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Sample records for semi-solid die casting

  1. Effect of magnesium content on the semi solid cast microstructure of hypereutectic aluminum-silicon alloys

    NASA Astrophysics Data System (ADS)

    Hekmat-Ardakan, Alireza

    2009-12-01

    A comprehensive study of microstructural evolution of A390 hypereutectic aluminum-silicon alloy (Al-17%Si-4.5%Cu-0.5%Mg) with addition of Mg contents up to 10% was carried out during semi solid metal processing as well as conventional casting. As a first step, the FACTSAGE thermodynamic databank and software was applied in order to investigate the phase diagram, the solidification behavior as well as the identification of the components that are formed during the solidification of A390 alloy with different Mg contents for equilibrium and non-equilibrium (Schiel) conditions. With higher Mg content between 4.2 - 7.2 %, the Mg2Si intermetallic phase is solidified in the eutectic network according to the ternary reaction together the primary silicon due to the binary reaction of Liq → Si + Mg2Si. However the primary silicon is still the first solidified phase in this critical Mg zone. For Mg contents greater than 7.2%, the Mg2Si solidifies first as a primary phase. In fact, the Mg2Si is solidified during the primary, the binary and the ternary reactions and can be observed in the microstructure as a eutectic phase and a pro-eutectic phase with different morphology. In the next stage, the experimental tests were carried out in order to verify the accuracy of the results obtained by the FACTSAGE software. The microstructures of the A390 and the 6 and 10 wt% Mg alloys were investigated using conventional casting and rheocasting (stir casting) processes with continuous cooling solidification. The results showed that, for both processes, the microstructure of the eutectic network for high Mg alloys, specifically the eutectic Si phase is modified compared to the eutectic Si in the microstructure of A390 alloy. However the alloys with 6% and 10% Mg have a similar eutectic morphology. The eutectic formation temperature was measured by placing the thermocouple into the melt for determination of the cooling curves. DSC (Differential Scanning Calorimeter) test were also carried

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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).

  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. 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.

  7. 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.

  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. 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.

  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 from the voxel model for display to the user.

  11. 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.

  12. 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,...

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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)

  8. 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.

  9. 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.

  10. 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)

  11. 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.

  12. 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.

  13. 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).

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Semi-solid electrodes having high rate capability

    DOEpatents

    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.

  9. 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)

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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).

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Deformation of Semi-Solid Metals - Refining, Strengthening, and Rheological Behavior.

    DTIC Science & Technology

    1982-07-15

    described. This work extends earlier studies on " Rheocasting " and has broad, practical implications. The original Rheocast work, sponsored by ARO, led to... Rheocasting has now finally become a commercial reality. The broad area of forming and otherwise processing of metals in the semi-solid state is one that...than Rheocasting , for forming metals in their semi-solid state. And we wondered as well if we might find some way, through deformation in the semi-solid

  8. 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.

  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. 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.

  11. 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.

  12. 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.

  13. Machine Casting of Ferrous Alloys.

    DTIC Science & Technology

    possible today. Extensive work was conducted on casting of semi-solid alloys when highly fluid (’ Rheocasting ’) and when thixotropically gelled...Thixocasting’). In initial phases of the program, copper base alloys and cast iron alloys were prepared with special non-dendritic Rheocast structure by batch...processing. Compatibility studies were carried out to select materials suitable for preparing cast iron with the Rheocast structure. Design

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. An investigation on the rheological behavior of metallic semi-solid slurries of Al-6.5 pct Si and semi-solid composite slurries of SiC particulates in an Al-6.5 pct Si alloy matrix

    NASA Technical Reports Server (NTRS)

    Moon, H.-K.; Ito, Y.; Cornie, J. A.; Flemings, M. C.

    1993-01-01

    The rheology of SiC particulate/Al-6.5 pct Si composite slurries was explored. The rheological behavior of the composite slurries shows both thixotropic and pseudoplastic behaviors. Isostructural experiments on the composite slurries revealed a Newtonian behavior beyond a high shear rate limit. The rheology of fully molten composite slurries over the low to high shear rate range indicates the existence of a low shear rate Newtonian region, an intermediate pseudoplastic region and a high shear rate Newtonian region. The isostructural studies indicate that the viscosity of a composite slurry depends upon the shearing history of a given volume of material. An unexpected shear thinning was noted for SiC particulate + alpha slurries as compared to semi-solid metallic slurries at the same fraction solid. The implications of these findings for the processing of slurries into cast components is discussed.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Machine Casting of Ferrous Alloys

    DTIC Science & Technology

    1976-08-01

    high- lights of the earlier reports and much detail about Rheocast - ing and the casting of aluminum containing superalloys by Hitchiner’s patented...Augmented Hipo-v Procer-s EVALUATION OF RHEOCASTING WITH TFT: CTA PROCESS fU.S. Pat. 3,863,706) . Introduction to Rheocasting ... Rheocasting ...Drawing of suspension Bomb Lug. 13 Apparatus used to CLA pour Rheocast aluminum. 14 collection of parts cast by CLA process in semi- solid 35 5 aluminum

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Preparation of semi-solid aluminum alloy slurry poured through a water-cooled serpentine channel

    NASA Astrophysics Data System (ADS)

    Chen, Zheng-Zhou; Mao, Wei-Min; Wu, Zong-Chuang

    2012-01-01

    A water-cooled serpentine channel pouring process was invented to produce semi-solid A356 aluminum alloy slurry for rheocasting, and the effects of pouring temperature and circulating cooling water flux on the microstructure of the slurry were investigated. The results show that at the pouring temperature of 640-680°C and the circulating cooling water flux of 0.9 m3/h, the semi-solid A356 aluminum alloy slurry with spherical primary α(Al) grains can be obtained, whose shape factors are between 0.78 and 0.86 and the grain diameter can reach 48-68 μm. When the pouring temperatures are at 660-680°C, only a very thin solidified shell remains inside the serpentine channel and can be removed easily. When the serpentine channel is cooled with circulating water, the microstructure of the semi-solid slurry can be improved, and the serpentine channel is quickly cooled to room temperature after the completion of one pouring. In terms of the productivity of the special equipment, the water-cooled serpentine channel is economical and efficient.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  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.

    2017-04-01

    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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Machine Casting of Ferrous Alloys

    DTIC Science & Technology

    1975-10-01

    C-0110 June 1975 by M. C. Flemings, R. Mehrabian, J. R. Melcher, R. G. Riek, K. P. Young N. Matsumoto, D. G. Backman, F. S. Blackall , &E. Bond, E...17. F. Blackall , "The Delivery and Casting of Semi-Solid Metals", S.M. Thesis, 1975, M.I.T. 18. V. Laxmanan, "Rheocasting of Superalloys", S.M...Flemings, R. Mehrabian, J.R. Melcher, R.G. Riek, K.P. Young, N. Matsumoto D.G.Backman, F.S. Blackall , B.E. Bond, E.J. McHal^ S. Schottman 8. CONTRACT

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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).

  6. Urinary casts

    MedlinePlus

    ... blood cell (WBC) casts are more common with acute kidney infections. Your provider will tell you more about your results. Risks There are no risks with this test. Alternative Names Hyaline casts; Granular casts; Renal tubular epithelial casts; Waxy casts; Casts in the ...

  7. 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.

  8. 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

  9. 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.

  10. Clean Metal Casting

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

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

  11. Anodizing Effect on the Wear and Corrosion Behavior of EN AC-46500 Components Produced by Semi-Solid Rheocasting (SSR)

    NASA Astrophysics Data System (ADS)

    Forn, A.; Baile, M. T.; Picas, J. A.; Martín, E.; Menargues, S.

    2011-05-01

    In this work the effect of the anodizing process on the surface properties of SSR components was investigated. EN AC-46500 aluminium alloy components were formed using a 700 Ton high pressure machine and an Idra Semi Solid Rheocasting Station (SSR). The samples were heat treated with the aim of modifying the form and distribution of the eutectic silicon phase and after the heat treatment they were shotpeened in different conditions to obtain different surface roughness. Finally, the components were anodized with the purpose of improving the tribological properties and corrosion resistance. Surface modifications were investigated as they might have beneficial effects on the wear and corrosion behaviour. Experiments using a tribometer (ball on disc configuration) were performed in order to evaluate the tribological properties of the material and salt spray corrosion tests were used to study the corrosion resistance. These studies were carried out before and after the anodizing process. The anodized components show a significant improvement of the corrosion and wear resistance under the tested conditions, in spite of the high percentage of intermetallics compounds present in the AC-46500 alloy.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. Rapid Tooling via Investment Casting and Rapid Prototype Patterns

    SciTech Connect

    Baldwin, Michael D.

    1999-06-01

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

  2. 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)

  3. 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

  4. 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.

  5. 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.

  6. 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 ...

  7. 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.

  8. 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.

  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. 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…

  12. 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)

  13. 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.

  14. 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.

  15. Investment cast AISI H13 tooling for automotive applications

    SciTech Connect

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

    1995-07-01

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

  16. Casting methods

    SciTech Connect

    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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  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...

  2. 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…

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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…

  15. 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.

  16. 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

  17. 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.

  18. 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' ...

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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…

  11. 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…

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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…

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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)

  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. 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…

  18. 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 ...

  19. 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.

  20. When Somebody Dies

    MedlinePlus

    ... A A What's in this article? When — and How — Does It Happen? Where Do Dead People Go? What Does Grieving Mean? What About Me? If I'm Going to Die Someday, What Should I Do Now? en español ...

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. Machine Casting of Ferrous Alloys

    DTIC Science & Technology

    1974-05-01

    castings. Liquid-solid slurries were cast Rheocasting ) to evaluate cast- ing properties and opportunities for enhanced mold life with a reduced temperature...pouring temperature, 600 0C mold temperature, all-metal mold. Figure 29 Schem.atic of rheocasting attachment for vacuum melting furnace. Motor and gear...33 Alumina paddle and rheocasting . Paddle cracked during itirring. Casting did not fill, probably due to poor stirring of melt. Figure 34 ZrO 2

  16. 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.

  17. Agile Manufacturing Development of Castings

    DTIC Science & Technology

    2007-11-02

    Consortium was tasked by GE Transportation Systems (GETS) with development of the IFE, a complex ductile iron casting for a commercial loco- motive that... ductile iron foundry with this tooling, it was clear that castings with acceptable quality could not be made. These castings were on the GE...requirements. Therefore, the design specifies a thin - walled casting with complex structures and the requirements demand tight dimensional tolerances and

  18. 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)

  19. 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.

  20. 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.

  1. 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.

  2. 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…

  3. 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.

  4. 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.

  5. 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.

  6. 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…

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. [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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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…

  9. 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.

  10. 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.

  11. 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

  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. 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.

  14. 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.

  15. 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 ...

  16. 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 ...

  17. 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 ...

  18. 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.

  19. 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.

  20. 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…

  1. 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)

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. Machine Casting of Ferrous Alloys

    DTIC Science & Technology

    1974-09-01

    t^ ~cMnrc.pVbU of evaluating rheocasting as tell as more conventional casting techniques has been designed and is presently under construction...construction. The immediate objective of this machine is to study rheocasting and conventional casting with respect to .processing and properties. The...used in small, bottom-pour ladles. The stirring required by the Rheocasting proce- dures is to be accomplished by the paddle assembly shown in Figure

  20. [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.

  1. 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.

  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. 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.

  4. 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…

  5. 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…

  6. 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

  7. 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.

  8. FEM stress analysis of the cooling hole of an HPDC die

    NASA Astrophysics Data System (ADS)

    Kimura, T.; Yamagata, H.; Tanikawa, S.

    2015-06-01

    Cracking at a cooling hole is a typical die failure mode in a high-pressure die-casting (HPDC) die. We simulated the thermal distortion of a die considering the HPDC machine deflection and revealed a stress concentration at the cooling hole. The stress concentration at the cooling hole changes after injection or after spraying and blowing air. The cooling hole top remains in a compression stress state 5, 10, and 20 mm deep from the die surface, but the stress amplitudes are higher when the depths are shallower. It was suggested that cracking takes place due to the high compressive stress and that the shear stress assists the propagation of the initiated crack. On the other hand, the stress condition at the R portion of the cooling hole is always a tensile state, but the mean stress and stress amplitude values were not found to be in the range that causes fatigue fracture. It was demonstrated that the developed analysis is valuable in designing the cooling hole of an HPDC die.

  9. Comparing the Accuracy of Three Different Impression Materials in Making Duplicate Dies

    PubMed Central

    Bajoghli, Farshad; Sabouhi, Mahmoud; Nosouhian, Saeid; Davoudi, Amin; Behnamnia, Zeynab

    2015-01-01

    Background: Marginal adaptation is very important in cast restorations. Maladaptation leads to plaque retention, reduction of mechanical and esthetic properties. The aim of this study was to evaluate the precision of three different impression materials (including: Additional silicone [AS] and condensational silicone [CS] and polyether [PE]) for duplicating master dies. Materials and Methods: Three master dies from an acrylic tooth model-with supragingival and shoulder finishing line was made by using PE: Impergum, CS: Speedex, and AS: Panasil separately. The Ni-Cr copings were prepared from master dies separately. They were placed on the acrylic model and the mean marginal difference was recorded by using a stereomicroscope. Then 30 duplicate test dies were made by using the same impression materials and the marginal gaps were recorded. The comparison was done by one-way ANOVA and SPSS software (Version 13) at a significant level of 0.05. Results: The mean marginal difference of four walls from Impergum (38.56 um) was the lowest than Speedex (38.92 um) and Panasil (38.24 um). The Impergum had the highest capability in making duplicate dies (P > 0.05). Conclusion: The Impergum impression material manifested the highest capability in making a better marginal adaptation of duplicate dies but further studies are needed to make a precise decision. PMID:26229364

  10. Should assisted dying be legalised?

    PubMed

    Frost, Thomas D G; Sinha, Devan; Gilbert, Barnabas J

    2014-01-15

    When an individual facing intractable pain is given an estimate of a few months to live, does hastening death become a viable and legitimate alternative for willing patients? Has the time come for physicians to do away with the traditional notion of healthcare as maintaining or improving physical and mental health, and instead accept their own limitations by facilitating death when requested? The Universities of Oxford and Cambridge held the 2013 Varsity Medical Debate on the motion "This House Would Legalise Assisted Dying". This article summarises the key arguments developed over the course of the debate. We will explore how assisted dying can affect both the patient and doctor; the nature of consent and limits of autonomy; the effects on society; the viability of a proposed model; and, perhaps most importantly, the potential need for the practice within our current medico-legal framework.

  11. 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

  12. 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.

  13. Guide for extrusion dies eliminates straightening operation

    NASA Technical Reports Server (NTRS)

    Gyorgak, C. A.; Hoover, R. J.

    1964-01-01

    To prevent distortion of extruded metal, a guidance assembly is aligned with the die. As the metal emerges from the extrusion dies, it passes directly into the receiver and straightening tube system, and the completed extrusion is withdrawn.

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. Contoured Orifice for Silicon-Ribbon Die

    NASA Technical Reports Server (NTRS)

    Mackintosh, B. H.

    1985-01-01

    Die configuration encourages purity and stable growth. Contour of die orifice changes near ribbon edges. As result, silicon ribbon has nearly constant width and little carbon contamination. Die part of furnace being developed to produce high-quality, low-cost material for solar cells.

  19. 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

  20. 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.

  1. Chimerical categories: caste, race, and genetics.

    PubMed

    Sabir, Sharjeel

    2003-12-01

    Is discrimination based on caste equivalent to racism? This paper explores the complex relationship between genetic, race and caste. It also discusses the debate over the exclusion of a discussion of caste-based discrimination at the 2001 World Conference against Racism, Racial Discrimination, Xenophobia and Related Intolerance held in Durban, South Africa.

  2. 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.

  3. Prediction of Microporosity in Shrouded Impeller Castings

    SciTech Connect

    Viswanathan, S. Nelson, C.D.

    1998-09-01

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

  4. Cure shrinkage in casting resins

    SciTech Connect

    Spencer, J. Brock

    2015-02-01

    A method is described whereby the shrinkage of a casting resin can be determined. Values for the shrinkage of several resin systems in frequent use by Sandia have been measured. A discussion of possible methods for determining the stresses generated by cure shrinkage and thermal contraction is also included.

  5. Advanced Lost Foam Casting Technology

    SciTech Connect

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

    2000-11-30

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

  6. SEGREGATION IN SMALL STEEL CASTINGS

    DTIC Science & Technology

    Carbon segregation in small castings often occurs near riser necks. Systematic studies were continued to determine effect on segregation of such...intensity of carbon segregation under ’neck-down’ risers varies directly as the neck length and inversely as the neck diameter. The degree of segregation

  7. Graphite Formation in Cast Iron

    NASA Technical Reports Server (NTRS)

    Stefanescu, D. M.

    1985-01-01

    In the first phase of the project it was proven that by changing the ratio between the thermal gradient and the growth rate for commercial cast iron samples solidifying in a Bridgman type furnace, it is possible to produce all types of graphite structures, from flake to spheroidal, and all types of matrices, from ferritic to white at a certain given level of cerium. KC-135 flight experiments have shown that in a low-gravity environment, no flotation occurs even in spheroidal graphite cast irons with carbon equivalent as high as 5%, while extensive graphite flotation occurred in both flake and spheroidal graphite cast irons, in high carbon samples solidified in a high gravity environment. This opens the way for production of iron-carbon composite materials, with high carbon content (e.g., 10%) in a low gravity environment. By using KC-135 flights, the influence of some basic elements on the solidification of cast iron will be studied. The mechanism of flake to spheroidal graphite transition will be studied, by using quenching experiments at both low and one gravity for different G/R ratios.

  8. Machine Casting of Ferrous Alloys

    DTIC Science & Technology

    1978-05-01

    produce porosity-free parts and to evaluate the Rheocasting and Thixocasting processes from both a technical and economical point of view. Analytical...and computer models were developed for solutionizing of Rheocast and conventional cast (dendritic) alloys. The predictions were compared with

  9. Casting Freedom, 1860-1862

    ERIC Educational Resources Information Center

    Social Education, 2005

    2005-01-01

    Thomas Crawford, an American Sculptor, created the full-size figure of Freedom in clay. Molds were made, from which a full-size positive plaster model was cast in five main sections. This model is on view today in the basement rotunda of the Russell Senate Office Building. Clark Mills was a self-taught American sculptor with experience in casting…

  10. Tape casting of magnesium oxide.

    SciTech Connect

    Ayala, Alicia; Corral, Erica L.; Loehman, Ronald E.; Bencoe, Denise Nora; Reiterer, Markus; Shah, Raja A.

    2008-02-01

    A tape casting procedure for fabricating ceramic magnesium oxide tapes has been developed as a method to produce flat sheets of sintered MgO that are thin and porous. Thickness of single layer tapes is in the range of 200-400 {micro}m with corresponding surface roughness values in the range of 10-20 {micro}m as measured by laser profilometry. Development of the tape casting technique required optimization of pretreatment for the starting magnesium oxide (MgO) powder as well as a detailed study of the casting slurry preparation and subsequent heat treatments for sintering and final tape flattening. Milling time of the ceramic powder, plasticizer, and binder mixture was identified as a primary factor affecting surface morphology of the tapes. In general, longer milling times resulted in green tapes with a noticeably smoother surface. This work demonstrates that meticulous control of the entire tape casting operation is necessary to obtain high-quality MgO tapes.

  11. The Effect of Casting Ring Liner Length and Prewetting on the Marginal Adaptation and Dimensional Accuracy of Full Crown Castings

    PubMed Central

    Haralur, Satheesh B.; Hamdi, Osama A.; Al-Shahrani, Abdulaziz A.; Alhasaniah, Sultan

    2017-01-01

    Aim: To evaluate the effect of varying cellulose casting ring liner length and its prewetting on the marginal adaptation and dimensional accuracy of full veneer metal castings. Materials and Methods: The master die was milled in stainless steel to fabricate the wax pattern. Sixty wax patterns were fabricated with a uniform thickness of 1.5 mm at an occlusal surface and 1 mm axial surface, cervical width at 13.5 mm, and 10 mm cuspal height. The samples were divided into six groups (n = 10). Groups I and II samples had the full-length cellulose prewet and dry ring liner, respectively. The groups III and IV had 2 mm short prewet and dry cellulose ring liner, respectively, whereas groups V and VI were invested in 6 mm short ring liner. The wax patterns were immediately invested in phosphate bonded investment, and casting procedure was completed with nickel-chrome alloy. The castings were cleaned and mean score of measurements at four reference points for marginal adaption, casting height, and cervical width was calculated. The marginal adaption was calculated with Imaje J software, whereas the casting height and cervical width was determined using a digital scale. The data was subjected to one-way analysis of varaince and Tukey post hoc statistical analysis with Statistical Package for the Social Sciences version 20 software. Results: The group II had the best marginal adaption with a gap of 63.786 μm followed by group I (65.185 μm), group IV (87.740 μm), and group III (101.455 μm). A large marginal gap was observed in group V at 188.871 μm. Cuspal height was more accurate with group V (10.428 mm), group VI (10.421 mm), and group II (10.488 mm). The cervical width was approximately similar in group I, group III, and group V. Statistically significant difference was observed in Tukey post hoc analysis between group V and group VI with all the other groups with regards to marginal adaptation. Conclusion: The dry cellulose ring liners provided better marginal

  12. Die Welt des Herrn Kuhn

    NASA Astrophysics Data System (ADS)

    Kern, Daniela

    Eines Morgens erwachte Herr Kuhn fröstelnd und staunte darüber, dass es in seinerWohnung eiskalt war. Dennoch quälte er sich aus seiner kuscheligen Bettdecke heraus und schlurfte ins Bad. "Hoffentlich wird wenigstens das Wasser warm", dachte er sich, als er den Wasserhahn betätigte - aber es kam nicht nur kein warmesWasser, außer einem unheilvollen Gluckser kam gar nichts aus der Leitung. "Dann werde ich wohl mal den Klempner anrufen", sprach er sich leise in den Bart und griff zu seinem Handy - doch das Netz war tot! Herr Kuhn begann nun, sich ernsthaft Sorgen zu machen, "Oje, was ist denn heute nur los? Ist irgendetwas Schlimmes passiert?" Um einen besseren Überblick über die Lage zu bekommen und sich austauschen zu können, brannte er nun förmlich darauf, rauszugehen und zur Arbeit zu fahren. An anderen Tagen, die er frisch geduscht und mit Kaffee und Marmeladen-Brot begann, war er selten so motiviert. So ging er also nun mit leerem Magen aus dem Haus. Hätte er den Versuch unternommen, sein tägliches Marmeladenbrot zuzubereiten, und dafür den Kühlschrank geöffnet, um das Marmeladenglas herauszunehmen, wäre ihm aufgefallen, dass auch die Stromversorgung Störungen unterworfen war, unschön zu erkennen an den ersten grünen, felligen Inseln auf seinem Lieblingskäse.

  13. Energy-Saving Melting and Revert Reduction Technology (E-SMARRT): Use of Laser Engineered Net Shaping for Rapid Manufacturing of Dies with Protective Coatings and Improved Thermal Management

    SciTech Connect

    Brevick, Jerald R.

    2014-06-13

    In the high pressure die casting process, molten metal is introduced into a die cavity at high pressure and velocity, enabling castings of thin wall section and complex geometry to be obtained. Traditional die materials have been hot work die steels, commonly H13. Manufacture of the dies involves machining the desired geometry from monolithic blocks of annealed tool steel, heat treating to desired hardness and toughness, and final machining, grinding and polishing. The die is fabricated with internal water cooling passages created by drilling. These materials and fabrication methods have been used for many years, however, there are limitations. Tool steels have relatively low thermal conductivity, and as a result, it takes time to remove the heat from the tool steel via the drilled internal water cooling passages. Furthermore, the low thermal conductivity generates large thermal gradients at the die cavity surfaces, which ultimately leads to thermal fatigue cracking on the surfaces of the die steel. The high die surface temperatures also promote the metallurgical bonding of the aluminum casting alloy to the surface of the die steel (soldering). In terms of process efficiency, these tooling limitations reduce the number of die castings that can be made per unit time by increasing cycle time required for cooling, and increasing downtime and cost to replace tooling which has failed either by soldering or by thermal fatigue cracking (heat checking). The objective of this research was to evaluate the feasibility of designing, fabricating, and testing high pressure die casting tooling having properties equivalent to H13 on the surface in contact with molten casting alloy - for high temperature and high velocity molten metal erosion resistance – but with the ability to conduct heat rapidly to interior water cooling passages. A layered bimetallic tool design was selected, and the design evaluated for thermal and mechanical performance via finite element analysis. H13 was

  14. Impact of Simulation Technology on Die and Stamping Business

    NASA Astrophysics Data System (ADS)

    Stevens, Mark W.

    2005-08-01

    Over the last ten years, we have seen an explosion in the use of simulation-based techniques to improve the engineering, construction, and operation of GM production tools. The impact has been as profound as the overall switch to CAD/CAM from the old manual design and construction methods. The changeover to N/C machining from duplicating milling machines brought advances in accuracy and speed to our construction activity. It also brought significant reductions in fitting sculptured surfaces. Changing over to CAD design brought similar advances in accuracy, and today's use of solid modeling has enhanced that accuracy gain while finally leading to the reduction in lead time and cost through the development of parametric techniques. Elimination of paper drawings for die design, along with the process of blueprinting and distribution, provided the savings required to install high capacity computer servers, high-speed data transmission lines and integrated networks. These historic changes in the application of CAE technology in manufacturing engineering paved the way for the implementation of simulation to all aspects of our business. The benefits are being realized now, and the future holds even greater promise as the simulation techniques mature and expand. Every new line of dies is verified prior to casting for interference free operation. Sheet metal forming simulation validates the material flow, eliminating the high costs of physical experimentation dependent on trial and error methods of the past. Integrated forming simulation and die structural analysis and optimization has led to a reduction in die size and weight on the order of 30% or more. The latest techniques in factory simulation enable analysis of automated press lines, including all stamping operations with corresponding automation. This leads to manufacturing lines capable of running at higher levels of throughput, with actual results providing the capability of two or more additional strokes per

  15. Process development of thin strip steel casting

    SciTech Connect

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

    1990-12-01

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

  16. Emulsion based cast booster - a priming system

    SciTech Connect

    Gupta, R.N.; Mishra, A.K.

    2005-07-01

    This paper explores the potential of emulsion based cast booster to be used as primer to initiate bulk delivered emulsion explosives used in mines. An attempt has been made for comparative study between conventional cast booster and emulsion based cast booster in terms of the initiation process developed and their capability to develop and maintain the stable detonation process in the column explosives. The study has been conducted using a continuous velocity of detonation (VOD) measuring instrument. During this study three blasts have been monitored. In each blast two holes have been selected for study, the first hole being initiated with conventional cast booster while the other one with emulsion based cast booster. The findings of the study advocates that emulsion based cast booster is capable of efficient priming of bulk delivered column explosive with stable detonation process in the column. Further, the booster had advantages over the conventional PETN/TNT based cast booster. 5 refs., 2 figs., 1 tab., 1 photo.

  17. Effect of Mold Coating Materials and Thickness on Heat Transfer in Permanent Mold Casting of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Hamasaiid, A.; Dargusch, M. S.; Davidson, C. J.; Tovar, S.; Loulou, T.; Rezaï-Aria, F.; Dour, G.

    2007-06-01

    In permanent mold casting or gravity die casting (GDC) of aluminum alloys, die coating at the casting-mold interface is the most important single factor controlling heat transfer and, hence, it has the greatest influence on the solidification rate and development of microstructure. This investigation studies the influence of coating thickness, coating composition, and alloy composition on the heat transfer at the casting-mold interface. Both graphite and TiO2-based coatings have been investigated. Two aluminum alloys have been investigated: Al-7Si-0.3Mg and Al-9Si-3Cu. Thermal histories throughout the die wall have been recorded by fine type-K thermocouples. From these measurements, die surface temperatures and heat flux density have been evaluated using an inverse method. Casting surface temperature was measured by infrared pyrometry, and the interfacial heat-transfer coefficient (HTC) has been determined using these combined pieces of information. While the alloy is liquid, the coating material has only a weak influence over heat flow and the thermal contact resistance seems to be governed more by coating porosity and thickness. The HTC decreases as the coating thickness increases. However, as solidification takes place and the HTC decreases, the HTC of graphite coating remains higher than that of ceramic coatings of similar thickness. After the formation of an air gap at the interface, the effect of coating material vanishes. The peak values of HTC and the heat flux density are larger for Al-7Si-0.3Mg than for Al-9Si-3Cu. Consequently, the apparent solidification time of Al-9Si-3Cu is larger than that of Al-7Si-0.3Mg and it increases with coating thickness.

  18. Treatment of Aluminum Die Casting Operations for the Purposes of NSR Applicability

    EPA Pesticide Factsheets

    This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  19. The Effects of Die Relief Agent on the Retention of Full Coverage Castings,

    DTIC Science & Technology

    1981-02-19

    modified zinc oxide- eugenol cement was studied; Forces required to dislodge non-relieved cas- 6.. tings from tooth preparations were significantly...Forge, VA 24422. -7, 3 cement, or a reinforced zinc oxide- eugenol cement. The cements * I were proportioned and mixed_ in accordance with their...abilities of modified zinc oxide- eugenol , zinc polyacrylate or zinc phosphate cement when used to retain crowns on preparations exhibitiig good retention

  20. The die is cast - Arsenic exposure in early life and disease susceptibility

    EPA Science Inventory

    Abstract Early life exposure to arsenic in humans and mice produces similar patterns of disease in later life. Given the long interval between exposure and effect, epigenetic effects of early life exposure to arsenic may account for development and progression of disease in bo...

  1. The die has been cast? Rediscovering the essence of psychiatric nursing.

    PubMed

    Cutcliffe, John R

    Examination of the international literature that focuses on the historical 'developments' in psychiatric nursing shows a 'back and forth' shift in emphasis from interpersonal/therapy-based models to a concentration on pathophysiology, pharmacology and biological causation. Within this context, a number of ontological questions appear with conspicuous regularity and these are worthwhile considerations as they are tied to the very nature of psychiatric nursing. Examination of the relevant literature reflects this historical duality and indicates the existence of (at least) two versions of psychiatric nurse, each with a distinct emphasis. Given this documented duality, it is the duty of each nurse to ask themselves: What type of psychiatric nurse am I? What type do I want to be and what type would I want participating in the care of someone I love? Consequently, this article draws on bodies of literature pertaining to the extent of mental health problems, the views of mental health service users, and the different types of psychiatric nurse, in order to assist nurses in considering these questions. In the light of the clear emphasis evident within contemporary mental health policy and psychiatric nursing curricula, the article concludes that it may not be possible to reconcile the activities associated with both types of psychiatric nurse.

  2. The Die Is Cast: Precision Electrophilic Modifications Contribute to Cellular Decision Making

    PubMed Central

    2016-01-01

    This perspective sets out to critically evaluate the scope of reactive electrophilic small molecules as unique chemical signal carriers in biological information transfer cascades. We consider these electrophilic cues as a new volatile cellular currency and compare them to canonical signaling circulation such as phosphate in terms of chemical properties, biological specificity, sufficiency, and necessity. The fact that nonenzymatic redox sensing properties are found in proteins undertaking varied cellular tasks suggests that electrophile signaling is a moonlighting phenomenon manifested within a privileged set of sensor proteins. The latest interrogations into these on-target electrophilic responses set forth a new horizon in the molecular mechanism of redox signal propagation wherein direct low-occupancy electrophilic modifications on a single sensor target are biologically sufficient to drive functional redox responses with precision timing. We detail how the various mechanisms through which redox signals function could contribute to their interesting phenotypic responses, including hormesis. PMID:27617777

  3. Inner surface roughness of complete cast crowns made by centrifugal casting machines.

    PubMed

    Ogura, H; Raptis, C N; Asgar, K

    1981-05-01

    Six variables that could affect the surface roughness of a casting were investigated. The variables were (1) type of alloy, (2) mold temperature, (3) metal casting temperature, (4) casting machine, (5) sandblasting, and (6) location of each section. It was determined that the training portion of a complete cast crown had rougher surfaces than the leading portion. Higher mold and casting temperatures produced rougher castings, and this effect was more pronounced in the case of the base metal alloy. Sandblasting reduced the roughness, but produced scratched surfaces. Sandblasting had a more pronounced affect on the surface roughness of the base metal alloy cast either at a higher mold temperature or metal casting temperature. The morphology and the roughness profile of the original cast surface differed considerably with the type of alloy used.

  4. Titanium casting: the surface reaction layer of castings obtained using ultra-low-temperature molds.

    PubMed

    Kikuchi, H; Onouchi, M; Hsu, H C; Kurotani, T; Nishiyama, M

    2001-03-01

    To examine whether the surface reaction layer of titanium castings can be reduced by lowering the mold temperature during casting, we cast titanium at three mold temperatures, including an ultra-low temperature produced by cooling the mold with liquid nitrogen, then measured the tensile strength and elongation of the castings. The titanium was cast using a centrifugal casting machine, and the molds were incinerated according to the manufacturers' instructions. Castings were then made with the molds at 200 degrees C, 600 degrees C, and an ultra-low temperature (-196 degrees C). The castability of titanium cast in the mold at the ultra-low temperature was good. The Vickers hardness near the surface layer of castings decreased as the mold temperature decreased.

  5. The cast structure of a 7075 alloy produced by a water-cooling centrifugal casting method

    SciTech Connect

    Yeh, J.W. . Dept. of Materials Science and Engineering); Jong, S.H.

    1994-03-01

    A water-cooling centrifugal casting method was applied to cast the 7075 Al alloy to generate a much finer cast structure than that produced by conventional ingot casting methods. The effects of casting parameters, i.e., rotation speed, pouring temperature, water flow, and grain refiner, on casting structure were systematically studied so that the optimum casting condition and the solidification mechanism could be established. The typical cast structure along the thickness direction of a cast ring could be divided into four equiaxed zones, including the chill zone which is in contact with the mold wall. All zones have their characteristic grain size, morphology, and relative thickness, which are all dependent on the casting condition. The optimum casting condition yielding the finest structure available was found to be 3,000 rpm, 650 C, and sufficient water cooling. A uniform portion occupying 90 pct of the whole thickness and having a grain size of 17 [mu]m could be achieved under such a casting condition. When a grain refiner was added, the whole ring became further concentrated with grains of fine structure. A mechanism concerning the overall effects of rapid solidification, turbulent flow, and centrifugal force has been proposed for the present casting method and might explain the zone-structure formation and the effects of the casting parameters on microstructural features.

  6. Innovative algorithm for cast detection

    NASA Astrophysics Data System (ADS)

    Gasparini, Francesca; Schettini, Raimondo; Gallina, Paolo

    2001-12-01

    The paper describes a method for detecting a color cast (i.e. a superimposed dominant color) in a digital image without any a priori knowledge of its semantic content. The color gamut of the image is first mapped in the CIELab color space. The color distribution of the whole image and of the so-called Near Neutral Objects (NNO) is then investigated using statistical tools then, to determine the presence of a cast. The boundaries of the near neutral objects in the color space are set adaptively by the algorithm on the basis of a preliminary analysis of the image color gamut. The method we propose has been tuned and successfully tested on a large data set of images, downloaded from personal web-pages or acquired using various digital and traditional cameras.

  7. Machine Casting of Ferrous Alloys

    DTIC Science & Technology

    1977-06-01

    During this year the basic Rheocasting system, which was fully operational at the beginning of the year, was improved in various ways to increase...graphite inserts at the bottom of the Rheocaster to eliminate ’hot spots’. Large quantities of 304 and 440C stainless steel alloys were cast during this...period (approximately 800 pounds of 304 and 2000 pounds of 440C) and smaller quantities of other materials were also Rheocast including M2 tool steel, and

  8. Machine Casting of Ferrous Alloys

    DTIC Science & Technology

    1974-10-01

    To protect the shot sleeve and plunger, a graphite wafer was inserted against the plunger tip, and a Fiberfrax (R) cloth was placed on the bottom...of the shot sleeve. After casting, (R) the Fiberfrax cloth was matted in the biscuit, and the wafer was on the end of the biscuit where it could... Fiberfrax cloth on the bottom of the shot sleeve, and insert a graphite wafer against the shot ram tip. Then, molten metal is poured into a preheated

  9. Die singulation method and package formed thereby

    DOEpatents

    Anderson, Robert C [Tucson, AZ; Shul, Randy J [Albuquerque, NM; Clews, Peggy J [Tijeras, NM; Baker, Michael S [Albuquerque, NM; De Boer, Maarten P [Albuquerque, NM

    2012-08-07

    A method is disclosed for singulating die from a substrate having a sacrificial layer and one or more device layers, with a retainer being formed in the device layer(s) and anchored to the substrate. Deep Reactive Ion Etching (DRIE) etching of a trench through the substrate from the bottom side defines a shape for each die. A handle wafer is then attached to the bottom side of the substrate, and the sacrificial layer is etched to singulate the die and to form a frame from the retainer and the substrate. The frame and handle wafer, which retain the singulated die in place, can be attached together with a clamp or a clip and to form a package for the singulated die. One or more stops can be formed from the device layer(s) to limit a sliding motion of the singulated die.

  10. Vacuum die attach for integrated circuits

    DOEpatents

    Schmitt, E.H.; Tuckerman, D.B.

    1991-09-10

    A thin film eutectic bond for attaching an integrated circuit die to a circuit substrate is formed by coating at least one bonding surface on the die and substrate with an alloying metal, assembling the die and substrate under compression loading, and heating the assembly to an alloying temperature in a vacuum. A very thin bond, 10 microns or less, which is substantially void free, is produced. These bonds have high reliability, good heat and electrical conduction, and high temperature tolerance. The bonds are formed in a vacuum chamber, using a positioning and loading fixture to compression load the die, and an IR lamp or other heat source. For bonding a silicon die to a silicon substrate, a gold silicon alloy bond is used. Multiple dies can be bonded simultaneously. No scrubbing is required. 1 figure.

  11. Reinraumtechnik für die Medizintechnik

    NASA Astrophysics Data System (ADS)

    Petek, Max; Jungbluth, Martin; Krampe, Erhard

    Die Reinraumtechnik ist heute ein unverzichtbarer Bestandteil bei der Fertigung von Produkten der Life Sciences, den Bereichen Pharma, Lebensmittel, Kosmetik und Medizintechnik. In Anbetracht der langen Historie der Medizintechnik ist sie jedoch eine sehr junge Disziplin. Die Bedeutung von Keimen und die richtige Einschätzung ihrer Größe wurden zwar sehr früh bereits durch Paracelsus erkannt, jedoch wurden daraus noch keine speziellen oder kontinuierlich umgesetzten Hygienevorschriften abgeleitet. Die erste bekannte technische Umsetzung von Hygieneempfehlungen geht auf den Franzosen François Nicolas Appert zurück, der eine aseptische Abfüllmethode für Lebensmittel entwickelte und diese 1810 veröffentlichte [1]. Die erste dokumentierte medizinische Umsetzung stellten Hygienevorschriften für Ärzte dar, die Ignaz Philipp Semmelweis nach 1847 in der Wiener Klinik für Geburtshilfe einführte [2].

  12. Vacuum die attach for integrated circuits

    DOEpatents

    Schmitt, Edward H.; Tuckerman, David B.

    1991-01-01

    A thin film eutectic bond for attaching an integrated circuit die to a circuit substrate is formed by coating at least one bonding surface on the die and substrate with an alloying metal, assembling the die and substrate under compression loading, and heating the assembly to an alloying temperature in a vacuum. A very thin bond, 10 microns or less, which is substantially void free, is produced. These bonds have high reliability, good heat and electrical conduction, and high temperature tolerance. The bonds are formed in a vacuum chamber, using a positioning and loading fixture to compression load the die, and an IR lamp or other heat source. For bonding a silicon die to a silicon substrate, a gold silicon alloy bond is used. Multiple dies can be bonded simultaneously. No scrubbing is required.

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

    PubMed Central

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

    2015-01-01

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

  14. Machine Casting of Ferrous Alloys

    DTIC Science & Technology

    1976-11-01

    ii TABLE OF CONTENTS ABSTRACT .......................... Introduction ........................ Continuous Rheocasting ...ferrous alloys is fully and reliably operational. The Continuous Rheocaster works dependably in production runs in which typically up to 500 pounds... Rheocast stainless steel and the initiation of large scale Thixocasting runs to test actual die life. More than 3000 pounds of Rheocast stainless

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

    SciTech Connect

    Gwyn, Mike

    2009-03-31

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

  16. [The cast structure after vacuum-pressure casting and centrifugal casting].

    PubMed

    Finger, W; Jung, T; Quast, U

    1975-02-01

    Evaluation of polished sections revealed the following: 1. Grain size in marginal areas of the crown is, in general, smaller than it is in the occlusal region. 2. Grain size varies depending on the casting method applied. Differences in hardness were found only to a limited extent. They were not always in line with the grain structure. This phenomenon deviating from the rule cannot satisfactorily be explained. The piping distribution was in accordance with observations made so far.

  17. Method for casting thin metal objects

    DOEpatents

    Pehrson, Brandon P; Moore, Alan F

    2015-04-14

    Provided herein are various embodiments of systems for casting thin metal plates and sheets. Typical embodiments include layers of mold cavities that are oriented vertically for casting the metal plates. In some embodiments, the mold cavities include a beveled edge such that the plates that are cast have a beveled edge. In some embodiments, the mold cavities are filled with a molten metal through an open horizontal edge of the cavity. In some embodiments, the mold cavities are filled through one or more vertical feed orifices. Further disclosed are methods for forming a thin cast metal plate or sheet where the thickness of the cast part is in a range from 0.005 inches to 0.2 inches, and the surface area of the cast part is in a range from 16 square inches to 144 square inches.

  18. Clean Cast Steel Technology, Phase IV

    SciTech Connect

    Charles E. Bates

    2003-02-24

    The objective of the Clean Cast Steel Technology Program was to improve casting product quality by removing or minimizing oxide defects and to allow the production of higher integrity castings for high speed machining lines. Previous research has concentrated on macro-inclusions that break, chip, or crack machine tool cutters and drills and cause immediate shutdown of the machining lines. The overall goal of the project is to reduce the amount of surface macro-inclusions and improve the machinability of steel castings. Macro-inclusions and improve the machinability of steel castings. Macro-inclusions have been identified by industrial sponsors as a major barrier to improving the quality and marketability of steel castings.

  19. Gating of Permanent Molds for ALuminum Casting

    SciTech Connect

    David Schwam; John F. Wallace; Tom Engle; Qingming Chang

    2004-03-30

    This report summarizes a two-year project, DE-FC07-01ID13983 that concerns the gating of aluminum castings in permanent molds. The main goal of the project is to improve the quality of aluminum castings produced in permanent molds. The approach taken was determine how the vertical type gating systems used for permanent mold castings can be designed to fill the mold cavity with a minimum of damage to the quality of the resulting casting. It is evident that somewhat different systems are preferred for different shapes and sizes of aluminum castings. The main problems caused by improper gating are entrained aluminum oxide films and entrapped gas. The project highlights the characteristic features of gating systems used in permanent mold aluminum foundries and recommends gating procedures designed to avoid common defects. The study also provides direct evidence on the filling pattern and heat flow behavior in permanent mold castings.

  20. Accuracy of Casting Single Crowns in Titanium

    DTIC Science & Technology

    1990-04-01

    in bone (Branemark, et.al. 1985). Titanium’s biocompatibility in dental implantology created an interest in its use in cast restorations. The aerospace...and dental implantology , but implants are fabricated by machining, not casting. The first use of Ti as a cast dental restoration was accomplished in...Chairman of Dental Research, WHMC) and Dr. Adrian F. VanDellen (Veterinary Research Pathologist) for their assistance in accomplishing the

  1. Integrally Cast Low-Cost Compressor.

    DTIC Science & Technology

    1983-01-03

    and AE355 for discs). Figures 3 through 6 sumarize cast Custom 450 properties compared with wrought A350 and 355 and cast 17 - 4PH (a common compressor...experience with the casting of other Custom 450 alloy and 17 - 4PH alloy components. Although higher cagting and mold temperatures normally assist alloy...by regulation of air pressure. Tip deflection was related to the stress at failure locations by strain gaging techniques. 94 AOL- TABLE 17 . TENSILE

  2. Directional Solidification of Nodular Cast Iron

    NASA Technical Reports Server (NTRS)

    Curreri, P. A.; Stefanescu, D. M.; Hendrix, J. C.

    1987-01-01

    Cerium enhances formation of graphite nodules. Preliminary experiments in directional solidification of cast iron shows quantitative correlation of graphite microstructure with growth rate and thermal gradient, with sufficient spheroidizing element to form spheroidal graphite under proper thermal conditions. Experimental approach enables use of directional solidification to study solidification of spheriodal-graphite cast iron in low gravity. Possible to form new structural materials from nodular cast iron.

  3. High-Density-Tape Casting System

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr.

    1987-01-01

    Centrifuge packs solids from slurry into uniform, dense layer. New system produces tapes of nearly theoretical packing density. Centrifugal system used to cast thin tapes for capacitors, fuel cells, and filters. Cylindrical rotary casting chamber mounted on high-speed bearings and connected to motor. Liquid for vapor-pressure control and casting slurry introduced from syringes through rotary seal. During drying step, liquid and vapor vented through feed tubes or other openings. Laminated tapes produced by adding more syringes to cast additional layers of different materials.

  4. The Right To Die. Public Talk Series.

    ERIC Educational Resources Information Center

    Pasquerella, Lynn

    This program guide on the right to die provides policy issue information where ethical concerns have a prominent place. Three positions about the right to die are presented: (1) mercy killing and assisted suicide should be legally permitted in certain cases; (2) legal status should be given to living wills and other advance directives that would…

  5. Die Evolution der Religiosität

    NASA Astrophysics Data System (ADS)

    Voland, Eckart

    Ein konsequent darwinischer Blick auf den Menschen bedeutet, auch im Denken, Fühlen und Handeln biologische Anpassungsgeschichte zu suchen, denn auch die psychischen und mentalen Eigenheiten des Homo sapiens unterliegen der natürlichen Selektion. Lässt sich die religiöse Lebenspraxis von Menschen daher auch aus einer Fitnessperspektive betrachten?

  6. Death and Dying: Issues for Educational Gerontologists.

    ERIC Educational Resources Information Center

    Wass, Hannelore, Myers, Jane E.

    1984-01-01

    Reviews research on death orientations, the dying process, and bereavement, with a major focus on the elderly. Suggests that relevant knowledge about death and dying are important for gerontological practitioners and proposes that death-related content be systematically integrated into academic curricula at the preservice and inservice levels.…

  7. Apparatus for restraining and transporting dies

    DOEpatents

    Allison, James W.; LaBarre, Timothy L.

    1994-01-01

    Apparatus for restraining and transporting dies in punch press operations is provided. A floatation platen for supporting a die on the platen's upper surface has a plurality of recessed gas exhaust ports on the platen's lower surface. A source of pressurized gas delivers gas to a platen manifold, for delivery to orifices located in the gas exhaust ports. The flow of gas is controlled by a first valve adjacent the gas source and a second valve adjacent the manifold, with the second valve being used to control the gas flow during movement of the die. In this fashion, a die may be moved on a cushion of air from one workstation to a selected second workstation. A moveable hydraulically operated restraining fixture is also provided, for clamping the die in position during the compacting phase, and for releasing the die after completion of the compacting phase by releasing the hydraulic pressure on the restraining fixture. When pressure in the hydraulic cylinders on the restraining fixture is reversed, the restraining fixture will retract so that there is no contact between the die and the restraining fixture, thereby allowing the die to be removed from a first workstation and moved to a second selected workstation.

  8. Student Nurses' Perception of Death and Dying

    ERIC Educational Resources Information Center

    Niederriter, Joan E.

    2009-01-01

    Student nurses are involved in caring for patients who are actively dying or who have been told they have a terminal illness and are faced with the process of dying. Students encounter these patients in hospitals, nursing homes, at home or in hospice care settings. According to Robinson (2004), "nurses are the healthcare providers that are most…

  9. Release of ToxCastDB and ExpoCastDB databases

    EPA Science Inventory

    EPA has released two databases - the Toxicity Forecaster database (ToxCastDB) and a database of chemical exposure studies (ExpoCastDB) - that scientists and the public can use to access chemical toxicity and exposure data. ToxCastDB users can search and download data from over 50...

  10. Spray casting project final report

    SciTech Connect

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

    1996-08-01

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

  11. Microdefects in cast multicrystalline silicon

    SciTech Connect

    Wolf, E.; Klinger, D.; Bergmann, S.

    1995-08-01

    The microdefect etching behavior of cast multicrystalline BAYSIX and SILSO samples is mainly the same as that of EFG silicon, in spite of the very different growth parameters applied to these two techniques and the different carbon contents of the investigated materials. Intentional decorating of mc silicon with copper, iron and gold did not influence the results of etching and with help of infrared transmission microscopy no metal precipitates at the assumed microdefects could be established. There are many open questions concerning the origin of the assumed, not yet doubtless proved microdefects.

  12. Influence of die geometry and material selection on the behavior of protective die covers in closed-die forging

    NASA Astrophysics Data System (ADS)

    Yu, Yingyan; Rosenstock, Dirk; Wolfgarten, Martin; Hirt, Gerhard

    2016-10-01

    Due to the fact that tooling costs make up to 30% of total costs of the final forged part, the tool life is always one main research topic in closed-die forging [1]. To improve the wear resistance of forging dies, many methods like nitriding and deposition of ceramic layers have been used. However, all these methods will lose its effect after a certain time, then tool repair or exchange is needed, which requires additional time and costs. A new method, which applies an inexpensive and changeable sheet metal on the forging die to protect it from abrasive wear, was firstly proposed in [2]. According to the first investigation, the die cover is effective for decreasing thermal and mechanical loads, but there are still several challenges to overcome in this concept, like wrinkling and thinning of the die cover. Therefore, an experimental study using different geometries and die cover materials is presented within this work. The results indicate the existence of feasible application cases of this concept, since conditions are found under which a die cover made of 22MnB5 still keeps its original shape even after 7 forging cycles.

  13. Optimization of a Permanent Step Mold Design for Mg Alloy Castings

    NASA Astrophysics Data System (ADS)

    Timelli, Giulio; Capuzzi, Stefano; Bonollo, Franco

    2015-02-01

    The design of a permanent Step mold for the evaluation of the mechanical properties of light alloys has been reviewed. An optimized Step die with a different runner and gating systems is proposed to minimize the amount of casting defects. Numerical simulations have been performed to study the filling and solidification behavior of an AM60B alloy to predict the turbulence of the melt and the microshrinkage formation. The results reveal how a correct design of the trap in the runners prevents the backwave of molten metal, which could eventually reverse out and enter the die cavity. The tapered runner in the optimized die configuration gently leads the molten metal to the ingate, avoiding turbulence and producing a balanced die cavity filling. The connection between the runner system and the die cavity by means of a fan ingate produces a laminar filling in contrast with a finger-type ingate. Solidification defects such as shrinkage-induced microporosity, numerically predicted through a dimensionless version of the Niyama criterion, are considerably reduced in the optimized permanent Step mold.

  14. Yield Improvement in Steel Casting (Yield II)

    SciTech Connect

    Richard A. Hardin; Christoph Beckermann; Tim Hays

    2002-02-18

    This report presents work conducted on the following main projects tasks undertaken in the Yield Improvement in Steel Casting research program: Improvement of Conventional Feeding and Risering Methods, Use of Unconventional Yield Improvement Techniques, and Case Studies in Yield Improvement. Casting trials were conducted and then simulated using the precise casting conditions as recorded by the participating SFSA foundries. These results present a statistically meaningful set of experimental data on soundness versus feeding length. Comparisons between these casting trials and casting trials performed more than forty years ago by Pellini and the SFSA are quite good and appear reasonable. Comparisons between the current SFSA feeding rules and feeding rules based on the minimum Niyama criterion reveal that the Niyama-based rules are generally less conservative. The niyama-based rules also agree better with both the trials presented here, and the casting trails performed by Pellini an d the SFSA years ago. Furthermore, the use of the Niyama criterion to predict centerline shrinkage for horizontally fed plate sections has a theoretical basis according to the casting literature reviewed here. These results strongly support the use of improved feeding rules for horizontal plate sections based on the Niyama criterion, which can be tailored to the casting conditions for a given alloy and to a desired level of soundness. The reliability and repeatability of ASTM shrinkage x-ray ratings was investigated in a statistical study performed on 128 x-rays, each of which were rated seven different times. A manual ''Feeding and Risering Guidelines for Steel Castings' is given in this final report. Results of casting trials performed to test unconventional techniques for improving casting yield are presented. These use a stacked arrangement of castings and riser pressurization to increase the casting yield. Riser pressurization was demonstrated to feed a casting up to four time s the

  15. Clean cast steel technology. Final report

    SciTech Connect

    Bates, C.E.; Griffin, J.A.

    1998-06-01

    This report documents the results obtained from the Clean Cast Steel Technology Program financially supported by the DOE Metal Casting Competitiveness Research Program and industry. The primary objective of this program is to develop technology for delivering steel free of oxide macroinclusions to mold cavities. The overall objective is to improve the quality of cast steel by developing and demonstrating the technology for substantially reducing surface and sub-surface oxide inclusions. Two approaches are discussed here. A total of 23 castings were produced by submerge pouring along with sixty conventionally poured castings. The submerged poured castings contained, on average, 96% fewer observable surface inclusions (11.9 vs 0.4) compared to the conventionally poured cast parts. The variation in the population of surface inclusions also decreased by 88% from 5.5 to 0.7. The machinability of the casting was also improved by submerged pouring. The submerge poured castings required fewer cutting tool changes and less operator intervention during machining. Subsequent to these trials, the foundry has decided to purchase more shrouds for continued experimentation on other problem castings where submerge pouring is possible. An examination of melting and pouring practices in four foundries has been carried out. Three of the four foundries showed significant improvement in casting quality by manipulating the melting practice. These melting practice variables can be grouped into two separate categories. The first category is the pouring and filling practice. The second category concerns the concentration of oxidizable elements contained in the steel. Silicon, manganese, and aluminum concentrations were important factors in all four foundries. Clean heats can consistently be produced through improved melting practice and reducing exposure of the steel to atmospheric oxygen during pouring and filling.

  16. The Role of Indian Caste Identity and Caste Inconsistent Norms on Status Representation

    PubMed Central

    Sankaran, Sindhuja; Sekerdej, Maciek; von Hecker, Ulrich

    2017-01-01

    The Indian caste system is a complex social structure wherein social roles like one’s profession became ‘hereditary,’ resulting in restricted social mobility and fixed status hierarchies. Furthermore, we argue that the inherent property of caste heightens group identification with one’s caste. Highly identified group members would protect the identity of the group in situations when group norms are violated. In this paper, we were interested in examining the consequence of caste norm violation and how an individual’s status is mentally represented. High caste norms are associated with moral values while the lower caste norms are associated with immorality. We predicted a ‘black sheep effect,’ that is, when high caste individuals’ group identity (caste norm violation condition) is threatened their salient high caste identity would increase, thereby resulting in devaluing the status of their fellow in-group member if the latter is perceived as perpetrator. We presented participants with a social conflict situation of a victim and a perpetrator that is ‘Caste norm consistent’ (Lower caste individual as a perpetrator and higher caste individual as a victim) and vice versa ‘Caste norm inconsistent’ condition (higher caste individual as perpetrator and lower caste individual as a victim). Then, participants had to choose from nine pictorial depictions representing the protagonists in the story on a vertical line, with varying degrees of status distance. Results showed evidence for the black sheep effect and, furthermore, revealed that no other identity (religious, national, and regional) resulted in devaluing the status of fellow in-group member. These results help us understand the ‘black sheep’ effect in the context of moral norms and status representation and are discussed in the framework of the Indian society.

  17. 21 CFR 888.5960 - Cast removal instrument.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) MEDICAL DEVICES ORTHOPEDIC DEVICES Surgical Devices § 888.5960 Cast removal instrument. (a) Identification... patient. This generic type of device includes the electric cast cutter and cast vacuum. (b)...

  18. DE LAVAUD CASTING FACING NORTH, NOTE CORE MOUNTED IN PREPARATION ...

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

    DE LAVAUD CASTING FACING NORTH, NOTE CORE MOUNTED IN PREPARATION FOR NEXT PIPE CASTING. - United States Pipe & Foundry Company Plant, Pipe Casting & Testing Area, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  19. Energy use in selected metal casting facilities - 2003

    SciTech Connect

    Eppich, Robert E.

    2004-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Tiberto, Dario; Klotz, Ulrich E.

    2012-07-01

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

  1. Casting fine grained, fully dense, strong inorganic materials

    DOEpatents

    Brown, Sam W.; Spencer, Larry S.; Phillips, Michael R.

    2015-11-24

    Methods and apparatuses for casting inorganic materials are provided. The inorganic materials include metals, metal alloys, metal hydrides and other materials. Thermal control zones may be established to control the propagation of a freeze front through the casting. Agitation from a mechanical blade or ultrasonic energy may be used to reduce porosity and shrinkage in the casting. After solidification of the casting, the casting apparatus may be used to anneal the cast part.

  2. 14 CFR 25.621 - Casting factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.621 Casting factors. (a... failure would preclude continued safe flight and landing of the airplane or result in serious injury to... mechanical properties of the material in the casting and provides for demonstration of these properties...

  3. 14 CFR 23.621 - Casting factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Design and Construction § 23.621... casting whose failure would preclude continued safe flight and landing of the airplane or result in... procured to a specification that guarantees the mechanical properties of the material in the casting...

  4. Slip casting and nitridation of silicon powder

    NASA Astrophysics Data System (ADS)

    Seiko, Y.

    1985-03-01

    Powdered Silicon was slip-cast with a CaSO4 x 0.5H2O mold and nitrided in a N atm. containing 0 or 5 vol. % H at 1000 to 1420 deg. To remove the castings, the modeling faces were coated successively with an aq. salt soap and powdered cellulose containing Na alginate, and thus prevented the sticking problem.

  5. 14 CFR 27.621 - Casting factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Casting factors. 27.621 Section 27.621... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.621 Casting factors. (a) General. The factors, tests, and inspections specified in paragraphs (b) and (c) of this section must...

  6. 14 CFR 29.621 - Casting factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Casting factors. 29.621 Section 29.621... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.621 Casting factors. (a) General. The factors, tests, and inspections specified in paragraphs (b) and (c) of this section must...

  7. 14 CFR 27.621 - Casting factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Casting factors. 27.621 Section 27.621... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.621 Casting factors. (a) General. The factors, tests, and inspections specified in paragraphs (b) and (c) of this section must...

  8. 14 CFR 29.621 - Casting factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Casting factors. 29.621 Section 29.621... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.621 Casting factors. (a) General. The factors, tests, and inspections specified in paragraphs (b) and (c) of this section must...

  9. 14 CFR 25.621 - Casting factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Casting factors. 25.621 Section 25.621... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.621 Casting factors. (a) General. The factors, tests, and inspections specified in paragraphs (b) through (d) of this section...

  10. 14 CFR 25.621 - Casting factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Casting factors. 25.621 Section 25.621... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.621 Casting factors. (a) General. The factors, tests, and inspections specified in paragraphs (b) through (d) of this section...

  11. Hand-based thumb spica casting.

    PubMed

    Roberts, W O

    1998-03-01

    A hand-based thumb spica cast can be used to protect the metacarpophalangeal (MCP) and interphalangeal (IP) joints of the thumb after uncomplicated ulnar collateral ligament (UCL) sprains and certain other thumb injuries. The cast allows continued participation in many activities, letting the patient grip an implement and move the wrist joint but immobilizing the thumb joints.

  12. Iron/Phosphorus Alloys for Continuous Casting

    NASA Technical Reports Server (NTRS)

    Dufresne, E. R.

    1986-01-01

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

  13. Processing of IN-718 Lattice Block Castings

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.

    2002-01-01

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

  14. Slip casting and nitridation of silicon powder

    NASA Technical Reports Server (NTRS)

    Seiko, Y.

    1985-01-01

    Powdered Silicon was slip-cast with a CaSO4 x 0.5H2O mold and nitrided in a N atm. containing 0 or 5 vol. % H at 1000 to 1420 deg. To remove the castings, the modeling faces were coated successively with an aq. salt soap and powdered cellulose containing Na alginate, and thus prevented the sticking problem.

  15. 14 CFR 25.621 - Casting factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... be applied in addition to those necessary to establish foundry quality control. The inspections must... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.621 Casting factors. (a...) Examples of these castings are structural attachment fittings, parts of flight control systems,...

  16. PRODUCTION OF SLIP CAST CALCIA HOLLOWWARE

    DOEpatents

    Stoddard, S.D.; Nuckolls, D.E.; Cowan, R.E.

    1963-12-31

    A method for producing slip cast calcia hollow ware in which a dense calcia grain is suspended in isobutyl acetate or a mixture of tertiary amyl alcohol and o-xylene is presented. A minor amount of triethanolamine and oleic acid is added to the suspension vehicle as viscosity adjusting agents and the suspension is cast in a plaster mold, dried, and fired. (AEC)

  17. Effect of microporosity on tensile properties of as-cast AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Lee, Choong Do

    2002-05-01

    In the present study, the effect of microporosity on the tensile properties of as-cast AZ91D magnesium alloy was investigated through experimental observation and numerical prediction. The test specimens were fabricated by die-casting and gravity-casting. For gravity-casting, the inoculation and use of various metallic moulds were applied to obtain a wide range of microporosity. The deficiency of the interdendritic feeding of the liquid phase acted as a dominant mechanism on the formation of the micropores in the Mg-Al-alloys, rather than the evolution of hydrogen gas. Although tensile strength and elongation has a nonlinear and very intensive dependence upon microporosity, the yield strength appeared to have a linear relationship with microporosity. However, it was possible to quantitatively estimate the linear contribution of microporosity on the individual tensile property for a range of microporosity, which was below about 1%. The numerical prediction suggests that the effect of microporosity on fractured strength and elongation decreased as the strain hardening exponent increased. Furthermore, the shape and distribution of micropores may play a more dominant role than local plastic deformation on the tensile behavior of AZ91D alloy.

  18. BMM SHAKEOUT AND VIBRATING CONVEYOR TRANSPORT SAND AND CASTINGS TO ...

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

    BMM SHAKEOUT AND VIBRATING CONVEYOR TRANSPORT SAND AND CASTINGS TO SEPARATIONS SCREENS. - Southern Ductile Casting Company, Shaking, Degating & Sand Systems, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  19. 27 CFR 447.22 - Forgings, castings, and machined bodies.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., castings, extrusions, and machined bodies) which have reached a stage in manufacture where they are clearly... components, accessories, attachments and parts) then the particular forging, casting, extrusion,...

  20. 27 CFR 447.22 - Forgings, castings, and machined bodies.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., castings, extrusions, and machined bodies) which have reached a stage in manufacture where they are clearly... components, accessories, attachments and parts) then the particular forging, casting, extrusion,...

  1. 27 CFR 447.22 - Forgings, castings, and machined bodies.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., castings, extrusions, and machined bodies) which have reached a stage in manufacture where they are clearly... components, accessories, attachments and parts) then the particular forging, casting, extrusion,...

  2. 27 CFR 447.22 - Forgings, castings, and machined bodies.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., castings, extrusions, and machined bodies) which have reached a stage in manufacture where they are clearly... components, accessories, attachments and parts) then the particular forging, casting, extrusion,...

  3. 27 CFR 447.22 - Forgings, castings, and machined bodies.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., castings, extrusions, and machined bodies) which have reached a stage in manufacture where they are clearly... components, accessories, attachments and parts) then the particular forging, casting, extrusion,...

  4. The role of water in slip casting

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  5. INDIAN CASTE SYSTEM: HISTORICAL AND PSYCHOANALYTIC VIEWS.

    PubMed

    Vallabhaneni, Madhusudana Rao

    2015-12-01

    This paper elucidates the historical origins and transformations of India's caste system. Surveying the complex developments over many centuries, it points out that three positions have been taken in this regard. One suggests that the caste one is born into can be transcended within one's lifetime by performing good deeds. The other declares caste to be immutable forever. And, the third says that one can be reborn into a higher caste if one lives a virtuous life. Moving on to the sociopolitical realm, the paper notes how these positions have been used and exploited. The paper then attempts to anchor the existence and purpose of the Hindu caste system in Freud's ideas about group psychology and Klein's proposals of splitting and projective identification. The paper also deploys the large group psychology concepts of Volkan and the culturally nuanced psychoanalytic anthropology of Roland and Kakar. It concludes with delineating some ameliorative strategies for this tragic problem in the otherwise robust democratic society of India.

  6. Final report on Expendable Pattern Casting Technology

    SciTech Connect

    Not Available

    1990-07-01

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

  7. Possible segregation caused by centrifugal titanium casting.

    PubMed

    Watanabe, K; Okawa, S; Kanatani, M; Nakano, S; Miyakawa, O; Kobayashi, M

    1996-12-01

    The possibility of the segregation under solidification process using a centrifugal casting machine was investigated using an electron probe microanalyzer with elemental distribution map, line analysis and quantitative analysis. When a very small quantity of platinum was added to local molten titanium during the casting process, macroscopic segregation was observed under conditions of density difference of 0.1 g/cm3 at the most, confirming that the centrifugal force of the casting machine is extremely strong. When a Ti-6Al-4V alloy was cast, however, no macroscopic segregation was observed. The centrifugal force of the casting machine examined in the present study hardly results in the body-force segregation in this titanium alloy.

  8. Deformation Behavior of the Percolating Eutectic Intermetallic in HPDC and Squeeze-Cast Mg Alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Bao; Yang, Kun V.; Nagasekhar, Anumalasetty V.; Cáceres, Carlos H.; Easton, Mark

    2014-10-01

    The structural compliance of the spatially interconnected intermetallic network in a squeeze-cast MRI230D alloy was determined using focused ion beam (FIB) data and finite element (FE) modeling, and compared with data for a high-pressure die-cast AZ91D and three binary Mg-RE alloys from the existing literature. The respective elastic responses were sorted out into two characteristic behaviors: for eutectic volume fractions less than ~22% the behavior was akin to that of highly compliant, bending-dominated structures, whereas for larger fractions, it reproduced that of structurally efficient, stretch-dominated microtruss structures. In all cases, the contribution from the interconnected network added to the total strength of the alloy an amount comparable with the strengthening expected from a similar volume fraction of dispersed particles. Being more compliant, the bending-dominated structures appeared less prone to developing damage by cracking at low strains than the stretch dominated ones.

  9. Assured fitness returns in a social wasp with no worker caste.

    PubMed

    Lucas, Eric R; Field, Jeremy

    2011-10-07

    The theory of assured fitness returns proposes that individuals nesting in groups gain fitness benefits from effort expended in brood-rearing, even if they die before the young that they have raised reach independence. These benefits, however, require that surviving nest-mates take up the task of rearing these young. It has been suggested that assured fitness returns could have favoured group nesting even at the origin of sociality (that is, in species without a dedicated worker caste). We show that experimentally orphaned brood of the apoid wasp Microstigmus nigrophthalmus continue to be provisioned by surviving adults for at least two weeks after the orphaning. This was the case for brood of both sexes. There was no evidence that naturally orphaned offspring received less food than those that still had mothers in the nest. Assured fitness returns can therefore represent a real benefit to nesting in groups, even in species without a dedicated worker caste.

  10. Is there a moral duty to die?

    PubMed

    Corlett, J A

    2001-01-01

    In recent years, there has been a great deal of philosophical discussion about the alleged moral right to die. If there is such a moral right, then it would seem to imply a moral duty of others to not interfere with the exercise of the right. And this might have important implications for public policy insofar as public policy ought to track what is morally right. But is there a moral duty to die? If so, under what conditions, if any, ought one to have such a duty, and why? In this paper, I distinguish between different moral grounds for the putative moral duty to die: deontological, intuitionist, and contractarian. Subsequently, I argue in support of Paul Menzel's theory of health care distribution. More precisely, I concur with his claim that there is a moral duty to die inexpensively in health care contexts. Then I provide and defend a philosophical analysis of the conditions in which such a duty could exist.

  11. House of Lords debates assisted dying (again).

    PubMed

    2003-07-01

    Lord Joffe's Patient (Assisted Dying) Bill (see Bulletin 187) had its Second Reading on 6 June. The debate was lively, informed and inevitably somewhat polarised. However, some common themes emerged and are outlined below.

  12. Bioinspired Design: Magnetic Freeze Casting

    NASA Astrophysics Data System (ADS)

    Porter, Michael Martin

    Nature is the ultimate experimental scientist, having billions of years of evolution to design, test, and adapt a variety of multifunctional systems for a plethora of diverse applications. Next-generation materials that draw inspiration from the structure-property-function relationships of natural biological materials have led to many high-performance structural materials with hybrid, hierarchical architectures that fit form to function. In this dissertation, a novel materials processing method, magnetic freeze casting, is introduced to develop porous scaffolds and hybrid composites with micro-architectures that emulate bone, abalone nacre, and other hard biological materials. This method uses ice as a template to form ceramic-based materials with continuously, interconnected microstructures and magnetic fields to control the alignment of these structures in multiple directions. The resulting materials have anisotropic properties with enhanced mechanical performance that have potential applications as bone implants or lightweight structural composites, among others.

  13. Thick film silicon growth techniques. [die materials

    NASA Technical Reports Server (NTRS)

    Bates, H. E.; Mlavsky, A. I.; Jewett, D. N.; White, V. E.

    1973-01-01

    The research which was directed toward finding an improved die material is reported. Wetting experiments were conducted with various materials to determine their compatibility with silicon. Work has also continued toward the development of quartz as a die material as new techniques have provided more optimistic results than observed in the past. As a result of the thermal modification previously described, improvements in growth stability have contributed to an increase in ribbon quality.

  14. Machining of Silicon-Ribbon-Forming Dies

    NASA Technical Reports Server (NTRS)

    Menna, A. A.

    1985-01-01

    Carbon extension for dies used in forming silicon ribbon crystals machined precisely with help of special tool. Die extension has edges beveled toward narrow flats at top, with slot precisely oriented and centered between flats and bevels. Cutting tool assembled from standard angle cutter and circular saw or saws. Angle cutters cuts bevels while slot saw cuts slot between them. In alternative version, custom-ground edges or additional circular saws also cut flats simultaneously.

  15. Casting of undoped CdTe crystals with high electrical resistivity

    NASA Astrophysics Data System (ADS)

    Rudolph, P.; Kawasaki, S.; Yamashita, S.; Usuki, Y.; Konagaya, Y.; Matada, S.; Yamamoto, S.; Fukuda, T.

    1995-04-01

    Undoped semi-insulating CdTe crystals with an as-grown shape similar to the device profile for radiation detection has been grown by casting and subsequent unidirectional solidification. Crystals with maximum electrical resistivity of 5.7 × 10 10 Ω · cm and an average value 5 × 10 9 Ω · cm have been grown in a die of uncoated fused silica. Neither Cd source nor an inert gas overpressure was employed in the growth container. No additional preparation steps were required before the analysis of their detection behaviour. First measurements of the integral X-ray response have been carried out.

  16. Characterization of Technetium Speciation in Cast Stone

    SciTech Connect

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

    2013-11-11

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

  17. Fatigue Properties of Cast Magnesium Wheels

    NASA Astrophysics Data System (ADS)

    Li, Zhenming; Luo, Alan A.; Wang, Qigui; Peng, Liming; Zhang, Peng

    2016-08-01

    This paper investigates the fatigue properties and deformation behavior of a newly developed Mg-2.96Nd-0.21Zn-0.39Zr magnesium alloy wheel in both as-cast and T6 conditions. Compared with the as-cast alloy, the T6-treated alloy shows a significant increase in fatigue strength and cyclic stress amplitude. This is believed to be attributed to the change of defect type from porosity to oxides and the increased matrix strength in the T6 (peak-aged) condition. For the as-cast alloy wheel, fatigue failure mainly originated from the cast defects including porosity, oxide film, and inclusion at or near the sample surface. In the T6-treated alloy, however, oxides and inclusions or slip bands initiate the fatigue cracks. Solution treatment appears to reduce or eliminate the shrinkage porosity because of grain growth and dissolution of as-cast eutectic phases in the grain boundaries. The cyclic stress amplitude of the as-cast alloy increases with increasing the number of cycles, while the T6-treated alloy shows cyclic softening after the stress reaches a maximum value. The Coffin-Manson law and Basquin equation can be used to evaluate the life of low cycle fatigue. The developed long crack model and multi-scale fatigue (MSF) models can be used to predict high-cycle fatigue life of the Mg-2.96Nd-0.21Zn-0.39Zr alloys with or without casting defects.

  18. AMCC casting development. Volume 1: Executive Summary

    NASA Astrophysics Data System (ADS)

    1995-03-01

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

  19. Celestial Fireworks from Dying Stars

    NASA Astrophysics Data System (ADS)

    2011-04-01

    This image of the nebula NGC 3582, which was captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile, shows giant loops of gas bearing a striking resemblance to solar prominences. These loops are thought to have been ejected by dying stars, but new stars are also being born within this stellar nursery. These energetic youngsters emit intense ultraviolet radiation that makes the gas in the nebula glow, producing the fiery display shown here. NGC 3582 is part of a large star-forming region in the Milky Way, called RCW 57. It lies close to the central plane of the Milky Way in the southern constellation of Carina (The Keel of Jason's ship, the Argo). John Herschel first saw this complex region of glowing gas and dark dust clouds in 1834, during his stay in South Africa. Some of the stars forming in regions like NGC 3582 are much heavier than the Sun. These monster stars emit energy at prodigious rates and have very short lives that end in explosions as supernovae. The material ejected from these dramatic events creates bubbles in the surrounding gas and dust. This is the probable cause of the loops visible in this picture. This image was taken through multiple filters. From the Wide Field Imager, data taken through a red filter are shown in green and red, and data taken through a filter that isolates the red glow characteristic of hydrogen are also shown in red. Additional infrared data from the Digitized Sky Survey are shown in blue. The image was processed by ESO using the observational data identified by Joe DePasquale, from the United States [1], who participated in ESO's Hidden Treasures 2010 astrophotography competition [2]. The competition was organised by ESO in October-November 2010, for everyone who enjoys making beautiful images of the night sky using astronomical data obtained using professional telescopes. Notes [1] Joe searched through ESO's archive and identified datasets that he used to compose his

  20. Dynamics of capillary transport in semi-solid channels.

    PubMed

    Andersson, Johanna; Ström, Anna; Gebäck, Tobias; Larsson, Anette

    2017-02-08

    Capillary action has been described by Lucas and Washburn and extensively studied experimentally in hard materials, but few studies have examined capillary action in soft materials such as hydrogels. In tissue engineering, cells or dispersions must be often distributed within a hydrogel via microporous paths. Capillary action is one way to disperse such substances. Here, we examine the dynamics of capillary action in a model system of straight capillaries in two hydrogels. The channels had a circular cross-section in the micrometer size range (180-630 μm). The distance travelled over time was recorded and compared with the predictions of Lucas and Washburn. Besides water, we used a sucrose solution and a hydroxyethyl cellulose solution, both with viscosities slightly higher than that of water. The results showed that the distance travelled is proportional to the square root of time, , and that larger capillaries and lower viscosities result, as expected, in faster speeds. However, the absolute experimental values display large discrepancies from the predictions. We demonstrate that several possible reasons for these discrepancies can be ruled out and we describe a novel hypothesis for the cause of the retarded meniscus movement.

  1. Living until we die: reflections on the dying person's spiritual agenda.

    PubMed

    Anderson, Herbert

    2006-03-01

    The spiritual agenda for the dying presumes a willingness to face the reality of imminent death. It also depends on support from caregivers who will encourage whatever agency is possible for the one who is dying. The spiritual practices that will enhance agency for the dying include remembering, thanking, relinquishing, waiting, and trusting. The absence of abandonment and the dependable presence of caregivers are essential to create communities and relationships in which hope can be found and sustained.

  2. Fractal analysis of complex microstructure in castings

    SciTech Connect

    Lu, S.Z.; Lipp, D.C.; Hellawell, A.

    1995-12-31

    Complex microstructures in castings are usually characterized descriptively which often raises ambiguity and makes it difficult to relate the microstructure to the growth kinetics or mechanical properties in processing modeling. Combining the principle of fractal geometry and computer image processing techniques, it is feasible to characterize the complex microstructures numerically by the parameters of fractal dimension, D, and shape factor, a, without ambiguity. Procedures of fractal measurement and analysis are described, and a test case of its application to cast irons is provided. The results show that the irregular cast structures may all be characterized numerically by fractal analysis.

  3. Improved Slip Casting Of Ceramic Models

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M.; Vasquez, Peter; Hicks, Lana P.

    1994-01-01

    Improved technique of investment slip casting developed for making precise ceramic wind-tunnel models. Needed in wind-tunnel experiments to verify predictions of aerothermodynamical computer codes. Ceramic materials used because of their low heat conductivities and ability to survive high temperatures. Present improved slip-casting technique enables casting of highly detailed models from aqueous or nonaqueous solutions. Wet shell molds peeled off models to ensure precise and undamaged details. Used at NASA Langley Research Center to form superconducting ceramic components from nonaqueous slip solutions. Technique has many more applications when ceramic materials developed further for such high-strength/ temperature components as engine parts.

  4. Methods for Casting Subterranean Ant Nests

    PubMed Central

    Tschinkel, Walter R.

    2010-01-01

    The study of subterranean ant nests has been impeded by the difficulty of rendering their structures in visible form. Here, several different casting materials are shown to make perfect casts of the underground nests of ants. Each material (dental plaster, paraffin wax, aluminum, zinc) has advantages and limitations, which are discussed. Some of the materials allow the recovery of the ants entombed in the casts, allowing a census of the ants to be connected with features of their nest architecture. The necessary equipment and procedures are described in the hope that more researchers will study this very important aspect of ant natural history. PMID:20673073

  5. Accuracy of Small Base Metal Dental Castings,

    DTIC Science & Technology

    1980-07-10

    aCCURACY OF SMALL BASE METAL DENTAL CASTINGS,(U) M JUL 80 E A HUBET, S 6 VERMILYEA, M .J KUFFLER UNCLASSIFIED NE7 hhhhh *EN UN~CLASSIFIED SECURITY...TPCCSI70NO. 3. RECIPIENT’S .CATALOG NUMBER I _% dSutte 5. TYPE OF REPORT & PERIOD COVERED Accuracy of Small Base Metal Dental Castings Manuscript S...base metal- alloys is countered by their inadequate casting accuracy . Until this problem can be overcome, the acceptance of such alloys for routine use

  6. The continuous production of stir cast material

    NASA Astrophysics Data System (ADS)

    Hamoen, A.

    1986-06-01

    The production of AlSi8 extrusion billets using a semicontinuous caster is described. The continuous casting process and the process parameters are outlined. The mathematical model, developed to calculate the temperature distribution within the billet during casting as a function of the process parameters, is explained. Quality control focussed on inversion segregation which causes the formation of a surface layer with a different structure and composition, imposing peeling of billets. Product development focussed on the production of stir-cast material of the same AlSi8 alloy. The use of AlSi8 as a wrought alloy by modification of the structure by stirring is discussed.

  7. Magsimal-59, an AlMgMnSi-type squeeze-casting alloy designed for temper F

    SciTech Connect

    Hielscher, U.; Sternau, H.; Koch, H.; Franke, A.J.

    1996-10-01

    To get high mechanical properties using standard squeeze casting alloys (for example A356) it is indispensable to make a heat treatment. That means solution heat treatment and quenching and artificially aging. For this reason, the authors were challenged to develop an alloy that provides sophisticated mechanical properties without any heat treatment. Compared to A 356 T6 values in brackets, the new alloy has yield strength > 21 ksi (> 32 ksi) tensile strengths > 42 ksi (43 ksi) and elongation > 15% (10%) in temper F. fatigue strength (r = {minus}1, high frequency pulsation test) is > {+-} 16 ksi (13.5). To meet these properties, a casting process with high solidification velocity like squeeze casting or high pressure die-casting is necessary. Magsimal-59 is of the AlMgMnSi-type. The microstructure consists of {alpha}-Al and a very fine dispersed ternary eutectic. The microstructure and the influence of cooling rate on the mechanical properties will be discussed including some examples of castings.

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

    SciTech Connect

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

    2011-01-17

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

  9. The effect of casting temperature on the fatigue properties of cast nickel aluminide alloys

    SciTech Connect

    Gieseke, B.; Sikka, V.K.

    1991-01-01

    The results of high cycle fatigue tests at 650{degree}C on several cast Ni{sub 3}Al alloys are reported and compared to cast IN-713C. These alloys include IC-221M and several variations to the IC-221M composition. The effect of casting temperature is investigated using castings poured at three different temperatures spanning a 56{degree}C range. The results show that IC-221M cast at the highest temperature has the best fatigue strength, exceeding that for IN-713C. In these alloys, crack initiation occurs at shrinkage microporosity and the effect of casting temperature on porosity is related to the observed differences in fatigue lives. 11 refs., 4 figs.

  10. GRINDING ROOM AT SOUTHERN DUCTILE CASTING COMPANY, BESSEMER FOUNDRY SHOWING ...

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

    GRINDING ROOM AT SOUTHERN DUCTILE CASTING COMPANY, BESSEMER FOUNDRY SHOWING WHEELABORATOR THAT IMPALE SHOT AT TUMBLING CASTINGS TO REMOVE EXCESS SURFACE METALS AND SAND; ANNEALING OVENS TO HEAT CERTAIN CASTINGS TO ACHIEVE A DESIRED CHARACTERISTIC; AND GRINDING WHEELS USED TO REMOVE GATES. - Southern Ductile Casting Company, Grinding & Shipping, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  11. 49 CFR 192.275 - Cast iron pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Cast iron pipe. 192.275 Section 192.275... Cast iron pipe. (a) Each caulked bell and spigot joint in cast iron pipe must be sealed with mechanical leak clamps. (b) Each mechanical joint in cast iron pipe must have a gasket made of a...

  12. 49 CFR 192.275 - Cast iron pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Cast iron pipe. 192.275 Section 192.275... Cast iron pipe. (a) Each caulked bell and spigot joint in cast iron pipe must be sealed with mechanical leak clamps. (b) Each mechanical joint in cast iron pipe must have a gasket made of a...

  13. 49 CFR 192.275 - Cast iron pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Cast iron pipe. 192.275 Section 192.275... Cast iron pipe. (a) Each caulked bell and spigot joint in cast iron pipe must be sealed with mechanical leak clamps. (b) Each mechanical joint in cast iron pipe must have a gasket made of a...

  14. 49 CFR 192.275 - Cast iron pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Cast iron pipe. 192.275 Section 192.275... Cast iron pipe. (a) Each caulked bell and spigot joint in cast iron pipe must be sealed with mechanical leak clamps. (b) Each mechanical joint in cast iron pipe must have a gasket made of a...

  15. 49 CFR 192.275 - Cast iron pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Cast iron pipe. 192.275 Section 192.275... Cast iron pipe. (a) Each caulked bell and spigot joint in cast iron pipe must be sealed with mechanical leak clamps. (b) Each mechanical joint in cast iron pipe must have a gasket made of a...

  16. Basic Casting from A to Z. Student's Instruction Booklet.

    ERIC Educational Resources Information Center

    Zebco, Tulsa, OK.

    A profusely illustrated student instruction booklet contains step-by-step directions and diagrams for learning four basic casting techniques. Separate sections cover basic spin-casting, spinning, bait-casting, and fly-casting. Each section details recommended equipment (reel, rod, line, plug, tackle, lures, leaders, flies), describes specific…

  17. Linear dimensional changes in plaster die models using different elastomeric materials.

    PubMed

    Pereira, Jefferson Ricardo; Murata, Karina Yumi; Valle, Accácio Lins do; Ghizoni, Janaina Salomon; Shiratori, Fábio Kenji

    2010-01-01

    Dental impression is an important step in the preparation of prostheses since it provides the reproduction of anatomic and surface details of teeth and adjacent structures. The objective of this study was to evaluate the linear dimensional alterations in gypsum dies obtained with different elastomeric materials, using a resin coping impression technique with individual shells. A master cast made of stainless steel with fixed prosthesis characteristics with two prepared abutment teeth was used to obtain the impressions. References points (A, B, C, D, E and F) were recorded on the occlusal and buccal surfaces of abutments to register the distances. The impressions were obtained using the following materials: polyether, mercaptan-polysulfide, addition silicone, and condensation silicone. The transfer impressions were made with custom trays and an irreversible hydrocolloid material and were poured with type IV gypsum. The distances between identified points in gypsum dies were measured using an optical microscope and the results were statistically analyzed by ANOVA (p < 0.05) and Tukey's test. The mean of the distances were registered as follows: addition silicone (AB = 13.6 µm, CD=15.0 µm, EF = 14.6 µm, GH=15.2 µm), mercaptan-polysulfide (AB = 36.0 µm, CD = 36.0 µm, EF = 39.6 µm, GH = 40.6 µm), polyether (AB = 35.2 µm, CD = 35.6 µm, EF = 39.4 µm, GH = 41.4 µm) and condensation silicone (AB = 69.2 µm, CD = 71.0 µm, EF = 80.6 µm, GH = 81.2 µm). All of the measurements found in gypsum dies were compared to those of a master cast. The results demonstrated that the addition silicone provides the best stability of the compounds tested, followed by polyether, polysulfide and condensation silicone. No statistical differences were obtained between polyether and mercaptan-polysulfide materials.

  18. Complexometric determination of magnesium in nodular cast iron and alloyed cast iron roll samples.

    PubMed

    Banerjee, S; Dutta, R K

    1980-02-01

    A complexometric method for the determination of magnesium in nodular cast iron, alloyed cast iron and roll samples has been developed. The bulk of the iron is removed by ether extraction and the phosphate as zirconium phosphate. The other elements are removed by extraction with dithiocarbamate into chloroform. Magnesium is then titrated with EDTA at pH 10, with Eriochrome Black T as indicator. Calcium interferes, but is very rarely present in such cast iron samples.

  19. Dimensional accuracy of small gold alloy castings. Part 4. The casting ring and ring liners.

    PubMed

    Morey, E F

    1992-04-01

    The role of the casting ring and its asbestos liner is discussed. Asbestos as a liner has now largely been replaced by two alternative materials, one based on cellulose and the other on ceramic fibres. The limited literature on the effect of these newer materials on casting accuracy is also reviewed as their introduction may require significant changes in the traditional technology of dental casting.

  20. Effect of casting methods on castability of pure titanium.

    PubMed

    Takahashi, J; Zhang, J Z; Okazaki, M

    1993-12-01

    Two types of patterns were tested for castability: 1) polyester mesh pattern (20mm x 22mm with 100 open squares) and 2) 20mm x 20mm wax plates 1.0 and 1.5 mm in thickness. These materials were invested using a pre-arranged commercial phosphate-bonded investment for titanium. Three different types of casting machines were selected: 1) a pressure-type casting machine with separate melting and casting chambers, 2) a pressure-type casting machine with one chamber and 3) a centrifugal-type casting machine at 3000 rpm. Pure titanium (> 99.5%) was cast into the molds at a mold temperature of 100 degrees C. The castability of mesh pattern was evaluated in terms of the number of cast segment, and the cast plate was evaluated using X-ray transparent images by a digital imaging technique. The centrifugal casting method showed the best castability among these three casting methods.

  1. Genetic structure of Rajaka caste and affinities with other caste populations of Andhra Pradesh, India.

    PubMed

    Parvatheesam, C; Babu, B V; Babu, M C

    1997-01-01

    The present study gives an account of the genetic structure in terms of distribution of a few genetic markers, viz., A1A2B0, Rh(D), G6PD deficiency and haemoglobin among the Rajaka caste population of Andhra Pradesh, India. The genetic relationships of the Rajaka caste with other Andhra caste populations were investigated in terms of genetic distance, i.e., Sq B (mn) of Balakrishnan and Sanghvi. Relatively lesser distance was established between the Rajaka and two Panchama castes. Also, the pattern of genetic distance corroborates the hierarchical order of the Hindu varna system.

  2. Roll Casting of Aluminum Alloy Clad Strip

    SciTech Connect

    Nakamura, R.; Tsuge, H.; Haga, T.; Watari, H.; Kumai, S.

    2011-01-17

    Casting of aluminum alloy three layers of clad strip was tried using the two sets of twin roll casters, and effects of the casting parameters on the cladding conditions were investigated. One twin roll caster was mounted on the other twin roll caster. Base strip was 8079 aluminum alloy and overlay strips were 6022 aluminum alloy. Effects of roll-load of upper and lower casters and melt temperature of the lower caster were investigated. When the roll-load of the upper and lower caster was large enough, the overlay strip could be solidified and be connected. The overlay strip could be connected when the melt of the overlay strip cast by the lower caster was low enough. Sound three layers of clad strip could be cast by proper conditions.

  3. Vacuum casting of thick polymeric films

    NASA Technical Reports Server (NTRS)

    Cuddihy, E. F.; Moacanin, J.

    1979-01-01

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

  4. Open Cast Mining: An Environmental Issue.

    ERIC Educational Resources Information Center

    McPartland, Michael

    1993-01-01

    Presents a case study in which students investigate the environmental issue of open cast coal mining. Students examine the issue from different perspectives; interpret the available evidence; draw appropriate conclusions; and evaluate such conclusions. (MDH)

  5. Caste in India, Past and Present

    ERIC Educational Resources Information Center

    Bishop, Donald H.

    1971-01-01

    Traced is the sociocultural framework for the system in Indian culture which emphasized duty and obligations rather than individual freedom and rights. Also discussed are contemporary changes in the caste system. (DB)

  6. Embedding Optical Fibers In Cast Metal Parts

    NASA Technical Reports Server (NTRS)

    Gibler, William N.; Atkins, Robert A.; Lee, Chung E.; Taylor, Henry F.

    1995-01-01

    Use of metal strain reliefs eliminates breakage of fibers during casting process. Technique for embedding fused silica optical fibers in cast metal parts devised. Optical fiber embedded in flange, fitting, or wall of vacuum or pressure chamber, to provide hermetically sealed feedthrough for optical transmission of measurement or control signals. Another example, optical-fiber temperature sensor embedded in metal structural component to measure strain or temperature inside component.

  7. Casting Process Developments for Improving Quality

    NASA Astrophysics Data System (ADS)

    El-Mahallawy, Nahed A.; Taha, Mohamed A.

    1985-09-01

    This paper presents a short synopsis of the important developments in casting/solidification processes, as well as the important advances in the conventional methods. These developments are discussed related to quality aspects. The position of each process with respect to practice, as well as expected gains in cost, are examined. The paper briefly features the author's work on innovative processes (directional solidification, rheocasting, squeeze-casting and rapid solidification) as well as work of other investigators on developments in conventional methods.

  8. Mathematical simulation of centrifugal casting of pipes

    SciTech Connect

    Minosyan, Ya.P.; Gerasimov, V.G.; Ryadno, A.A.; Solov'yev, Yu.G.

    1983-01-01

    A mathematical description of centrifugal casting of long pipes in rapidly-rotating ingot molds is given. The effect of gravity force is neglected. A numerical solution is obtained for the solidification of a steel casting in a thermally insulated mold. The effect of the rate of metal pouring on the motion of the solidification interface is investigated. The disagreement with experimental data is less then 7 percent.

  9. Combination Of Investment And Centrifugal Casting

    NASA Technical Reports Server (NTRS)

    Creeger, Gordon A.

    1994-01-01

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

  10. Durability and Damage Tolerance of Aluminum Castings

    DTIC Science & Technology

    1988-09-01

    casting alloys A357 and A201. On completion of the program, revisions to material, process, and DADT specifications will be recommended, if necessary...and the effects of process variables on the properties of A357 -T6 and A201-T7 castings were described. This second interim report covers additional...damage tolerance properties of A357 -T6 and A201-T7 produced using the specifications selected earlier [1] in Task 2 were determined. These alloys were

  11. Compassionate community networks: supporting home dying.

    PubMed

    Abel, Julian; Bowra, Jon; Walter, Tony; Howarth, Glennys

    2011-09-01

    How may communities be mobilised to help someone dying at home? This conceptual article outlines the thinking behind an innovative compassionate community project being developed at Weston-super-Mare, UK. In this project, a health professional mentors the dying person and their carer to identify and match: (a) the tasks that need to be done and (b) the members of their social network who might help with these tasks. Network members may subsequently join a local volunteer force to assist others who are network poor. Performing practical tasks may be more acceptable to some family, friends and neighbours than having to engage in a conversation about dying, and provides a familiarity with dying that is often lacking in modern societies, so in this model, behavioural change precedes attitudinal change. The scheme rejects a service delivery model of care in favour of a community development model, but differs from community development schemes in which the mentor is a volunteer rather than a health professional, and also from those approaches that strive to build community capacity before any one individual dying person is helped. The pros and cons of each approach are discussed. There is a need for evaluation of this and similar schemes, and for basic research into naturally occurring resource mobilisation at the end of life.

  12. Silica exposure in hand grinding steel castings.

    PubMed

    O'Brien, D; Froehlich, P A; Gressel, M G; Hall, R M; Clark, N J; Bost, P; Fischbach, T

    1992-01-01

    Exposure to silica dust was studied in the grinding of castings in a steel foundry that used conventional personal sampling methods and new real-time sampling techniques developed for the identification of high-exposure tasks and tools. Approximately one-third of the personal samples exceeded the National Institute for Occupational Safety and Health recommended exposure limit for crystalline silica, a fraction similar to that identified in other studies of casting cleaning. Of five tools used to clean the castings, the tools with the largest wheels, a 6-in. grinder and a 4-in. cutoff wheel, were shown to be the major sources of dust exposure. Existing dust control consisted of the use of downdraft grinding benches. The size of the casting precluded working at a distance close enough to the grates of the downdraft benches for efficient capture of the grinding dust. In addition, measurements of air recirculated from the downdraft benches indicated that less than one-half of the respirable particles were removed from the contaminated airstream. Previous studies have shown that silica exposures in the cleaning of castings can be reduced or eliminated through the use of mold coatings, which minimize sand burn-in on the casting surface; by application of high-velocity, low-volume exhaust hoods; and by the use of a nonsilica molding aggregate such as olivine. This study concluded that all these methods would be appropriate control options.

  13. Microbiological Study of Cast Posts before Cementation

    PubMed Central

    Ojeda-Garces, Juan Carlos

    2017-01-01

    This study identifies the most common microorganisms present in type III gold cast posts related to pulpal disease and evaluates the sterilization/disinfection method before cementation in the root canal. Forty-five type III gold cast posts were aseptically collected in sterile sealed plastic bags and taken to the microbiology laboratory to carry out the study: fifteen cast posts had no treatment, fifteen were disinfected (immersion in 70% alcohol during 15 minutes), and fifteen were autoclaved at 121°C for 15 minutes by using saturated steam under 15 psi pressure. By using a two-proportion z-test, the difference was statistically significant (p > 0.05) and demonstrates that, in spite of the aseptic pattern used in the cast post collection and laboratory procedures, some cast posts arrive contaminated at the consulting office. The disinfection process worked out in a high percentage and demonstrated that the sterilization by autoclaving eliminated completely the pathogenic microbiota without affecting the cast post shape and integrity that could compromise their final fitting. PMID:28316625

  14. ToxCast Phase I

    EPA Pesticide Factsheets

    Background: Chemical toxicity testing is being transformed by advances in biology and computer modeling, concerns over animal use and the thousands of environmental chemicals lacking toxicity data. EPA's ToxCast program aims to address these concerns by screening and prioritizing chemicals for potential human toxicity using in vitro assays and in silico approaches. Objectives: This project aims to evaluate the use of in vitro assays for understanding the types of molecular and pathway perturbations caused by environmental chemicals and to build initial prioritization models of in vivo toxicity. Methods: We tested 309 mostly pesticide active chemicals in 467 assays across 9 technologies, including high-throughput cell-free assays and cell-based assays in multiple human primary cells and cell lines, plus rat primary hepatocytes. Both individual and composite scores for effects on genes and pathways were analyzed. Results: Chemicals display a broad spectrum of activity at the molecular and pathway levels. Many expected interactions are seen, including endocrine and xenobiotic metabolism enzyme activity. Chemicals range in promiscuity across pathways, from no activity to affecting dozens of pathways. We find a statistically significant inverse association between the number of pathways perturbed by a chemical at low in vitro concentrations and the lowest in vivo dose at which a chemical causes toxicity. We also find associations between a small set in vitro ass

  15. Apollo 14 composite casting demonstration

    NASA Technical Reports Server (NTRS)

    1971-01-01

    This program assisted in the design and implementation of the composite casting demonstration for the Apollo 14 mission. Both flight and control samples were evaluated. Some conclusions resulting from a comparison of the flight and control samples were: (1) Solidification in neither the flight nor control samples was truly directional. (2) Apparent intermittent contact of the melt with the container in the flight samples led to unusual nucleation and growth structures. (3) There was greater uniformity, on a macro scale, of both pores and structural features in the flight sample; presumably the result of the reduced gravity conditions. (4) It seems quite feasible to produce enhanced dispersions of gases and dense phases in a melt which is solidified in reduced gravity. (5) A two-stage heating/cooling cycle may help directional solidification. (6) Sample materials should be selected from materials in which the dispersant fully wets the matrix material. (7) Experiments should be conducted in two modes: (1) where the melt is in good thermal contact with the container, and (2) where the melt is in a free-float condition.

  16. Effect of composition and processing on the thermal fatigue and toughness of high performance die steels. Final report

    SciTech Connect

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

    1997-06-01

    The objective of this study was to improve average die life by optimizing die steel composition and the die processing. Four different steels, K,Q,C and Premium Grade H-13 have been investigated for thermal fatigue resistance and toughness. Optimum heat treatment processing has been determined for each steel with respect to austenitizing temperature and tempering conditions. The effect of the quenching rate on the thermal fatigue resistance and toughness of the die steels and the effect of Electro-Discharge Machining (EDM) on the thermal fatigue resistance were also determined. The immersion thermal fatigue specimen developed at CWRU was used to determine the thermal fatigue resistance as characterized by the two parameters of average maximum crack length and total crack area. The Charpy V-notch impact test was used over a -100{degrees}F to 450{degrees}F testing temperature range to evaluate the toughness and the brittle-ductile transition behavior. K steel has been identified as superior in performance compared to Premium Grade H-13. Q and C provide lower toughness and thermal fatigue resistance than H-13. Faster cooling rates provide higher thermal fatigue resistance and toughness. Higher austenitizing temperatures such as 1925{degrees}F compared to 1875{degrees}F provide better thermal fatigue resistance, but lower austenitizing temperatures of 1875{degrees}F provide better toughness. Higher hardness improves thermal fatigue resistance, but reduces toughness. A minimum of Rc 46 hardness is desired for aluminum die casting dies. EDM reduces the thermal fatigue resistance compared to conventional machining operations. When the EDM process of multiple small steps of decreasing energy and post-EDM treatments are employed, the effect can be reduced to a very slight amount. Preliminary evidence of the superior performance of the K steel has been provided by ongoing field testing of inserts in multiple cavity dies.

  17. Killing, letting die and moral perception.

    PubMed

    Gillett, Grant

    1994-10-01

    There are a number of arguments that purport to show, in general terms, that there is no difference between killing and letting die. These are used to justify active euthanasia on the basis of the reasons given for allowing patients to die. I argue that the general and abstract arguments fail to take account of the complex and particular situations which are found in the care of those with terminal illness. When in such situations, there are perceptions and intuitions available that do not easily find propositional form but lead most of those whose practice is in the care of the dying to resist active euthanasia. I make a plea for their intuitions to be heeded above the sterile voice of abstract premises and arguments by examining the completeness of the outline form of the pro-euthanasia argument. In doing so, I make use of Nussbaum's discussion of moral perception and general claims to be found in the literature of moral particularism.

  18. CAE Based Die Face Engineering Development to Contribute to the Revitalization of the Tool & Die Industry

    NASA Astrophysics Data System (ADS)

    Tang, Arthur; Lee, Wing C.; St. Pierre, Shawn; He, Jeanne; Liu, Kesu; Chen, Chin C.

    2005-08-01

    Over the past two decades, the Computer Aided Engineering (CAE) tools have emerged as one of the most important engineering tools in various industries, due to its flexibility and accuracy in prediction. Nowadays, CAE tools are widely used in the sheet metal forming industry to predict the forming feasibility of a wide variety of complex components, ranging from aerospace and automotive components to household products. As the demand of CAE based formability accelerates, the need for a robust and streamlined die face engineering tool becomes more crucial, especially in the early stage when the tooling layout is not available, but a product design decision must be made. Ability to generate blank, binder and addendum surfaces with an appropriate layout of Drawbead, Punch Opening Line, Trim Line are the primary features and functions of a CAE based die face engineering tool. Once the die face layout is ready, a formability study should be followed to verify the die face layout is adequate to produce a formable part. If successful, the established die face surface should be exported back to the CAD/CAM environment to speed up the tooling and manufacturing design process with confidence that this particular part is formable with this given die face. With a CAE tool as described above, the tool & die industry will be greatly impacted as the processes will enable the bypass of hardware try-out and shorten the overall vehicle production timing. The trend has shown that OEMs and first tiers will source to low cost producers in the world which will have a negative impact to the traditional tool & die makers in the developed countries. CAE based tool as described should be adopted, along with many other solutions, in order to maintain efficiency of producing high quality product and meeting time-to-market requirements. This paper will describe how a CAE based die face engineering (DFE) tool could be further developed to enable the traditional tool & die makers to meet the

  19. Neutron radiography inspection of investment castings.

    PubMed

    Richards, W J; Barrett, J R; Springgate, M E; Shields, K C

    2004-10-01

    Investment casting, also known as the lost wax process, is a manufacturing method employed to produce near net shape metal articles. Traditionally, investment casting has been used to produce structural titanium castings for aero-engine applications with wall thickness less than 1 in (2.54 cm). Recently, airframe manufacturers have been exploring the use of titanium investment casting to replace components traditionally produced from forgings. Use of titanium investment castings for these applications reduces weight, cost, lead time, and part count. Recently, the investment casting process has been selected to produce fracture critical structural titanium airframe components. These airframe components have pushed the traditional inspection techniques to their physical limits due to cross sections on the order of 3 in (7.6 cm). To overcome these inspection limitations, a process incorporating neutron radiography (n-ray) has been developed. In this process, the facecoat of the investment casting mold material contains a cocalcined mixture of yttrium oxide and gadolinium oxide. The presence of the gadolinium oxide, allows for neutron radiographic imaging (and eventual removal and repair) of mold facecoat inclusions that remain within these thick cross sectional castings. Probability of detection (POD) studies have shown a 3 x improvement of detecting a 0.050 x 0.007 in2 (1.270 x 0.178 mm2) inclusion of this cocalcined material using n-ray techniques when compared to the POD using traditional X-ray techniques. Further, it has been shown that this n-ray compatible mold facecoat material produces titanium castings of equal metallurgical quality when compared to the traditional materials. Since investment castings can be very large and heavy, the neutron radiography facilities at the University of California, Davis McClellan Nuclear Radiation Center (UCD/MNRC) were used to develop the inspection techniques. The UCD/MNRC has very unique facilities that can handle large

  20. Die Arbeitsunfähigkeit in der Statistik der GKV

    NASA Astrophysics Data System (ADS)

    Busch, Klaus

    Der vorliegende Beitrag gibt anhand der Statistiken des Bundesministeriums für Gesundheit (BMG) einen Überblick über die Arbeitsunfähigkeitsdaten der Gesetzlichen Krankenkassen (GKV). Zunächst werden die Arbeitsunfähigkeitsstatistiken der Krankenkassen und die Erfassung der Arbeitsunfähigkeit erläutert. Hiernach wird auf die Entwicklung der Fehlzeiten auf GKV-Ebene eingegangen. Ebenfalls wird Bezug auf die Unterschiede der Fehlzeiten zwischen den verschiedenen Kassen genommen.