Don Sirois, an Auburn University research associate, and Bruce Strom, a mechanical engineering Co-Op Student, are evaluating the dimensional characteristics of an aluminum automobile engine casting. More accurate metal casting processes may reduce the weight of some cast metal products used in automobiles, such as engines. Research in low gravity has taken an important first step toward making metal products used in homes, automobiles, and aircraft less expensive, safer, and more durable. Auburn University and industry are partnering with NASA to develop one of the first accurate computer model predictions of molten metals and molding materials used in a manufacturing process called casting. Ford Motor Company's casting plant in Cleveland, Ohio is using NASA-sponsored computer modeling information to improve the casting process of automobile and light-truck engine blocks.

  5. Improving Metal Casting Process

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Don Sirois, an Auburn University research associate, and Bruce Strom, a mechanical engineering Co-Op Student, are evaluating the dimensional characteristics of an aluminum automobile engine casting. More accurate metal casting processes may reduce the weight of some cast metal products used in automobiles, such as engines. Research in low gravity has taken an important first step toward making metal products used in homes, automobiles, and aircraft less expensive, safer, and more durable. Auburn University and industry are partnering with NASA to develop one of the first accurate computer model predictions of molten metals and molding materials used in a manufacturing process called casting. Ford Motor Company's casting plant in Cleveland, Ohio is using NASA-sponsored computer modeling information to improve the casting process of automobile and light-truck engine blocks.

  6. Performance Steel Castings

    DTIC Science & Technology

    2012-09-30

    alloys , foundry, muzzle brake, supply center, tooling, sources Notice Distribution Statement A Format Information Report created in Microsoft Word...Development of Sand Properties 103 Advanced Modeling Dataset.. 105 High Strength Low Alloy (HSLA) Steels 107 Steel Casting and Engineering Support...University, University of Northern Iowa, Non- Ferrous Founders’ Society, QuesTek, buyCASTINGS.com, Spokane Industries, Nova Precision Casting, Waukesha

  7. 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.

  8. Is Dying Young Worse than Dying Old?

    ERIC Educational Resources Information Center

    Jecker, Nancy S.; Schneiderman, Lawrence J.

    1994-01-01

    Notes that, in contemporary Western society, people feel death of small child is greater injustice than death of older adult and experience correspondingly greater sorrow, anger, regret, or bitterness when very young person dies. Contrasts these attitudes with those of ancient Greece and shows relevance that different attitudes toward death have…

  9. Is Dying Young Worse than Dying Old?

    ERIC Educational Resources Information Center

    Jecker, Nancy S.; Schneiderman, Lawrence J.

    1994-01-01

    Notes that, in contemporary Western society, people feel death of small child is greater injustice than death of older adult and experience correspondingly greater sorrow, anger, regret, or bitterness when very young person dies. Contrasts these attitudes with those of ancient Greece and shows relevance that different attitudes toward death have…

  10. Cast Aluminum Bonding Study

    DTIC Science & Technology

    1988-05-01

    fabricated using P?-’r;est11 bur)ld II19 te(hnll I Oly with 6 cIsL nqs. The cast a lumi num alloy used was A357 . The sur- face preparation was phosphoric acid...from a cast aluminum alloy designated A357 . The bonding surfaces of the adherends were prepared using PAA. One primer and two adhesives considered...System, Cast Aluminum Lap Shear 18 11 Bond Area of 350°F Adhesive System, Cast Aluminum Lap Shear 19 vi LIST OF TABLES TABLE PAGE 1 A357 Chemical

  11. Evolution of halictine castes

    NASA Astrophysics Data System (ADS)

    Knerer, Gerd

    1980-03-01

    Social halictine bees have female castes that range from species with no size differences to those with a discrete bimodality. Female caste differences are inversely correlated with the number of males produced in the first brood. It is proposed that the sexual dimorphism of solitary forms is being usurped by the female caste system of species in the process of turning social. Thus, caste differences and summer male suppression are greatest in the social species originating from solitary precursors with distinct sexual dimorphism, and are least in species evolving from solitary ancestors with a continuous sexual polymorphism.

  12. Experimental and numerical study of the effect of mold vibration on aluminum castings alloys

    NASA Astrophysics Data System (ADS)

    Abu-Dheir, Numan

    2005-07-01

    The recent advances in scientific and engineering tools have allowed researchers to integrate more science into manufacturing, leading to improved and new innovative processes. As a result, important accomplishments have been reached in the area of designing and engineering new materials for various industrial applications. This subject is of critical significance because of the impact it could have on the manufacturing industry. In the casting industry, obtaining the desired microstructure and properties during solidification may reduce or eliminate the need for costly thermo-mechanical processing prior to secondary manufacturing processes. Several techniques have been developed to alter and control the microstructure of castings during solidification including semi-solid processing, electromagnetic stirring, electromagnetic vibration, and mechanical vibration. Although it is established that mold vibration can significantly influence the structure and properties of castings, however, most of the studies are generally qualitative, limited to a small range of conditions and no attempts have been made to simulate the effect of vibration on casting microstructure. In this work, a detailed experimental and numerical investigation is carried out to advance the utilization of mold vibration as an effective tool for controlling and modifying the casting microstructure. The effects of a wide range of vibration amplitudes and frequencies on the solidification kinetics, microstructure formation and mechanical properties of Al-Si alloys are examined. Results show strong influence of mold vibration on the resulting casting. The presence of porosity was significantly reduced as a result of mold vibration. In addition, the changes in microstructure and mechanical properties can be successfully represented by the changes in solidification characteristics. Increasing the vibration amplitude tends to reduce the lamellar spacing and change the silicon morphology to become more

  13. Pultrusion Die Assembly

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L. (Inventor); Johnson, Gary S. (Inventor); Frye, Mark W. (Inventor); Stanfield, Clarence E. (Inventor)

    1988-01-01

    This invention relates generally to pultrusion die assemblies, and more particularly, to a pultrusion die assembly which incorporates a plurality of functions in order to produce a continuous, thin composite fiber reinforced thermoplastic material. The invention is useful for making high performance thermoplastic composite materials in sheets which can be coiled on a spool and stored for further processing.

  14. Extrusion die and method

    DOEpatents

    Lipp, G. Daniel

    1994-05-03

    A method and die apparatus for manufacturing a honeycomb body of triangular cell cross-section and high cell density, the die having a combination of (i) feedholes feeding slot intersections and (ii) feedholes feeding slot segments not supplied from slot intersections, whereby a reduction in feedhole count is achieved while still retaining good extrusion efficiency and extrudate uniformity.

  15. Micromechanical die attachment surcharge

    DOEpatents

    Filter, William F.; Hohimer, John P.

    2002-01-01

    An attachment structure is disclosed for attaching a die to a supporting substrate without the use of adhesives or solder. The attachment structure, which can be formed by micromachining, functions purely mechanically in utilizing a plurality of shaped pillars (e.g. round, square or polygonal and solid, hollow or slotted) that are formed on one of the die or supporting substrate and which can be urged into contact with various types of mating structures including other pillars, a deformable layer or a plurality of receptacles that are formed on the other of the die or supporting substrate, thereby forming a friction bond that holds the die to the supporting substrate. The attachment structure can further include an alignment structure for precise positioning of the die and supporting substrate to facilitate mounting the die to the supporting substrate. The attachment structure has applications for mounting semiconductor die containing a microelectromechanical (MEM) device, a microsensor or an integrated circuit (IC), and can be used to form a multichip module. The attachment structure is particularly useful for mounting die containing released MEM devices since these devices are fragile and can otherwise be damaged or degraded by adhesive or solder mounting.

  16. Extrusion die and method

    SciTech Connect

    Lipp, G.D.

    1994-05-03

    A method and die apparatus for manufacturing a honeycomb body of triangular cell cross-section and high cell density, the die having a combination of (i) feedholes feeding slot intersections and (ii) feedholes feeding slot segments not supplied from slot intersections, whereby a reduction in feedhole count is achieved while still retaining good extrusion efficiency and extrudate uniformity. 4 figures.

  17. Non-aqueous semi-solid flow battery based on Na-ion chemistry. P2-type Na(x)Ni(0.22)Co(0.11)Mn(0.66)O(2)-NaTi2(PO4)3.

    PubMed

    Ventosa, Edgar; Buchholz, Daniel; Klink, Stefan; Flox, Cristina; Chagas, Luciana Gomes; Vaalma, Christoph; Schuhmann, Wolfgang; Passerini, Stefano; Morante, Joan Ramon

    2015-04-30

    We report the first proof of concept for a non-aqueous semi-solid flow battery (SSFB) based on Na-ion chemistry using P2-type NaxNi0.22Co0.11Mn0.66O2 and NaTi2(PO4)3 as positive and negative electrodes, respectively. This concept opens the door for developing a new low-cost type of non-aqueous semi-solid flow batteries based on the rich chemistry of Na-ion intercalating compounds.

  18. A cast orientation index.

    PubMed

    Ivanhoe, J R; Mahanna, G K

    1994-12-01

    This article describes a technique that allows multiple master casts to be precisely oriented to the same path of insertion and withdrawal. This technique is useful in situations where multiple fixed prosthodontic preparations require surveyed restorations and a single master cast is not available.

  19. Cast segment evaluation

    NASA Technical Reports Server (NTRS)

    Diem, H. G.; Studhalter, W. R.

    1971-01-01

    Evaluation program to determine feasibility of fabricating segmented rocket engine thrust chambers using low cost, lightweight castings extends state of the art in areas of casting size and complexity, and in ability to provide thin sections and narrow, deep, cooling channels. Related developments are discussed.

  20. Higher Education's Caste System

    ERIC Educational Resources Information Center

    Iannone, Ron

    2004-01-01

    In this article, the author discusses the history of the present caste system in higher education. He shows how the public's perception of this caste system is based on image and not usually on the quality of teaching and curriculum in colleges and universities. Finally, he discusses a model for accessibility to higher education and how higher…

  1. Die Kometenmission Rosetta

    NASA Astrophysics Data System (ADS)

    Krüger, Harald

    2016-11-01

    Die Rosetta-Mission ist ein Meilenstein in der Erforschung der Kometen und ihrer Entstehung. Eine der größten üerraschungen war die unregelmäßge hantelförmige Gestalt des Zielkometen 67P/Tschurjumow-Gerassimenko. Er besteht wahrscheinlich aus zwei Einzelkörpern, die durch ihre Schwerkraft aneinander gehalten werden. Seine Oberfläche ist sehr rau und zeigt eine sehr vielf ältige Morphologie, die auf eine Vielzahl von ablaufenden Prozessen hindeutet. Der Kometenkern ist vermutlich auf Gr ößnskalen von mehr als etwa 10 bis 100 Metern homogen, Inhomogenitäten auf kleineren Skalen k nnten f r seine Aktivä t verantwortlich sein. Diese ist auf kleine Gebiete konzentriert, und auch Oberflächenveränderungen, die sich innerhalb von einigen Tagen bis wenigen Wochen abspielen, sind lokal. Im Kometenmaterial wurde eine Vielzahl an organischen Substanzen gemessen, die zum Teil als Schlüsselmoleküle für die Synthese der Grundbausteine des Lebens gelten, wie wir es kennen.

  2. An Application of Trapped-Air Analysis to Large Complex High-Pressure Magnesium Casting

    SciTech Connect

    Prindiville, J; Lee, S; Gokhale, A

    2004-07-08

    The usual method for simulating die-castings consists of a solidification analysis of the casting process - a computer calculation of heat transfer between the casting and the die components. The use of cyclic simulations, coupled with the geometric accuracy of the finite element method, has advanced this procedure to the point where it is routinely used for reliable prediction of shrinkage defects in die-castings. Filling analysis is also routinely used to get a glimpse of cavity filling and ensures that overflows are at their most effective location. When coupled with heat transfer, a filling analysis is also very effective in demonstrating the effects of heat loss in the fluid and how it consequentially can negatively affect filling.

  3. Death, dying, and domination.

    PubMed

    Spindelman, Marc

    2008-06-01

    This Article critiques conventional liberal arguments for the right to die on liberal grounds. It contends that these arguments do not go far enough to recognize and address private, and in particular structural, forms of domination. It presents an alternative that does, which is thus more respectful of true freedom in the context of death and dying, and also more consistent with liberalism. After discussing obstacles to the achievement of a right to die that encompasses freedom from both public and private domination, the Article closes with a significant reform project within bioethics that might help bring it about.

  4. Microstructure Evolution and Mechanical Properties of Rheo-Squeeze Cast Mg-9Al-1Zn Alloy by Experiments and Thermodynamic Calculation

    NASA Astrophysics Data System (ADS)

    Guo, Hong-Min; Zhang, Shu-Guo; Yang, Xiang-Jie; Liu, Xu-Bo; Jin, Hua-Lan

    2015-05-01

    Microstructure evolution and mechanical properties of Mg-9Al-1Zn alloy produced by rheo-squeeze casting (R-SQC) were investigated. It was revealed that R-SQC has produced high integrity castings with fine and uniform microstructure, diminished defects, and improved mechanical properties. The solid content in semi-solid slurry determined the grain size of α-Mg phase, the volume content, and distribution of β-Mg17Al12 phase, and predominantly controlled the mechanical properties. A two-stage thermodynamic calculation procedure to analyze R-SQC has been developed, and the solidification path and phase formation of Mg-9Al-1Zn alloy in R-SQC were discussed deeply.

  5. Low Cost Al-Si Casting Alloy As In-Situ Composite for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2000-01-01

    A new aluminum-silicon (Al-Si) alloy has been successfully developed at NASA- Marshall Space Flight Center (MSFC) that has significant improvement in tensile and fatigue strength at elevated temperatures (500 F-700 F). The alloy offers a number of benefits such as light weight, high hardness, low thermal expansion and high surface wear resistance. In hypereutectic form, this alloy is considered as an in-situ Al-Si composite with tensile strength of about 90% higher than the auto industry 390 alloy at 600 F. This composite is very economically produced by using either conventional permanent steel molds or die casting. The projected material cost is less than $0.90 per pound, and automotive components such as pistons can be cast for high production rate using conventional casting techniques with a low and fully accounted cost. Key Words: Metal matrix composites, In-situ composite, aluminum-silicon alloy, hypereutectic alloy, permanent mold casting, die casting.

  6. Die Zeitung der Zukunft

    NASA Astrophysics Data System (ADS)

    Wieser, Christoph; Schaffert, Sebastian

    Schon lange wird spekuliert, wie wir in Zukunft Zeitung lesen werden. Werden wir am Frühstückstisch wie gewohnt in einer Zeitung aus Papier schmökern oder werden wir die Zeitung als biegsame Folie beschrieben mit elektronischer Tinte in Händen halten? Wird die Zeitung mit anderen Medien wie Radio und Fernsehen verschmelzen? Viele Varianten sind denkbar. Heute lässt sich schon ein Trend ablesen: Immer mehr Leser entdecken die Online-Zeitung als Informationsmedium, eine Voraussetzung für die Nutzung neuer Technologien in der Zeitung der Zukunft. In diesem Kapitel stellen wir Entwicklungsmöglichkeiten der Online-Zeitung dar, wie sie im Social Semantic Web möglich werden.

  7. 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

  8. [Evaluation of cervical discrepancy of gold crowns in stone dies from various impression materials].

    PubMed

    Mantovani, A V; Stephano, C B; Roselino, R F; Roselino, R B; Campos, G M

    1990-01-01

    A stainless steel master die simulating a dental preparation for crown was used to make 3 gold castings from wax patterns obtained in 3 different ways: a) directly from the naked master die; b) from the same master die with a copper coping 30 microns thick; and c) with a similar copper coping, but 40 microns thick. The discrepancies of fit of the 3 master gold crowns were evaluated in 99 stones dies (33 for each casting) obtained from 11 different elastomeric impression materials (3 replicae of each). The results showed that: 1) stone dies with no coping presented a medium discrepancy of 284 microns, inadequate for clinical use; 2) the 30 microns and 40 microns copings presented medium discrepancies of 18 and 9 microns respectively, both suitable for clinical use. Thus, the use of copings tend to equalize the cervical discrepancy of fit of gold crowns, whatever be the elastomeric impression material used.

  9. Casting in Sport

    PubMed Central

    DeCarlo, Mark; Malone, Kathy; Darmelio, John; Rettig, Arthur

    1994-01-01

    Attempts by sports medicine professionals to return high school athletes with hand and wrist injuries to competition quickly and safely have been the source of confusion and debate on many playing fields around the country. In addition to the differing views regarding the appropriateness of playing cast usage in high school football, a debate exists among sports medicine professionals as to which material is best suited for playing cast construction. Materials used in playing cast construction should be hard enough to provide sufficient stabilization to the injured area and include adequate padding to absorb blunt impact forces. The purpose of the biomechanical portion of this investigation was to attempt to determine the most appropriate materials for use in constructing playing casts for the hand and wrist by assessing different materials for: 1) hardness using a Shore durometer, and 2) ability to absorb impact using a force platform. Results revealed that RTV11 and Scotchcast were the “least hard” of the underlying casting materials and that Temper Stick foam greatly increased the ability of RTV11 to absorb impact. Assessment of the mechanical properties of playing cast materials and review of current developments in high school football rules are used to aid practitioners in choosing the most appropriate materials for playing cast construction. ImagesFig 1.Fig 2.Fig 3. PMID:16558257

  10. Assisted Dying & Disability.

    PubMed

    Riddle, Christopher A

    2017-07-01

    This article explores at least two dominant critiques of assisted dying from a disability rights perspective. In spite of these critiques, I conclude that assisted dying ought to be permissible. I arrive at the conclusion that if we respect and value people with disabilities, we ought to permit assisted dying. I do so in the following manner. First, I examine recent changes in legislation that have occurred since the Royal Society of Canada Expert Panel on End-of-Life Decision-Making report, published in this journal. I suggest that these changes are likely to only strengthen opposition to assisted dying from disability rights activists and people with disabilities. Second, I focus on respect for people with disabilities and in particular, respect for their autonomy and decision-making abilities. Third, I explore the opposition to assisted dying that focuses on risk and the vulnerability of people with disabilities. Here I suggest that this risk ought not to be of special concern. Ultimately, I conclude that upholding respect for the disabled requires the legalization of assisted dying, rather than the denial of access in a misguided effort to protect people with disabilities. © 2017 John Wiley & Sons Ltd.

  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. 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.

  13. 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.

  14. Adhesion Casting In Low Gravity

    NASA Technical Reports Server (NTRS)

    Noever, David A.; Cronise, Raymond J.

    1996-01-01

    Adhesion casting in low gravity proposed as technique for making new and improved materials. Advantages of low-gravity adhesion casting, in comparison with adhesion casting in normal Earth gravity, comes from better control over, and greater uniformity of, thicknesses of liquid films that form on and adhere to solid surfaces during casting.

  15. Method of casting aerogels

    DOEpatents

    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.

  16. 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.

  17. 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)

  18. Advanced Cast Aluminum Alloys

    DTIC Science & Technology

    2009-02-01

    microstructure of the Al - Zn -Mg- Cu alloys was similar to the as-cast microstructure ...Further, new research has been initiated on ultra-high strength, microalloyed Al - Zn -Mg- Cu alloys with the goal of producing complex castings with...wrought 2519 alloy . Further, new research has been initiated on ultra-high strength, microalloyed Al - Zn -Mg- Cu alloys with the goal of producing

  19. 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.

  20. Effect of composition and processing on the thermal fatigue and toughness of high performance die steels. Year 1 report

    SciTech Connect

    Wallace, J.F.; Wang, Yumin; Schwam, D.

    1996-06-01

    The goal of this project is to extend the lifetime of dies for die casting by 20%. Since the die contributes about 10% to the cost of die cast parts, such an improvement in lifetime would result in annual savings of over $200 Million dollars. This is based on the estimated annual die production of one Billion dollars in the US. The major tasks of this two year project are: (1) Evaluate NEW DIE STEEL COMPOSITIONS that have been developed for demanding applications and compare them to Premium Grade H-13 die steel. (2) Optimize the AUSTENITIZING TREATMENT of the new composition. Assess the effects of fast, medium and slow COOLING RATES DURING HEAT TREATMENT, on the thermal fatigue resistance and toughness of the die steel. (3) Determine the effect of ELECTRO-DISCHARGE MACHINING (EDM) on the thermal fatigue resistance and impact properties of the steel. (4) Select demanding components and conduct IN-PLANT TESTING by using the new steel. Compare the performance of the new steel with identical components made of Premium Grade H-13. The immersion thermal fatigue specimen developed at CWRU is being used to determine resistance to heat checking, and the Charpy V-notch test for evaluating the toughness. The overall result of this project will be identification of the best steel available on the market and the best processing methods for aluminum die casting dies. This is an interim report for year 1 of the project.

  1. Die einzelnen Beanspruchungsarten

    NASA Astrophysics Data System (ADS)

    Böge, Gert; Böge, Wolfgang

    Wird ein Stab mit beliebigem, gleichbleibendem Querschnitt durch die äußere Kraft F in der Schwerachse auf Zug oder Druck beansprucht, so wird bei gleichmäßiger Spannungsverteilung, also in genügender Entfernung vom Angriffspunkt der Kraft, die Zug- oder Druckspannung σ_{z,d}= Zug- oder Druckkraft F/Querschnittsfläche A {Zug- und Druck-Hauptgleichung} σ_{z,d}=F/A\\qquad σ&F&A N/mm2 & N&mm2 Je nach vorliegender Aufgabe kann die Hauptgleichung umgestellt werden zur Berechnung des erforderlichen Querschnitts (Querschnittsnachweis): A_{erf}=F/σ_{zul} Berechnung der vorhandenen Spannung (Spannungsnachweis): σ_{vorh}=F/A Berechnung der maximal zulässigen Belastung (Belastungsnachweis): F_{max}=σ_{zul}A Treten Zug- und Druckspannungen in einer Rechnung gleichzeitig auf, werden sie durch den Index z und d oder durch das Vorzeichen + und - unterschieden.

  2. Heat transfer at the mold-metal interface in permanent mold casting of aluminum alloys project. Quarterly project status report, April 1--June 30, 1998

    SciTech Connect

    Pehlke, R.D.; Hao, S.W.

    1998-06-30

    Extensive progress in development of an HTC (heat transfer coefficient) Evaluator and in the preparation of the experiments at CMI and Amcast have been achieved in the last three months. The interface of the HTC Evaluator has been developed in Visual C++ for the PC platform. It provides a tool to collect and store the published data on heat transfer coefficients in a database for further analysis. It also supports the mathematical model for evaluation of heat transfer coefficients. More than 100 papers related to this project have been cited and most of them have been collected. The preparation of the experiments at CMI is almost completed. A hockey-puck mold has been selected for the experiments for squeeze casting and semi-solid casting. A direct cavity pressure measurement system was purchased from Kistler. The pressure probes and data acquisition software as well as the necessary accessories have been delivered. The instrumented mold modification has been designed and the modifications completed. At Amcast Automotive, a new wheel-like mold for low-pressure permanent mold casting was designed. The CAD file for mold fabrication has been generated. The modeling of the casting has been done. An extensive survey on the ultrasonic gap formation measurement was fulfilled. It is concluded that the ultrasonic probe is capable of measuring a gap under the authors` casting conditions. In the last three months, four project meetings has been organized and held with the industrial partners.

  3. Assisted Dying in Canada.

    PubMed

    Schuklenk, Udo

    2014-01-01

    This paper makes an affirmative ethical case in favour of the decriminalization of assisted dying in Canada. It then proceeds to defending the affirmative case against various slippery-slope arguments that are typically deployed by opponents of assisted dying. Finally, a recent case of questionable professional conduct by anti-euthanasia campaigners cum academics is flagged as a warning to all of us not to permit the quality of the professional debate to deteriorate unacceptably, despite the personal emotional investments involved on all sides of the debate.

  4. Static and Dynamic Studies on LiNi1/3 Co1/3 Mn1/3 O2 -Based Suspensions for Semi-Solid Flow Batteries.

    PubMed

    Biendicho, Jordi Jacas; Flox, Cristina; Sanz, Laura; Morante, Joan Ramon

    2016-08-09

    LiNi1/3 Co1/3 Mn1/3 O2 (LNCM)-based suspensions for semi-solid flow batteries (SSFB) have been investigated by galvanostatic charge/discharge an electrochemical impedance spectroscopy (EIS). The resistance and electrochemical performance of half cells (vs. Li/Li(+) ) as well as the rheological properties are affected by the content of a commercially available electroconductive carbon black [KetjenBlack (KB), AkzoNobel] in the suspensions. In static conditions, a cell with 11.87 and 13.97 % by volume of KB and LNCM delivers high capacity 130 mA h g(-1) at 5 mA cm(-2) , respectively, and a coulombic efficiency of 90 % over 10 injections. The impedance of half cells is dominated by a contact resistance fitted with a resistor and a constant phase element (CPE) in parallel. In flow conditions, cell potential depends on applied current density and measured over potentials are ∼0.3 and 0.7 V for 0.33 and 1 mA cm(-2) , respectively, for a cell containing a suspension with 9.53 % in volume of KB and 13.90 % in volume of LNCM. The effect of the cell contact resistance on the electrochemical performance is discussed. ©2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  5. When Somebody Dies

    MedlinePlus

    ... to have fun with. That absence leaves a big hole in our lives. Maybe you had a pet that died . Remember the first few times you walked into the house after your dog or cat was gone? It was strange not to have ...

  6. When a Baby Dies.

    ERIC Educational Resources Information Center

    Church, Martha Jo; And Others

    Written especially for grieving mothers whose babies have died, this booklet offers an overview of stages and experiences through which bereaved parents commonly pass. Specifically, the text is intended to give comfort to bereaved parents, offer insight into the grieving process, and provide thoughts on leave-taking ceremonies. The first section…

  7. Die Kosmologie der Griechen.

    NASA Astrophysics Data System (ADS)

    Mittelstraß, J.

    Contents: 1. Mythische Eier. 2. Thales-Welten. 3. "Alles ist voller Götter". 4. Griechische Astronomie. 5. "Rettung der Phänomene". 6. Aristotelische Kosmololgie. 7. Aristoteles-Welt und Platon-Welt. 8. Noch einmal: die Göttlichkeit der Welt. 9. Griechischer Idealismus.

  8. Poetry and the Dying.

    ERIC Educational Resources Information Center

    Kramer, Aaron

    1992-01-01

    Demonstrates roles poetry can play as people confront the death of loved ones and their own dying. Gives examples of Heinrich Heine transforming his agony into art and, from the poetry of two college students, both in advanced stages of neurological disease, which was read aloud in class, teaching all present something about how to approach their…

  9. When a Student Dies.

    ERIC Educational Resources Information Center

    Dowling-Sendor, Benjamin

    1998-01-01

    A student athlete died after the first day of football practice in Texas. His parents brought suit (Roventini v. Pasadena Independent School District) for monetary damages in federal district court contending that the defendants violated the student's rights. Presents the judge's analysis of the legal issues. Advises board members and…

  10. Dying to Play.

    ERIC Educational Resources Information Center

    Miller, John K.

    1998-01-01

    In August 1995, a young football player died as a result of heat exhaustion suffered on the first day of football practice in Arkansas. Spurred by this tragedy, the district made some changes that every school district with an athletic program should consider. These include using a heat-stress monitor; abandoning the practice of group physical…

  11. Dying in hospital.

    PubMed

    Pearce, Lynne

    2016-06-22

    While surveys consistently show that about two thirds of people want to die at home, more than half of all deaths happen in hospitals. And in their last days, many people are cared for by generalist nursing staff who may be reticent, or even afraid, to talk about what is happening.

  12. When Somebody Dies

    MedlinePlus

    ... container is gone, but what's inside — the water — remains. The part of a person that's left after the body dies is often called the "soul" or "spirit." Some people believe the soul is the part of a human that loves, feels, and creates; it's the part ...

  13. INTERNAL ADAPTATION OF CAST TITANIUM CROWNS

    PubMed Central

    da Rocha, Sicknan Soares; Adabo, Gelson Luis; Ribeiro, Ricardo Faria; Fonseca, Renata Garcia

    2007-01-01

    As the adaptation of titanium crowns obtained by Rematitan Plus investment, specific for titanium, is not recognized to be suitable, this study evaluated the effect of the concentration of the specific liquid and the temperature of the mold of investments on the internal misfit of crowns cast on commercially pure titanium. Individual dies of epoxy resin were obtained, representing teeth prepared for full-crown restoration with a 6-degree axial surface convergence angle and shoulder (1.0 mm). For the waxing of each crown, a ring-shaped stainless steel matrix (8.0mm internal diameter; 7.5 mm height) was adapted above the individual dies of epoxy resin. The Rematian Plus investment was mixed according to the manufacturer's instructions using two different concentrations of the specific liquid: 100%, 75%. Casting was performed in a Discovery Plasma Ar-arc vacuum-pressure casting machine with molds at temperatures of 430°C, 515°C and 600°C. The crowns were cleaned individually in a solution (1% HF + 13% HNO3) for 10 min using a ultrasonic cleaner, with no internal adaptations, and luted with zinc phosphate cement under a 5 kg static load. The crown and die assemblies were embedded in resin and sectioned longitudinally. The area occupied by cement was observed using stereoscopic lens (10X) and measured by the Leica Qwin image analysis system (mm2). The data for each experimental condition (n=8) were analyzed by Kruskal-Wallis non-parametric test (á=0.05). The results showed that liquid dilution and the increase in mold temperature did not significantly influence the levels of internal fit of the cast titanium crowns. The lowest means (±SD) of internal misfit were obtained for the 430°C/100%: (7.25 mm2 ±1.59) and 600°C/100% (8.8 mm2 ±2.25) groups, which presented statistically similar levels of internal misfit. PMID:19089139

  14. 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

  15. Herausforderungen durch die deutsche Wiedervereinigung

    NASA Astrophysics Data System (ADS)

    Stäglin, Reiner

    Die Wiedervereinigung stellte auch die Statistik vor große Aufgaben. Die als Organ der staatlichen Planung staatsnah orientierte Statistik der DDR musste auf das zur Neutralität und wissenschaftlichen Unabhängigkeit verpflichtete System der Bundesrepublik umgestellt werden. Ebenso verlangten die Universitäten eine Neuorientierung. Die Deutsche Statistische Gesellschaft hat sich vor allem dreier Aufgaben mit großem Engagement, aber auch mit Bedachtsamkeit angenommen: Aufnahme und Integration der Statistiker aus den neuen Bundesländern in die Gesellschaft, Begleitung der Neuausrichtung des Faches Statistik an deren Hochschulen und Sicherung sowie Nutzung von Datenbeständen der ehemaligen DDR.

  16. Application of Numerical Optimization to Aluminum Alloy Wheel Casting

    NASA Astrophysics Data System (ADS)

    Duan, J.; Reilly, C.; Maijer, D. M.; Cockcroft, S. L.; Phillion, A. B.

    2015-06-01

    A method of numerically optimizing the cooling conditions in a low- pressure die casting process from the standpoint of maintaining good directional solidification, high cooling rates and reduced cycle times has been developed for the production of aluminumalloy wheels. The method focuses on the optimization of cooling channel timing and utilizes an open source numerical optimization algorithm coupled with an experimentally validated, ABAQUS-based, heat transfer model of the casting process. Key features of the method include: 1) carefully designed constraint functions to ensure directional solidification along the centerlineof the wheel; and 2) carefully formulated objective functions to maximize cooling rate. The method has been implemented on a prototype production die and the results have been tested with plant trial test.

  17. Sealing micropores in thin castings

    NASA Technical Reports Server (NTRS)

    Mersereau, G. A.; Nitzschke, G. O.; Ochs, H. L.; Sutch, F. S.

    1981-01-01

    Microscopic pores in thin-walled aluminum castings are sealed by impregnation pretreatment. Technique was developed for investment castings used in hermetically sealed chassic for electronic circuitry. Excessively high leakage rates were previously measured in some chassis.

  18. 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.

  19. 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.

  20. Die kalte Zunge

    NASA Astrophysics Data System (ADS)

    Bartels, Sören; Müller, Rüdiger

    Gefühlte Temperaturen. Ist ein Null Grad Celsius kalter Metallstab eigentlich kälter als ein Holzstab mit der selben Temperatur? Rein physikalisch gesehen natürlich nicht, aber wenn wir beide Stäbe anfassen, kommt uns der Metallstab deutlich kälter vor. Und wer kennt nicht die Szene aus dem Film Dumm und Dümmer in der Harry mit seiner Zunge am Metallrahmen des Skilifts hängen bleibt.Würde das auch passieren, wenn man an einem eiskalten Stück Holz lecken würde? Wohl kaum, doch woran liegt das eigentlich? Unterschiedliche Materialien haben verschiedene Fähigkeiten, Wärme zu übertragen und zu leiten. So transportiert Metall die von der Zunge ausgehende Wärme sehr schnell weiter und verändert seine Temperatur kaum, während die Zunge abkühlt. Holz hingegen leitet Wärme fast gar nicht und daher wird der Teil, der von der Zunge berührt wird, aufgewärmt.

  1. Skin surface pressure beneath an above-the-knee cast: plaster casts compared with fiberglass casts.

    PubMed

    Davids, J R; Frick, S L; Skewes, E; Blackhurst, D W

    1997-04-01

    Complications related to immobilization in a cast after an injury or an operation may be related to the materials used for the cast or to the techniques of application, or to both. To evaluate the widely held clinical opinion that the use of a fiberglass cast is dangerous and inappropriate when subsequent swelling of the extremity is anticipated, we studied the skin surface pressures that were generated beneath above-the-knee casts made with different materials and applied with different techniques. A prosthetic model of the lower extremity was designed with an expandable calf compartment to simulate swelling after an injury or an operation. With use of this model, we measured the skin surface pressure beneath a plaster-of-Paris cast, a fiberglass cast that had been applied with a standard technique, and a fiberglass cast that had been applied with a stretch-relax technique. The highest mean skin surface pressure after application of the cast (p < 0.001) and after simulated swelling of the limb (p = 0.04) was generated by the fiberglass cast that had been applied with a standard technique. The lowest mean skin surface pressure after application of the cast (p = 0.006), simulated swelling of the limb (p < 0.001), and all subsequent steps of the experimental protocol (p < 0.001) was generated by the fiberglass cast that had been applied with the stretch-relax technique. The mean skin surface pressure generated by the plaster cast and by the fiberglass cast applied with the standard technique did not return to the value before application of the cast until anterior and posterior longitudinal cuts had been made in the cast and the cast had been spread at those cuts. When the fiber-glass cast had been applied with the stretch-relax technique, the mean pressure returned to the baseline value after only an anterior longitudinal cut and spreading at that cut. The principal pitfall of the use of a fiberglass cast is related to the technique of application. When the

  2. 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.

  3. Evaluation of an improved centrifugal casting machine.

    PubMed

    Donovan, T E; White, L E

    1985-05-01

    A Type III gold alloy, a silver-palladium alloy, and a base metal alloy were cast in two different centrifugal casting machines. With the number of complete cast mesh squares as an indicator of castability, the Airspin casting machine produced superior castings with all three alloys. The base metal alloy produced the greatest number of complete squares with both casting machines.

  4. Heated die facilitates tungsten forming

    NASA Technical Reports Server (NTRS)

    Chattin, J. H.; Haystrick, J. E.; Laughlin, J. C.; Leidy, R. A.

    1966-01-01

    Tungsten forming in a press brake employs a bottom die assembly with a heating manifold between two water-cooled die sections. The manifold has hydrogen-oxygen burners spaced along its length for even heat during forming.

  5. 'We Have No Dying Patients'

    ERIC Educational Resources Information Center

    Robinson, Lisa

    1974-01-01

    A course on death and dying offered by the University of Maryland School of Nursing focuses on developing relationships between health care workers and dying people, using actual clients as the vehicle for learning. (Author/EA)

  6. ToxCast Dashboard

    EPA Pesticide Factsheets

    The ToxCast Dashboard helps users examine high-throughput assay data to inform chemical safety decisions. To date, it has data on over 9,000 chemicals and information from more than 1,000 high-throughput assay endpoint components.

  7. Casting and Angling.

    ERIC Educational Resources Information Center

    Little, Mildred J.; Bunting, Camille

    The self-contained packet contains background information, lesson plans, 15 transparency and student handout masters, drills and games, 2 objective examinations, and references for teaching a 15-day unit on casting and angling to junior high and senior high school students, either as part of a regular physical education program or as a club…

  8. 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…

  9. Microporosity in casting alloys.

    PubMed

    Lewis, A J

    1975-06-01

    Three series of tensile test pieces were produced using a nickel base partial denture casting alloy. For the first series induction heating was employed, for the second a resistance crucible, and for the third an oxy-acetylene torch. Samples from each series were sectioned longitudinally, mounted, polished and examined microscopically for evidence of microporosity.

  10. 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.

  11. 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.

  12. Casting and Angling.

    ERIC Educational Resources Information Center

    Little, Mildred J.; Bunting, Camille

    The self-contained packet contains background information, lesson plans, 15 transparency and student handout masters, drills and games, 2 objective examinations, and references for teaching a 15-day unit on casting and angling to junior high and senior high school students, either as part of a regular physical education program or as a club…

  13. Differential Scanning Calorimetry (DSC) and Thermodynamic Prediction of Liquid Fraction vs Temperature for Two High-Performance Alloys for Semi-Solid Processing (Al-Si-Cu-Mg (319s) and Al-Cu-Ag (201))

    NASA Astrophysics Data System (ADS)

    Zhang, Duyao; Atkinson, Helen V.; Dong, Hongbiao; Zhu, Qiang

    2017-10-01

    There is a need to extend the application of semi-solid processing (SSP) to higher performance alloys such as 319s (Al-Si-Cu-Mg) and 201 (Al-Cu-Ag). The melting of these two alloys was investigated using differential scanning calorimetry (DSC) and thermodynamic prediction. The alloys had been processed by magneto-hydrodynamic (MHD) stirring before receipt to produce a microstructure suitable for SSP. The DSC results for the as-received MHD material were compared with those for material which has been taken through a complete DSC cycle and then reheated for a second DSC run. The effects of microsegregation were then analyzed. A higher liquid fraction for a particular temperature is found in the second DSC run than the first. Microstructural observations suggest this is because the intermetallics which form during the first cooling cycle tend to co-located. Quaternary and ternary reactions then occur during the second DSC heat and the co-location leads to enhanced peaks. The calculated liquid fraction is lower with 10 K/min DSC heating rate comparing with 3 K/min at a given temperature. The DSC scan rate must therefore be carefully considered if it is to be used to identify temperature parameters or the suitability of alloys for SSP. In addition, the starting material for DSC must represent the starting material for the SSP. With thermodynamic prediction, the equilibrium condition will provide better guidance for the thixoforming of MHD stirred starting material than the Scheil condition. The Scheil mode approximates more closely with a strongly microsegregated state.

  14. Accuracy of Multiple Pour Cast from Various Elastomer Impression Methods.

    PubMed

    Haralur, Satheesh B; Saad Toman, Majed; Ali Al-Shahrani, Abdullah; Ali Al-Qarni, Abdullah

    2016-01-01

    The accurate duplicate cast obtained from a single impression reduces the profession clinical time, patient inconvenience, and extra material cost. The stainless steel working cast model assembly consisting of two abutments and one pontic area was fabricated. Two sets of six each custom aluminum trays were fabricated, with five mm spacer and two mm spacer. The impression methods evaluated during the study were additional silicone putty reline (two steps), heavy-light body (one step), monophase (one step), and polyether (one step). Type IV gypsum casts were poured at the interval of one hour, 12 hours, 24 hours, and 48 hours. The resultant cast was measured with traveling microscope for the comparative dimensional accuracy. The data obtained were subjected to Analysis of Variance test at significance level <0.05. The die obtained from two-step putty reline impression techniques had the percentage of variation for the height -0.36 to -0.97%, while diameter was increased by 0.40-0.90%. The values for one-step heavy-light body impression dies, additional silicone monophase impressions, and polyether were -0.73 to -1.21%, -1.34%, and -1.46% for the height and 0.50-0.80%, 1.20%, and -1.30% for the width, respectively.

  15. Accuracy of Multiple Pour Cast from Various Elastomer Impression Methods

    PubMed Central

    Saad Toman, Majed; Ali Al-Shahrani, Abdullah; Ali Al-Qarni, Abdullah

    2016-01-01

    The accurate duplicate cast obtained from a single impression reduces the profession clinical time, patient inconvenience, and extra material cost. The stainless steel working cast model assembly consisting of two abutments and one pontic area was fabricated. Two sets of six each custom aluminum trays were fabricated, with five mm spacer and two mm spacer. The impression methods evaluated during the study were additional silicone putty reline (two steps), heavy-light body (one step), monophase (one step), and polyether (one step). Type IV gypsum casts were poured at the interval of one hour, 12 hours, 24 hours, and 48 hours. The resultant cast was measured with traveling microscope for the comparative dimensional accuracy. The data obtained were subjected to Analysis of Variance test at significance level <0.05. The die obtained from two-step putty reline impression techniques had the percentage of variation for the height −0.36 to −0.97%, while diameter was increased by 0.40–0.90%. The values for one-step heavy-light body impression dies, additional silicone monophase impressions, and polyether were −0.73 to −1.21%, −1.34%, and −1.46% for the height and 0.50–0.80%, 1.20%, and −1.30% for the width, respectively. PMID:28096815

  16. Dimensional accuracy of an epoxy die material using different polymerization methods.

    PubMed

    Prisco, Rosario; Cozzolino, Giancarlo; Vigolo, Paolo

    2009-02-01

    Shrinkage of resinous die materials during setting reaction limits their acceptance, even though these materials show several advantages compared to stone die materials with respect to strength, abrasion resistance, and detail reproduction. The purpose of this study was to determine if retarding the setting reaction during polymerization and altering the base-to-catalyst ratio, as suggested by previous studies, can be recommended for resinous die materials to reduce the inaccuracy in transferring the spatial position of teeth or implants from the oral cavity to the master cast. A Blue Star Type E epoxy resin die material was tested. A reference triangular metal master die was fabricated. Forty medium-consistency polyether impressions of this model were made. Four groups (S, M, N, P) were compared, and ten dies were fabricated for each group. In the S group, the epoxy resin die material was manipulated according to the manufacturer's instructions; in the other three groups, the epoxy resin die material was manipulated by retarding the setting reaction and by modifying the epoxy resin base/activator ratio. One-way ANOVA revealed significant differences between the four groups of the epoxy resin die material (p < 0.0001). Tukey's multiple comparisons test (p < 0.05) revealed that none of the resin groups was similar to the metal master die for each of the tested dimensions (A, B, and C). For the specific dimension C, however, the P group was statistically closer to the metal master die than the S group. The epoxy resin die material tested in this research did not improve its dimensional accuracy following retarding polymerization or modifying the epoxy resin base/activator ratio. The epoxy resin material exhibited higher contraction variability across all tested groups. This shrinkage can significantly affect the dimension of the master cast.

  17. Designing a Die for Hydroforming

    NASA Astrophysics Data System (ADS)

    Vasile, Radu

    2016-12-01

    Designing a die is in every application field an intensive process of bringing together know how from design, testing and every-day use from previous dies with the new application requirements. Contribution deals with a knowledge oriented, modular and feature integrated computer aided design system for die development. This paper describes the concepts behind designing a hydroforming die for sheet metal forming, with easy application-use in small workshops for testing hydroforming capabilities of different materials.

  18. Computer cast blast modelling

    SciTech Connect

    Chung, S.; McGill, M.; Preece, D.S.

    1994-07-01

    Cast blasting can be designed to utilize explosive energy effectively and economically for coal mining operations to remove overburden material. The more overburden removed by explosives, the less blasted material there is left to be transported with mechanical equipment, such as draglines and trucks. In order to optimize the percentage of rock that is cast, a higher powder factor than normal is required plus an initiation technique designed to produce a much greater degree of horizontal muck movement. This paper compares two blast models known as DMC (Distinct Motion Code) and SABREX (Scientific Approach to Breaking Rock with Explosives). DMC, applies discrete spherical elements interacted with the flow of explosive gases and the explicit time integration to track particle motion resulting from a blast. The input to this model includes multi-layer rock properties, and both loading geometry and explosives equation-of-state parameters. It enables the user to have a wide range of control over drill pattern and explosive loading design parameters. SABREX assumes that heave process is controlled by the explosive gases which determines the velocity and time of initial movement of blocks within the burden, and then tracks the motion of the blocks until they come to a rest. In order to reduce computing time, the in-flight collisions of blocks are not considered and the motion of the first row is made to limit the motion of subsequent rows. Although modelling a blast is a complex task, the DMC can perform a blast simulation in 0.5 hours on the SUN SPARCstation 10--41 while the new SABREX 3.5 produces results of a cast blast in ten seconds on a 486-PC computer. Predicted percentage of cast and face velocities from both computer codes compare well with the measured results from a full scale cast blast.

  19. Psychotherapy with Older Dying Persons.

    ERIC Educational Resources Information Center

    Dye, Carol J.

    Psychotherapy with older dying patients can lead to problems of countertransference for the clinician. Working with dying patients requires flexibility to adapt basic therapeutics to the institutional setting. Goals of psychotherapy must be reconceptualized for dying clients. The problems of countertransference arise because clinicians themselves…

  20. Cast Aluminum Primary Aircraft Structure

    DTIC Science & Technology

    1979-12-01

    ABSTRAC R A A A357 cast aluminum alloy forward fuselage pressure bulkhead has been developed and manufactured for the AMST-YC-14 aircraft. This work...urring in castings. Test coupons were! removed from castings containing defU-ts and subjected to repeated loads. The shift of the S-N curve for A357 ...selected for the casting is A357 . The cast bulkhead (Fig 2) measures approximately 2.29 m (7.5 ft) by 1.37 m (4.5 ft). It is designed to replace the

  1. Precision cast vs. wrought superalloys

    NASA Technical Reports Server (NTRS)

    Tien, J. K.; Borofka, J. C.; Casey, M. E.

    1986-01-01

    While cast polycrystalline superalloys recommend themselves in virtue of better 'buy-to-fly' ratios and higher strengthening gamma-prime volume fractions than those of wrought superalloys, the expansion of their use into such critical superalloy applications as gas turbine hot section components has been slowed by insufficient casting process opportunities for microstructural control. Attention is presently drawn, however, to casting process developments facilitating the production of defect-tolerant superalloy castings having improved fracture reliability. Integrally bladed turbine wheel and thin-walled turbine exhaust case near-net-shape castings have been produced by these means.

  2. Precision cast vs. wrought superalloys

    NASA Technical Reports Server (NTRS)

    Tien, J. K.; Borofka, J. C.; Casey, M. E.

    1986-01-01

    While cast polycrystalline superalloys recommend themselves in virtue of better 'buy-to-fly' ratios and higher strengthening gamma-prime volume fractions than those of wrought superalloys, the expansion of their use into such critical superalloy applications as gas turbine hot section components has been slowed by insufficient casting process opportunities for microstructural control. Attention is presently drawn, however, to casting process developments facilitating the production of defect-tolerant superalloy castings having improved fracture reliability. Integrally bladed turbine wheel and thin-walled turbine exhaust case near-net-shape castings have been produced by these means.

  3. Dying with dignity.

    PubMed

    Madan, T N

    1992-08-01

    Death is a theme of central importance in all cultures, but the manner in which it is interpreted varies from society to society. Even so, traditional cultures, including Christian, Hindu and Jain religious traditions, exhibited a positive attitude to death and did not look upon it in a dualistic framework of good vs bad, or desirable vs undesirable. Nor was pessimism the dominant mood in their thinking about death itself. A fundamental paradigm shift occurred in the West in the eighteenth century when death was desacralized and transformed into a secular event amenable to human manipulation. From those early beginnings, dying and death have been thoroughly medicalized and brought under the purview of high technology in the twentieth century. Once death is seen as a problem for professional management, the hospital displaces the home, and specialists with different kinds and degrees of expertise take over from the family. Everyday speech and the religious idiom yield place to medical jargon. The subject (an ageing, sick or dying person) becomes the object of this make-believe yet real world. As the object of others' professional control, he or she loses the freedom of self-assessment, expression and choice. Or, he or she may be expected to choose when no longer able to do so. Thus, not only freedom but dignity also is lost, and lawyers join doctors in crisis manipulation and perpetuation. Although the modern medical culture has originated in the West, it has gradually spread to all parts of the world, subjugating other kinds of medical knowledge and other attitudes to dying and death.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. A comparative assessment of crystallite size and lattice strain in differently cast A356 aluminium alloy

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Roy, H.; Lohar, A. K.; Samanta, S. K.; Tiwari, S.; Dutta, K.

    2015-02-01

    In this investigation, A356 aluminium alloy has been prepared by different routes viz. gravity casting, rheo pressure die casting (RPDC) and RPDC with T6 heat treatment. X-ray diffraction studies of these samples have been done in the scanning range of 20 - 90°. X-ray peak broadening analysis has been used to estimate the crystallite size and lattice stain, in all the samples. The sample prepared by RPDC with T6 treatment has comparatively smaller crystallite size and lesser lattice strain than gravity cast and RPDC samples.

  5. 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.

  6. Low Temperature Consolidation of Micro/Nanosilver Die-Attach Preforms

    NASA Astrophysics Data System (ADS)

    McCoppin, Jared; Reitz, Thomas L.; Miller, Ryan; Vijwani, Hema; Mukhopadhyay, Sharmila; Young, Daniel

    2014-09-01

    Organically passivated silver nanopowder paste-based sintering is considered a promising solution for die-attach in high temperature power and sensing electronic devices. However, oxygen requirements during burnout and inherently high shrinkage rates limit their use to small die sizes. This work reports an alternative fabrication method that resolves decomposition and shrinkage issues of the die-attach by utilizing a prestressed optimized tape cast mixture of micro- and nanosilver particles with a polypropylene carbonate binder. The effects of prestressing, micro/nanosilver bimodal distribution, and polymer content on resulting microstructure and shear strength were investigated. Prior to application as a die-attach, uniaxial compression of the tape was found to significantly decrease shrinkage and improve green strength. This pre-stressing strategy allows for a decoupling of the resulting die-attach materials properties from the pressure applied during assembly. Bimodal mixtures consisting of 1-3 μm spherical powders with nanosilver resulted in shear strengths comparable to those of pure nanosilver. Shear strength decreased as bimodal particle size increased above 5 μm. A polymer content of ˜10 wt.% polypropylene carbonate combined with prestressing was identified as optimal for maximizing die-attach shear strength while still maintaining pliability and formability. Tape casts that were prestressed to 212 MPa by uniaxially compression and formulated with 10 wt.% of polypropylene carbonate resulted in a die-attach material with a shear strength of 54 MPa when sintered. These materials were used to demonstrate void-free 25-mm2 die-attach assemblies, suggesting that tape cast micro/nanosilver materials may be a promising die-attach method for high temperature and large-area electronics devices.

  7. Rep. George Brown dies

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    George E. Brown, ranking Democratic member of the U.S. House of Representatives Science Committee, died on July 15 at the age of 79 due to complications following a heart valve replacement last May. He was a strong advocate for science and environmental protection measures, and an independent thinker who sometimes found himself alone or far ahead of other people on issues. A congressman for 34 years who represented first the 29th Congressional District and then the 42nd District in California, Brown served on the science committee since 1965 and was chair from 1991 through 1994.

  8. 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.

  9. First Results of Energy Saving at Process Redesign of Die Forging Al-Alloys

    SciTech Connect

    Pepelnjak, Tomaz; Kuzman, Karl; Kokol, Anton

    2011-05-04

    The contribution deals with eco-friendly solutions for shortened production chains of forging light alloys. During the die forging operations a remarkable amount of material goes into the flash and later on into chips during finish machining. These low value side products are rich with embedded energy therefore recycling or reprocessing could be very energy saving procedure.In cooperation with a die forging company a shortened reprocessing cycle has been studied starting from re-melting the forging flash and without additional heating to cast preforms for subsequent die forging. As such preforms have not as good formability characteristics as those done from extruded billets the isothermal forging process has been adopted. First results showed that without cracks and other defects the formability is sufficient for a broad spectrum of forgings.To improve the formability a homogenization process of cast preforms has been implemented. As the process started immediately after casting, amount of additional energy for heating was minimized. To reduce voids forging process was redesigned in a way to assure greater hydrostatic pressures in parts during forging. First results were promising therefore research is going towards improving processes without adding significantly more energy as it is needed for casting with homogenization and die forging.

  10. 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.

  11. [Casting faults and structural studies on bonded alloys comparing centrifugal castings and vacuum pressure castings].

    PubMed

    Fuchs, P; Küfmann, W

    1978-07-01

    The casting processes in use today such as centrifugal casting and vacuum pressure casting were compared with one another. An effort was made to answer the question whether the occurrence of shrink cavities and the mean diameter of the grain of the alloy is dependent on the method of casting. 80 crowns were made by both processes from the baked alloys Degudent Universal, Degudent N and the trial alloy 4437 of the firm Degusa. Slice sections were examined for macro and micro-porosity and the structural appearance was evaluated by linear analysis. Statistical analysis showed that casting faults and casting structure is independent of the method used and their causes must be found in the conditions of casting and the composition of the alloy.

  12. Advanced Casting Technology

    DTIC Science & Technology

    1982-08-01

    water , aged 5 hrs on 155 C. Fig. 15 Time required for 19 mm thick test slab casting, poured in sand, to cool...fraction rare earth could be solution treated, quenched and artificially aged to give high tensile properties at room temperature, which were well...Strength. MagnesiumrZincrRare. Earth . Alloys In parallel with the development of silver containing alloy systems, further improvements were obtained

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Effect of dental technician disparities on the 3-dimensional accuracy of definitive casts.

    PubMed

    Emir, Faruk; Piskin, Bulent; Sipahi, Cumhur

    2017-03-01

    Studies that evaluated the effect of dental technician disparities on the accuracy of presectioned and postsectioned definitive casts are lacking. The purpose of this in vitro study was to evaluate the accuracy of presectioned and postsectioned definitive casts fabricated by different dental technicians by using a 3-dimensional computer-aided measurement method. An arch-shaped metal master model consisting of 5 abutments resembling prepared mandibular incisors, canines, and first molars and with a 6-degree total angle of convergence was designed and fabricated by computer-aided design and computer-aided manufacturing (CAD-CAM) technology. Complete arch impressions were made (N=110) from the master model, using polyvinyl siloxane (PVS) and delivered to 11 dental technicians. Each technician fabricated 10 definitive casts with dental stone, and the obtained casts were numbered. All casts were sectioned, and removable dies were obtained. The master model and the presectioned and postsectioned definitive casts were digitized with an extraoral scanner, and the virtual master model and virtual presectioned and postsectioned definitive casts were obtained. All definitive casts were compared with the master model by using computer-aided measurements, and the 3-dimensional accuracy of the definitive casts was determined with best fit alignment and represented in color-coded maps. Differences were analyzed using univariate analyses of variance, and the Tukey honest significant differences post hoc tests were used for multiple comparisons (α=.05). The accuracy of presectioned and postsectioned definitive casts was significantly affected by dental technician disparities (P<.001). The largest dimensional changes were detected in the anterior abutments of both of the definitive casts. The changes mostly occurred in the mesiodistal dimension (P<.001). Within the limitations of this in vitro study, the accuracy of presectioned and postsectioned definitive casts is susceptible

  18. Die großen Zeppeline: Die Geschichte des Luftschiffbaus

    NASA Astrophysics Data System (ADS)

    Kleinheins, Peter; Meighörner, Wolfgang

    Über die glanzvolle Zeit der Zeppeline sind viele Bücher erschienen, die vorwiegend den Einsatz der Luftschiffe in Frieden und Krieg schildern. Nur wenige wissen, dass die Baugeschichte der Zeppeline eine der faszinierendsten Phasen der modernen Technik ist. Peter Kleinheins hat dieses Geschehen sachkundig aufgearbeitet und zusammengestellt. Entstanden ist eine reich illustrierte Dokumentation in einer interessanten Mischform aus zeitgenössischen Berichten und hochwertigen Originalquellen.

  19. Cast Aluminum Structures Technology (CAST). Phase I. Preliminary Design

    DTIC Science & Technology

    1977-05-01

    49 26 Assumed Crack Growth Rate -- A357 . . . . . . . . . .. 50 27 Flaw Growth at Hole of Gear Attachment Point .... .... 52 28 A357 S-N...wo TABLES Number ?Ile 1 Statistics on.16 Classes of A357 Aluminum Casting Data .. 14 2 "CAST" Preliminary Design Allowables .. .. .. ....... 20 3...damage tolerance criteria; development of preliminary design allowables data for A357 aluminum casting alloy to be used for design until completion

  20. Cast Aluminum Structures Technology (CAST) Phase VI. Technology Transfer.

    DTIC Science & Technology

    1980-04-01

    system and ultimately fill the mold cavity to produce a casting. The fluidity of a given metal is measured with standard fluidity test molds. One...showed that the pouring temperature for large, thin-wall aluminum castings must be (1) high enough to provide sufficient fluidity for complete filling of...castings should have the following specific characteristics: good flowability , permeability, tensile strength, and compressive strength; high hot

  1. Comparison of the Microstructure and Mechanical Properties of As-Cast A356/SiC MMC Processed by ARB and CAR Methods

    NASA Astrophysics Data System (ADS)

    Jamaati, Roohollah; Amirkhanlou, Sajjad; Toroghinejad, Mohammad Reza; Niroumand, Behzad

    2012-07-01

    Accumulative roll bonding (ARB) and continual annealing and roll-bonding (CAR) processes were used in this study for improving the microstructure and mechanical properties of the A356/10 vol.% SiC metal matrix composite (MMC) produced by semi-solid metal processing (SSM). The results showed that using the ARB and CAR processes led to the following points: (a) the uniformity of the silicon and silicon carbide in the aluminum matrix improved, (b) the Si particles became finer and more spheroidal in appearance, (c) the porosity disappeared, (d) the bonding quality between the reinforcement and the matrix improved, (e) the particle-free zone disappeared, and therefore (f) the tensile strength (TS), elongation, and formability index of the MMC samples improved. However, it was found that the CAR process is a better method for improvement of microstructure and mechanical properties of as-cast MMC compared to ARB process.

  2. Accurate defect die placement and nuisance defect reduction for reticle die-to-die inspections

    NASA Astrophysics Data System (ADS)

    Wen, Vincent; Huang, L. R.; Lin, C. J.; Tseng, Y. N.; Huang, W. H.; Tuo, Laurent C.; Wylie, Mark; Chen, Ellison; Wang, Elvik; Glasser, Joshua; Kelkar, Amrish; Wu, David

    2015-10-01

    Die-to-die reticle inspections are among the simplest and most sensitive reticle inspections because of the use of an identical-design neighboring-die for the reference image. However, this inspection mode can have two key disadvantages: (1) The location of the defect is indeterminate because it is unclear to the inspector whether the test or reference image is defective; and (2) nuisance and false defects from mask manufacturing noise and tool optical variation can limit the usable sensitivity. The use of a new sequencing approach for a die-to-die inspection can resolve these issues without any additional scan time, without sacrifice in sensitivity requirement, and with a manageable increase in computation load. In this paper we explore another approach for die-to-die inspections using a new method of defect processing and sequencing. Utilizing die-to-die double arbitration during defect detection has been proven through extensive testing to generate accurate placement of the defect in the correct die to ensure efficient defect disposition at the AIMS step. The use of this method maintained the required inspection sensitivity for mask quality as verified with programmed-defectmask qualification and then further validated with production masks comparing the current inspection approach to the new method. Furthermore, this approach can significantly reduce the total number of defects that need to be reviewed by essentially eliminating the nuisance and false defects that can result from a die-to-die inspection. This "double-win" will significantly reduce the effort in classifying a die-to-die inspection result and will lead to improved cycle times.

  3. Where people die.

    PubMed Central

    Katz, B P; Zdeb, M S; Therriault, G D

    1979-01-01

    Death certificates for 1977 filed with the New York State Department of Health were studied to determine where people died. Data were examined by the location and cause of death and by the age, sex, race, and marital status of the decedent. Comparisons were made with a similar study in which U.S. data were used for 1958 events. Approximately 60 percent of all the 1977 deaths in upstate New York occurred in hospitals; only 27 percent occurred outside an institution. The location of death varied by all the factors studied. Within all age categories, males had a higher percentage of hospital deaths. In those age categories in which nursing home deaths comprised a significant proportion of total deaths, females had a higher percentage of such deaths than males. Differences in the location of death according to its cause reflect the nature of the cause of death, for example, whether it was of sudden onset or the result of chronic disease. Most people do not consider in advance where they might die. The idea that age, sex, and marital status, as well as the more obvious cause, all play a part in the location may seem surprising. Yet all these factors were found to be associated withe location of deaths in upstate New York, and there is no reason to believe that this association does not hold true for the entire nation. More research, however, needs to be done based on more years and other geographic artal stutus may be instructive as to the present state of health resources. PMID:515338

  4. Marginal discrepancy as affected by selective placement of die-spacer: an in vitro study.

    PubMed

    Aditya, Priyam; Madhav, V N V; Bhide, S V; Aditya, Amita

    2012-09-01

    An increase in the marginal discrepancy is seen after cementation with a luting agent and provision of cement space with a die-spacer is the most preferred method to avoid it. Recommended thickness of die-spacer is 25-40 μm. Smaller die-spacer thickness was consistently found at the axio-occlusal line angles as compared to the other surfaces which has been postulated to that the spacer paint tends to flow away from the sharp line angles and cusp tips as a result of increased surface tension. The absence of adequate relief spaces in these areas impedes the flow of cement beyond the occlusal portion of the casting, which would result in incomplete seating because of hydraulic pressure. Fifty stone dies were duplicated from a steel die and were divided into five groups of sample size 10, where the die-spacer was selectively placed. Measurements were taken at four points, 90° apart from each other with the help of optical microscope. Later all the castings were cemented using Glass Inomer cement as a luting agent, under a 10 kg static load and measurements were recorded. Statistical analysis showed samples with no spacer had the maximum pre and post cementation gap while the least discrepancy was seen in group with additional layer of die-spacer painted over the axio-occlusal line angle. The results were highly significant which clearly indicated the superiority of this group over others. Within limitations of the study, it can be said that application of additional layer of die-spacer at the axio-occlusal line angle will help in decreasing the post cementation marginal discrepancy in full cast metal crowns.

  5. 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.

  6. Dying while living: a critique of allowing-to-die legislation.

    PubMed

    Lappé, M

    1978-12-01

    Several US states are enacting 'right-to-die' laws, in the wake of the Karen Quinlan case. But the way such a law is drafted may cast doubt on a patient's existing common law right to control all aspects of his own treatment; it may give legal sanction to a lower standard of medical care that society at present expects from doctors; and it may lead to conflict between the patient's directive and his doctor's clinical judgement which cannot readily be resolved. The laws themselves are categorised as a) legalising active killing or b) defining rights of patients to control treatment or c) assigning to others the rights to control treatment where the patient is not competent. The California law is discussed critically. The conclusion is that such legislation is not a satisfactory answer to the ethical problem of euthanasia.

  7. Dying while living: a critique of allowing-to-die legislation.

    PubMed Central

    Lappé, M

    1978-01-01

    Several US states are enacting 'right-to-die' laws, in the wake of the Karen Quinlan case. But the way such a law is drafted may cast doubt on a patient's existing common law right to control all aspects of his own treatment; it may give legal sanction to a lower standard of medical care that society at present expects from doctors; and it may lead to conflict between the patient's directive and his doctor's clinical judgement which cannot readily be resolved. The laws themselves are categorised as a) legalising active killing or b) defining rights of patients to control treatment or c) assigning to others the rights to control treatment where the patient is not competent. The California law is discussed critically. The conclusion is that such legislation is not a satisfactory answer to the ethical problem of euthanasia. PMID:739516

  8. Graphite/Thermoplastic-Pultrusion Die

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L.; Frye, Mark W.; Johnson, Gary S.; Stanfield, Clarence E.

    1990-01-01

    Attachment to extruder produces thermoplastic-impregnated graphite tape. Consists of profile die, fiber/resin collimator, and crosshead die body. Die designed to be attached to commercially available extrusion machine capable of extruding high-performance thermoplastics. Simple attachment to commercial extruder enables developers of composites to begin experimenting with large numbers of proprietary resins, fibers, and hybrid composite structures. With device, almost any possible fiber/resin combination fabricated.

  9. Die Milchstraße.

    NASA Astrophysics Data System (ADS)

    Henbest, N.; Couper, H.

    This book is a German translation, by M. Röser, from the English original "The guide to the Galaxy", published in 1994 (see Abstr. 61.003.065). Contents: 1. Die Entdeckung unserer Galaxis. 2. Die Lokale Gruppe. 3. Die Geographie der Galaxis. 4. Der Perseus-Arm. 5. Der Orion-Arm. 6. Unsere lokale Nachbarschaft: ein typischer Winkel der Galaxis. 7. Der Sagittarius-Arm: innerhalb der Sonnenumlaufbahn. 8. Das Zentrum der Galaxis.

  10. Graphite/Thermoplastic-Pultrusion Die

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L.; Frye, Mark W.; Johnson, Gary S.; Stanfield, Clarence E.

    1990-01-01

    Attachment to extruder produces thermoplastic-impregnated graphite tape. Consists of profile die, fiber/resin collimator, and crosshead die body. Die designed to be attached to commercially available extrusion machine capable of extruding high-performance thermoplastics. Simple attachment to commercial extruder enables developers of composites to begin experimenting with large numbers of proprietary resins, fibers, and hybrid composite structures. With device, almost any possible fiber/resin combination fabricated.

  11. Maintaining Low Voiding Solder Die Attach for Power Die While Minimizing Die Tilt

    SciTech Connect

    Hamm, Randy; Peterson, Kenneth A.

    2015-10-01

    This paper addresses work to minimize voiding and die tilt in solder attachment of a large power die, measuring 9.0 mm X 6.5 mm X 0.1 mm (0.354” x 0.256” x 0.004”), to a heat spreader. As demands for larger high power die continue, minimizing voiding and die tilt is of interest for improved die functionality, yield, manufacturability, and reliability. High-power die generate considerable heat, which is important to dissipate effectively through control of voiding under high thermal load areas of the die while maintaining a consistent bondline (minimizing die tilt). Voiding was measured using acoustic imaging and die tilt was measured using two different optical measurement systems. 80Au-20Sn solder reflow was achieved using a batch vacuum solder system with optimized fixturing. Minimizing die tilt proved to be the more difficult of the two product requirements to meet. Process development variables included tooling, weight and solder preform thickness.

  12. 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.

  13. Cast Aluminum Components. Volume 1

    DTIC Science & Technology

    1983-02-01

    program was to produce a one-piece cast aluminum alloy turret to replace a welded lightweight turret and reduce the cost of manu- facturing. During...PIECES ii LIST OF ILLUSTRATIONS Figure and Title Page Figure I Welded Lightweight Turret ....... ... .............. 2 Figure 2 Potential Replacement ...Phase I. 1 Figure 1 Welded Lightweight Turret L Figure 2 Potential Replacement Casting 3 D CHANGES FROM STANDARO M2 TURRET Figure 3 Cast Turret Showing

  14. Development of an Optimization Methodology for the Aluminum Alloy Wheel Casting Process

    NASA Astrophysics Data System (ADS)

    Duan, Jianglan; Reilly, Carl; Maijer, Daan M.; Cockcroft, Steve L.; Phillion, Andre B.

    2015-08-01

    An optimization methodology has been developed for the aluminum alloy wheel casting process. The methodology is focused on improving the timing of cooling processes in a die to achieve improved casting quality. This methodology utilizes (1) a casting process model, which was developed within the commercial finite element package, ABAQUS™—ABAQUS is a trademark of Dassault Systèms; (2) a Python-based results extraction procedure; and (3) a numerical optimization module from the open-source Python library, Scipy. To achieve optimal casting quality, a set of constraints have been defined to ensure directional solidification, and an objective function, based on the solidification cooling rates, has been defined to either maximize, or target a specific, cooling rate. The methodology has been applied to a series of casting and die geometries with different cooling system configurations, including a 2-D axisymmetric wheel and die assembly generated from a full-scale prototype wheel. The results show that, with properly defined constraint and objective functions, solidification conditions can be improved and optimal cooling conditions can be achieved leading to process productivity and product quality improvements.

  15. Melting, casting, and alpha-phase extrusion of the uranium-2. 4 weight percent niobium alloy

    SciTech Connect

    Anderson, R C; Beck, D E; Kollie, T G; Zorinsky, E J; Jones, J M

    1981-10-01

    The experimental details of the melting, casting, homogenization, and alpha-phase extrusion process used to fabricate the uranium-2.4 wt % niobium alloy into 46-mm-diameter rods is described. Extrusion defects that were detected by an ultrasonic technique were eliminated by proper choice of extrusion parameters; namely, reduction ratio, ram speed, die angle, and billet preheat temperature.

  16. Casting Equipment. Casting and Angling Skills Series. Instructor Manual.

    ERIC Educational Resources Information Center

    Staton, Robert D., Jr.

    Part of a series of self-contained instructional units designed by the Missouri Department of Conservation to teach Missourians how to use outdoor resources wisely and skillfully, the instructor manual, the first in the casting and angling series, is intended both as a reference book on casting equipment and as an introduction to the sport.…

  17. Adapt or die?

    PubMed

    Visser, S S; Nel, A H

    1996-12-01

    The worldwide economic recession and the concomitant limited stock of finances have had an influence on the available money of every household and have also inhibited the improvement of socio-economic conditions and medicine. The Reconstruction and Development Programme (RDP) has the objective of improving the living conditions of the people with regard to housing, education, training and health care. The latter seems to be a major problem which has to be addressed with the emphasis on the preventive and promotional aspects of health care. A comprehensive health care system did not come into being property in the past because of the maldistribution of health care services, personnel and differences in culture and health care beliefs and values. The question that now arises, is how to render a quality health care service within the constraints of inadequate financing and resources. A comprehensive literature study has been done with reference to quality health care and financing followed by a survey of existing health services and finances. Recommendations are made about minimum requirements to be accepted if one were to adapt rather than die in terms of the provision of healthcare: the decentralization and rationalization of the administration of health care, the stress on and realization of effective and efficient primary health care, the acceptance of participative management in health providing organizations, the provision of financial management training for health care managers and the application of management accounting principles for the improvement of the efficiency and effectiveness of management.

  18. Dying and 'euthanasia'.

    PubMed

    Benatar, S R

    1992-07-01

    Medical progress, secularisation of life, growing acceptance of individual human rights (including the right to refuse medical treatment) and of shared decision-making in medicine have focused public attention on the ways in which life may, and perhaps even ought to, be allowed to end in our complex modern era. Intense and thoughtful bio-ethical debate over many years has 'unpacked' the many different understandings and interpretations of the word euthanasia. The consequent conceptual clarification together with recognition and acknowledgement of psychological implications has facilitated a growing rational consensus on openly accepting the withholding and withdrawing of treatment (under defined conditions) within the realm of sound medical practice. This is clearly distinct from assisted suicide and active euthanasia which are generally considered unacceptable perversions of medical practice. Given the ability to sustain life for prolonged periods, often in a permanent state of unconsciousness, the unrealistic expectations of some medical personnel and the lay public, the severe constraints on health care facilities in South Africa and the totally inadequate allocation of resources for highly effective medical treatments, it is appropriate to re-open public debate on the limits of 'striving officiously to keep alive' and on the distinction between 'allowing to die' and 'killing'. Concern that 'rational' arguments reflect moral decay rather than moral progress keeps the debate open and focuses attention on some 'slippery slope' consequences.

  19. Influence of Process Parameters on the Microstructure and Casting Defects of a LPDC Engine Block

    NASA Astrophysics Data System (ADS)

    Timelli, Giulio; Caliari, Daniele

    The growing demand in the automotive industry for lighter vehicles has led to increasing use of Al-Si based alloys in the production of engine blocks. Low-pressure die casting (LPDC) is an enhanced process generally used for parts with premium requirements, therefore it is one of the most promising technologies for the production of engine blocks. This work is aimed to study the effects of Sr modification and holding pressure on the microstructure and casting defects of a low-pressure die cast A356 engine block. The microstructural scale, evaluated by secondary dendrite arm spacing, the amount of porosity and inclusions, and the morphology of eutectic Si particles were investigated by metallographic and image analysis. The results were correlated with the variation of input process variables such as holding pressure and Sr level. The measured amount of porosity is low, therefore confirming LPDC as a useful foundry process for the production of Al blocks for high performance engines.

  20. When Your Child Needs a Cast

    MedlinePlus

    ... that's usually made of material like fiberglass or plaster. Casts keep bones in place while they heal. ... Types of Casts Casts usually are made of: Plaster of Paris: This heavy white powder forms a ...

  1. Cast Care: Do's and Don'ts

    MedlinePlus

    ... typically lighter and more durable than are traditional plaster casts. Air circulates more freely inside a fiberglass ... Also, X-rays penetrate fiberglass casts better than plaster casts. This is helpful if your child's doctor ...

  2. 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 ...

  3. I Could Have Died Laughing.

    ERIC Educational Resources Information Center

    Maher, Michael Forrest; Smith, Douglas

    1993-01-01

    Notes that caregivers of the dying would do well to consider the prescriptive power of humor when confronting the challenges of healthy care for the terminally ill. Addresses laughter as the best medicine not only for the dying person but also for family and principal caregivers. Includes examples of therapeutic use of humor with the terminally…

  4. Biomaterials by freeze casting.

    PubMed

    Wegst, Ulrike G K; Schecter, Matthew; Donius, Amalie E; Hunger, Philipp M

    2010-04-28

    The functional requirements for synthetic tissue substitutes appear deceptively simple: they should provide a porous matrix with interconnecting porosity and surface properties that promote rapid tissue ingrowth; at the same time, they should possess sufficient stiffness, strength and toughness to prevent crushing under physiological loads until full integration and healing are reached. Despite extensive efforts and first encouraging results, current biomaterials for tissue regeneration tend to suffer common limitations: insufficient tissue-material interaction and an inherent lack of strength and toughness associated with porosity. The challenge persists to synthesize materials that mimic both structure and mechanical performance of the natural tissue and permit strong tissue-implant interfaces to be formed. In the case of bone substitute materials, for example, the goal is to engineer high-performance composites with effective properties that, similar to natural mineralized tissue, exceed by orders of magnitude the properties of its constituents. It is still difficult with current technology to emulate in synthetic biomaterials multi-level hierarchical composite structures that are thought to be the origin of the observed mechanical property amplification in biological materials. Freeze casting permits to manufacture such complex, hybrid materials through excellent control of structural and mechanical properties. As a processing technique for the manufacture of biomaterials, freeze casting therefore has great promise.

  5. Two Piece Compaction Die Design

    SciTech Connect

    Coffey, Ethan N

    2010-03-01

    Compaction dies used to create europium oxide and tantalum control plates were modeled using ANSYS 11.0. Two-piece designs were considered in order to make the dies easier to assemble than the five-piece dies that were previously used. The two areas of concern were the stresses at the interior corner of the die cavity and the distortion of the cavity wall due to the interference fit between the two pieces and the pressure exerted on the die during the compaction process. A successful die design would have stresses less than the yield stress of the material and a maximum wall distortion on the order of 0.0001 in. Design factors that were investigated include the inner corner radius, the value of the interference fit, the compaction force, the size of the cavity, and the outer radius and geometry of the outer ring. The results show that for the europium oxide die, a 0.01 in. diameter wire can be used to create the cavity, leading to a 0.0055 in. radius corner, if the radial interference fit is 0.003 in. For the tantalum die, the same wire can be used with a radial interference fit of 0.001 in. Also, for the europium oxide die with a 0.003 in. interference fit, it is possible to use a wire with a diameter of 0.006 in. for the wire burning process. Adding a 10% safety factor to the compaction force tends to lead to conservative estimates of the stresses but not for the wall distortion. However, when the 10% safety factor is removed, the wall distortion is not affected enough to discard the design. Finally, regarding the europium oxide die, when the cavity walls are increased by 0.002 in. per side or the outer ring is made to the same geometry as the tantalum die, all the stresses and wall distortions are within the desired range. Thus, the recommendation is to use a 0.006 in. diameter wire and a 0.003 in. interference fit for the europium oxide die and a 0.01 in. diameter wire and a 0.001 in. interference fit for the tantalum die. The dies can also be made to have the

  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. Predicting lifetime of cast parts

    NASA Technical Reports Server (NTRS)

    Cooper, R. A.

    1980-01-01

    Life expectancy of cast aluminum machine parts can be predicted accurately from fatigue tests at 78 K on notched specimens of aluminum alloy. Method was developed for rocket engine turbopump parts made of high strength, heat treatable alloy with high silicon content; however, technique is applicable to other aluminum casting alloys.

  8. 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)

  9. 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…

  10. Machinability Study of Stir Cast Hypoeutectic Aluminum-Silicon Alloys During Turning

    NASA Astrophysics Data System (ADS)

    Sood, P. K.; Sehgal, Rakesh; Dwivedi, D. K.

    2013-02-01

    The influence of Be and Cd (iron correctors) on mechanical properties and machining behavior of hypoeutectic Al-Si alloy (Al-7Si-0.5Mg-1.2Fe) processed by conventional and semi-solid metal (SSM) processing (stir casting) techniques is investigated. The alloys under investigation were prepared by controlling melt in an induction melting furnace. The stirring of SSM was carried out at a constant stirring speed of 400 rpm under constant cooling conditions from liquidus temperature. The turning operations were carried out under dry conditions on a CNC turning center using coated-carbide insert by varying cutting speed, feed rate, depth of cut, and approaching angle. An orthogonal array, the signal-to-noise ratio, and analysis of variance were employed to study the machining performance characteristics. The results indicate that Be/Cd modification of the alloy and selected cutting parameters significantly affect the machining characteristics. The feed rate, cutting speed, and Cd as an iron corrector have more effect on the machining behavior of the alloys under study.

  11. A Membrane Process for Recycling Die Lube from Wastewater Solutions

    SciTech Connect

    Eric S. Peterson; Jessica Trudeau; Bill Cleary; Michael Hackett; William A. Greene

    2003-04-01

    An active-surface membrane technology was used to separate a die lube manufacturing wastewater stream consisting of various oils, hydrocarbons, heavy metals, and silicones. The ultrafiltration membranes reduced organics from initial oil and grease contents by 20–25X, carbon oxygen demand (COD) by 1.5 to 2X, and total organic carbon (TOC) by 0.6, while the biological oxygen demand (BOD) remained constant. The active-surface membranes were not fouled as badly as non-active-surface systems and the active-surface membrane flux levels were consistently higher and more stable than those of the non-active-surface membranes tested. Field testing demonstrated that the rotary microfilter can concentrate the die lube, i.e. remove the glycerin component, and produce a die lube suitable for recycling. The recycling system operated for six weeks with only seven cleaning cycles and no mechanical or electrical failures. Test data and quality records indicate that the die casting scrap was reduced from 8.4 to 7.8%. There is no doubt that this test yielded tremendous results. This separation process presents significant opportunities that can be evaluated further.

  12. A Membrane Process for Recycling Die Lube from Wastewater Solutions

    SciTech Connect

    Peterson, E. S.; Trudeau, J.; Cleary, B.; Hackett, M.; Greene, W. A.

    2003-04-30

    An active-surface membrane technology was used to separate a die lube manufacturing wastewater stream consisting of various oils, hydrocarbons, heavy metals, and silicones. The ultrafiltration membranes reduced organics from initial oil and grease contents by 20-25X, carbon oxygen demand (COD) by 1.5 to 2X, and total organic carbon (TOC) by 0.6, while the biological oxygen demand (BOD) remained constant. The active-surface membranes were not fouled as badly as non-active-surface systems and the active-surface membrane flux levels were consistently higher and more stable than those of the non-active-surface membranes tested. Field testing demonstrated that the rotary microfilter can concentrate the die lube, i.e. remove the glycerin component, and produce a die lube suitable for recycling. The recycling system operated for six weeks with only seven cleaning cycles and no mechanical or electrical failures. Test data and quality records indicate that the die casting scrap was reduced from 8.4 to 7.8%. There is no doubt that this test yielded tremendous results. This separation process presents significant opportunities that can be evaluated further.

  13. Laser-Ultrasonic Inspection of MG/AL Castings

    SciTech Connect

    Blouin, Alain; Levesque, Daniel; Monchalin, Jean-Pierre; Baril, Eric; Fischersworring-Bunk, Andreas

    2005-04-09

    Laser-ultrasonics is used to assess the metallurgical bond between Mg/Al materials in die-cast Magnesium/Aluminum composite. The acoustic impedances of Mg, Al and air are such that the amplitude of ultrasonic echoes reflected back from a void is many times larger than the amplitude of those reflected back from a well-bonded interface. In addition, the polarity of echoes from a void is inverted compared to that from a well-bonded interface. Laser-ultrasonic F-SAFT is also used for imaging tilted Mg/Al interfaces. Experimental setup, signal processing and results for detecting voids in the Mg/Al interface of cast parts are presented.

  14. Dying: A universal human experience?

    PubMed

    Bregman, L

    1989-03-01

    This paper explores the question, "Is there a universal psychological experience suffered by all dying persons?" a question to which the popular theory of Kübler-Ross presupposes an affirmative answer. Our answer takes three steps: first, a comparison between the Kübler-Ross model of dying and that of the late medievalBook of the Craft of Dying centered upon the five Kübler-Ross "stages"; second, a philosophical critique of the terms of this comparison; and third, a revised look at the alleged similarities between the two models, providing a deeper look at the moral and spiritual assumptions behind each.

  15. MACHINING ELIMINATION THROUGH APPLICATION OF THREAD FORMING FASTENERS IN NET SHAPED CAST HOLES

    SciTech Connect

    Cleaver, Ryan J; Cleaver, Todd H; Talbott, Richard

    2012-05-02

    The ultimate objective of this work was to eliminate approximately 30% of the machining performed in typical automotive engine and transmission plants by using thread forming fasteners in as-cast holes of aluminum and magnesium cast components. The primary issues at the source of engineers reluctance to implementing thread forming fasteners in lightweight castings are: * Little proof of consistency of clamp load vs. input torque in either aluminum or magnesium castings. * No known data to understand the effect on consistency of clamp load as casting dies wear. The clamp load consistency concern is founded in the fact that a portion of the input torque used to create clamp load is also used to create threads. The torque used for thread forming may not be consistent due to variations in casting material, hole size and shape due to tooling wear and process variation (thermal and mechanical). There is little data available to understand the magnitude of this concern or to form the basis of potential solutions if the range of clamp load variation is very high (> +/- 30%). The range of variation that can be expected in as-cast hole size and shape over the full life cycle of a high pressure die casting die was established in previous work completed by Pacific Northwest National Laboratory, (PNNL). This established range of variation was captured in a set of 12 cast bosses by designing core pins at the size and draft angles identified in the sited previous work. The cast bosses were cut into nuts that could be used in the Ford Fastener Laboratory test-cell to measure clamp load when a thread forming fastener was driven into a cast nut. There were two sets of experiments run. First, a series of cast aluminum nuts were made reflecting the range of shape and size variations to be expected over the life cycle of a die casting die. Taptite thread forming fasteners, (a widely used thread forming fastener suitable for aluminum applications), were driven into the various cored, as-cast

  16. Faster, Less Expensive Dies Using RSP Tooling

    NASA Astrophysics Data System (ADS)

    Knirsch, James R.

    2007-08-01

    RSP Tooling is an indirect spray form additive process that can produce production tooling for virtually any forming process and from virtually any metal. In the past 24 months a significant amount of research and development has been performed. This resulted in an increase in the basic metallurgical understanding of what transpires during the rapid solidification of the metal, significant improvements in the production machine up time, ceramic developments that have improved finish, process changes that have resulted in a shorter lead time for tool delivery, and the testing of many new alloys. RSP stands for Rapid Solidification Process and is the key to the superior metallurgical properties that result from the technology. Most metals that are sprayed in the process leave the machine with the same physical properties as the same metal normally achieves through heat treatment and in some cases the properties are superior. Many new applications are being pursued including INVAR tools for aerospace composite materials, and bimetallic tools made from tool steel and beryllium copper for die casting and plastic injection molding. Recent feasibility studies have been performed with tremendous success.

  17. Effect of Pressure and Temperature Factors on the Solidification of Cast Iron and Its Structure in Liquid Forging

    NASA Astrophysics Data System (ADS)

    Sosenushkin, E. N.; Frantsuzova, L. S.; Kozlova, E. M.

    2015-09-01

    This article examines the properties and microstructure of cast iron after fabrication of grinding balls by different kinds of casting and forging, with crystallization of the metal under pressure. A mathematical model of the process of solidification of a forging in a die is presented. Joint solution of two Fourier equations of heat conduction for the melt and for the solid skin is used to derive a kinetic equation of solidification and hence to determine the rate of solidification of the forging in the die. The effect of the pressure on the structure of the crystallizing metal and the quality of the forged grinding balls that are obtained is determined.

  18. 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.

  19. Energy Saving Melting and Revert Reduction Technology (E-SMARRT): Mechanical Performance of Dies

    SciTech Connect

    R. Allen Miller, Principal Investigator; Kabiri-Bamoradian, Contributors: Khalil; Delgado-Garza, Abelardo; Murugesan, Karthik; Ragab, Adham

    2011-09-13

    As a net shape process, die casting is intrinsically efficient and improvements in energy efficiency are strongly dependent on design and process improvements that reduce scrap rates so that more of the total consumed energy goes into acceptable, usable castings. A casting that is distorted and fails to meet specified dimensional requirements is typically remelted but this still results in a decrease in process yield, lost productivity, and increased energy consumption. This work focuses on developing, and expanding the use of, computer modeling methods that can be used to improve the dimensional accuracy of die castings and produce die designs and machine/die setups that reduce rejection rates due to dimensional issues. A major factor contributing to the dimensional inaccuracy of the casting is the elastic deformations of the die cavity caused by the thermo mechanical loads the dies are subjected to during normal operation. Although thermal and die cavity filling simulation are widely used in the industry, structural modeling of the die, particularly for managing part distortion, is not yet widely practiced. This may be due in part to the need to have a thorough understanding of the physical phenomenon involved in die distortion and the mathematical theory employed in the numerical models to efficiently model the die distortion phenomenon. Therefore, two of the goals of this work are to assist in efforts to expand the use of structural modeling and related technologies in the die casting industry by 1) providing a detailed modeling guideline and tutorial for those interested in developing the necessary skills and capability and 2) by developing simple meta-models that capture the results and experience gained from several years of die distortion research and can be used to predict key distortion phenomena of relevance to a die caster with a minimum of background and without the need for simulations. These objectives were met. A detailed modeling tutorial was

  20. Heat transfer at the mold-metal interface in permanent mold casting of aluminum alloys project. Annual project status report for the period October 1, 1997 to September 30, 1998

    SciTech Connect

    Pehlke, R.D.; Hao, S.W.

    1998-09-30

    In the first year of this three-year project, substantial progress has been achieved. This project on heat transfer coefficients in metal permanent mold casting is being conducted in three areas. They are the theoretical study at the University of Michigan, the experimental investigations of squeeze casting and semi-solid casting at CMI-Tech Center, and the experimental investigation of low pressure permanent mold casting at Amcast Automotive. U-M did an initial geometry which was defined for ProCAST to solve, and then a geometry half the size was defined and solved using the same boundary conditions. A conceptual mold geometry was examined and is represented as an axisymmetric element.Furthermore, the influences of the localized heat transfer coefficients on the casting process were carefully studied. The HTC Evaluator has been proposed and initially developed by the U-M team. The Reference and the Database Modules of the HTC Evaluator have been developed, and extensively tested. A series of technical barriers have been cited and potential solutions have been surveyed. At the CMI-Tech Center, the Kistler direct cavity pressure measurement system has been purchased and tested. The calibrations has been evaluated. The probe is capable of sensing a light finger pressure. The experimental mold has been designed and modified. The experimental mold has been designed and modified. The first experiment is scheduled for October 14, 1998. The geometry of the experimental hockey-puck casting has been given to the U-M team for numerical analysis.

  1. Strip casting with fluxing agent applied to casting roll

    SciTech Connect

    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.

  2. 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.

  3. Die Sonne, Stern unserer Erde

    NASA Astrophysics Data System (ADS)

    Lang, Kenneth R.; Ehlers, A.

    Dieses reich bebilderte Buch gibt eine Einführung in die Physik der Sonne und ihre Bedeutung für die Erde. Gestützt auf neueste Forschungsergebnisse aus Radioteleskop- und Satellitenbeobachtungen beschreibt der Autor die gewaltigen atomenergetischen Prozesse der Sonne, ihren geheimnisvollen Neutrinofluß, ihre seismischen Aktivitäten, Magnetfelder und Sonnenflecke, Korona, Sonnenausbrüche und Protuberanzen, den Sonnenwind, und die außerordentlich wichtige und vielfältige Bedeutung des Sonnenlichts, das Leben auf der Erde entstehen läßt und es auch gefährdet. Gut verständlich und in ansprechender Sprache geschrieben ist es ein wunderbares Buch für den Leser populärwissenschaftlicher Literatur, ein wertvolles Geschenk für Studenten der Astronomie und verwandter Disziplinen sowie Amateurastronomen.

  4. 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.

  5. Slip-Cast Superconductive Parts

    NASA Technical Reports Server (NTRS)

    Wise, Stephanie A.; Buckley, John D.; Vasquez, Peter; Buck, Gregory M.; Hicks, Lana P.; Hooker, Matthew W.; Taylor, Theodore D.

    1993-01-01

    Complex shapes fabricated without machining. Nonaqueous slip-casting technique used to form complexly shaped parts from high-temperature superconductive materials like YBa(2)Cu(3)O(7-delta). Such parts useful in motors, vibration dampers, and bearings. In process, organic solvent used as liquid medium. Ceramic molds made by lost-wax process used instead of plaster-of-paris molds, used in aqueous slip-casting but impervious to organic solvents and cannot drain away liquid medium. Organic-solvent-based castings do not stick to ceramic molds as they do to plaster molds.

  6. Rapid Cycle Casting of Steel

    DTIC Science & Technology

    1981-07-01

    Figs. 10 and 11 show carbon segregation as a function of a N at casting temperatures of 1185 0 C and 1360°C. 5.7.5 Macrosegregation for non-ideal...casting temperature. Run# T a N Carbon Segregation , % 0 C L 7.5mm L 35mn L =65nm L =90nm R53 1185 .3900 11 -2 -2 -2 R52 1185 .0860 17 -3 -3 -3 R51 1185...superheated shot and melt; superheat = 66cc and casting temperature = 1198 C. Run# tI Carbon segregation , % sL = 29mm L = 43mm L = 80mm L =98mm Rl 0.35

  7. 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.

  8. Slip-Cast Superconductive Parts

    NASA Technical Reports Server (NTRS)

    Wise, Stephanie A.; Buckley, John D.; Vasquez, Peter; Buck, Gregory M.; Hicks, Lana P.; Hooker, Matthew W.; Taylor, Theodore D.

    1993-01-01

    Complex shapes fabricated without machining. Nonaqueous slip-casting technique used to form complexly shaped parts from high-temperature superconductive materials like YBa(2)Cu(3)O(7-delta). Such parts useful in motors, vibration dampers, and bearings. In process, organic solvent used as liquid medium. Ceramic molds made by lost-wax process used instead of plaster-of-paris molds, used in aqueous slip-casting but impervious to organic solvents and cannot drain away liquid medium. Organic-solvent-based castings do not stick to ceramic molds as they do to plaster molds.

  9. REFRACTORY DIE FOR EXTRUDING URANIUM

    DOEpatents

    Creutz, E.C.

    1959-08-11

    A die is presented for the extrusion of metals, said die being formed of a refractory complex oxide having the composition M/sub n/O/sub m/R/sub x/O/sub y/ where M is magnesium, zinc, manganese, or iron, R is aluminum, chromic chromium, ferric iron, or manganic manganese, and m, n, x, and y are whole numbers. Specific examples are spinel, magnesium aluminate, magnetite, magnesioferrite, chromite, and franklinite.

  10. Study of Thermal Fatigue of H13 Die Steel with Various Surface Treatments

    NASA Astrophysics Data System (ADS)

    Ivanov, V. V.; Ferguson, W. G.; Paine, I. R.

    Surfaces of die-casting dies are subjected to very severe conditions of cyclical thermal and mechanical load, and chemical and mechanical wear. Dies mostly fail due to a combination of heat checking, erosion, corrosion and soldering. It is conceivable that appropriate surface treatments and coatings have a favourable influence on the temperature dependant performance of the surface of the die. The objective of this study was to examine various surface treatments and coatings. including shot peening, nitriding, nitro-carburizing, laser hardening and remelting, electro-spark alloying (deposition) and plasma spraying, under thermal fatigue conditions. Thermal cycling tests were conducted by alternate dipping of treated samples in an LM24 melt and in water. Results and interpretation are presented in this paper. The best thermal fatigue resistance was shown for a double surface treatment of laser hardening plus electro-spark deposition.

  11. Heat treatment of forging dies

    NASA Astrophysics Data System (ADS)

    Dovnar, S. A.; Kadnikov, S. A.

    1987-08-01

    In forging-die production there is a considerable range of forging dies which are promising for a changeover into advanced heat treatment involving bulk temper hardening and surface hardening using induction heating. The heat treatment suggested provides a saving of material resources as a result of improving the life of forging dies by a factor of 1.5-3 depending on the grade of die steel. As a result of induction hardening of forging dies, after temper hardening close to the boundary of the hardened layer a zone of reduced hardness forms whose unfavorable effect may be reduced by using before induction surface hardening bulk warming in a furnace or deep induction heating with a reduced energy concentration in the heating zone to the tempering temperature in the temper hardening cycle. In order to improve the uniformity of induction surface hardening for dies with a complex working shape it is desirable to use heating at reduced power with an increase in heating time.

  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. Effect of Varying Layers of Two Die Spacers on Precementation Space of Full Coverage Restorations.

    PubMed

    Mule, Shivkumar A; Dange, Shankar P; Khalikar, Arun N; Vaidya, Smita P

    2014-12-01

    The purpose of this study was to evaluate and compare the effect of varying layers of two commercially available die spacers on pre-cementation space of full coverage restorations in vitro and in vivo. Seven dies were prepared for each of 15 subjects. On three dies 1, 2, 3 layers of Pico-fit and on other three dies 1, 2, 3 layers of Yeti die spacers applied, wax pattern fabricated, invested and cast. Metal copings seated in vitro on die without die spacer and on prepared tooth of respective subject with fit-checker. Thickness of fit checker was measured using micrometer at mid-axial, mid-occlusal and near finish line locations that provided pre-cementation space. Result of ANOVA tests suggested significant difference among groups with varying layers. There was no significant difference between pre-cementation space achieved with Pico-fit and Yeti die spacers. The r values suggested positive correlation between the respective pair of in vivo and in vitro groups. (1) There was significant difference between pre-cementation space at mid-axial and mid-occlusal sites achieved with 1, 2 and 3 layers of die spacers except between 1 and 2 layers and 1 and 3 layers at mid-occlusal site. (2) Pre-cementation space achieved with Pico-fit and Yeti die spacers did not differ significantly for same location, layers and in vitro and in vivo. (3) Pre-cementation space achieved in vitro was analogous to pre-cementation space achieved in vivo for respective location, layers and die spacer.

  14. Moldless casting by laser

    NASA Astrophysics Data System (ADS)

    McLean, Marc A.; Shannon, G. J.; Steen, William M.

    1997-09-01

    The principle of laser cladding involves the use of high power carbon-dioxide lasers and powder deposition technology to provide wear and corrosion resistant surface coatings to engineering components. By injecting metal powder into a laser generated melt pool on a moving substrate a solidified metal track can be produced. Deposition of successive tracks produces a multi-layer build. Laser direct casting (LDC) utilizes a coaxial nozzle enabling consistent omnidirectional deposition to produce 3D components from a selection of metal powders. The influence of the principal process parameters over the process features namely, powder catchment efficiency, beam shape and build rates are presented with several successfully generated 3D components. Nickel, stainless steel and satellite powders were deposited at laser powders of 0.4 to 1.4 kW and speeds of 500 to 1000 mm/min achieving build rates of 3 to 9 mm3/s. Fully dense metallurgical structures have been produced with no cracking or porosity and powder catchment efficiencies up to 85% have been achieved.

  15. Acting to let someone die.

    PubMed

    McGee, Andrew

    2015-02-01

    This paper examines the recent prominent view in medical ethics that withdrawing life-sustaining treatment (LST) is an act of killing. I trace this view to the rejection of the traditional claim that withdrawing LST is an omission rather than an act. Although that traditional claim is not as problematic as this recent prominent view suggests, my main claim is that even if we accepted that withdrawing LST should be classified as an act rather than as an omission, it could still be classified as letting die rather than killing. Even though omissions are contrasted with acts, letting die need not be, for one can let die by means of acts. The remainder of the paper is devoted to establishing this claim and addresses certain objections to it. © 2013 John Wiley & Sons Ltd.

  16. Clinical management of dying patients.

    PubMed Central

    Gavrin, J; Chapman, C R

    1995-01-01

    Dying is universal, and death should be a peaceful time. Myriad comfort measures are available in the last weeks before life ends. Discussions about end-of-life issues often suffer from lack of informed opinion. Palliative care experts have identified specific somatic and psychological sources of distress for dying patients and their loved ones. Pain, shortness of breath, nausea and vomiting, and fear of abandonment contribute substantially to both physical and psychological discomfort toward the end of life. Simple, effective methods exist for relieving those symptoms. Knowledge about the natural events associated with dying and an informed approach to medical and psychological interventions contribute to systematic and successful comfort care. We describe the origin of physical and psychological distress at the end of life and provide strategies for alleviating many of the discomforts. PMID:7571591

  17. Development and Demonstration of Adanced Tooling Alloys for Molds and Dies

    SciTech Connect

    Kevin M. McHugh; Enrique J. Lavernia

    2006-01-01

    This report summarizes research results in the project Development and Demonstration of Advanced Tooling Alloys for Molds and Dies. Molds, dies and related tooling are used to manufacture most of the plastic and metal products we use every day. Conventional fabrication of molds and dies involves a multiplicity of machining, benching and heat treatment unit operations. This approach is very expensive and time consuming. Rapid Solidifcation Process (RSP) Tooling is a spray-forming technology tailored for producing molds and dies. The appraoch combines rapid solidifcation processing and net-shape materials processing in a single step. An atomized spray of a tool-forming alloy, typically a tool steel, is deposited onto an easy-to-form tool pattern to replicate the pattern's shape and surface features. By so doing, the approach eliminates many machining operations in conventional mold making, significantly reducing cost, lead time and energy. Moreover, rapid solidification creates unique microstructural features by suppressing carbide precipitation and growth, and creating metastable phases. This can result in unique material properties following heat treatment. Spray-formed and aged tool steel dies have exhibited extended life compared to conventional dies in many forming operations such as forging, extrusion and die casting. RSP Tooling technolocy was commercialized with the formation of RSP Tooling, LLC in Solon, Oh.

  18. 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

  19. 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.

  20. Portable punch and die jig

    DOEpatents

    Lewandowski, Edward F.; Anderson, Petrus A.

    1978-01-01

    A portable punch and die jig includes a U-shaped jig of predetermined width having a slot of predetermined width in the base thereof extending completely across the width of the jig adapted to fit over the walls of rectangular tubes and a punch and die assembly disposed in a hole extending through the base of the jig communicating with the slot in the base of the jig for punching a hole in the walls of the rectangular tubes at precisely determined locations.

  1. [Dying with cancer: Hollywood lessons].

    PubMed

    Niemeyer, Fernanda; Kruse, Maria Henriqueta Luce

    2013-12-01

    The study attempts to understand how dying from cancer is portrayed by five movies produced in Hollywood between 1993 and 2006. Based on the cultural studies and their post-structuralism version and supported by the notions of discourse and subjectivity, as proposed by philosopher Michel Foucault, we suggest one of the possible readings of the movie picture corpus. We assess how the movie picture discourse acts as a cultural pedagogy that produces ways of seeing dying with cancer: immortalizing the healthy body image, silencing death, taking care of the dead body and, finally, accepting death. Our proposal is intended to stimulate reflections that may contribute to care and education in nursing.

  2. Die Herz-Lungen-Maschine

    NASA Astrophysics Data System (ADS)

    Krane, Markus; Bauernschmitt, Robert; Lange, Rüdiger

    Das Kapitel der modernen Herzchirurgie mit Einsatz der Herz-Lungen-Maschine am Menschen beginnt am 6. Mai 1953, als J. Gibbon bei einer 18-jährigen Patientin einen angeborenen Defekt in der Vorhofscheidewand verschließt [1]. Mit ersten experimentellen Versuchen zur extrakorporalen Zirkulation begann Gibbon bereits in den 30er Jahren des 20. Jahrhunderts. Die Grundlage für die heute gebräuchliche Rollerpumpe schufen Porter und Bradley mit ihrer "rotary pump“, welche sie 1855 zum Patent anmeldeten. Diese Pumpe wurde von DeBakey und Schmidt modifiziert und entspricht im Wesentlichen noch der heute sich im Routinebetrieb befindlichen Rollerpumpe [2].

  3. Robert Merton Dies at 92

    ERIC Educational Resources Information Center

    Snell, Joel C.

    2006-01-01

    This article features Robert Merton, who died recently at age 92. Merton came into this world as a Jewish baby named Meyer Schkolnick. He lived in South Philly where his parents wrenched a living as blue-collar workers. Merton chose an Anglicized name to move into the Yankee dominated America of the 20's and 30's. At Harvard, he studied under…

  4. Robert Merton Dies at 92

    ERIC Educational Resources Information Center

    Snell, Joel C.

    2006-01-01

    This article features Robert Merton, who died recently at age 92. Merton came into this world as a Jewish baby named Meyer Schkolnick. He lived in South Philly where his parents wrenched a living as blue-collar workers. Merton chose an Anglicized name to move into the Yankee dominated America of the 20's and 30's. At Harvard, he studied under…

  5. Attitudes on Death and Dying.

    ERIC Educational Resources Information Center

    Andrus, Charles E.

    This paper explored attitudes toward death and dying revealed through interviews with members of the clergy, the medical profession, funeral directors, nursing home residents, and selected others. The sampling was small and results are not intended to be representative of the groups to which these people belong. Rather, the study may be used as a…

  6. Attitudes on Death and Dying.

    ERIC Educational Resources Information Center

    Andrus, Charles E.

    This paper explored attitudes toward death and dying revealed through interviews with members of the clergy, the medical profession, funeral directors, nursing home residents, and selected others. The sampling was small and results are not intended to be representative of the groups to which these people belong. Rather, the study may be used as a…

  7. Morphological castes in a vertebrate

    PubMed Central

    O'Riain, M. J.; Jarvis, J. U. M.; Alexander, R.; Buffenstein, R.; Peeters, C.

    2000-01-01

    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. PMID:11087866

  8. Centrifugal slip casting of components

    SciTech Connect

    Steinlage, G.A.; Roeder, R.K.; Trumble, K.P.; Bowman, K.J.

    1996-05-01

    Research in layered and functionally gradient materials has emerged because of the increasing demand for high-performance engineering materials. Many techniques have been used to produce layered and functionally gradient components. Common examples include thermal spray processing, powder processing, chemical and physical vapor deposition, high-temperature or combustion synthesis, diffusion treatments, microwave processing and infiltration. Of these techniques, powder processing routes offer excellent microstructural control and product quality, and they are capable of producing large components. Centrifugal slip casting is a powder-processing technique combining the effects of slip casting and centrifugation. In slip casting, consolidation takes place as fluid is removed by the porous mold. Particles within the slip move with the suspending fluid until reaching the mold wall, at which point they are consolidated. In centrifugation, particles within the slip move through the fluid at a rate dependent upon the gravitational force and particle drag.

  9. An in vitro study to evaluate the effect of storage time and application of subsequent layers on the variation in thickness of three commercially available die spacers.

    PubMed

    Jacob, Sunil J; Hegde, Chethan; Prasad, Krishna D; Shetty, Manoj

    2010-01-01

    The application of a paint-on die spacer onto the dies prior to the fabrication of cast crowns is an acceptable procedure to improve the fit of the restoration. The primary purpose of this study was to evaluate the variation in thickness of different brands of die spacer based on the effect of storage time and application of additional layers. Dies were duplicated from a master model of ivorine teeth, with a full ceramic preparation. Dies obtained were then painted with one, two, and three coats of each brand of die-spacers separately. These dies were embedded in die stone and sectioned bucco-lingually. The same procedure was done after three and six months. The thickness of the paint on die spacer was measured at five points on the die using an optical microscope, and the data were statistically analyzed. There was a definite variation in the thickness of the die spacer with all the three brands and at various points on the die. Two coat thicknesses were found to be in the range of tolerance of 20-40 microns. Thickness at occlusal groove was noted to be the maximum with least at occlusoaxial line angles. Thickness also showed a very significant increase when bottles were stored for a period of three to six months and then applied.

  10. 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.

  11. 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

  12. 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

  13. Casting behavior of titanium alloys in a centrifugal casting machine.

    PubMed

    Watanabe, K; Miyakawa, O; Takada, Y; Okuno, O; Okabe, T

    2003-05-01

    Since dental casting requires replication of complex shapes with great accuracy, this study examined how well some commercial titanium alloys and experimental titanium-copper alloys filled a mold cavity. The metals examined were three types of commercial dental titanium [commercially pure titanium (hereinafter noted as CP-Ti), Ti-6Al-4V (T64) and Ti-6Al-7Nb (T67)], and experimental titanium-copper alloys [3%, 5% and 10% Cu (mass %)]. The volume percentage filling the cavity was evaluated in castings prepared in a very thin perforated sheet pattern and cast in a centrifugal casting machine. The flow behavior of the molten metal was also examined using a so-called "tracer element technique." The amounts of CP-Ti and all the Ti-Cu alloys filling the cavity were similar; less T64 and T67 filled the cavity. However, the Ti-Cu alloys failed to reach the end of the cavities due to a lower fluidity compared to the other metals. A mold prepared with specially designed perforated sheets was effective at differentiating the flow behavior of the metals tested. The present technique also revealed that the more viscous Ti-Cu alloys with a wide freezing range failed to sequentially flow to the end of the cavity.

  14. A comparison of an accelerated technique for casting post-and-core restorations with conventional techniques.

    PubMed

    Campagni, W V; Reisbick, M H; Jugan, M

    1993-09-01

    This project compares an accelerated technique for the casting of post-and-core restorations with four traditional techniques. The accelerated technique uses two phosphate-bonded investments and the traditional techniques use a gypsum- and a phosphate-bonded investment. The study measures and compares the differences between the seating of the casting and the seating of the acrylic resin pattern. The effects of the techniques on the fit of castings with and without a ferrule are also compared. Six groups of 10 castings were made from plastic patterns formed on a stainless steel test die. A different investment and/or burnout method was used for each group. Each group had two subgroups: ferruled and nonferruled. The fit of the plastic patterns was measured at two time intervals after forming, 2 weeks and 3 months. The patterns were invested immediately after the 3-month measurement, and the difference in fit of the castings was calculated. An ANOVA and Tuckey-Kramer test were done to determine the statistical validity. The seating of the patterns after 3 months of storage was consistently worse than the 2-week measurements of fit. The ferrule and nonferrule patterns were not statistically different in seating. Measurement of the castings showed that the ferruled castings seated significantly worse than the nonferrule castings. The difference in the seating of the castings as compared with the patterns was considered clinically unacceptable, showing a range of 0.301 mm to 0.528 mm. The nonferrule castings showed a significant difference in seating among groups. The difference ranged from -0.099 mm to 0.322 mm. The castings of the ferrule subgroups were considered clinically unacceptable and were not analyzed for significance. Among the nonferrule castings, the group using a gypsum investment and conventional technique for investing and burnout but no ring liner showed the best seating. The accelerated technique was intermediate in seating with a difference of 0

  15. Mundrabilla: A Microgravity Casting

    NASA Astrophysics Data System (ADS)

    Budka, P. Z.; Viertl, J. R. M.

    1993-07-01

    The name "Mundrabilla" is applied to two nickel-iron meteorite masses (combined mass over 22,700 kg), which apparently were a single mass before atmospheric entry [1]. A medium octahedrite, Mundrabilla exhibits the microstructural features common to other nickel-iron meteorites such as Widmanstatten structure and troilite; however, its macrostructure is anything but common. Described by Buchwald as "anomalous" [1], Mundrabilla's macrostructural morphology is characterized by strikingly prominent, rounded Widmanstatten areas separated by regions of sulfur segregation (Fig. 1). While microstructural development of a metal can reflect both solidification and solid state reactions, macrostructural features are determined during solidification. Thus, a typical metallurgist, unfamiliar with microgravity solidification, might describe Mundrabilla's macrostructure as an "anomalous" casting. Those familiar with microgravity solidification might characterize Mundrabilla's macrostructural features as due to solidification of two immiscible liquids [2]--one rich in nickel-iron, the other rich in sulfur. Combining these observations, Mundrabilla's macrostructural features are consistent with that of a liquid mass solidified under microgravity conditions [3,4]. Since nickel-iron meteorite cooling rates often serve as the foundation for assumptions about the formation of solar system bodies, information on the solidification time for the Mundrabilla mass may give additional insights. How long did it take for Mundrabilla, with a minimum "as received" mass of approximately 22,700 kg to solidify? Because Mundrabilla's mass before atmospheric entry is unknown, we take as an upper boundary a mass of 4.1 x 10^15kg. These masses, assumed spherical, range in diameter between 1.8 meters and 10 kilometers, respectively. Mundrabilla can be idealized as a pure iron liquid mass cooling from the melting point of pure iron (1535C) by radiation into space at absolute zero. The latent heat of

  16. Effect of ferrite on cast stainless steels

    SciTech Connect

    Nadezhdin, A.; Cooper, K. ); Timbers, G. . Kraft Pulp Division)

    1994-09-01

    Premature failure of stainless steel castings in bleach washing service is attributed to poor casting quality high porosity and to a high ferrite content, which makes the castings susceptible to corrosion by hot acid chloride solutions. A survey of the chemical compositions and ferrite contents of corrosion-resistant castings in bleach plants at three pulp mills found high [delta]-ferrite levels in the austenitic matrix due to the improper balance between austenite and ferrite stabilizers.

  17. An in vitro comparison of vertical marginal gaps of CAD/CAM titanium and conventional cast restorations.

    PubMed

    Tan, Philip L; Gratton, David G; Diaz-Arnold, Ana M; Holmes, David C

    2008-07-01

    To determine if there was a significant difference between the vertical marginal openings of cast restorations, computer-aided design, and computer-aided machining restorations. Ten working dies were created from a single master die and used to fabricate ten restorations in each of the following groups: computer-aided design/computer-assisted machining (CAD/CAM), WAX/CAM, and WAX/CAST. The CAD/CAM titanium restorations were fabricated using the scanning and crown design modules of the KaVo Everest system. The WAX/CAM titanium restorations were fabricated using the double scan technique with the KaVo Everest system. The WAX/CAST high noble copings were fabricated using the conventional lost wax casting technique. The restorations were seated on the master die, and high-resolution digital photographs were made of the marginal area on all four sides. The vertical marginal opening was then measured using a calibrated digital software program. One-way ANOVA and Tukey's post hoc tests were used to determine the presence of statistically significant differences. The vertical margin openings were CAD/CAM: 79.43 +/- 25.46 microm; WAX/CAM: 73.12 +/- 24.15 microm; WAX/CAST: 23.91 +/- 9.80 microm. There was a statistically significant difference between the WAX/CAST group and the remaining groups. There was no difference between the vertical marginal gaps of the CAD/CAM and WAX/CAM. The WAX/CAST technique resulted in smaller vertical marginal gaps than either CAD/CAM or WAX/CAM.

  18. A micro-mechanical evaluation of the effects of die hardener on die stone.

    PubMed

    He, Li-Hong; van Vuuren, Ludwig Jansen; Planitz, Nina; Swain, Michael V

    2010-08-01

    The purpose of this study was to investigate the properties of a die hardener penetrated layer and evaluate its protective effects on the surface of die stone. A commercial die hardener (PDQ die hardener, Whipmix corp., USA) was tested on a die stone (GC Fujirock EP die stone, GC Europe, Belgium) and a dental plaster (Dental Stone, United States Gypsum Company, USA). Nanoindentation and micro-scratch tests were performed on both coated and uncoated specimens. The scratch damage was observed by SEM and the penetration depth of die hardener was detected by the affiliated EDX. Upon drying, the die hardener penetrated into the die stone to a depth of 3-5 microm, and deposited a thin film on the surface of die stone. Although the die hardener penetrated layer did not show improved mechanical properties, the die hardener film on the surface did protect the specimens from abrasion damage.

  19. 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

  20. Pressure distribution in centrifugal dental casting.

    PubMed

    Nielsen, J P

    1978-02-01

    Equations are developed for liquid metal pressure in centrifugal dental casting, given the instantaneous rotational velocity, density, and certain dimensions of the casting machine and casting pattern. A "reference parabola" is introduced making the fluid pressure concept more understandable. A specially designed specimen demonstrates experimentally the reference parabola at freezing.