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Sample records for microstructured molding technique

  1. Recent advancements in optical microstructure fabrication through glass molding process

    NASA Astrophysics Data System (ADS)

    Zhou, Tianfeng; Liu, Xiaohua; Liang, Zhiqiang; Liu, Yang; Xie, Jiaqing; Wang, Xibin

    2017-02-01

    Optical microstructures are increasingly applied in several fields, such as optical systems, precision measurement, and microfluid chips. Microstructures include microgrooves, microprisms, and microlenses. This paper presents an overview of optical microstructure fabrication through glass molding and highlights the applications of optical microstructures in mold fabrication and glass molding. The glass-mold interface friction and adhesion are also discussed. Moreover, the latest advancements in glass molding technologies are detailed, including new mold materials and their fabrication methods, viscoelastic constitutive modeling of glass, and microstructure molding process, as well as ultrasonic vibrationassisted molding technology.

  2. Microstructures of poly (ethylene glycol) by molding and dewetting

    NASA Astrophysics Data System (ADS)

    Suh, Kahp Y.; Langer, Robert

    2003-08-01

    We report on the fabrication of microstructures of poly (ethylene glycol) (PEG) using a soft molding technique. When a patterned poly (dimethylsiloxane) stamp is placed on a wet PEG film, the polymer in contact with the stamp spontaneously moves into the void space as a result of capillary action. Three types of microstructures are observed with the substrate surface completely exposed: a negative replica of the stamp, a two-dimensional projection of the simple cubic structure, and a two-dimensional projection of the diamond structure. A molding process is responsible for the first type and a dewetting process for the final two. A phase diagram is constructed based on the effects of molecular weight and concentration, which shows that mobility and confinement play a crucial role in determining the particular type of microstructure obtained. The PEG microstructure could be used as a lithographic resist in fabricating electronic devices and a resistant layer for preventing nonspecific adsorption of proteins or cells.

  3. Precision molding techniques for optical waveguide devices

    NASA Astrophysics Data System (ADS)

    Kalveram, Stefan; Neyer, Andreas

    1997-09-01

    Single-mode optical waveguide devices with integrated fiber- alignment grooves have been fabricated by injection molding of structured substrates and by subsequent filling of the waveguide channels with higher refractive index polymer. The master forms of the microstructures have been micro-machined channels with higher refractive index polymers. The master forms of the microstructures have been micro-machined in silicon. A special injection molding tool has been developed to yield plastic substrate chips with high surface planarity and replicated microstructures with details in the submicron range. Hot embossing is a further technology applied for the fabrication of large area waveguide devices with integrated mirrors, mainly intended for optical backplane applications. The hot embossing tool is driven on an injection molding machine which is a more cost effective method than the acquisition of conventional hot embossing equipment. In this paper, the injection molding as well as the hot embossing tool will be described together with the process and the results in the field of passive components for optical telecommunications and datacommunications.

  4. Incipient flocculation molding: A new ceramic-forming technique

    NASA Astrophysics Data System (ADS)

    Arrasmith, Steven Reade

    Incipient Flocculation Molding (IFM) was conceived as a new near-net-shape forming technique for ceramic components. It was hypothesized that the development of a temperature-dependent deflocculant would result in a forming technique that is flexible, efficient, and capable of producing a superior microstructure with improved mechanical properties from highly reactive, submicron ceramic powders. IFM utilizes a concentrated, nonaqueous, sterically stabilized ceramic powder and/or colloidal suspension which is injected into a non-porous mold. The suspension is then flocculated by destabilizing the suspension by lowering the temperature. Flocculation is both rapid and reversible. Cooling to -20°C produces a green body with sufficient strength for removal from the mold. The solvent is removed from the green body by evaporation. The dried green body is subsequently sintered to form a dense ceramic monolith. This is the first ceramic forming method based upon the manipulation of a sterically-stabilized suspension. To demonstrate IFM, the process of grafting polyethylene glycol (PEG), with molecular weights from 600 to 8000, to alumina powders was investigated. The maximum grafted amounts were achieved by the technique of dispersing the alumina powders in molten polymer at 195°C. The ungrafted PEG was then removed by repeated centrifuging and redispersion in fresh distilled water. The rheological behavior of suspensions of the PEG-grafted powders in water, 2-propanol and 2-butanol were characterized. All of the aqueous suspensions were shear thinning. The PEG 4600-grafted alumina powder aqueous suspensions were the most fluid. Sample rods and bars were molded from 52 vol% PEG-grafted alumina suspensions in 2-butanol. The best results were obtained with a preheated aluminum mold lubricated with a fluorinated oil mold-release. The samples were dried, sintered, and their microstructure and density were compared with sintered samples dry pressed from the same alumina powder

  5. Surface micro-structuring of glassy carbon for precision glass molding of diffractive optical elements

    NASA Astrophysics Data System (ADS)

    Prater, Karin; Dukwen, Julia; Scharf, Toralf; Herzig, Hans Peter; Hermerschmidt, Andreas

    2014-09-01

    Glassy carbon is used nowadays for a variety of applications because of its mechanical strength, thermal stability and non-sticking adhesion properties. This makes it also a suitable candidate as mold material for precision compression molding of low and high glass-transition temperature materials. To fabricate molds for diffractive optics a highresolution structuring technique is needed. We introduce a process that allows the micro-structuring of glassy carbon by reactive ion etching. Key parameters such as uniformity, surface roughness, edge definition and lateral resolution are discussed. They are the most relevant parameters for a stamp in optical applications. The use of titanium as a hard mask makes it possible to achieve a reasonable selectivity of 4:1, which has so far been one of the main problems in microstructuring of glassy carbon. We investigate the titanium surface structure with its 5-10 nm thick layer of TiO2 grains and its influence on the shape of the hard mask. In our fabrication procedure we were able to realize optically flat diffractive structures with slope angles of more than 80° at typical feature sizes of 5 μm and at 700 nm depth. The fabricated glassy carbon molds were applied to thermal imprinting onto different glasses. Glassy carbon molds with 1 mm thickness were tested with binary optical structures. Our experiments show the suitability of glassy carbon as molds for cost efficient mass production with a high quality.

  6. Injection molding of thermoplastic elastomers for microstructured substrates

    NASA Astrophysics Data System (ADS)

    Birkar, Smita

    Amorphous and semi-crystalline thermoplastic polymers have been widely investigated for injection molding of parts with microstructured surfaces. Microstructured surfaces injection molded from thermoplastic elastomers have emerging applications as superhydrobic surfaces and patterned adhesives, but there is a limited understanding of the factors affecting replication with these materials. This research was a continued investigation of block copolymer thermoplastic elastomers as well as the first in-depth examination of thermoplastic vulcanizates for injection molding microfeatures. The first focus of this research was the interactions between tooling aspect ratio and feature orientation (negative and positive tooling) and thermoplastic elastomer hard segment content on microfeature replication. Electroformed nickel tooling having positive and negative features with different geometries and aspect ratios of 0.02:1 to 2:1 were molded from three copolyester thermoplastic elastomers with similar chemistry and different hardness values. The tooling and part features were characterized for feature depth and height as well as feature definition using scanning electron microscopy and optical profilometry. Results were correlated with elastomer properties. In the second parts of this research, the effects of microfeature spacing on the replication of thermoplastic elastomer features was investigated using micropillars with two diameters (10 and 20 mum) and three spacing ratios (0.5:1, 1:1, and 2:1). The tooling and part features were characterized for feature depth and height as well as feature definition using scanning electron microscopy and optical profilometry. Feature spacing significantly affected the replication of micropillars using a thermoplastic elastomer. This replication was competition between cooling and pressurization of the melt. Wider spacing between smaller features allowed cooling in the tooling lands to dominate the feature filling. Higher pressures did

  7. Pinna synthetic mold for otoplasty techniques application.

    PubMed

    Reis, Mariah Guieiro Alves Dos; Marim, Ricardo Guimarães; Souto, Luis Ricardo Martinhão

    2017-02-14

    The ear deformity Tanzer type V, also known as prominent ears, is the most common genetic defect of the pinna. The surgery designed for its correction is known as otoplasty. This esthetic surgery can be performed using different techniques, which requires great skill of its operator. The purpose of this work is the development of a new tool for otoplasty techniques training, aimed on the possibility to minimize errors during the otoplasty. Synthetic molds of the external ear from patients with Tanzer type V deformity were made, using silicone material and Rayon. The main procedures of otoplasty could be performed in the molds made of silicone and Rayon with a good esthetic result. The elaborated molds had identical size and shape of a human ear and could be positioned in the same shape of the patient ears. Thus, the synthetic molds were presented as promising simulation tools for the training and surgical enhancement of otoplasty, especially for doctors beginners. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  8. Multilevel micro-structuring of glassy carbon molds for precision glass molding

    NASA Astrophysics Data System (ADS)

    Prater, Karin; Dukwen, Julia; Scharf, Toralf; Herzig, Hans Peter; Plöger, Sven; Hermerschmidt, Andreas

    2015-09-01

    Replication techniques for diffractive optical elements (DOEs) in soft materials such as plastic injection molding are state of the art. For precision glass molding in glasses with high transition temperatures, molds with extreme thermal resistivity, low chemical reactivity and high mechanical strength are needed. Glassy Carbon can be operated up to 2000°C making it possible to mold almost all glasses including Fused Silica with a transition temperatures above 1060°C. For the structuring of Glassy Carbon wafers photolithography and a RIE process is used. We have developed a process using Si as a hard mask material. If the flow rates of the etching gases O2 and SF6 are chosen properly, high selectivity of GC to Si 19:1 can be achieved, which provides excellent conditions to realize high resolution elements with feature size down to 1 micron and fulfills requirements for optical applications. We fabricated several multilevel GC molds with 8 levels of structuring. Two different optical functionalities were implemented: 6x6 array beamsplitter and 1x4 linear beamsplitter. The molds were applied for precision glass molding of a low Tg glass L-BAL 42 (from Ohara) with a transition temperature of 565°C. Their optical performance was measured. A more detailed analysis of the impact of mold fabrication defects on optical performance is done. Rigorous coupled wave analysis simulations are performed, where we included fabrication constrains such as duty cycle, edge depth errors, wall verticality and misalignment errors. We will compare the results with the design specifications and discuss the influence of fabrication errors introduced during the different process steps.

  9. Fabrication of a seamless roller mold with wavy microstructures using mask-less curved surface beam pen lithography

    NASA Astrophysics Data System (ADS)

    Tsai, Sung-Wen; Chen, Po-Yu; Lee, Yung-Chun

    2014-04-01

    Roller imprinting is one of the most commonly used methods for the fabrication of continuous functional structures over large areas. However, the fabrication of roller molds with seamless and complex patterns poses a significant challenge. This paper presents an innovative technique for fabricating a seamless roller mold with wavy microstructures using a novel mask-less curved surface beam pen lithography technique. The major steps in the proposed technique include spray coating a thin photo-resist (PR) layer on the roller, exposing the PR layer though a translating micro-lens array (MLA), etching the patterned PR layer, and electro-polishing the etched microstructures. The proposed method is used to pattern roller molds with different wavy microstructures by varying the rotation speed of the roller, the translation speed of the MLA holder, and the translation distance of the MLA holder. The patterned metal roller molds are then used to replicate wavy microstructures on a thin polyethylene terephthalate substrate by means of continuous UV-type roller imprinting methods. The line-width and height of the wavy microstructure are 84.5 µm and 25.5 µm, respectively.

  10. Survey Of Present Lens Molding Techniques

    NASA Astrophysics Data System (ADS)

    Pollicove, Harvey M.

    1988-07-01

    This survey will provide an overview of glass molding technologies, with a concentration in the newest of the technologies - Precision Glass Molding (PGM). A brief description of various forms of glass molding, including an historical review of patents associated with precision molding, is given. A worldwide survey of known commercial availability and recent innovations in PGM at Kodak are presented as examples of the potential of the precision molding technology.

  11. The Effects of Molding Materials on Microstructure and Wear Behavior of A356 Alloy

    NASA Astrophysics Data System (ADS)

    Yildirim, Musa; Özyürek, Dursun; Tunçay, Tansel

    2017-05-01

    In this study, the effect of molding materials on microstructure and wear behavior of A356 alloy was investigated. Different microstructures were obtained by casting A356 alloy into the molds made from three different materials. Homogenization and aging heat treatments were applied as cast blocks. The aged samples were tested by pin-on-disk-type standard wear equipment. The results showed that casting into different mold materials resulted in different microstructures of A356 alloy. Microstructures of the Al-Si-Mg alloy differ depending on the mold materials. Secondary dendrite arm space (SDAS) decreased proportionally with increasing cooling rate. Based on the cooling rate, hardness values of the alloy also differ. As the cooling rate increased, hardness of the alloy increased. The SDAS increased due to the decreasing cooling rate. In wear tests, increasing weight loss was observed with decreasing cooling rate.

  12. Molds

    MedlinePlus

    ... cause health problems. Inhaling or touching mold or mold spores may cause allergic reactions or asthma attacks in sensitive people. Molds can cause fungal infections. In addition, mold exposure ...

  13. Numerical Simulation of and Experiment on Electroforming Microstructure Mold Insert

    NASA Astrophysics Data System (ADS)

    Fu, Ming-Nan

    2008-09-01

    Microstructures are a vital component in various systems such as bionic chips, micro-fluidics sensor, optical communication systems, and micro-fuel cells. Micro-mold inserts should be produced by precise electroforming; however, interchanging the plating solution in an extremely small tunnel has been a main problem, where flow field and mass transfer are the major variances. In this paper we will concentrate on single- and three-micro hole array mode insert electroform flow fields and the mass transfer effect. Single-hole results show that the interchange of the plating fluid is more efficient at a lower aspect ratio of similar apertures with different aspect ratios. A lower coefficient of viscosities results in a weaker microelectroforming effect. The electroforming effect is better at an entry flow field speed of 0.01 m/s than at that of 0.001 m/s. The three-hole array results show that the first hole proved the best among the three holes, followed by the second hole; the third hole showed the worst results. The 10:1 ratio of distance to diameter of the hole produces better electroforming results than the 1:1 ratio. Lastly, this paper will contribute to the development of microelectro-mechanical manufacturing technologies.

  14. A Combined Experimental and Computational Approach for the Design of Mold Topography that Leads to Desired Ingot Surface and Microstructure in Aluminum Casting.

    SciTech Connect

    Dr. Zabaras, N.J.; Samanta, D.; Tan, L.

    2005-10-30

    A design methodology will be developed with which casting mold surface topographies can be tuned to produce required surface features and micro-structural properties of Aluminum ingots. Both static and continuous casting processes will be examined with instrumented molds. Mold surface topographies, which consist of unidirectional and bi-directional groove textures, will be generated using contact and non-contact techniques to elicit a radiator-like effect at the mold-casting interface. The rate of heat extraction, the evolution of near-surface cast microstructure, and shell macro-morphology can be controlled once the proper balance between mold surface area extension and the degree of imperfect wetting at the instant solidification starts is determined. Once this control is achieved, it will be possible to minimize or even eliminate costly post-casting surface milling or scalping which is currently a major barrier to the development of new Aluminum casting processes.

  15. High-throughput plastic microlenses fabricated using microinjection molding techniques

    NASA Astrophysics Data System (ADS)

    Appasamy, Sreeram; Li, Weizhuo; Lee, Se Hwan; Boyd, Joseph T.; Ahn, Chong H.

    2005-12-01

    A novel fabrication scheme to develop high-throughput plastic microlenses using injection-molding techniques is realized. The initial microlens mold is fabricated using the well-known reflow technique. The reflow process is optimized to obtain reliable and repeatable microlens patterns. The master mold insert for the injection-molding process is fabricated using metal electroforming. The electroplating process is optimized for obtaining a low stress electroform. Two new plastic materials, cyclo olefin copolymer (COC) and Poly IR 2 are introduced in this work for fabricating microlenses. The plastic microlenses have been characterized for their focal lengths that range from 200 µm to 1.9 mm. This technique enables high-volume production of plastic microlenses with cycle times for a single chip being of the order of 60 s.

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

    PubMed

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

    2014-02-01

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

  17. Fabrication of polymer and nanocomposite microstructures and microactuators by capillary infiltration and replica molding

    NASA Astrophysics Data System (ADS)

    Copic, Davor

    Addition of micro- and/or nanoscale textures to surfaces can enable engineering of a wide range of properties. Passive surfaces (using fixed microstructures) can manipulate cell adhesion, liquid drag, and thermal and electrical contact resistance. Active surfaces (using shape-changing microstructures) can enable modulation of liquid wetting, adhesion, and optical properties. Nevertheless, it remains a challenge to fabricate the mechanically and environmentally robust microstructures and microactuators in large arrays. This thesis presents new fabrication methods for microstructured polymer and nanocomposite surfaces. Two approaches are pursued: capillary driven infiltration of fabricated carbon nanotube (CNT) microstructures and replica molding (REM) of master templates in liquid crystal networks (LCNs). First, it is demonstrated that CNT-polymer microstructures can function as robust large-area master molds. The fabricated microstructures include pins, tubes, re-entrant microwells, bent pillars, and high-aspect-ratio honeycombs (thickness of 400nm, aspect ratio 50:1). All are used as master structures for replica molding. A 25-fold replication sequence is shown with no physical degradation of the master or the replicas. Further, the increased stiffness and toughness of CNT-SU-8 microstructures is quantified. Second, active surfaces were created by capillary infiltration of paraffin into CNT forests. Large stroke sheet actuators, exhibiting up to 20% thermal strain at 175°C are shown. Third, thermally and optically active LCN microstructure replicas were created. Their generated strains were measured to be 6% and 0.25%, respectively. In situ monitoring of the LCN phase and order was also performed. Although having low strains, optically active microstructures are attractive for future work because they can be actuated individually and remotely. These scalable methods of fabricating microstructured surfaces, both with robust mechanical properties and active

  18. Multilevel micro-structuring of glassy carbon for precision glass molding of diffractive optical elements

    NASA Astrophysics Data System (ADS)

    Prater, Karin; Dukwen, Julia; Scharf, Toralf; Herzig, Hans Peter; Plöger, Sven; Hermerschmidt, Andreas

    2015-03-01

    A consumer market for diffractive optical elements in glass can only be created if high efficient elements are available at affordable prices. In diffractive optics the efficiency and optical properties increases with the number of levels used, but in the same way the costs are multiplied by the number if fabrication steps. Replication of multilevel diffractive optical elements in glass would allow cost efficient fabrication but a suitable mold material is needed. Glassy carbon shows a high mechanical strength, thermal stability and non-sticking adhesion properties, which makes it an excellent candidate as mold material for precision compression molding of low and high glass-transition temperature materials. We introduce an 8 level micro structuring process for glassy carbon molds with standard photolithography and a Ti layer as hard mask for reactive ion etching. The molds were applied to thermal imprinting onto low and high transition temperature glass. Optical performance was tested for the molded samples with different designs for laser beamsplitters. The results show a good agreement to the design specification. Our result allow us to show limitations of our fabrication technique and we discussed the suitability of precision glass molding for cost efficient mass production with a high quality.

  19. Polymer microlens array integrated with imaging sensors by UV-molding technique

    NASA Astrophysics Data System (ADS)

    Lai, Jianjun; Zhao, Yue; Ke, Caijun; Yi, Xinjian; Zhang, TianXu

    2005-01-01

    Fabrication of Polymer microlens array based on UV-molding techniques is presented. UV-molding enables for the integration of polymer microlens array on top of arbitrary substrates like glass, silicon other polymeric films. In this technique, photoresist or glass mold is first fabricated by conventional photolithnic method and subsequently served as transparent replication tool. UV curable polymer resin is then coated on patterned or unpatterned substrates and a contact mask aligner is used to align substrates and replication mold tool and then make the mold immersed into the resin. Replication of polymer on substrates is achieved by UV photopolymerisation of the resin. Resin thickness and gap distance between mold and substrate are carefully controlled in order to obtain acceptable thickness of cured polymer base. The UV molding technique was used to molding of a polymer film carring microlens array on the surface of an experimental CCD imaging sensor chip in this paper to enhance its fill factor and sensitivity.

  20. Introduction to glass microstructuring techniques.

    PubMed

    Mazurczyk, Radoslaw; Mansfield, Colin D

    2013-01-01

    In this chapter an overview of manufacturing methods, leading to the fabrication of microstructures in glass substrates, is presented. Glass is a material of excellent optical properties, a very good electric insulator, biocompatible and chemically stable. In addition to its intrinsic qualities, glass can be processed with the use of manufacturing methods originating from the microelectronic industry. In this text two complete manufacturing protocols are described, each composed of standard microfabrication steps; namely, the deposition of masking layers, photolithographic patterning and pattern transfer via wet or dry etching. As a result, a set of building blocks is provided, allowing the manufacture of various microfluidic components that are frequently used in the domain of micro-total analysis system technology.

  1. Acrylic Resin Molding Based Head Fixation Technique in Rodents.

    PubMed

    Roh, Mootaek; Lee, Kyungmin; Jang, Il-Sung; Suk, Kyoungho; Lee, Maan-Gee

    2016-01-12

    Head fixation is a technique of immobilizing animal's head by attaching a head-post on the skull for rigid clamping. Traditional head fixation requires surgical attachment of metallic frames on the skull. The attached frames are then clamped to a stationary platform resulting in immobilization of the head. However, metallic frames for head fixation have been technically difficult to design and implement in general laboratory environment. In this study, we provide a novel head fixation method. Using a custom-made head fixation bar, head mounter is constructed during implantation surgery. After the application of acrylic resin for affixing implants such as electrodes and cannula on the skull, additional resins applied on top of that to build a mold matching to the port of the fixation bar. The molded head mounter serves as a guide rails, investigators conveniently fixate the animal's head by inserting the head mounter into the port of the fixation bar. This method could be easily applicable if implantation surgery using dental acrylics is necessary and might be useful for laboratories that cannot easily fabricate CNC machined metal head-posts.

  2. Sintering Behavior and Microstructure Formation of Titanium Aluminide Alloys Processed by Metal Injection Molding

    NASA Astrophysics Data System (ADS)

    Soyama, Juliano; Oehring, Michael; Ebel, Thomas; Kainer, Karl Ulrich; Pyczak, Florian

    2017-04-01

    The sintering behavior of metal injection molded titanium aluminide alloys, their microstructure formation and resulting mechanical properties were investigated. As reference material, the alloy Ti-45Al-5Nb-0.2B-0.2C at.% (TNB-V5) was selected. Additionally, two other variations with Mo and Mo + Si additions were prepared: Ti-45Al-3Nb-1Mo-0.2B-0.2C at.% and Ti-45Al-3Nb-1Mo-1Si-0.2B-0.2C at.%. The results indicate that the optimum sintering temperature was slightly above the solidus line. With proper sintering parameters, very low porosities (<0.5%) and fine microstructures with a colony size <85 µm could be achieved. Considering the sintering temperatures applied, the phase transformations upon cooling could be described as L + β → β → α + β → α → α + γ → α2 + γ, which was in agreement with the microstructures observed. The effects of Mo and Si were opposite regarding the sintering behavior. Mo addition led to an increase in the optimum sintering temperature, whereas Si caused a significant decrease.

  3. Sintering Behavior and Microstructure Formation of Titanium Aluminide Alloys Processed by Metal Injection Molding

    NASA Astrophysics Data System (ADS)

    Soyama, Juliano; Oehring, Michael; Ebel, Thomas; Kainer, Karl Ulrich; Pyczak, Florian

    2017-01-01

    The sintering behavior of metal injection molded titanium aluminide alloys, their microstructure formation and resulting mechanical properties were investigated. As reference material, the alloy Ti-45Al-5Nb-0.2B-0.2C at.% (TNB-V5) was selected. Additionally, two other variations with Mo and Mo + Si additions were prepared: Ti-45Al-3Nb-1Mo-0.2B-0.2C at.% and Ti-45Al-3Nb-1Mo-1Si-0.2B-0.2C at.%. The results indicate that the optimum sintering temperature was slightly above the solidus line. With proper sintering parameters, very low porosities (<0.5%) and fine microstructures with a colony size <85 µm could be achieved. Considering the sintering temperatures applied, the phase transformations upon cooling could be described as L + β → β → α + β → α → α + γ → α2 + γ, which was in agreement with the microstructures observed. The effects of Mo and Si were opposite regarding the sintering behavior. Mo addition led to an increase in the optimum sintering temperature, whereas Si caused a significant decrease.

  4. Development of processes and techniques for molding thermally stable, fire-retardant, low-smoke-emitting polymeric materials

    NASA Technical Reports Server (NTRS)

    Silverman, B.

    1979-01-01

    All available newly developed nonmetallic thermally stable polymers were examined for the development of processes and techniques by compression molding, injection molding, or thermoforming cabin interior parts. Efforts were directed toward developing molding techniques of new polymers to economically produce usable nonmetallic molded parts. Data on the flame resistant characteristics of the materials were generated from pilot plant batches. Preliminary information on the molding characteristics of the various thermoplastic materials was obtained by producing actual parts.

  5. [The control of microstructures during consolidation and injection molding of colloidal dispersions]. Progress report

    SciTech Connect

    Not Available

    1991-12-31

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

  6. (The control of microstructures during consolidation and injection molding of colloidal dispersions)

    SciTech Connect

    Not Available

    1991-01-01

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

  7. Preparation of Microstructure Molds of Montmorillonite/Polyethylene Glycol Diacrylate and Multi-Walled Carbon Nanotube/Polyethylene Glycol Diacrylate Nanocomposites for Miniaturized Device Applications.

    PubMed

    Kim, Young Ho; Sohn, Jeong-Woo; Woo, Youngjae; Hong, Joo-Hyun; Kim, Gyu Man; Kang, Bong Keun; Park, Juyoung

    2015-10-01

    Environmentally friendly microstructure molds with montmorillonite (MMT) or multi-walled carbon nanotube (MWCNT) reinforced polyethylene glycol diacrylate (PEGDA) nanocomposites have been prepared for miniaturized device applications. The micropatterning of MMT/PEGDA and MWCNT/PEGDA with 0.5 to 2.0 wt% of MMTs and MWCNTs was achieved through a UV curing process with micro-patterned masks. Hexagonal dot arrays and complex patterns for microstructures of the nanocomposites were produced and characterized with an optical microscope; their thermal properties were studied by thermogravimetric analysis (TGA). The TGA results showed that these nanocomposites were thermally stable up to 350 °C. Polydimethylsiloxane thin replicas with different microstructures were prepared by a casting method using the microstructured nanocomposites as molds. It is considered that these microstructure molds of the nanocomposites can be used as microchip molds to fabricate nanobio-chips and medical diagnostic chip devices.

  8. Metallographic techniques and microstructures: uranium alloys

    SciTech Connect

    Romig, A.D. Jr.

    1982-08-01

    The techniques used for the metallographic analysis of uranium and its alloys are discussed. Sample preparation and characterization procedures are described for: optical metallography, scanning electron microscopy, electron microprobe analysis, transmission electron microscopy, and scanning transmission electron microscopy. A brief overview of electron optics, electron/sample interactions, signal detectors, and x-ray microanalysis is presented. Typical uranium alloy microstructures observed by these techniques are presented and discussed. The microstructures examined include those produced by the diffusional decomposition of ..gamma..:U-0.75Ti and ..gamma..:U-6Nb, the martensitic decomposition of U-2Mo, U-6Nb, U-0.75Ti and Mulberry, and the aging of quenched U-2Mo.

  9. Evaluation of the microstructure, secondary dendrite arm spacing, and mechanical properties of Al-Si alloy castings made in sand and Fe-Cr slag molds

    NASA Astrophysics Data System (ADS)

    Narasimha Murthy, I.; Babu Rao, J.

    2017-07-01

    The microstructure and mechanical properties of as-cast A356 (Al-Si) alloy castings were investigated. A356 alloy was cast into three different molds composed of sand, ferrochrome (Fe-Cr) slag, and a mixture of sand and Fe-Cr. A sodium silicate-CO2 process was used to make the necessary molds. Cylindrical-shaped castings were prepared. Cast products with no porosity and a good surface finish were achieved in all of the molds. These castings were evaluated for their metallography, secondary dendrite arm spacing (SDAS), and mechanical properties, including hardness, compression, tensile, and impact properties. Furthermore, the tensile and impact samples were analyzed by fractography. The results show that faster heat transfer in the Fe-Cr slag molds than in either the silica sand or mixed molds led to lower SDAS values with a refined microstructure in the products cast in Fe-Cr slag molds. Consistent and enhanced mechanical properties were observed in the slag mold products than in the castings obtained from either sand or mixed molds. The fracture surface of the slag mold castings shows a dimple fracture morphology with a transgranular fracture nature. However, the fracture surfaces of the sand mold castings display brittle fracture. In conclusion, products cast in Fe-Cr slag molds exhibit an improved surface finish and enhanced mechanical properties compared to those of products cast in sand and mixed molds.

  10. Microstructures, mechanical properties, and fracture behaviors of metal-injection molded 17-4PH stainless steel

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Wei; Huang, Zeng-Kai; Tseng, Chun-Feng; Hwang, Kuen-Shyang

    2015-05-01

    Metal injection molding (MIM) is a versatile technique for economically manufacturing various metal parts with complicated shapes and excellent properties. The objective of this study was to clarify the effects of powder type (water-atomized and gas-atomized powders) and various heat treatments (sintering, solutioning, H900, and H1100) on the microstructures, mechanical properties, and fracture behaviors of MIM 17-4PH stainless steels. The results showed that better mechanical properties of MIM 17-4PH can be achieved with gas-atomized powder than with water-atomized powder due mainly to the lower silicon and oxygen contents and fewer SiO2 inclusions in the steels. The presence of 10 vol% δ ferrite does not impair the UTS or elongation of MIM 17-4PH stainless steels. The δ ferrite did not fracture, even though the neighboring martensitic matrix was severely cracked. Moreover, H900 treatment produces the highest hardness and UTS, along with moderate elongation. H1100 treatment produces the best elongation, along with moderate hardness and UTS.

  11. Fabrication of high-aspect-ratio polymer microstructures and hierarchical textures using carbon nanotube composite master molds.

    PubMed

    Copic, Davor; Park, Sei Jin; Tawfick, Sameh; De Volder, Michael F L; Hart, A John

    2011-05-21

    Scalable and cost effective patterning of polymer structures and their surface textures is essential to engineer material properties such as liquid wetting and dry adhesion, and to design artificial biological interfaces. Further, fabrication of high-aspect-ratio microstructures often requires controlled deep-etching methods or high-intensity exposure. We demonstrate that carbon nanotube (CNT) composites can be used as master molds for fabrication of high-aspect-ratio polymer microstructures having anisotropic nanoscale textures. The master molds are made by growth of vertically aligned CNT patterns, capillary densification of the CNTs using organic solvents, and capillary-driven infiltration of the CNT structures with SU-8. The composite master structures are then replicated in SU-8 using standard PDMS transfer molding methods. By this process, we fabricated a library of replicas including vertical micro-pillars, honeycomb lattices with sub-micron wall thickness and aspect ratios exceeding 50:1, and microwells with sloped sidewalls. This process enables batch manufacturing of polymer features that capture complex nanoscale shapes and textures, while requiring only optical lithography and conventional thermal processing.

  12. Electrowetting assisted air detrapping in transfer micromolding for difficult-to-mold microstructures.

    PubMed

    Li, Xiangming; Tian, Hongmiao; Wang, Chunhui; Li, Xin; Shao, Jinyou; Ding, Yucheng; Wang, Li

    2014-08-13

    As a widely applicable process for fabricating micro- or nanostructures, micromolding in atmosphere would require the removal or minimization of air-trapping in mold cavities so as to fill the liquid prepolymer fully into the mold for generating an exact polymer duplicate. This has been difficult, if not impossible, especially for a mold with high aspect ratio, varying size/shape, or isolated cavities because the air can be trapped inside such mold cavities in most variants of the molding process. This paper presents an electrowetting assisted transfer micromolding process to solve this problem. A feeding blade continuously supplies a UV-curable prepolymer over a dielectric-coated conductive mold placed on a progressively advancing stage. A voltage applied to the electrode pair composed of the feeding blade and mold generates an electrowetting of the prepolymer to the mold. The electrowetting allows for the three-phase contact line to pass progressively along the sidewalls and bottoms of the cavities, completely pushing out the air initially occupying the cavities, or generates an electrocapillary force large enough to pull the prepolymer deeply into the mold by compressing the air already trapped inside the cavities to a minimized volume. An experiment has been performed for micromolding with deep cavities of various shapes and sizes, demonstrating an essential improvement in the structural integrity of the polymer duplicates.

  13. Dimensional Changes of Acrylic Resin Denture Bases: Conventional Versus Injection-Molding Technique

    PubMed Central

    Gharechahi, Jafar; Asadzadeh, Nafiseh; Shahabian, Foad; Gharechahi, Maryam

    2014-01-01

    Objective: Acrylic resin denture bases undergo dimensional changes during polymerization. Injection molding techniques are reported to reduce these changes and thereby improve physical properties of denture bases. The aim of this study was to compare dimensional changes of specimens processed by conventional and injection-molding techniques. Materials and Methods: SR-Ivocap Triplex Hot resin was used for conventional pressure-packed and SR-Ivocap High Impact was used for injection-molding techniques. After processing, all the specimens were stored in distilled water at room temperature until measured. For dimensional accuracy evaluation, measurements were recorded at 24-hour, 48-hour and 12-day intervals using a digital caliper with an accuracy of 0.01 mm. Statistical analysis was carried out by SPSS (SPSS Inc., Chicago, IL, USA) using t-test and repeated-measures ANOVA. Statistical significance was defined at P<0.05. Results: After each water storage period, the acrylic specimens produced by injection exhibited less dimensional changes compared to those produced by the conventional technique. Curing shrinkage was compensated by water sorption with an increase in water storage time decreasing dimensional changes. Conclusion: Within the limitations of this study, dimensional changes of acrylic resin specimens were influenced by the molding technique used and SR-Ivocap injection procedure exhibited higher dimensional accuracy compared to conventional molding. PMID:25584050

  14. An Integrated Approach Linking Process to Structural Modeling With Microstructural Characterization for Injections-Molded Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Bapanapalli, Satish K.; Smith, Mark T.; Kunc, Vlastimil; Frame, Barbara; Norris, Robert E.; Phelps, Jay; Tucker III, Charles L.; Jin, Xiaoshi; Wang, Jin

    2008-09-01

    The objective of our work is to enable the optimum design of lightweight automotive structural components using injection-molded long fiber thermoplastics (LFTs). To this end, an integrated approach that links process modeling to structural analysis with experimental microstructural characterization and validation is developed. First, process models for LFTs are developed and implemented into processing codes (e.g. ORIENT, Moldflow) to predict the microstructure of the as-formed composite (i.e. fiber length and orientation distributions). In parallel, characterization and testing methods are developed to obtain necessary microstructural data to validate process modeling predictions. Second, the predicted LFT composite microstructure is imported into a structural finite element analysis by ABAQUS to determine the response of the as-formed composite to given boundary conditions. At this stage, constitutive models accounting for the composite microstructure are developed to predict various types of behaviors (i.e. thermoelastic, viscoelastic, elastic-plastic, damage, fatigue, and impact) of LFTs. Experimental methods are also developed to determine material parameters and to validate constitutive models. Such a process-linked-structural modeling approach allows an LFT composite structure to be designed with confidence through numerical simulations. Some recent results of our collaborative research will be illustrated to show the usefulness and applications of this integrated approach.

  15. Computational Modeling of Temperature, Flow, and Crystallization of Mold Slag During Double Hot Thermocouple Technique Experiments

    NASA Astrophysics Data System (ADS)

    Zhou, Lejun; Wang, Wanlin; Liu, Rui; Thomas, Brian G.

    2013-10-01

    A three-dimensional finite-difference model has been developed to study heat transfer, fluid flow, and isothermal crystallization of mold slag during double hot thermocouple technique (DHTT) experiments. During the preheating stage, temperature in the middle of the mold slag sample was found to be significantly [~350 K (~77 °C)] lower than near the two thermocouples. During the quenching stage, the mold slag temperature decreases with the cooled thermocouple. The temperature across the mold slag achieves a steady, nonlinear temperature profile during the holding stage; the insulating effect of the crystallizing layer in the middle of the slag sample causes the high temperature region to become hotter, while the lower temperature mold slag becomes cooler. Fluid flow is driven by Marangoni forces along the mold slag surface from the hotter region to the cooler region, and then recirculates back through the interior. Slag velocities reach 7 mm/s. Crystallization is predicted to start in the middle of the slag sample first and then grows toward both thermocouples, which matches well with observations of the DHTT experiment.

  16. Innovations in molding technologies for microfabrication

    NASA Astrophysics Data System (ADS)

    Benzler, Tobias; Piotter, Volker; Hanemann, Thomas; Mueller, K.; Norajitra, Prachai; Ruprecht, Robert; Hausselt, Juergen H.

    1999-08-01

    Micromolding is a key technology for the economic production of components for microsystems. It is applied in several manufacturing techniques including the LIGA process. Especially MicroInjection Molding allows cost-effective large-scale production of components for many applications to be used in microsystems technology. Using special molding machines, lateral dimensions in the micrometer range, structural details down to 200nm and maximum aspect ratios of more than 20 are achieved. Examples for applications are PSU-made housings for microfluidic systems or microcomponents made of PMMA for cardiac catheters. PC or LCP are appropriate materials for interconnection devices in microoptics and electronics. Other examples are injection molded lost plastic molds for electroforming or electroless plating of metal microstructures. An important economic factor is the optimization of the molding process and tool using different simulation techniques. Recently, novel techniques for manufacturing metal or ceramic microstructures were developed by adapting Powder Injection Molding to microtechnologies. Using commercially available feedstocks, microstructures were made of metals or ceramics. Rapid manufacturing of microcomponents is achieved by the so-called Photomolding process using reactive polymer resins as photocurable material and e.g. mold inserts fabricated by laser ablation. The addition of micro- or nanosized ceramics to the resin allows the molding of filled composite with enhanced mechanical properties. Subsequent debindering and sintering steps yield the pure ceramic microcomponents.

  17. Effects of size reduction on deformation, microstructure, and surface roughness of micro components for micro metal injection molding

    NASA Astrophysics Data System (ADS)

    Liu, Lin; Wang, Xin-da; Li, Xiang; Qi, Xiao-tong; Qu, Xuan-hui

    2017-09-01

    The fabrication of 17-4PH micro spool mandrils by micro metal injection molding was described here. The effects of size reduction on deformation, microstructure and surface roughness were studied by comparing a ϕ500 μm micro post and a ϕ1.7 mm cylinder after debinding and sintering. Experimental results show that slumping of the micro posts occurred due to a dramatic increase in outlet vapor pressure initiated at the thermal degradation onset temperature and the moment of gravity. Asymmetrical stress distribution within the micro component formed during the cooling stage may cause warping. Prior solvent debinding and adjustment in a thermal debinding scheme were useful for preventing the deformation of the micro components. Smaller grain size and higher micro hardness due to impeded grain growth were observed for the micro posts compared with the ϕ1.7 mm cylinder. Surface roughness increased with distance from the gate of the micro spool mandril due to melt front advancement during mold filling and the ensuing pressure distribution. At each position, surface roughness was dictated by injection molding and increased slightly after sintering.

  18. Sintering techniques for microstructure control in ceramics

    NASA Astrophysics Data System (ADS)

    Rosenberger, Andrew T.

    Sintering techniques can be manipulated to enhance densification in difficult to sinter materials and to produce property enhancing microstructures. However, the interplay between materials, sintering techniques, and end properties is not fully understood in many material systems, and some fundamental aspects of sintering such as the nature of the effects of electric fields remains unknown. The processing property relationships were examined in two classes of materials; zirconium diboride ultra high temperature ceramic composites, and all solid lithium-ion battery phosphate materials. Investigation of zirconium diboride ceramics focused on the effects of zirconium carbide as a secondary or tertiary phase in ZrB2 and ZrB2 -- SiC. Addition of zirconium carbide was observed to increase flexural strength of composites up to 590MPa at 50wt% ZrC, significantly higher than the flexural strength of 380MPa observed in similarly prepared ZrB2 -- SiC. This difference was attributed to the absence of CTE mismatch induced residual stresses in the ZrB2 -- ZrC composites. A high temperature reaction between ZrB2 and TiC producing Zr1-xTixB2 -- ZrC composites was discovered and found to enhance densification while reducing the average grain size to as small as 1.4mum, lower than the starting powder size of 1.8mum. While a high flexural strength of 670MPa was observed, a strength dependence on the ZrC grain size indicative of CTE mismatch residual stresses was also seen. Finally, the oxidation and ablation resistance of ZrB2 -- ZrC -- SiC composites as a function of ZrC fraction and ZrC:SiC ratio was investigated. Above 5vol% ZrC, the oxidation and ablation resistance of the composites was significantly reduced due to ZrC oxidation, regardless of SiC content. While ZrC can significantly enhance the mechanical properties of the composite, the volume fraction must be kept low to avoid an undesirable reduction in the oxidation resistance. The influence of applied electrical fields

  19. Combinatorial-mold imprint lithography: A versatile technique for fabrication of three-dimensional polymer structures

    NASA Astrophysics Data System (ADS)

    Low, Hong Yee; Zhao, Wei; Dumond, Jarrett

    2006-07-01

    A two-step fabrication technique based on nanoimprint lithography is described for the fabrication of three-dimensional micro- and nanostructures. By combining simple two-dimensional geometries from two molds, complex and useful three-dimensional structures are obtained. The careful selection of mold geometries constitutes a simplified and efficient approach toward building up desirable three-dimensional structures without resorting to the use of a sacrificial process or components. Three-dimensional structures fabricated for a variety of specific applications are presented using both thermoplastic and cross-linked polymer materials.

  20. Levofloxacin implants with predefined microstructure fabricated by three-dimensional printing technique.

    PubMed

    Huang, Weidong; Zheng, Qixin; Sun, Wangqiang; Xu, Huibi; Yang, Xiangliang

    2007-07-18

    A novel three-dimensional (3D) printing technique was utilized in the preparation of drug implants that can be designed to have complex drug release profiles. The method we describe is based on a lactic acid polymer matrix with a predefined microstructure that is amenable to rapid prototyping and fabrication. We describe how the process parameters, especially selection of the binder, were optimized. Implants containing levofloxacin (LVFX) with predefined microstructures using an optimized binder solution of ethanol and acetone (20:80, v/v) were prepared by a 3D printing process that achieved a bi-modal profile displaying both pulsatile and steady state LVFX release from a single implant. The pulse release appeared from day 5 to 25, followed by a steady state phase of 25 days. The next pulse release phase then began at the 50th day and ended at the 80th day. To evaluate the drug implants structurally and analytically, the microscopic morphologies and the in vitro release profiles of the implants fabricated by both the 3D printing technique and the conventional lost mold technique were assessed using environmental scanning electron microscopy (ESEM) and UV absorbance spectrophotometry. The results demonstrate that the 3D printing technology can be used to fabricate drug implants with sophisticated micro- and macro-architecture in a single device that may be rapidly prototyped and fabricated. We conclude that drug implants with predefined microstructure fabricated by 3D printing techniques can have clear advantages compared to implants fabricated by conventional compressing methods.

  1. Improved wax mold technique forms complex passages in solid structures

    NASA Technical Reports Server (NTRS)

    Hellbaum, R. F.; Page, A. D.; Phillips, A. R.

    1971-01-01

    Low-cost fabricating technique produces minute, complex air passages in fluidic devices. Air jet interactions in these function as electronic and electromechanical control systems. Wax cores are fabricated without distortion by two-wax process using nonsoluble pattern-wax and water-soluble wax. Significant steps in fabrication process are discussed.

  2. Monitoring of resin transfer in CFRP molding using 3D-DIC technique

    NASA Astrophysics Data System (ADS)

    Chen, Dingding; Arakawa, Kazuo; Uchino, Masakazu

    2014-06-01

    Vacuum-assisted resin transfer molding (VARTM) is a manufacturing process that is used to make large and complex composite structures. While promising, VARTM still suffers from relatively low fiber volume fractions and high void content in the final products. The infusion step of VARTM is very important, because the quality of the final product is usually decided by this process. Consequently, a comprehensive understanding of the infusion process is essential. In this study, a three-dimensional digital image correlation (3D-DIC) testing system was set up to research the entire infusion process through the monitor of the thickness change of the laminates in this process. Two distinct VARTM processes, with and without a rigid cover mold, were designed to be studied. The 3D-DIC technique proved to be a valid method that not only can monitor the thickness evolution of isolated points but also can give a full-field distribution of the thickness change of the laminate. The results showed that, without the use of a rigid cover mold, the stack of reinforcements initially shrank and then expanded as the resin filled the cavities before closing the inlet, while when using a rigid cover mold there was an additional expansion period before the shrinkage occurred. Such an expansion stage could promote the flow of the resin, shortening the infusion time.

  3. The Influence of Heat Treatment on the Microstructure and Machinability of a Prehardened Mold Steel

    NASA Astrophysics Data System (ADS)

    Hoseiny, Hamed; Caballero, Francisca G.; M'Saoubi, Rachid; Högman, Berne; Weidow, Jonathan; Andrén, Hans-Olof

    2015-05-01

    The machinability performance of a modified AISI P20 steel, heat treated to have the same hardness but three different microstructures, lower bainite, tempered martensite, and primary spheroidized carbides in a tempered martensite matrix, was studied. The microstructures were characterized using light optical and scanning electron microscopy and X-ray diffraction, and mechanical properties were compared by means of tensile and Charpy V-notch impact tests. The influence of microstructure and the resultant mechanical properties on machinability was studied in the context of single tooth end milling operation. The results showed that the material containing primary spheroidized carbides exhibited a superior machinability at the expense of a marginal loss of tensile strength and impact toughness, with comparable yield strength to that of the material containing tempered martensite. By contrast, the material with bainitic microstructure showed the lowest yield strength and the poorest machinability performance while having the highest uniform elongation.

  4. Correction of Congenital Auricular Deformities Using the Ear-Molding Technique.

    PubMed

    Woo, Taeyong; Kim, Young Seok; Roh, Tai Suk; Lew, Dae Hyun; Yun, In Sik

    2016-11-01

    Studies of the ear-molding technique have emphasized the importance of initiating molding early to achieve the best results. In the present study, we describe the immediate effects and long-term outcomes of this technique, focusing on children who were older than the ideal age of treatment initiation. Patients who visited our institution from July 2014 to November 2015 were included. Medical charts were reviewed to collect data on demographics, the duration of treatment, the types of deformities, and the manner of recognition of the deformity and referral to our institution. Parents were surveyed to assess the degree of improvement, the level of procedural discomfort at the end of treatment, any changes in the shape of the molded auricle, and overall satisfaction 12 months after their last follow-up visits. A review of 28 ears in 18 patients was conducted, including the following types of deformities: constricted ear (64.2%), Stahl ear (21.4%), prominent ear (7.1%), and cryptotia (7.1%). The average score for the degree of improvement, rated on a 5-point scale (1, very poor; 5, excellent), was 3.5 at the end of treatment, with a score of 2.6 for procedural discomfort (1, very mild; 5, very severe). After 12 months, the shapes of all ears were well maintained. The average overall satisfaction score was 3.6 (1, very dissatisfied; 5, very satisfied). We had reasonable outcomes in older patients. After 1 year of follow-up, these outcomes were well maintained. Patients past the ideal age at presentation can still be candidates for the molding technique.

  5. Adjuvant brachytherapy for endometrial cancer: advantages of the vaginal mold technique.

    PubMed

    El Khoury, Clement; Dumas, Isabelle; Tailleur, Anne; Morice, Philippe; Haie-Meder, Christine

    2015-01-01

    Treatment of endometrial carcinoma in the adjuvant setting includes in most cases vaginal brachytherapy. In our institution, we use the customized vaginal mold technique. Herein, we report the advantages of this personalized applicator in terms of target coverage, normal tissue preservation, the incidence of air pockets, and its potential impact on dosimetry. A total of 15 patients receiving postoperative vaginal cuff high-dose-rate brachytherapy with the mold applicator technique were enrolled in this prospective data collection study. Patients were treated with either two or four fractions of 5 Gy prescribed to the clinical target volume, which consisted of an irradiation of the vaginal cuff and the upper third of the vagina. Target coverage; dose to organs at risk, in addition to the volume; and the dosimetric impact of air pockets surrounding the mold were evaluated. In 15 patients, a total of 27 air pockets were identified. The average number of air pockets per patient was 1.8 (range, 0-4), with the average total air pocket volume being 0.1 cc (range, 0.01-0.54). The average dose reduction at 5mm from the air pocket was 26% (range, 6-45%). The minimal clinical target volume coverage reported was 95% and the maximal dose received by 2 cc of the bladder, rectum, and sigmoid never exceeded 110% of the prescribed dose. Vaginal cuff high-dose-rate brachytherapy using the molded applicator provides personalized tailored treatment in terms of anatomical conformity. This translates into a dosimetrical advantage with smaller and fewer air pockets than reported in the literature with the use of cylinders. Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  6. Microstructure and mechanical behavior of metal injection molded Ti-Nb binary alloys as biomedical material.

    PubMed

    Zhao, Dapeng; Chang, Keke; Ebel, Thomas; Qian, Ma; Willumeit, Regine; Yan, Ming; Pyczak, Florian

    2013-12-01

    The application of titanium (Ti) based biomedical materials which are widely used at present, such as commercially pure titanium (CP-Ti) and Ti-6Al-4V, are limited by the mismatch of Young's modulus between the implant and the bones, the high costs of products, and the difficulty of producing complex shapes of materials by conventional methods. Niobium (Nb) is a non-toxic element with strong β stabilizing effect in Ti alloys, which makes Ti-Nb based alloys attractive for implant application. Metal injection molding (MIM) is a cost-efficient near-net shape process. Thus, it attracts growing interest for the processing of Ti and Ti alloys as biomaterial. In this investigation, metal injection molding was applied to the fabrication of a series of Ti-Nb binary alloys with niobium content ranging from 10wt% to 22wt%, and CP-Ti for comparison. Specimens were characterized by melt extraction, optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Titanium carbide formation was observed in all the as-sintered Ti-Nb binary alloys but not in the as-sintered CP-Ti. Selected area electron diffraction (SAED) patterns revealed that the carbides are Ti2C. It was found that with increasing niobium content from 0% to 22%, the porosity increased from about 1.6% to 5.8%, and the carbide area fraction increased from 0% to about 1.8% in the as-sintered samples. The effects of niobium content, porosity and titanium carbides on mechanical properties have been discussed. The as-sintered Ti-Nb specimens exhibited an excellent combination of high tensile strength and low Young's modulus, but relatively low ductility.

  7. Laser origami: a new technique for assembling 3D microstructures

    NASA Astrophysics Data System (ADS)

    Piqué, Alberto; Mathews, Scott A.; Charipar, Nicholas A.; Birnbaum, Andrew J.

    2012-03-01

    The ability to manufacture and assemble complex three-dimensional (3D) systems via traditional photolithographic techniques has attracted increasing attention. However, most of the work to date still utilizes the traditional patterning and etching processes designed for the semiconductor industry where 2D structures are first fabricated, followed by some alternative technique for releasing these structures out-of-plane. Here we present a novel technique called Laser Origami, which has demonstrated the ability to generate 3D microstructures through the controlled out-of-plane folding of 2D patterns. This non-lithographic, and non silicon-based process is capable of microfabricating 3D structures of arbitrary shape and geometric complexity on a variety of substrates. The Laser Origami technique allows for the design and fabrication of arrays of 3D microstructures, where each microstructure can be made to fold independently of the others. Application of these folded micro-assemblies might make possible the development of highly complex and interconnected electrical, optical and mechanical 3D systems. This article will describe the unique advantages and capabilities of Laser Origami, discuss its applications and explore its role for the assembly and generation of 3D microstructures.

  8. Comparative evaluation of border molding, using two different techniques in maxillary edentulous arches - An in vivo study.

    PubMed

    Yarapatineni, Rameshbabu; Vilekar, Abhishek; Kumar, J Phani; Kumar, G Ajay; Aravind, Prasad; Kumar, P Anil

    2013-12-01

    This study was undertaken to compare the retention between sectional border molding using low fusing greenstick compound and single step border molding using condensation silicone (putty) impression material in three stages- A. Immediately following border molding, B. After final impression and C. With the finished permanent denture base. In this study evaluation of retentive values of sectional border molding (Group I) (custom impression trays border molded with green stick compound ) and single step border molding (Group II) ( border molding with condensation silicone (putty) impression material ). In both techniques definitive wash impression were made with light body condensation silicone and permanent denture base with heat cure polymerization resin. Group II was significantly higher (mean=8011.43) than Group I (mean=5777.43) in test-A. The t-value (1.5883) infers that there was significant difference between Group I and Group II (p =0.15). Group I was significantly higher (mean=6718.57) than Group II (mean=5224.29) in test -B. The t-value (1.6909) infers that there was significant difference between Group I and Group II (p=0.17). Group II was higher (mean=4025.14) than Group I (mean=3835.07) in test -C. The t-value was 0.1239. But it was found to be statistically insignificant (p=0.005). Within the limitation of this clinical study border molding custom tray with low fusing green stick compound provided similar retention as compared to custom impression tray with condensation silicone in permanent denture base. How to cite this article: Yarapatineni R, Vilekar A, Kumar JP, Kumar GA, Aravind P, Kumar PA. Comparative evaluation of border molding, using two different techniques in maxillary edentulous arches - An in vivo study. J Int Oral Health 2013; 5(6):82-7 .

  9. Comparative evaluation of border molding, using two different techniques in maxillary edentulous arches - An in vivo study

    PubMed Central

    Yarapatineni, Rameshbabu; Vilekar, Abhishek; Kumar, J Phani; Kumar, G Ajay; Aravind, Prasad; Kumar, P Anil

    2013-01-01

    Background: This study was undertaken to compare the retention between sectional border molding using low fusing greenstick compound and single step border molding using condensation silicone (putty) impression material in three stages- A. Immediately following border molding, B. After final impression and C. With the finished permanent denture base. Materials & Methods: In this study evaluation of retentive values of sectional border molding (Group I) (custom impression trays border molded with green stick compound ) and single step border molding (Group II) ( border molding with condensation silicone (putty) impression material ). In both techniques definitive wash impression were made with light body condensation silicone and permanent denture base with heat cure polymerization resin. Results: Group II was significantly higher (mean=8011.43) than Group I (mean=5777.43) in test-A. The t-value (1.5883) infers that there was significant difference between Group I and Group II (p =0.15). Group I was significantly higher (mean=6718.57) than Group II (mean=5224.29) in test -B. The t-value (1.6909) infers that there was significant difference between Group I and Group II (p=0.17). Group II was higher (mean=4025.14) than Group I (mean=3835.07) in test -C. The t-value was 0.1239. But it was found to be statistically insignificant (p=0.005). Conclusion: Within the limitation of this clinical study border molding custom tray with low fusing green stick compound provided similar retention as compared to custom impression tray with condensation silicone in permanent denture base. How to cite this article: Yarapatineni R, Vilekar A, Kumar JP, Kumar GA, Aravind P, Kumar PA. Comparative evaluation of border molding, using two different techniques in maxillary edentulous arches - An in vivo study. J Int Oral Health 2013; 5(6):82-7 . PMID:24453450

  10. Glass microstructure capping and bonding techniques.

    PubMed

    Mazurczyk, Radoslaw; Mansfield, Colin D; Lygan, Marcin

    2013-01-01

    The capping of microfluidic features fabricated in glass substrates is achievable by various technological methods. Of the entire spectrum of possibilities (gluing, glass bonding via intermediate layers, pressure or plasma-assisted glass bonding, etc.) a detailed description of three techniques is presented here. The first is a low temperature PDMS-glass adhesion bonding, the second is medium temperature pressure assisted glass-glass bonding, and finally, high temperature glass-glass fusion bonding. All these protocols allow completion of the manufacturing process for a fully enclosed microfluidic chip. Nevertheless, as they are complementary rather than competing methods, they effectively extend the range of tools available to fabricate lab-on-a-chip microdevices. Each has its own merits and each could feasibly be used at different developmental stages of a given microfluidic device.

  11. Fabrication of 3D cell-laden hydrogel microstructures through photo-mold patterning.

    PubMed

    Occhetta, P; Sadr, N; Piraino, F; Redaelli, A; Moretti, M; Rasponi, M

    2013-09-01

    Native tissues are characterized by spatially organized three-dimensional (3D) microscaled units which functionally define cells-cells and cells-extracellular matrix interactions. The ability to engineer biomimetic constructs mimicking these 3D microarchitectures is subject to the control over cell distribution and organization. In the present study we introduce a novel protocol to generate 3D cell laden hydrogel micropatterns with defined size and shape. The method, named photo-mold patterning (PMP), combines hydrogel micromolding within polydimethylsiloxane (PDMS) stamps and photopolymerization through a recently introduced biocompatible ultraviolet (UVA) activated photoinitiator (VA-086). Exploiting PDMS micromolds as geometrical constraints for two methacrylated prepolymers (polyethylene glycol diacrylate and gelatin methacrylate), micrometrically resolved structures were obtained within a 3 min exposure to a low cost and commercially available UVA LED. The PMP was validated both on a continuous cell line (human umbilical vein endothelial cells expressing green fluorescent protein, HUVEC GFP) and on primary human bone marrow stromal cells (BMSCs). HUVEC GFP and BMSCs were exposed to 1.5% w/v VA-086 and UVA light (1 W, 385 nm, distance from sample = 5 cm). Photocrosslinking conditions applied during the PMP did not negatively affect cells viability or specific metabolic activity. Quantitative analyses demonstrated the potentiality of PMP to uniformly embed viable cells within 3D microgels, creating biocompatible and favorable environments for cell proliferation and spreading during a seven days' culture. PMP can thus be considered as a promising and cost effective tool for designing spatially accurate in vitro models and, in perspective, functional constructs.

  12. The Development of Layered Photonic Band Gap Structures Using a Micro-Transfer Molding Technique

    SciTech Connect

    Sutherland, Kevin Jerome

    2001-01-01

    Photonic band gap (PBG) crystals are periodic dielectric structures that manipulate electromagnetic radiation in a manner similar to semiconductor devices manipulating electrons. Whereas a semiconductor material exhibits an electronic band gap in which electrons cannot exist, similarly, a photonic crystal containing a photonic band gap does not allow the propagation of specific frequencies of electromagnetic radiation. This phenomenon results from the destructive Bragg diffraction interference that a wave propagating at a specific frequency will experience because of the periodic change in dielectric permitivity. This gives rise to a variety of optical applications for improving the efficiency and effectiveness of opto-electronic devices. These applications are reviewed later. Several methods are currently used to fabricate photonic crystals, which are also discussed in detail. This research involves a layer-by-layer micro-transfer molding ({mu}TM) and stacking method to create three-dimensional FCC structures of epoxy or titania. The structures, once reduced significantly in size can be infiltrated with an organic gain media and stacked on a semiconductor to improve the efficiency of an electronically pumped light-emitting diode. Photonic band gap structures have been proven to effectively create a band gap for certain frequencies of electro-magnetic radiation in the microwave and near-infrared ranges. The objective of this research project was originally two-fold: to fabricate a three dimensional (3-D) structure of a size scaled to prohibit electromagnetic propagation within the visible wavelength range, and then to characterize that structure using laser dye emission spectra. As a master mold has not yet been developed for the micro transfer molding technique in the visible range, the research was limited to scaling down the length scale as much as possible with the current available technology and characterizing these structures with other methods.

  13. Characterization of microstructure with low frequency electromagnetic techniques

    SciTech Connect

    Cherry, Matthew R.; Sathish, Shamachary; Pilchak, Adam L.; Blodgett, Mark P.; Cherry, Aaron J.

    2014-02-18

    A new computational method for characterizing the relationship between surface crystallography and electrical conductivity in anisotropic materials with low frequency electromagnetic techniques is presented. The method is discussed from the standpoint of characterizing the orientation of a single grain, as well as characterizing statistical information about grain ensembles in the microstructure. Large-area electron backscatter diffraction (EBSD) data was obtained and used in conjunction with a synthetic aperture approach to simulate the eddy current response of beta annealed Ti-6Al-4V. Experimental eddy current results are compared to the computed eddy current approximations based on electron backscatter diffraction (EBSD) data, demonstrating good agreement. The detectability of notches in the presence of noise from microstructure is analyzed with the described simulation method and advantages and limitations of this method are discussed relative to other NDE techniques for such analysis.

  14. Lightweight custom composite prosthetic components using an additive manufacturing-based molding technique.

    PubMed

    Leddy, Michael T; Belter, Joseph T; Gemmell, Kevin D; Dollar, Aaron M

    2015-01-01

    Additive manufacturing techniques are becoming more prominent and cost-effective as 3D printing becomes higher quality and more inexpensive. The idea of 3D printed prosthetics components promises affordable, customizable devices, but these systems currently have major shortcomings in durability and function. In this paper, we propose a fabrication method for custom composite prostheses utilizing additive manufacturing, allowing for customizability, as well the durability of professional prosthetics. The manufacturing process is completed using 3D printed molds in a multi-stage molding system, which creates a custom finger or palm with a lightweight epoxy foam core, a durable composite outer shell, and soft urethane gripping surfaces. The composite material was compared to 3D printed and aluminum materials using a three-point bending test to compare stiffness, as well as gravimetric measurements to compare weight. The composite finger demonstrates the largest stiffness with the lowest weight compared to other tested fingers, as well as having customizability and lower cost, proving to potentially be a substantial benefit to the development of upper-limb prostheses.

  15. Advances in Aluminum Mold Block for Plastic Injection Molding Operations

    NASA Astrophysics Data System (ADS)

    Kim, Jinsoo; Smierciak, Ron; Shin, Yong Seung; Cooper, Leighton

    Mold performance with high strength aluminum alloy QC-10® in injection molding was investigated and compared with NAK 80 steel mold. Two different shapes of molds were tooled and tested. Interfacial heat fluxes between cooling mold and solidifying polymer melt were measured using the IHCP (Inverse Heat Conduction Method) technique during the injection molding cycles. The influence of thermo-physical properties of mold materials and polymer resins on molding cycle time and internal residual stress were also investigated by injection molding control optimization and birefringence analyzer. Evaluation of the thermal energy absorbed and uniform heat extraction during injection molding revealed that aluminum mold QC-10® resulted in significant cycle time reduction and produced the part with less distortion. In addition to the benefit of reduced tooling time, it was proven that aluminum mold is a promising mold material for increasing the productivity in plastic injection molding operations.

  16. Single Stage Silicone Border Molded Closed Mouth Impression Technique-Part II.

    PubMed

    Solomon, E G R

    2011-09-01

    Functioning of a complete denture depends to a great extent on the impression technique. Several impression techniques have been described in the literature since the turn of this century when Greene [Clinical courses in dental prothesis, 1916] brothers introduced the first scientific system of recording dental impression. Advocates of each technique have their own claim of superiority over the other. The introduction of elastomeric impression materials [Skinner and Cooper, J Am Dent Assoc 51:523-536, 1955] has made possible new techniques of recording impression for complete denture construction. These rubber like materials are of two types; one has a polysulfide base and is popularily known as polysulfide rubber (Thiokol and Mercaptan). The other variety has a silicone base known as silicone rubber or silicone elastomer. Silicone elastomers are available in four different consistencies; a thin easy flowing light bodied material,a creamy medium bodied material, a highly viscous heavy bodied material and a kneadable putty material. This paper describes an active closed mouth impression technique with one stage border molding using putty silicone material as a substitute for low fusing compound.

  17. A novel technique for presurgical nasoalveolar molding using computer-aided reverse engineering and rapid prototyping.

    PubMed

    Yu, Quan; Gong, Xin; Wang, Guo-Min; Yu, Zhe-Yuan; Qian, Yu-Fen; Shen, Gang

    2011-01-01

    To establish a new method of presurgical nasoalveolar molding (NAM) using computer-aided reverse engineering and rapid prototyping technique in infants with unilateral cleft lip and palate (UCLP). Five infants (2 males and 3 females with mean age of 1.2 w) with complete UCLP were recruited. All patients were subjected to NAM before the cleft lip repair. The upper denture casts were recorded using a three-dimensional laser scanner within 2 weeks after birth in UCLP infants. A digital model was constructed and analyzed to simulate the NAM procedure with reverse engineering software. The digital geometrical data were exported to print the solid model with rapid prototyping system. The whole set of appliances was fabricated based on these solid models. Laser scanning and digital model construction simplified the NAM procedure and estimated the treatment objective. The appliances were fabricated based on the rapid prototyping technique, and for each patient, the complete set of appliances could be obtained at one time. By the end of presurgical NAM treatment, the cleft was narrowed, and the malformation of nasoalveolar segments was aligned normally. We have developed a novel technique of presurgical NAM based on a computer-aided design. The accurate digital denture model of UCLP infants could be obtained with laser scanning. The treatment design and appliance fabrication could be simplified with a computer-aided reverse engineering and rapid prototyping technique.

  18. Surface 3D Micro Free Forms: Multifunctional Microstructured Mesoporous α-Alumina by in Situ Slip Casting Using Excimer Laser Ablated Polycarbonate Molds.

    PubMed

    Rowthu, Sriharitha; Böhlen, Karl; Bowen, Paul; Hoffmann, Patrik

    2015-11-11

    Ceramic surface microstructuring is a rapidly growing field with a variety of applications in tribology, wetting, biology, and so on. However, there are limitations to large-area microstructuring and fabrication of three-dimensional (3D) micro free forms. Here, we present a route to obtain intricate surface structures through in situ slip casting using polydimethylsiloxane (PDMS) negative molds which are replicated from excimer laser ablated polycarbonate (PC) master molds. PC sheets are ablated with a nanosecond KrF (λ = 248 nm) excimer laser mask projection system to obtain micron-scale 3D surface features over a large area of up to 3 m(2). Complex surface structures that include 3D free forms such as 3D topography of Switzerland, shallow structures such as diffractive optical elements (60 nm step) and conical micropillars have been obtained. The samples are defect-free produced with thicknesses of up to 10 mm and 120 mm diameter. The drying process of the slip cast alumina slurry takes place as a one-dimensional process, through surface evaporation and water permeation through the PDMS membrane. This allows homogeneous one-dimensional shrinkage during the drying process, independent of the sample's lateral dimensions. A linear mass diffusion model has been proposed to predict and explain the drying process of these ceramic colloidal suspensions. The calculated drying time is linearly proportional to the height of the slurry and the thickness of the negatively structured PDMS and is validated by the experimental results. An experimentally observed optimum Sylgard PDMS thickness range of ∼400 μm to 1 mm has achieved the best quality microstructured green compacts. Further, the model predicts that the drying time is independent of the microstructured areas and was validated using experimental observations carried out with microstructured areas of 300 mm(2), 1200 mm(2), and 120 cm(2). Therefore, in principle, the structures can be further replicated in areas up

  19. EVALUATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE STYRENE EMISIONS FROM OPEN CONTACT MOLDING PROCESSES - VOLUME 1. FINAL REPORT

    EPA Science Inventory

    The report gives results of a study to evaluate several pollution prevention techniques that could be used to reduce styrene emissions from open molding processes in the fiberglass-reinforced
    plastics/composites (FRP/C) and fiberglass boat building industries. Styrene emission...

  20. EVALUATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE STYRENE EMISSIONS FROM OPEN CONTACT MOLDING PROCESSES - VOLUME 2. APPENDICES

    EPA Science Inventory

    The report gives results of a study to evaluate several pollution prevention techniques that could be used to reduce styrene emissions from open molding processes in the fiberglass-reinforced plastics/composites (FRP/C) and fiberglass boat building industries. Styrene emissions u...

  1. EVALUATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE STYRENE EMISSIONS FROM OPEN CONTACT MOLDING PROCESSES - VOLUME 2. APPENDICES

    EPA Science Inventory

    The report gives results of a study to evaluate several pollution prevention techniques that could be used to reduce styrene emissions from open molding processes in the fiberglass-reinforced plastics/composites (FRP/C) and fiberglass boat building industries. Styrene emissions u...

  2. EVALUATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE STYRENE EMISIONS FROM OPEN CONTACT MOLDING PROCESSES - VOLUME 1. FINAL REPORT

    EPA Science Inventory

    The report gives results of a study to evaluate several pollution prevention techniques that could be used to reduce styrene emissions from open molding processes in the fiberglass-reinforced
    plastics/composites (FRP/C) and fiberglass boat building industries. Styrene emission...

  3. A modified nasoalveolar molding technique for correction of unilateral cleft nose deformity.

    PubMed

    Chen, Yun-Fang; Liao, Yu-Fang

    2015-12-01

    Traditional Figueroa nasoalveolar molding (NAM) requires weekly or biweekly adjustments to remove acrylic from the palatal plate to narrow the alveolar gap. These frequent adjustments create a burden for patients living far from a hospital. To minimize this burden, we developed a modified NAM technique using simplified lip taping and a passive palatal plate. Herein we present our clinical experience and outcomes using the traditional and modified methods. In this blinded, retrospective study of 66 patients with complete unilateral cleft lip and palate, 33 received the traditional NAM and 33 received the modified NAM. Pretreatment and posttreatment facial photographs and clinical charts were used to compare efficacy (nostril height ratio, nostril width ratio, columellar angle, nasal base angle), efficiency (molding frequency), incidence of complications (facial irritation, mucosal ulceration), and medical cost. Traditional and modified NAM did not differ in treatment efficacy for nostril height ratio (0.88 ± 0.14 vs. 0.90 ± 0.12), nostril width ratio (2.22 ± 0.39 vs. 2.38 ± 0.50), columellar angle (73.5 ± 9.1 degrees vs. 71.3 ± 11.8 degrees), nasal base angle (5.1 ± 2.4 degrees vs. 5.9 ± 2.7 degrees), or alveolar gap width (2.0 ± 2.0 mm vs. 2.0 ± 1.7 mm) (all p > 0.05). Traditional NAM was less efficient, i.e., required more adjustments (8.6 ± 2.0 vs. 6.7 ± 1.1), and cost more (22016.4 ± 2012.7 New Taiwan dollars vs. 20137.6 ± 1173.4 New Taiwan dollars) (both p < 0.001). Both NAM techniques similarly improved nasal deformities and reduced alveolar gaps, but the modified technique was more efficient and cost less in terms of insurance reimbursement and supplies (labial tapes). Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  4. A neural network technique for remeshing of bone microstructure.

    PubMed

    Fischer, Anath; Holdstein, Yaron

    2012-01-01

    Today, there is major interest within the biomedical community in developing accurate noninvasive means for the evaluation of bone microstructure and bone quality. Recent improvements in 3D imaging technology, among them development of micro-CT and micro-MRI scanners, allow in-vivo 3D high-resolution scanning and reconstruction of large specimens or even whole bone models. Thus, the tendency today is to evaluate bone features using 3D assessment techniques rather than traditional 2D methods. For this purpose, high-quality meshing methods are required. However, the 3D meshes produced from current commercial systems usually are of low quality with respect to analysis and rapid prototyping. 3D model reconstruction of bone is difficult due to the complexity of bone microstructure. The small bone features lead to a great deal of neighborhood ambiguity near each vertex. The relatively new neural network method for mesh reconstruction has the potential to create or remesh 3D models accurately and quickly. A neural network (NN), which resembles an artificial intelligence (AI) algorithm, is a set of interconnected neurons, where each neuron is capable of making an autonomous arithmetic calculation. Moreover, each neuron is affected by its surrounding neurons through the structure of the network. This paper proposes an extension of the growing neural gas (GNN) neural network technique for remeshing a triangular manifold mesh that represents bone microstructure. This method has the advantage of reconstructing the surface of a genus-n freeform object without a priori knowledge regarding the original object, its topology, or its shape.

  5. Fabrication of high-transmission microporous membranes by proton beam writing-based molding technique

    NASA Astrophysics Data System (ADS)

    Wang, Liping; Meyer, Clemens; Guibert, Edouard; Homsy, Alexandra; Whitlow, Harry J.

    2017-08-01

    Porous membranes are widely used as filters in a broad range of micro and nanofluidic applications, e.g. organelle sorters, permeable cell growth substrates, and plasma filtration. Conventional silicon fabrication approaches are not suitable for microporous membranes due to the low mechanical stability of thin film substrates. Other techniques like ion track etching are limited to the production of randomly distributed and randomly orientated pores with non-uniform pore sizes. In this project, we developed a procedure for fabricating high-transmission microporous membranes by proton beam writing (PBW) with a combination of spin-casting and soft lithography. In this approach, focused 2 MeV protons were used to lithographically write patterns consisting of hexagonal arrays of high-density pillars of few μm size in a SU-8 layer coated on a silicon wafer. After development, the pillars were conformably coated with a thin film of poly-para-xylylene (Parylene)-C release agent and spin-coated with polydimethylsiloxane (PDMS). To facilitate demolding, a special technique based on the use of a laser-cut sealing tape ring was developed. This method facilitated the successful delamination of 20-μm thick PDMS membrane with high-density micropores from the mold without rupture or damage.

  6. A Comparative Study on Permanent Mold Cast and Powder Thixoforming 6061 Aluminum Alloy and Sicp/6061Al Composite: Microstructures and Mechanical Properties.

    PubMed

    Zhang, Xuezheng; Chen, Tijun; Qin, He; Wang, Chong

    2016-05-24

    Microstructural and mechanical characterization of 10 vol% SiC particles (SiCp) reinforced 6061 Al-based composite fabricated by powder thixoforming (PTF) was investigated in comparison with the PTF and permanent mold cast (PMC) 6061 monolithic alloys. The results reveal that the microstructure of the PMC alloy consists of coarse and equiaxed α dendrites and interdendritic net-like eutectic phases. However, the microstructure of the PTF composite, similar to that of the PTF alloy, consists of near-spheroidal primary particles and intergranular secondarily solidified structures except SiCp, which are distributed in the secondarily solidified structures. The eutectics amount in the PTF materials is distinctly lower than that in the PMC alloy, and the microstructures of the former materials are quite compact while that of the latter alloy is porous. Therefore, the PTF alloy shows better tensile properties than the PMC alloy. Owing to the existence of the SiC reinforcing particles, the PTF composite attains an ultimate tensile strength and yield strength of 230 MPa and 128 MPa, representing an enhancement of 27.8% and 29.3% than those (180 MPa and 99 MPa) of the PTF alloy. A modified model based on three strengthening mechanisms was proposed to calculate the yield strength of the PTF composite. The obtained theoretical results were quite consistent with the experimental data.

  7. A Comparative Study on Permanent Mold Cast and Powder Thixoforming 6061 Aluminum Alloy and Sicp/6061Al Composite: Microstructures and Mechanical Properties

    PubMed Central

    Zhang, Xuezheng; Chen, Tijun; Qin, He; Wang, Chong

    2016-01-01

    Microstructural and mechanical characterization of 10 vol% SiC particles (SiCp) reinforced 6061 Al-based composite fabricated by powder thixoforming (PTF) was investigated in comparison with the PTF and permanent mold cast (PMC) 6061 monolithic alloys. The results reveal that the microstructure of the PMC alloy consists of coarse and equiaxed α dendrites and interdendritic net-like eutectic phases. However, the microstructure of the PTF composite, similar to that of the PTF alloy, consists of near-spheroidal primary particles and intergranular secondarily solidified structures except SiCp, which are distributed in the secondarily solidified structures. The eutectics amount in the PTF materials is distinctly lower than that in the PMC alloy, and the microstructures of the former materials are quite compact while that of the latter alloy is porous. Therefore, the PTF alloy shows better tensile properties than the PMC alloy. Owing to the existence of the SiC reinforcing particles, the PTF composite attains an ultimate tensile strength and yield strength of 230 MPa and 128 MPa, representing an enhancement of 27.8% and 29.3% than those (180 MPa and 99 MPa) of the PTF alloy. A modified model based on three strengthening mechanisms was proposed to calculate the yield strength of the PTF composite. The obtained theoretical results were quite consistent with the experimental data. PMID:28773527

  8. Characterizing TPS Microstructure: A Review of Some techniques

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew; Stackpole, Mairead; Agrawal, Parul; Chavez-Garcie, Jose

    2011-01-01

    I. When seeking to understand ablator microstructure and morphology there are several useful techniques A. SEM 1) Visual characteriza3on at various length scales. 2) Chemical mapping by backscatter or x-ray highlights areas of interest. 3) Combined with other techniques (density, weight change, chemical analysis) SEM is a powerful tool to aid in explaining thermo/structural data. B. ASAP. 1) Chemical characteriza3on at various length scales. 2) Chemical mapping of pore structure by gas adsorption. 3) Provides a map of pore size vs. pore volume. 4) Provided surface area of exposed TPS. II. Both methods help characterize and understand how ablators react with other chemical species and provides insight into how they oxidize.

  9. Diamond Field Emission Source using Transfer Mold Technique Prepared by Diamond Powder Seeding

    NASA Astrophysics Data System (ADS)

    Tezuka, Sachiaki; Matsuba, Yohei; Takahashi, Kohro

    Diamond thin films fabricated by MPCVD (microwave plasma chemical vapor deposition) are available for use as a field emitter material, because of its high mechanical quality, thermal conductivity, chemical stability, environmental tolerance, and NEA (negative electron affinity). Diode and triode emitter arrays using P-doped polycrystalline diamond were manufactured on a SiO2/Si(100) substrate with reverse pyramids formed by the transfer mold technique. As the diamond nucleation process, spin-coat seeding with pure diamond powder dispersed in isoamyl acetate has been introduced in place of the bias method. SEM (scanning electron microscopy) images and Raman spectroscopy indicate that the crystal quality of the diamond thin film fabricated by spin-coat seeding is superior to that fabricated by the bias method. The diamond crystal completely grew on top of the diode emitter by the US (ultrasonic) treatment in a diamond powder solution before spin-coat seeding. The tip radius was smaller than 50 nm. The beginning voltage of the emission of the diode emitter is 3 V after the DC glow discharge treatment in H2, which is lower than that of an emitter array fabricated by the bias method, 40 V. On the other hand, the emission of the diamond triode emitter starts at a gate voltage of only 0.5 V, and the emission current of 50∼60 mA is obtained at a gate voltage of 2 V.

  10. Microstructural characterization of ferromagnetic materials using magnetic NDE techniques

    SciTech Connect

    Ranjan, R.

    1987-01-01

    Magnetic NDE techniques, namely, the acoustic Barkhausen noise, the magnetic Barkhausen noise, and the magnetic hysteresis curves were simultaneously used for microstructural characterization of nickel and steels. Results showed that, in nickel, the non-180/sup 0/ domain walls interact more strongly with dislocations than the 180/sup 0/ domain walls. A study of the grain-size effect on the magnetic and acoustic Barkhausen noises showed a great potential as a NDE grain-size-measurement tool. Moreover, the Barkhausen signals indicate that the 180/sup 0/ domain walls in nickel seem to have a stronger interaction with grain boundaries than the non-180/sup 0/ domain walls, as indicated by the acoustic Barkhausen signal. Based on the experimental observations, a theoretical model is being proposed to explain the grain size effect on the Barkhausen signals. The model takes into account the density of magnetic domain walls and their initial velocity, with both quantities being strongly dependent on microstructure. The acoustic and magnetic Barkhausen noises were also found to be very sensitive to the change in carbide morphology. It is proposed that the magnetic Barkhausen peak signal is caused by mainly domain nucleation and the acoustic Barkhausen peak signal due to domain growth.

  11. Microstructural characterization of ferromagnetic materials using magnetic NDE techniques

    SciTech Connect

    Ranjan, R.

    1987-06-01

    Magnetic NDE techniques, namely, the acoustic Barkhausen noise, the magnetic Barkhausen noise and the magnetic hysteresis curves, were simultaneously used for microstructural characterization of nickel and steels. Results showed that, in nickel, the non-180/sup 0/ domain walls interact more strongly with dislocations than the 180/sup 0/ domain walls. A study of the grain size effect on the magnetic and acoustic Barkhausen noises showed a great potential as a NDE grain size measurement tool. Moreover, the Barkhausen signals indicate that the 180/sup 0/ domain walls in nickel seem to have a stronger interaction with grain boundaries than the non-180/sup 0/ domain walls, as indicated by the acoustic Barkhausen signal. A theoretical model is being proposed to explain the grain size effect on the Barkhausen signals. The model takes into account the density of magnetic domain walls and their initial velocity, with both quantities being strongly dependent on microstructure. The acoustic and magnetic Barkhausen noises were also found to be very sensitive to the change in carbide morphology. It is proposed that the magnetic Barkhausen peak signal is caused by mainly domain nucleation and the acoustic Barkhausen peak signal due to domain growth.

  12. Microstructure and Mechanical Properties of Aluminum-Alumina Bulk Nanocomposite Produced by a Novel Two-Step Ultrasonic Casting Technique

    NASA Astrophysics Data System (ADS)

    Vishwanatha, H. M.; Eravelly, Jayakumar; Kumar, Cheruvu Siva; Ghosh, Sudipto

    2016-11-01

    An unprecedented uniform distribution of nano-dispersoids in aluminum-alumina bulk nanocomposite and enhancement in mechanical properties were achieved through a novel ultrasonic casting technique involving two-step ultrasonication. Ultrasonic casting can be classified into two types: (a) contact type, in which the sonicating probe is in direct contact with the liquid melt during ultrasonication and (b) non-contact type, in which the ultrasonic waves reach the liquid melt through the mold wall. Each of the processes has certain disadvantages, and the present study aims at eliminating the primary disadvantages of both the processes, through a novel two-step ultrasonic casting technique. The significant improvement in distribution was possibly due to the cavitation in the mold, leading to the elimination of non-uniformity in the cooling rate at the mesoscopic scale. The improvement in mechanical properties is explained through microstructure analysis in correlation with EBSD analysis, TEM analysis, hardness test, and tensile test. The yield strength of the nanocomposite produced by the two-step process was ~38 pct higher than that produced by non-contact and contact methods.

  13. Impact toughness of cellulose-fiber reinforced polypropylene : influence of microstructure in laminates and injection molded composites

    Treesearch

    Craig Clemons; Daniel Caulfield; A. Jeffrey Giacomin

    2003-01-01

    Unlike their glass reinforced counterparts, microstructure and dynamic fracture behavior of natural fiber-reinforced thermoplastics have hardly been investigated. Here, we characterize the microstructure of cellulose fiber-reinforced polypropylene and determined its effect on impact toughness. Fiber lengths were reduced by one-half when compounded in a high-intensity...

  14. Effect of Inoculation Techniques and Relative Humidity on the Growth of Molds on the Surfaces of Yellow Layer Cakes

    PubMed Central

    Fustier, Patrick; Lafond, Alain; Champagne, Claude P.; Lamarche, François

    1998-01-01

    Four inoculation techniques were compared for initiation of growth on cake surfaces: spot, air cabinet, spray (atomizer), and talc addition methods. Molds were isolated from commercial cakes and were identified as Aspergillus sydowii, Aspergillus ochraceus, Penicillium funiculosum, and Eurotium herbariorum. Cake surfaces were inoculated with mold spores and incubated under three equilibrium relative humidity (ERH) levels: 97, 85, and 75%. Random contamination by spores in a ventilated air cabinet was the simplest method of inoculation, but standard deviations in the inoculation rates (20% on a relative scale) were almost twice those observed with the other methods. The spot method was the most reproducible. Cake samples inoculated in the air cabinet had colony counts 10 times lower than those obtained for potato dextrose agar plates at 97% ERH, which was not the case with the spray and talc methods. Growth of molds was much slower in the samples incubated in 75% relative humidity, with all methods. Colony counts were generally similar in systems adjusted at 85 to 97% ERH but were lower for samples incubated at 75% ERH. In comparisons of the shelf life estimates obtained by the various inoculation methods, a correlation coefficient (r2) of 0.70 was obtained between the spot method and the other methods of inoculation, while talc, air cabinet, and spray shelf life data were correlated better (r2 ≈ 0.97). The spot method appeared to be the method of choice in consideration of ease of use, precision, and the ability to enable the study of the effects of the environment on mold-free shelf life as well as on the rate of growth of molds on cakes. PMID:16349479

  15. Fabrication of metallic microstructures by micromolding nanoparticles

    DOEpatents

    Morales, Alfredo M.; Winter, Michael R.; Domeier, Linda A.; Allan, Shawn M.; Skala, Dawn M.

    2002-01-01

    A method is provided for fabricating metallic microstructures, i.e., microcomponents of micron or submicron dimensions. A molding composition is prepared containing an optional binder and nanometer size (1 to 1000 nm in diameter) metallic particles. A mold, such as a lithographically patterned mold, preferably a LIGA or a negative photoresist mold, is filled with the molding composition and compressed. The resulting microstructures are then removed from the mold and the resulting metallic microstructures so provided are then sintered.

  16. Interferometric technique for microstructure metrology using an index matching liquid

    NASA Astrophysics Data System (ADS)

    Purcell, Daryl

    Non-null interferometry offers a viable alternative to traditional interferometric testing of aspheric micro-lenses since computer generated holograms or null optics whose fabrication and testing are very expensive, are not required. However, due to the violation of the Nyquist sampling theorem these non-null tests provide limited dynamic range. The dynamic range of these non-null tests can be extended by implementing an index liquid which allows the measurement of micro-lenses with several microns of departure from a sphere. The first objective of this dissertation was to test important micro-lens properties such as the sag, radius of curvature and form errors for a micro-lens by using an index liquid. The results compared favorably to measurements taken on a Twyman-Green interferometer, a contact profilometer and an optical non-contact profilometer. Also, retrace errors, which are aberrations caused by altered ray paths of the test beam through a micro-lens were investigated. Reverse ray-trace and reverse optimization techniques are typically used to calibrate retrace errors, but in depth knowledge of the interferometer optics is assumed, and hence cannot be used for systems containing commercial optics. In this dissertation, re-trace errors are quantified and a novel calibration procedure derived to experimentally compensate for these errors. This retrace error calibration led to agreement of within 1% for the sag values between the index liquid technique and a profilometer. The second objective of this dissertation was to enable measurements of arbitrary geometries and to reduce testing time compared to profilometry. The index liquid technique was applied to faceted microstructured optical products which are becoming more widespread due to advances in manufacturing. Many of these structures contain faceted surfaces with steep slopes. Adequate metrology for such surfaces is lacking. The use of the index liquid technique achieved high quality, high speed

  17. A novel 2D silicon nano-mold fabrication technique for linear nanochannels over a 4 inch diameter substrate.

    PubMed

    Yin, Zhifu; Qi, Liping; Zou, Helin; Sun, Lei

    2016-01-11

    A novel low-cost 2D silicon nano-mold fabrication technique was developed based on Cu inclined-deposition and Ar(+) (argon ion) etching. With this technique, sub-100 nm 2D (two dimensional) nano-channels can be etched economically over the whole area of a 4 inch n-type <100> silicon wafer. The fabricating process consists of only 4 steps, UV (Ultraviolet) lithography, inclined Cu deposition, Ar(+) sputter etching, and photoresist &Cu removing. During this nano-mold fabrication process, we investigated the influence of the deposition angle on the width of the nano-channels and the effect of Ar(+) etching time on their depth. Post-etching measurements showed the accuracy of the nanochannels over the whole area: the variation in width is 10%, in depth it is 11%. However, post-etching measurements also showed the accuracy of the nanochannels between chips: the variation in width is 2%, in depth it is 5%. With this newly developed technology, low-cost and large scale 2D nano-molds can be fabricated, which allows commercial manufacturing of nano-components over large areas.

  18. A novel 2D silicon nano-mold fabrication technique for linear nanochannels over a 4 inch diameter substrate

    PubMed Central

    Yin, Zhifu; Qi, Liping; Zou, Helin; Sun, Lei

    2016-01-01

    A novel low-cost 2D silicon nano-mold fabrication technique was developed based on Cu inclined-deposition and Ar+ (argon ion) etching. With this technique, sub-100 nm 2D (two dimensional) nano-channels can be etched economically over the whole area of a 4 inch n-type <100> silicon wafer. The fabricating process consists of only 4 steps, UV (Ultraviolet) lithography, inclined Cu deposition, Ar+ sputter etching, and photoresist & Cu removing. During this nano-mold fabrication process, we investigated the influence of the deposition angle on the width of the nano-channels and the effect of Ar+ etching time on their depth. Post-etching measurements showed the accuracy of the nanochannels over the whole area: the variation in width is 10%, in depth it is 11%. However, post-etching measurements also showed the accuracy of the nanochannels between chips: the variation in width is 2%, in depth it is 5%. With this newly developed technology, low-cost and large scale 2D nano-molds can be fabricated, which allows commercial manufacturing of nano-components over large areas. PMID:26752559

  19. COMPREHENSIVE STRUCTURAL STUDY OF PRE-AND POST-HEAT TREATED COMPRESSION MOLDED POLYURETHANE SAMPLES OF VARYING COMPOSITION STUDIES BY SCANNING PROBE TECHNIQUES

    SciTech Connect

    M. HAWLEY; E. ORLER; ET AL

    2001-03-01

    Only a limited number of structural studies have been performed on polyurethanes using scanning probe techniques to determine both the microstructure and the corresponding distribution of hard and soft segments within samples. This type of information is needed to better understand the mechanical properties of these materials and to facilitate modeling. In order to address these issues, we have fabricated a series of compression molded segmented poly(ester urethane) samples with hard (HS) to soft segment ratios from 19 to 100%. Samples were examined using scanning probe phase imaging techniques to obtain the topography and corresponding distribution of hard domains before and after heating at 100 C. A number of significant differences were observed between the pre- and post-heat treated samples. Variations in structure and heat-induced morphological changes were directly related to HS content. Fine strand- or fibril-like structures were most prominent in the 23 and 19% HS sample but first appeared at 30% HS. Harder, thicker elongated structures dominated the surface of the 100% HS sample and were seen to a limited extent on all samples, especially after annealing and quenching. The 23% HS sample surface structure depended on quenching rate and time after treatment.

  20. Three-dimensional microstructural characterization of bulk plutonium and uranium metals using focused ion beam technique

    DOE PAGES

    Chung, Brandon W.; Erler, Robert G.; Teslich, Nick E.

    2016-03-03

    Nuclear forensics requires accurate quantification of discriminating microstructural characteristics of the bulk nuclear material to identify its process history and provenance. Conventional metallographic preparation techniques for bulk plutonium (Pu) and uranium (U) metals are limited to providing information in two-dimension (2D) and do not allow for obtaining depth profile of the material. In this contribution, use of dual-beam focused ion-beam/scanning electron microscopy (FIB-SEM) to investigate the internal microstructure of bulk Pu and U metals is demonstrated. Our results demonstrate that the dual-beam methodology optimally elucidate microstructural features without preparation artifacts, and the three-dimensional (3D) characterization of inner microstructures can revealmore » salient microstructural features that cannot be observed from conventional metallographic techniques. As a result, examples are shown to demonstrate the benefit of FIB-SEM in improving microstructural characterization of microscopic inclusions, particularly with respect to nuclear forensics.« less

  1. Three-dimensional microstructural characterization of bulk plutonium and uranium metals using focused ion beam technique

    SciTech Connect

    Chung, Brandon W.; Erler, Robert G.; Teslich, Nick E.

    2016-03-03

    Nuclear forensics requires accurate quantification of discriminating microstructural characteristics of the bulk nuclear material to identify its process history and provenance. Conventional metallographic preparation techniques for bulk plutonium (Pu) and uranium (U) metals are limited to providing information in two-dimension (2D) and do not allow for obtaining depth profile of the material. In this contribution, use of dual-beam focused ion-beam/scanning electron microscopy (FIB-SEM) to investigate the internal microstructure of bulk Pu and U metals is demonstrated. Our results demonstrate that the dual-beam methodology optimally elucidate microstructural features without preparation artifacts, and the three-dimensional (3D) characterization of inner microstructures can reveal salient microstructural features that cannot be observed from conventional metallographic techniques. As a result, examples are shown to demonstrate the benefit of FIB-SEM in improving microstructural characterization of microscopic inclusions, particularly with respect to nuclear forensics.

  2. Three-dimensional microstructural characterization of bulk plutonium and uranium metals using focused ion beam technique

    NASA Astrophysics Data System (ADS)

    Chung, Brandon W.; Erler, Robert G.; Teslich, Nick E.

    2016-05-01

    Nuclear forensics requires accurate quantification of discriminating microstructural characteristics of the bulk nuclear material to identify its process history and provenance. Conventional metallographic preparation techniques for bulk plutonium (Pu) and uranium (U) metals are limited to providing information in two-dimension (2D) and do not allow for obtaining depth profile of the material. In this contribution, use of dual-beam focused ion-beam/scanning electron microscopy (FIB-SEM) to investigate the internal microstructure of bulk Pu and U metals is demonstrated. Our results demonstrate that the dual-beam methodology optimally elucidate microstructural features without preparation artifacts, and the three-dimensional (3D) characterization of inner microstructures can reveal salient microstructural features that cannot be observed from conventional metallographic techniques. Examples are shown to demonstrate the benefit of FIB-SEM in improving microstructural characterization of microscopic inclusions, particularly with respect to nuclear forensics.

  3. Development of improved asbestos reinforced phenolic insulating composites (optimization of physical properties as a function of molding technique and post cure conditions)

    NASA Technical Reports Server (NTRS)

    Hedges, L. M. (Editor)

    1973-01-01

    Detailed data are presented on phenolic-glass and phenolic-asbestos compounds which compare the effect of compression molding without degas to the effects of four variations of compression molding. These variations were designed to improve elimination of entrapped volatiles and the volatile products of the condensate reaction associated with the cure of phenolic resins. The utilization of conventional methods of degas plus degas by vacuum and directional heat flow methods are involved. Detailed data are also presented on these same compounds, comparing the effect of changes in post-bake time, and post-bake temperature for the five molding techniques.

  4. MOLDING APPARATUS

    DOEpatents

    Fleming, P.G.

    1963-10-01

    Molding apparatus capable of coating multiple elements each molding cycle is described. The apparatus comprises a centrally disposed reservoir penetrated by a plurality of circumferentially arranged and radially extending passageways. These passageways, in turn, communicate with passages in a separable annular member that retains selectively configured molds and mold seating arrangements. Each mold, which is readily removable from its respective seat, is adapted to retain an element therein in spaced relation to the interior of the mold by utilizing element positioning means within the mold seat and the mold so that coating material may flow about the entire outer surface of the element. (AEC)

  5. Characterization of Microstructure with Low Frequency Electromagnetic Techniques (Preprint)

    DTIC Science & Technology

    2014-02-01

    about grain ensembles in the microstructure. Large-area electron backscatter diffraction ( EBSD ) data was obtained and used in conjunction with a...computed eddy current approximations based on electron backscatter diffraction ( EBSD ) data, demonstrating good agreement. The detectability of notches in...about grain ensembles in the microstructure. Large-area electron backscatter diffraction ( EBSD ) data was obtained and used in conjunction with a

  6. Vacuum isostatic micro molding of diffractive structures into PTFE materials

    NASA Astrophysics Data System (ADS)

    Lizotte, Todd E.; Ohar, Orest

    2007-09-01

    Polytetrafluoroethylene (PTFE) is an ideal material for use in industrial, automotive and consumer electronics. Specifically, PTFE has outstanding physical properties; such as chemical inertness and resistance to chemical corrosion, even when exposed to a strong acid, alkali and oxidants. Its properties provide for superior electrical insulation and thermal stability, which is not affected by wide ranges in temperature and frequency. Its non-absorption of moisture makes it a perfect material for consideration in micro optical, retro-reflector or diffuser type devices used in handheld displays, flat panel displays as well as automotive, industrial and home lighting. This paper presents an overview of a unique fabrication method that incorporates a variety of elements to establish a processing technique that can form micro diffractive, holographic and reflective structures into PTFE materials. By means of modifying an existing known molding process, this new technique incorporates the addition of a vacuum to assist in the reliable molding and densification of the PTFE as well the use of a micro-structured electroformed shim to form small microstructures into the surface of the PTFE material. The combination of the vacuum and the electroformed shim within the molding process noticeably increases the precision, reproducibility and resolution of micro-structures that can be realized. The paper will describe the molding hardware involved, process parameters and the resulting structures formed. Optical function testing and metrology of the micro-structure geometry formed on each sample will be compared to the original design mandrel geometry [1].

  7. Fiber Length and Orientation in Long-Fiber Injection-Molded Thermoplastics. Part I: Modeling of Microstructure and Elastic Properties

    SciTech Connect

    Nguyen, Ba Nghiep; Bapanapalli, Satish K.; Holbery, James D.; Smith, Mark T.; Kunc, Vlastimil; Frame, Barbara J.; Phelps, Jay; Tucker III, Charles L.

    2008-05-01

    This paper investigates the effects of fiber length and orientation distributions on the elastic properties of long-fiber injection-molded thermoplastics (LFTs). The corrected experimental fiber length distribution and the predicted and experimental orientation distributions were used in modeling to compute the elastic properties of the composite. First, from the fiber length distribution (FLD) data in terms of number of fibers versus fiber length, the probability density functions were built and used in the computation. Also, it has been shown that the two-parameter Weibull’s distribution can be used to represent the actual FLD. Next, the Mori-Tanaka model that employs the Eshelby’s equivalent inclusion method was applied to calculate the stiffness matrix of the aligned fiber composite containing the established FLD. The stiffness of the actual as-formed composite was then determined from the stiffness of the computed aligned fiber composite that was averaged over all possible orientations using the orientation averaging method. The methodology to predict the elastic properties of LFTs was validated via experimental verification of the longitudinal and transverse moduli determined for long glass fiber injection-molded polypropylene specimens. Finally, a sensitivity analysis was conducted to determine the effect of a variation of FLD on the composite elastic properties.

  8. Pressure molding of powdered materials improved by rubber mold insert

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Pressure molding tungsten microspheres is accomplished by applying hydraulic pressure to a silicone rubber mold insert with several barrel shaped chambers which is placed in a steel die cavity. This technique eliminates castings containing shear fractures.

  9. Make it clear: molds, transparent casts and lightning techniques for stereomicroscopic analysis of taphonomic modifications on bone surfaces.

    PubMed

    Camarós, Edgard; Sánchez-Hernández, Carlos; Rivals, Florent

    2016-06-20

    This paper provides detailed description of a non-destructive, low-cost, and low-time consuming technique for producing high-resolution casts for the observation of taphonomic modifications on bone surfaces. The aim of the whole process is to obtain molds that accurately replicate the original bone surface at both the macro- and microscopic levels. The high quality transparent epoxy casts produced are analyzed by light microscopy and used to produce detailed microphotographs of bone surfaces. After describing each step of the process, we present some examples of its application in the case of anthropic activity, carnivores, or other post-depositional modifications.

  10. An Investigation of the Mold-Flux Performance for the Casting of Cr12MoV Steel Using a Mold Simulator Technique

    NASA Astrophysics Data System (ADS)

    Zhou, Lejun; Wang, Wanlin; Xu, Chao; Zhang, Chen

    2017-08-01

    Mold flux plays important roles in the process of continuous casting. In this article, the performance of mold flux for the casting of Cr12MoV steel was investigated by using a mold simulator. The results showed that the slag film formed in the gap between the initial shell and mold hot surface is thin and discontinuous during the casting process with the Flux BM, due to the absorption of chromic oxide inclusions into the liquid slag, while the slag film formed in the case of the optimized Flux NEW casting process is uniform. The main precipitated crystals in Flux BM slag film are cuspidine (Ca4Si2O7F2) and Cr3O4, but only Ca4Si2O7F2 precipitated in the Flux NEW case. Besides, both the responding temperature and heat flux in the case of Flux BM are relatively higher and fluctuate in a larger amplitude. The surface of the shell obtained in the case of the Flux BM experiment is quite uneven, and many severe depressions, cracks, and entrapped slags are observed in the surface due to the lack of lubrication. However, the obtained shell surface in the case of the Flux NEW shows good surface quality due to the addition of B2O3 and the adjustment of basicity, which can compensate for the negative effects of the mold-flux properties caused by the absorption of chromic oxide during the casting process.

  11. The Development of Layered Photonic Band Gap Structures Using a Micro-Transfer Molding Technique

    SciTech Connect

    Sutherland, Kevin Jerome

    2001-06-27

    Over the last ten years, photonic band gap (PBG) theory and technology have become an important area of research because of the numerous possible applications ranging from high-efficiency laser diodes to optical circuitry. This research concentrates on reducing the length scale in the fabrication of layered photonic band gap structures and developing procedures to improve processing consistency. Various procedures and materials have been used in the fabrication of layered PBG structures. This research focused on an economical micro transfer molding approach to create the final PBG structure. A poly dimethylsiloxane (PDMS) rubber mold was created from a silicon substrate. It was filled with epoxy and built layer-by-layer to create a 3-D epoxy structure. This structure was infiltrated with nanoparticle titania or a titania sol-gel, then fired to remove the polymer mold, leaving a monolithic ceramic inverse of the epoxy structure. The final result was a lattice of titania rolds that resembles a face-centered tetragonal structure. The original intent of this research was to miniaturize this process to a bar size small enough to create a photonic band gap for wavelengths of visible electro-magnetic radiation. The factor limiting progress was the absence of a silicon master mold of small enough dimensions. The Iowa State Microelectronics Research Center fabricated samples with periodicities of 2.5 and 1.0 microns with the existing technology, but a sample was needed on the order of 0.3 microns or less. A 0.4 micron sample was received from Sandia National Laboratory, which was made through an electron beam lithography process, but it contained several defects. The results of the work are primarily from the 2.5 and 1.0 micron samples. Most of the work focused on changing processing variables in order to optimize the infiltration procedure for the best results. Several critical parameters were identified, ranging from the ambient conditions to the specifics of the

  12. Single and Dual Drug Release Patterns from Shellac Wax-Lutrol Matrix Tablets Fabricated with Fusion and Molding Techniques

    PubMed Central

    Phaechamud, T.; Choncheewa, C.

    2015-01-01

    The objective of this investigation was to prepare the shellac wax matrix tablets by fusion and molding technique incorporated with Lutrol in different ratios to modify the hydrophobicity of matrix tablet. The matrix tablets with single drug were loaded either with propranolol hydrochloride or hydrochlorothiazide as hydrophilic and hydrophobic model drugs, and a dual drug formula was also prepared. The single and dual drug release patterns were studied in a dissolution apparatus using distilled water as medium. Propranolol hydrochloride released from matrix was easier than hydrochlorothiazide. Drug release from shellac wax matrix could be enhanced by incorporation of Lutrol. However retardation of drug release from some matrix tablets was evident for the systems that could form dispersion in the dissolution medium. The gel network from high content of Lutrol was hexagonal which was a dense and more compact structure than the other structures found when low amounts of Lutrol were present in the formula. Therefore, the formulae with high content of Lutrol could prolong drug release more efficiently than those containing low content of Lutrol. Hence shellac wax matrix could modulate the drug release with the addition of Lutrol. Sustainable dual drug release was also obtained from these developed matrix tablets. Thus shellac wax-Lutrol component could be used as a potential matrix tablet prepared with fusion and molding technique with excellent controlled drug release. PMID:25767320

  13. Characterization of Microstructure with Low Frequency Electromagnetic Techniques (Postprint)

    DTIC Science & Technology

    2013-08-01

    microstructure. Large-area electron backscatter diffraction ( EBSD ) data was obtained and used in conjunction with a synthetic aperture approach to...based on electron backscatter diffraction ( EBSD ) data, demonstrating good agreement. The detectability of notches in the presence of noise from

  14. Studying microstructure and microstructural changes in plant tissues by advanced diffusion magnetic resonance imaging techniques.

    PubMed

    Morozov, Darya; Tal, Iris; Pisanty, Odelia; Shani, Eilon; Cohen, Yoram

    2017-04-08

    As sessile organisms, plants must respond to the environment by adjusting their growth and development. Most of the plant body is formed post-embryonically by continuous activity of apical and lateral meristems. The development of lateral adventitious roots is a complex process, and therefore the development of methods that can visualize, non-invasively, the plant microstructure and organ initiation that occur during growth and development is of paramount importance. In this study, relaxation-based and advanced diffusion magnetic resonance imaging (MRI) methods including diffusion tensor (DTI), q-space diffusion imaging (QSI), and double-pulsed-field-gradient (d-PFG) MRI, at 14.1 T, were used to characterize the hypocotyl microstructure and the microstructural changes that occurred during the development of lateral adventitious roots in tomato. Better contrast was observed in relaxation-based MRI using higher in-plane resolution but this also resulted in a significant reduction in the signal-to-noise ratio of the T2-weighted MR images. Diffusion MRI revealed that water diffusion is highly anisotropic in the vascular cylinder. QSI and d-PGSE MRI showed that in the vascular cylinder some of the cells have sizes in the range of 6-10 μm. The MR images captured cell reorganization during adventitious root formation in the periphery of the primary vascular bundles, adjacent to the xylem pole that broke through the cortex and epidermis layers. This study demonstrates that MRI and diffusion MRI methods allow the non-invasive study of microstructural features of plants, and enable microstructural changes associated with adventitious root formation to be followed.

  15. Modified Activation Technique for Nasal Stent of Nasoalveolar Molding Appliance for Columellar Lengthening in Bilateral Cleft Lip/Palate.

    PubMed

    Patil, Pravinkumar G; Nimbalkar-Patil, Smita P

    2016-03-22

    Bilateral cleft lip/cleft palate is associated with nasal deformities typified by a short columella. The presurgical nasoalveolar molding (NAM) therapy approach includes reduction of the size of the intraoral alveolar cleft as well as positioning of the surrounding deformed soft tissues and cartilages. In a bilateral cleft patient, NAM, along with columellar elongation, eliminates the need for columellar lengthening surgery. Thus the frequent surgical intervention to achieve the desired esthetic results can be avoided. This article proposes a modified activation technique of the nasal stent for a NAM appliance for columellar lengthening in bilateral cleft lip/palate patients. The design highlights relining of the columellar portion of the nasal stent and the wire-bending of the nasal stent to achieve desirable results within the limited span of plasticity of the nasal cartilages. With this technique the vertical taping of the premaxilla to the oral plate can be avoided.

  16. Prototyping of radially oriented piezoelectric ceramic-polymer tube composites using fused deposition and lost mold processing techniques

    NASA Astrophysics Data System (ADS)

    McNulty, Thomas Francis

    Piezoelectric tube composite hydrophones of 3-1, 3-2, and 2-2 connectivity were developed using Fused Deposition (FD) and lost mold processing (LMP). In this work, a new series of thermoplastic binder formulations, named the ECG series, were developed for the FD process. The ECG-9 formulation exhibits mechanical, thermal, and rheological properties suitable for the Fused Deposition of functional lead zirconate titanate ceramic devices. This binder consists of 100 parts (by weight) Vestoplast 408, 20 parts Escorez 2520, 15 parts Vestowax A-227, and 5 parts Indopol H-1500. Oleic acid, oleyl alcohol, stearic acid, and stearyl alcohol (in toluene) were tested for use as a dispersant in the PZT/ECG-9 system. It was found that stearic acid adsorbs the most onto PZT powder, adsorbing 8.1 mg/m2. Using stearic acid, solutions of increasing concentration (5.0--50.0 g/l) were measured for adsorption. It was found that 30.0 g/l is the minimum concentration necessary for optimum surface coverage. The surfactant-coated powder was compounded with ECG-9 binder to create a 54 vol.% mix. The mix was extruded using a single screw extrusion apparatus into continuous lengths (>30 m) of 1.78 mm diameter filament. Fused Deposition was used to create composite designs of 3-1, 3-2, and 2-2 connectivity. After sintering, samples exhibit a sintered density greater than 97%. Sanders Prototyping (SPI) was used to manufacture molds for use with LMP techniques. Molds of 3-1, 3-2, and 2-2 connectivity were developed. The molds were infiltrated with a 55 vol.% aqueous based PZT slurry. The parts were subjected to a binder decomposition cycle, followed by sintering. Resultant samples were highly variable due to random macro-pores present in the samples after sintering. The resultant preforms were embedded in epoxy, and polished to dimensions of 8.0 mm inside diameter (ID), 14.0 mm outside diameter (OD), and 10.0 mm length (l) the OD and l dimensions are accurate to +/--2%, while the ID is accurate

  17. Presurgical Nasoalveolar Molding Therapy Using Figueroa's NAM Technique in Unilateral Cleft Lip and Palate Patients: A Preliminary Study.

    PubMed

    Koya, Shafees; Shetty, Sandeep; Husain, Akhter; Khader, Mustafa

    The objective of the study was to evaluate the results of nasoalveolar molding (NAM) in the treatment of patients with unilateral cleft lip and palate using a modified technique in a South Indian population. The design was a prospective study with blinded measurements. The sample constituted 10 complete unilateral cleft lip and palate (UCLP) patients who underwent NAM therapy by the same operator. Direct extra and intra oral anthropometric measurements were done using a digital vernier caliper before and after NAM therapy. A photographic evaluation was also done to rate the nasal deformity post NAM therapy. The differences between measurements were statistically analyzed using paired t tests. The extra oral measurements revealed a statistically significant increase in bi-alar width, columellar length and width. The intraoral measurements demonstrated a statistically significant reduction in anterior alveolar cleft width. There was also a significant increase in arch width and greater and lesser segments length. All cases were rated as improved by the surgeons in photographic analysis. The study has quantitatively shown that the modified NAM therapy improved nasal asymmetry by columellar lengthening and effectively molded the maxillary alveolar arch.

  18. Effects of Processing and Medical Sterilization Techniques on 3D-Printed and Molded Polylactic Acid

    NASA Astrophysics Data System (ADS)

    Geritano, Mariah Nicole

    Manufacturing industries have evolved tremendously in the past decade with the introduction of Additive Manufacturing (AM), also known as 3D Printing. The medical device industry has been a leader in adapting this new technology into research and development. 3D printing enables medical devices and implants to become more customizable, patient specific, and allows for low production numbers. This study compares the mechanical and thermal properties of traditionally manufactured parts versus parts manufactured through 3D printing before and after sterilization, and the ability of an FDM printer to produce reliable, identical samples. It was found that molded samples and 100% infill high-resolution samples have almost identical changes in properties when exposed to different sterilization methods, and similar cooling rates. The data shown throughout this investigation confirms that manipulation of printing parameters can result in an object with comparable material properties to that created through traditional manufacturing methods.

  19. Mold Allergy

    MedlinePlus

    ... homes and in other buildings. Everyone breathes in mold spores in the air, but some people have an ... your immune system is overly-sensitive to specific mold spores and treats them as an allergen . When you ...

  20. Rapid mold replication

    SciTech Connect

    Heestand, G.M.; Beeler, R.G. Jr.; Brown, D.L.

    1995-06-01

    The desire to reduce tooling costs have driven manufacturers to investigate new manufacturing methods and materials. In the plastics injection molding industry replicating molds to meet production needs is time consuming (up to 6 months) and costly in terms of lost business. We have recently completed a feasibility study demonstrating the capability of high rate Electron Beam Physical Vapor Deposition (EBPVD) in producing mold inserts in days, not months. In the current practice a graphite mandrel, in the shape of the insert`s negative image, was exposed to a jet of metal vapor atoms emanating from an electron beam heated source of an aluminum-bronze alloy. The condensation rate of the metal atoms on the mandrel was sufficient to allow the deposit to grow at over 30 {mu}m/min or 1.2 mils per minute. The vaporization process continued for approximately 14 hours after which the mandrel and deposit were removed from the EBPVD vacuum chamber. The mandrel and condensate were easily separated resulting in a fully dense aluminum-bronze mold insert about 2.5 cm or one inch thick. This mold was subsequently cleaned and drilled for water cooling passages and mounted on a fixture for operation in an actual injection molding machine. Results of the mold`s operation were extremely successful showing great promise for this technique. This paper describes the EBPVD feasibility demonstration in more detail and discusses future development work needed to bring this technique into practice.

  1. Phenolic Molding Compounds

    NASA Astrophysics Data System (ADS)

    Koizumi, Koji; Charles, Ted; de Keyser, Hendrik

    Phenolic Molding Compounds continue to exhibit well balanced properties such as heat resistance, chemical resistance, dimensional stability, and creep resistance. They are widely applied in electrical, appliance, small engine, commutator, and automotive applications. As the focus of the automotive industry is weight reduction for greater fuel efficiency, phenolic molding compounds become appealing alternatives to metals. Current market volumes and trends, formulation components and its impact on properties, and a review of common manufacturing methods are presented. Molding processes as well as unique advanced techniques such as high temperature molding, live sprue, and injection/compression technique provide additional benefits in improving the performance characterisitics of phenolic molding compounds. Of special interest are descriptions of some of the latest innovations in automotive components, such as the phenolic intake manifold and valve block for dual clutch transmissions. The chapter also characterizes the most recent developments in new materials, including long glass phenolic molding compounds and carbon fiber reinforced phenolic molding compounds exhibiting a 10-20-fold increase in Charpy impact strength when compared to short fiber filled materials. The role of fatigue testing and fatigue fracture behavior presents some insight into long-term reliability and durability of glass-filled phenolic molding compounds. A section on new technology outlines the important factors to consider in modeling phenolic parts by finite element analysis and flow simulation.

  2. A Combined Experimental and Computational Approach for the Design of Mold Topography that Leads to Desired Ingot Surface and Microstructure in Aluminum Casting.

    SciTech Connect

    Dr. Zabaras, N.; Tan, L.

    2005-07-12

    A thermomechanical study of the effects of mold topography on the solidification of Aluminum alloys at early times is provided. The various coupling mechanisms between the solid-shell and mold deformation and heat transfer at the mold/solid-shell interface during the early stages of Aluminum solidification on molds with uneven topographies are investigated. The air-gap nucleation time, the stress evolution and the solid-shell growth pattern are examined for different mold topographies to illustrate the potential control of Aluminum cast surface morphologies during the early stages of solidification using proper design of mold topographies. The unstable shell growth pattern in the early solidification stages results mainly from the unevenness of the heat flux between the solid-shell and the mold surface. This heat flux is determined by the size of the air-gaps formed between the solidifying shell and mold surface or from the value of the contact pressure. Simulation results show that a sinusoidal mold surface with a smaller wavelength leads to nucleation of air-gaps at earlier times. In addition, the unevenness in the solid-shell growth pattern decreases faster for a smaller wavelength. Such studies can be used to tune mold surfaces for the control of cast surface morphologies.

  3. Characterization of Indomethacin Release from Polyethylene Glycol Tablet Fabricated With Mold Technique

    PubMed Central

    Mesnukul, A.; Yodkhum, K.; Mahadlek, J.; Phaechamud, T.

    2010-01-01

    The purpose of this study was to use polyethylene glycol as a carrier to improve the solubility of an aqueous insoluble drug by melting and molding method. The release of dissolved drug was designed to be subsequently sustained with an addition of xanthan gum. The release of indomethacin from the developed system into phosphate buffer pH 6.2 was conducted using the dissolution apparatus. This carrier system could effectively enhance the solubility of indomethacin and an addition of xanthan gum could sustain the drug release. Eudragit L100 film coating could protect the carrier not to be disturbed with HCl buffer pH 1.2 and could dissolve in phosphate buffer pH 6.2, therefore, the drug release from coated tablet was initially very low but subsequently gradually released and prolonged in phosphate buffer pH 6.2. Differential scanning calorimetry study indicated the amorphous state of drug in polyethylene glycol carrier. Scanning electron microscopy photomicrograph indicated the drug diffusion outward through the porous network of matrix tablets into the dissolution fluid and curve fitting signified that the drug release kinetic was Fickian diffusion. PMID:20582196

  4. Supersoft lithography: candy-based fabrication of soft silicone microstructures.

    PubMed

    Moraes, Christopher; Labuz, Joseph M; Shao, Yue; Fu, Jianping; Takayama, Shuichi

    2015-01-01

    We designed a fabrication technique able to replicate microstructures in soft silicone materials (E < 1 kPa). Sugar-based 'hard candy' recipes from the confectionery industry were modified to be compatible with silicone processing conditions, and used as templates for replica molding. Microstructures fabricated in soft silicones can then be easily released by dissolving the template in water. We anticipate that this technique will be of particular importance in replicating physiologically soft, microstructured environments for cell culture, and demonstrate a first application in which intrinsically soft microstructures are used to measure forces generated by fibroblast-laden contractile tissues.

  5. Supersoft lithography: Candy-based fabrication of soft silicone microstructures

    PubMed Central

    Moraes, Christopher; Labuz, Joseph M.; Shao, Yue; Fu, Jianping; Takayama, Shuichi

    2015-01-01

    We designed a fabrication technique able to replicate microstructures in soft silicone materials (E < 1 kPa). Sugar-based ‘hard candy’ recipes from the confectionery industry were modified to be compatible with silicone processing conditions, and used as templates for replica molding. Microstructures fabricated in soft silicones can then be easily released by dissolving the template in water. We anticipate that this technique will be of particular importance in replicating physiologically soft, microstructured environments for cell culture, and demonstrate a first application in which intrinsically soft microstructures are used to measure forces generated by fibroblast-laden contractile tissues. PMID:26245893

  6. MCFET - A MICROSTRUCTURAL LATTICE MODEL FOR STRAIN ORIENTED PROBLEMS: A COMBINED MONTE CARLO FINITE ELEMENT TECHNIQUE

    NASA Technical Reports Server (NTRS)

    Gayda, J.

    1994-01-01

    A specialized, microstructural lattice model, termed MCFET for combined Monte Carlo Finite Element Technique, has been developed to simulate microstructural evolution in material systems where modulated phases occur and the directionality of the modulation is influenced by internal and external stresses. Since many of the physical properties of materials are determined by microstructure, it is important to be able to predict and control microstructural development. MCFET uses a microstructural lattice model that can incorporate all relevant driving forces and kinetic considerations. Unlike molecular dynamics, this approach was developed specifically to predict macroscopic behavior, not atomistic behavior. In this approach, the microstructure is discretized into a fine lattice. Each element in the lattice is labeled in accordance with its microstructural identity. Diffusion of material at elevated temperatures is simulated by allowing exchanges of neighboring elements if the exchange lowers the total energy of the system. A Monte Carlo approach is used to select the exchange site while the change in energy associated with stress fields is computed using a finite element technique. The MCFET analysis has been validated by comparing this approach with a closed-form, analytical method for stress-assisted, shape changes of a single particle in an infinite matrix. Sample MCFET analyses for multiparticle problems have also been run and, in general, the resulting microstructural changes associated with the application of an external stress are similar to that observed in Ni-Al-Cr alloys at elevated temperatures. This program is written in FORTRAN for use on a 370 series IBM mainframe. It has been implemented on an IBM 370 running VM/SP and an IBM 3084 running MVS. It requires the IMSL math library and 220K of RAM for execution. The standard distribution medium for this program is a 9-track 1600 BPI magnetic tape in EBCDIC format.

  7. MCFET - A MICROSTRUCTURAL LATTICE MODEL FOR STRAIN ORIENTED PROBLEMS: A COMBINED MONTE CARLO FINITE ELEMENT TECHNIQUE

    NASA Technical Reports Server (NTRS)

    Gayda, J.

    1994-01-01

    A specialized, microstructural lattice model, termed MCFET for combined Monte Carlo Finite Element Technique, has been developed to simulate microstructural evolution in material systems where modulated phases occur and the directionality of the modulation is influenced by internal and external stresses. Since many of the physical properties of materials are determined by microstructure, it is important to be able to predict and control microstructural development. MCFET uses a microstructural lattice model that can incorporate all relevant driving forces and kinetic considerations. Unlike molecular dynamics, this approach was developed specifically to predict macroscopic behavior, not atomistic behavior. In this approach, the microstructure is discretized into a fine lattice. Each element in the lattice is labeled in accordance with its microstructural identity. Diffusion of material at elevated temperatures is simulated by allowing exchanges of neighboring elements if the exchange lowers the total energy of the system. A Monte Carlo approach is used to select the exchange site while the change in energy associated with stress fields is computed using a finite element technique. The MCFET analysis has been validated by comparing this approach with a closed-form, analytical method for stress-assisted, shape changes of a single particle in an infinite matrix. Sample MCFET analyses for multiparticle problems have also been run and, in general, the resulting microstructural changes associated with the application of an external stress are similar to that observed in Ni-Al-Cr alloys at elevated temperatures. This program is written in FORTRAN for use on a 370 series IBM mainframe. It has been implemented on an IBM 370 running VM/SP and an IBM 3084 running MVS. It requires the IMSL math library and 220K of RAM for execution. The standard distribution medium for this program is a 9-track 1600 BPI magnetic tape in EBCDIC format.

  8. Injection molding of engineering plastics

    NASA Astrophysics Data System (ADS)

    Kalyon, Dilhan M.

    1991-03-01

    This final report summarizes the findings of a study in injection molding of engineering plastics. Two engineering plastic resins, i.e., unmodified grades of a polyetherimide and a poly (2,6-dimethyl-1,4-phenylene ether) were thoroughly characterized. The characterization included rheology, thermal properties and P-V-T behavior. The data were employed to predict various microstructural distributions including density, residual stress and birefringence distributions in compression and injection molded specimens of these two engineering plastics. The detailed microstructural distributions were also studied experimentally upon processing the two engineering plastics, employing instrumented machines and industrial practices. The experimental findings were elucidated under the light of the numerical simulation results. Overall, this study should furnish a first order understanding of the microstructure development in articles injection molded from amorphous engineering plastic resins.

  9. Morphology Evolution during Injection Molding: effect of packing pressure

    NASA Astrophysics Data System (ADS)

    Pantani, R.; Coccorullo, I.; Speranza, V.; Titomanlio, G.

    2007-04-01

    Injection molding is one of the most widely employed methods for manufacturing polymeric products. The final properties and the quality of an injection molded part are to a great extent affected by morphology. Thus, the prediction of microstructure formation is of technological importance, also for optimizing processing variables, in order to cut down on the expensive costs of tooling and the trial-and-error procedures. In this work, some injection molding tests were performed with the aim of studying the effects of packing pressure on morphology distribution. The resulting morphology of the moldings was in fact characterized by adopting different experimental techniques and, in order to underline the effects of holding pressure, it was compared with previous results gathered on samples obtained applying a lower holding pressure. Furthermore, the molding tests were simulated by means of a code developed at University of Salerno, which implements procedures able to model molecular orientation, crystallization kinetics and morphology evolution. The results obtained show that on increasing holding pressure the molecular orientation inside the samples increases, and simulations show that this is due mainly to the increase of relaxation time caused by the higher pressures. Furthermore, a sensible reduction of the percentage of α-phase is found on increasing the holding pressure, whereas the percentage of mesomorphic phase increases and a small fraction of γ-phase is found, which was not present in the samples molded at lower holding pressures.

  10. Precision glass molding of high-resolution diffractive optical elements

    NASA Astrophysics Data System (ADS)

    Prater, Karin; Dukwen, Julia; Scharf, Toralf; Herzig, Hans P.; Plöger, Sven; Hermerschmidt, Andreas

    2016-04-01

    The demand of high resolution diffractive optical elements (DOE) is growing. Smaller critical dimensions allow higher deflection angles and can fulfill more demanding requirements, which can only be met by using electron-beam lithography. Replication techniques are more economical, since the high cost of the master can be distributed among a larger number of replicas. The lack of a suitable mold material for precision glass molding has so far prevented an industrial use. Glassy Carbon (GC) offers a high mechanical strength and high thermal strength. No anti-adhesion coatings are required in molding processes. This is clearly an advantage for high resolution, high aspect ratio microstructures, where a coating with a thickness between 10 nm and 200 nm would cause a noticeable rounding of the features. Electron-beam lithography was used to fabricate GC molds with highest precision and feature sizes from 250 nm to 2 μm. The master stamps were used for precision glass molding of a low Tg glass L-BAL42 from OHARA. The profile of the replicated glass is compared to the mold with the help of SEM images. This allows discussion of the max. aspect-ratio and min. feature size. To characterize optical performances, beamsplitting elements are fabricated and their characteristics were investigated, which are in excellent agreement to theory.

  11. An investigation into techniques for cleaning mold-contaminated home contents.

    PubMed

    Wilson, S C; Brasel, T L; Carriker, C G; Fortenberry, G D; Fogle, M R; Martin, J M; Wu, C; Andriychuk, L A; Karunasena, E; Straus, D C

    2004-07-01

    This study examined the efficacy of the following treatments to reduce selected fungal spore and mycotoxin levels on materials commonly found in home contents: (1) gamma irradiation at a 10-13 kiloGray exposure, (2) a detergent/bleach wash, and (3) a steam cleaning technique. A minimum of six replicates were performed per treatment. Paper, cloth, wood, and carpet were inoculated with either fungal spores (Stachybotrys chartarum, Aspergillus niger, Penicillium chrysogenum, or Chaetomium globosum) at 240,000 spores/2.54 cm2 of material or with the mycotoxins roridin A, T-2, and verrucarin A at 10 microg per 2.54 cm2 of material. Treatments were evaluated with an agar plating technique for fungal spores and a yeast toxicity culture assay for mycotoxins. Results showed that gamma irradiation inactivated fungal spores, but the treatment was not successful in inactivating mycotoxins. The washing technique completely inactivated or removed spores on all materials except for C. globosum, which was reduced on all items except paper (p < 0.05). Washing inactivated all mycotoxins on paper and cloth but not on carpet or untreated wood (p < 0.001). The steam cleaning treatment did not completely eliminate any fungal spores; however, it reduced P. chrysogenum numbers on all materials, C. globosum was reduced on wood and carpet, and S. chartarum was reduced on wood (p < 0.05). Steam cleaning was unsuccessful in inactivating any of the tested mycotoxins. These results show that the bleach/detergent washing technique was more effective overall in reducing spore and mycotoxin levels than gamma irradiation or steam cleaning. However, the other examined techniques were successful in varying degrees. Copyright 2004 JOEH, LLC

  12. Evaluation of the safety and efficiency of novel metallic implant scaler tips manufactured by the powder injection molding technique.

    PubMed

    Chun, Kyung A; Kum, Kee-Yeon; Lee, Woo-Cheol; Baek, Seung-Ho; Choi, Hae-Won; Shon, Won-Jun

    2017-07-11

    Although many studies have compared the properties of ultrasonic scaling instruments, it remains controversial as to which is most suitable for implant scaling. This study evaluated the safety and efficiency of novel metallic ultrasonic scaler tips made by the powder injection molding (PIM) technique on titanium surfaces. Mechanical instrumentation was carried out using four types of metal scaler tips consisting of copper (CU), bronze (BR), 316 L stainless steel (316 L), and conventional stainless steel (SS) tips. The instrumented surface alteration image of samples was viewed with scanning electron microscope (SEM) and surface profile of the each sample was investigated with confocal laser scanning microscopy (CLSM). Arithmetic mean roughness (Ra) and maximum height roughness (Rmax) of titanium samples were measured and dissipated power of the scaler tip was estimated for scaling efficiency. The average Ra values caused by the 316 L and SS tip were about two times higher than those of the CU and BR tips (p < 0.05). The Rmax value showed similar results. The efficiency of the SS tip was about 3 times higher than that of CU tip, the 316 L tip is about 2.7 times higher than that of CU tip, and the BR tip is about 1.2 times higher than that of CU tip. Novel metallic bronze alloy ultrasonic scaler tip minimally damages titanium surfaces, similar to copper alloy tip. Therefore, this bronze alloy scaler tip may be promising instrument for implant maintenance therapy.

  13. Strong, easy-to-mold, spiral buttress thread

    NASA Technical Reports Server (NTRS)

    Heier, W. C.

    1971-01-01

    Buttress thread with steep taper connects two molded plastic cylinders without changing wall thickness or sacrificing longitudinal strength at the juncture. Technique lends itself to conventional molding methods.

  14. Technologies and microstructures for separation techniques in chemical analysis

    NASA Astrophysics Data System (ADS)

    Spiering, Vincent L.; Lammerink, Theo S. J.; Jansen, Henri V.; Fluitman, Jan H.; van den Berg, Albert

    1996-09-01

    The possibilities for microtechnology in chemical analysis and separation techniques are discussed. The combination of the materials and the dimensions of structures can limit the sample and waste volumes on the one hand, but also increases the performance of the chemical systems. Especially in high performance chromatography separation systems, where the separation quality is directly depending on the length to width ratio of the fluid channels, there is a large potential for applications. Novel technologies as well as demonstrator devices for different applications will be presented in this paper. Finally, a modular concept for microfluidic systems, in which these micromachined structures can be incorporated, is described and illustrated with a demonstrator.

  15. MOLD POLLUTION

    EPA Science Inventory

    Mold pollution is the growth of molds in a building resulting in a negative impact on the use of that structure. The negative impacts generally fall into two categories: destruction of the structure itself and adverse health impacts on the building's occupants. It is estimated...

  16. Mold Charlatans.

    ERIC Educational Resources Information Center

    Woody, Daniel

    2002-01-01

    Offers a primer on toxic mold and its removal, warning against ignorant or unethical mold remediation companies and offering five considerations (checking references, considering the big picture, sampling more than the air, considering release, and considering the source) when hiring such services. (EV)

  17. Mold Charlatans.

    ERIC Educational Resources Information Center

    Woody, Daniel

    2002-01-01

    Offers a primer on toxic mold and its removal, warning against ignorant or unethical mold remediation companies and offering five considerations (checking references, considering the big picture, sampling more than the air, considering release, and considering the source) when hiring such services. (EV)

  18. MOLD POLLUTION

    EPA Science Inventory

    Mold pollution is the growth of molds in a building resulting in a negative impact on the use of that structure. The negative impacts generally fall into two categories: destruction of the structure itself and adverse health impacts on the building's occupants. It is estimated...

  19. Improvement of metal-semiconductor contact on silicon microstructured surface by electroless nickel technique

    NASA Astrophysics Data System (ADS)

    Long, Fei; Guo, Anran; Huang, Lieyun; Yu, Feng; Li, Wei

    2016-11-01

    Si micro-structures served as anti-reflection layer are widely employed in Si-based solar cells and detectors to enhance light harvesting. However, performance of these devices is suffered from the poor contact between the metal electrode and micro-structured surface. Conventional vacuum deposited metal electrode makes only superficial contact with the top of micro-structured surface and unable to fill the holes in the micro-structures. In this paper, instead, electroless nickel technique is applied to form low resistance ohmic contact. The surface micro-structures were fabricated by electrochemistry etching while the metal electrodes were deposited by sputtering and electroless pasting. Results show that only electroless nickel layer could fully fill the holes and achieve better ohmic contact than the sputtering ones before rapid annealing. Furthermore, a higher temperature rapid annealing process could improve the contact of all samples prepared by different ways. The specific contact resistance achieved by high alkalinity (pH=12) electroless nickel is 1.34×10-1Ω·cm2.

  20. Use of acrylic sheet molds for elastomeric products

    NASA Technical Reports Server (NTRS)

    Heisman, R. M.; Koerner, A. E.; Messineo, S. M.

    1970-01-01

    Molds constructed of acrylic sheet are more easily machined than metal, are transparent to ensure complete filling during injection, and have smooth surfaces free of contamination. Technique eliminates flashing on molded parts and mold release agents.

  1. Curved hierarchically micro-micro structured polypropylene surfaces by injection molding

    NASA Astrophysics Data System (ADS)

    Mielonen, K.; Suvanto, M.; Pakkanen, T. A.

    2017-01-01

    Structural hierarchy of polymer surfaces has been of central interest due to its diverse surface functionalities. However, the research on hierarchically structured polymer surfaces has been focused on planar surfaces even though applications may also be variously curved. This study demonstrates the fabrication of curved rigid polymer surfaces with precisely controlled hierarchical microstructures. The surface structuration was made on an aluminum foil with a microworking robot, and polypropylene replicas were produced by injection molding. Depending on the mold structuration procedure, the curved mold can have either radially or vertically oriented structures. Both convex and concave curvatures were here applied to spherically and cylindrically curved surfaces. A simple structure protection technique was applied to support the structures during mechanical bending of the foil. The planar hierarchically microstructured polypropylene surfaces were characterized to exhibit superhydrophobicity, and similar structures were obtained on the curved surfaces. Introducing the curvature to the hierarchically structured surfaces may further widen the applicability of functionalized polymer surfaces.

  2. Microstructure refinement of commercial 7xxx aluminium alloys solidified by the electromagnetic vibration technique

    NASA Astrophysics Data System (ADS)

    Li, M.; Tamura, T.; Omura, N.; Murakami, Y.; Tada, S.

    2016-03-01

    This paper examines the microstructure refinement of commercial 7xxx aluminium alloys solidified by the electromagnetic vibration technique (EMV) as a function of vibration frequency, f. The microstructure evolution reveals that at the low frequency of f = 62.5 Hz, the solidified microstructure is coarse and with the increase of vibration frequency to f = 500 Hz, the grain size becomes the finest and further increase of frequency to f = 2000 Hz results in coarsening of microstructures. The refinement mechanism is clarified when considering the significant difference in electrical resistivities of the solid and the liquid in mushy zone, in which both phases coexist and subject to vibration. The frequency-dependent refinement behaviour is revealed when the displacement of the mobile solid and sluggish liquid is taken into account during solidification. In contrast to 3xxx aluminium alloys, no giant compounds have been discerned in the present 7xxx alloy regardless of the solidification condition. The formation of crystalline twin is briefly discussed when considering the vibration condition.

  3. Micro-structural characterization of materials using synchrotron hard X-ray imaging techniques

    SciTech Connect

    Agrawal, Ashish Singh, Balwant; Kashyap, Yogesh; Sarkar, P. S.; Shukla, Mayank; Sinha, Amar

    2015-06-24

    X-ray imaging has been an important tool to study the materials microstructure with the laboratory based sources however the advent of third generation synchrotron sources has introduced new concepts in X-ray imaging such as phase contrast imaging, micro-tomography, fluorescence imaging and diffraction enhance imaging. These techniques are being used to provide information of materials about their density distribution, porosity, geometrical and morphological characteristics at sub-micron scalewith improved contrast. This paper discusses the development of various imaging techniques at synchrotron based imaging beamline Indus-2 and few recent experiments carried out at this facility.

  4. Surface Replication of Molded Products with Microneedle Features in Injection Molding

    NASA Astrophysics Data System (ADS)

    Uchiumi, Kazuyasu; Takayama, Tetsuo; Ito, Hiroshi; Inou, Akinori

    Micro-molding of microneedle features was conducted using several injection-molding techniques. Injection compression molding and injection molding were performed with supercritical carbon dioxide fluid and with or without vacuum processing inside the mold cavity. Effects of process parameters on processability and surface replication of the molded parts were evaluated. The height replication ratio for microneedles was improved using injection compression molding. At a shorter compression stroke, the needle height was improved, and the influence of compression delay time was also small. Moreover, the effects of vacuum processing inside the mold cavity under the filling process were slight. The height replication ratio for microneedles showed the highest values using injection molding using supercritical carbon dioxide fluid with vacuum inside the mold cavity.

  5. Micro-Structures of Hard Coatings Deposited on Titanium Alloys by Laser Alloying Technique

    NASA Astrophysics Data System (ADS)

    Li, Wei; Yu, Huijun; Chen, Chuanzhong; Wang, Diangang; Weng, Fei

    2013-01-01

    This work is based on micro-structural performance of the Ti-B4C-C laser alloying coatings on Ti-6Al-4V titanium alloy. The test results indicated that laser alloying of the Ti-B4C-C pre-placed powders on the Ti-6Al-4V alloy substrate can form the ceramics reinforced hard alloying coatings, which increased the micro-hardness and wear resistance of substrate. The test result also indicated that the TiB phase was produced in alloying coating, which corresponded to its (101) crystal plane. In addition, yttria has a refining effect on micro-structures of the laser alloying coating, and its refinement mechanism was analyzed. This research provided essential experimental and theoretical basis to promote the applications of the laser alloying technique in manufacturing and repairing of the aerospace parts.

  6. Mold and Health

    EPA Pesticide Factsheets

    Molds have the potential to cause health problems. Molds produce allergens (substances that can cause allergic reactions) and irritants. Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals.

  7. Mold Testing or Sampling

    EPA Pesticide Factsheets

    In most cases, if visible mold growth is present, sampling is unnecessary. Since no EPA or other federal limits have been set for mold or mold spores, sampling cannot be used to check a building's compliance with federal mold standards.

  8. Transfer of microstructure pattern of CNTs onto flexible substrate using hot press technique for sensing applications

    SciTech Connect

    Mishra, Prabhash; Harsh

    2013-08-01

    Graphical abstract: - Highlights: • Successfully transfer of microstructure patterned CNTs on PET substrate. • Demonstrate as resistor-based NH{sub 3} gas sensor in the sub-ppm range. • Excellent photodetector having instantaneous response and recovery characteristics. • An effective technique to grow and produce flexible electronic device. - Abstract: In this work, we report the successful and efficient transfer process of two- dimensional (2-D) vertically aligned carbon nanotubes (CNTs) onto polyethylene terephthalate (PET) substrate by hot pressing method with an aim to develop flexible sensor devices. Carbon nanotubes are synthesized by cold wall thermal chemical vapor deposition using patterned SiO{sub 2} substrate under low pressure. The height of the pattern of CNTs is controlled by reaction time. The entire growth and transfer process is carried out within 30 min. Strong adhesion between the nanotube and polyethylene terephthalate substrate was observed in the post-transferred case. Raman spectroscopy and scanning electron microscope (SEM) studies are used to analyze the microstructure of carbon nanotube film before and after hot pressing. This technique shows great potential for the fabrication of flexible sensing devices. We report for the first time, the application of patterned microstructure developed by this technique in the development of gas sensor and optoelectronic device. Surface resistive mode is used for detection of ammonia (NH{sub 3}) gas in the sub-ppm range. An impressive photoconducting response is also observed in the visible wavelength. The reproducibility of the sample was checked and the results indicate the possibility of use of carbon nanotube as gas sensor, photodetector, CCDs etc.

  9. Correlating Observations of Deformation Microstructures by TEM and Automated EBSD Techniques

    SciTech Connect

    Schwartz, A.J.; King, W.E.

    2000-06-05

    The evolution of the deformed microstructure as a function of imposed plastic strain is of interest as it provides information on the material hardening characteristics and mechanism(s) by which cold work energy is stored. This has been extensively studied using transmission electron microscopy (TEM), where the high spatial and orientational resolution of the technique is used to advantage to study local phenomenon such as dislocation core structures and interactions of dislocations. With the recent emergence of scanning electron microscope (SEM) based automated electron backscatter diffraction (EBSD) techniques, it has now become possible to make mesoscale observations that are statistical in nature and complement the detailed TEM observations. Correlations of such observations will be demonstrated for the case of Ni-base alloys, which are typically non-cell forming solid solution alloys when deformed at ambient temperatures. For instance, planar slip is dominant at low strain levels but evolves into a microstructure where distinct crystallographic dislocation-rich walls form as a function of strain and grain orientation. Observations recorded using both TEM and EBSD techniques are presented and analyzed for their implication on subsequent annealing characteristics.

  10. Electrohydrodynamic direct-writing lithography: An alternative maskless technique for microstructure fabrication

    NASA Astrophysics Data System (ADS)

    He, Jiankang; Xu, Fangyuan; Cao, Yi; Liu, Yaxiong; Li, Dichen; Jin, Zhongmin

    2014-12-01

    A maskless electrohydrodynamic direct-writing lithographic strategy was presented to flexibly fabricate user-specific micropatterns on silicon substrates. By optimizing the operating parameters, parallel lines as well as lattices with line width of about 2 μm could be stably deposited. The printed micropatterns were found to function as sacrificial template to transfer microstructures into silicon substrates and the etching processes had little effect on the predefined size. It is envisioned that this simple approach provides an alternative to the existing microfabrication techniques, which might enable the wide accessibility of microscale technologies to advance various research fields such as microfluidics, biomedical chips, and microscale tissue engineering.

  11. X-ray microscopy: An emerging technique for semiconductor microstructure characterization

    SciTech Connect

    Padmore, H.A.

    1998-05-01

    The advent of third generation synchrotron radiation x-ray sources, such as the Advanced Light Source (ALS) at Berkeley have enabled the practical realization of a wide range of new techniques in which mature chemical or structural probes such as x-ray photoelectron spectroscopy (XPS) and x-ray diffraction are used in conjunction with microfocused x-ray beams. In this paper the characteristics of some of these new microscopes are described, particularly in reference to their applicability to the characterization of semiconductor microstructures.

  12. INGOT MOLD

    DOEpatents

    Mangold, A.J. Jr.; MaHaffey, J.W.; Reese, S.L.

    1958-04-29

    An improved ingot-mold assembly is described, consisting of a body having a cavity and a recess extending through to the bottom of the body from the cavity, and the bottom of the cavity having an internal shoulder extending downward and a plug having an external shoulder. The plug extends above the shoulders and below the bottom of the body.

  13. 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

  14. A multi-stage curing technique toward improved dimensional infidelity of curve-shaped composites manufactured with vacuum assisted resin transfer molding

    NASA Astrophysics Data System (ADS)

    Teoh, Kai Jin

    The occurrence of dimensional infidelity during the curing process is detected as curved composites are being released from the mold after full consolidation. On the other hand, the lengthy cure cycle, thermal spiking and non-uniform consolidation in thick composite manufacturing are often strong deterrents to widespread industrial implementation. Therefore, a multi-stage curing technique is implemented and its outcome toward the spring-in phenomenon is investigated in this research. The composite processing technique of stage curing is useful for assessing the effects of thermal spiking, non-uniform consolidation and fiber wrinkling on mechanical integrity for thick composite structures. However, the prediction of spring-in behavior for a multi-stage curing process is still a relatively unexplored area in engineering research. As a result, a compatibility model based on the residual stress that builds up at each curing stage is performed in our study. Since the resin provides a lubricant effect between each curing stage, a partial slipping interface factor w is introduced to our numerical simulation model. The newly developed multi-stage curing model shows good agreement with the experimental results under Vacuum Assisted Resin Transfer Molding (VARTM) process.

  15. Curbing indoor mold growth with mold inhibitors

    Treesearch

    Carol A. Clausen; Vina W. Yang

    2004-01-01

    Environmentally acceptable mold inhibitors are needed to curb the growth of mold fungi in woodframe housing when moisture management measures fail. Excess indoor moisture can lead to rapid mold establishment which, in turn, can have deleterious affects on indoor air quality. Compounds with known mold inhibitory properties and low mammalian toxicity, such as food...

  16. Microstructures and Mechanical Properties of Co-Cr Dental Alloys Fabricated by Three CAD/CAM-Based Processing Techniques

    PubMed Central

    Kim, Hae Ri; Jang, Seong-Ho; Kim, Young Kyung; Son, Jun Sik; Min, Bong Ki; Kim, Kyo-Han; Kwon, Tae-Yub

    2016-01-01

    The microstructures and mechanical properties of cobalt-chromium (Co-Cr) alloys produced by three CAD/CAM-based processing techniques were investigated in comparison with those produced by the traditional casting technique. Four groups of disc- (microstructures) or dumbbell- (mechanical properties) specimens made of Co-Cr alloys were prepared using casting (CS), milling (ML), selective laser melting (SLM), and milling/post-sintering (ML/PS). For each technique, the corresponding commercial alloy material was used. The microstructures of the specimens were evaluated via X-ray diffractometry, optical and scanning electron microscopy with energy-dispersive X-ray spectroscopy, and electron backscattered diffraction pattern analysis. The mechanical properties were evaluated using a tensile test according to ISO 22674 (n = 6). The microstructure of the alloys was strongly influenced by the manufacturing processes. Overall, the SLM group showed superior mechanical properties, the ML/PS group being nearly comparable. The mechanical properties of the ML group were inferior to those of the CS group. The microstructures and mechanical properties of Co-Cr alloys were greatly dependent on the manufacturing technique as well as the chemical composition. The SLM and ML/PS techniques may be considered promising alternatives to the Co-Cr alloy casting process. PMID:28773718

  17. Injection molding ceramics to high green densities

    NASA Technical Reports Server (NTRS)

    Mangels, J. A.; Williams, R. M.

    1983-01-01

    The injection molding behavior of a concentrated suspension of Si powder in wax was studied. It was found that the injection molding behavior was a function of the processing techniques used to generate the powder. Dry ball-milled powders had the best molding behavior, while air classified and impact-milled powders demonstrated poorer injection moldability. The relative viscosity of these molding batches was studied as a function of powder properties: distribution shape, surface area, packing density, and particle morphology. The experimental behavior, in all cases, followed existing theories. The relative viscosity of an injection molding composition composed of dry ball-milled powders could be expressed using Farris' relation.

  18. An imaging technique using rotational polarization microscopy for the microstructure analysis of carbon/carbon composites.

    PubMed

    Miaoling, Li; Lehua, Qi; Hejun, Li

    2012-01-01

    A novel image analysis technique was proposed for microstructure investigation of carbon/carbon (C/C) composites. The rotational polarization microscopy was developed to meet the special imaging requirements. The samples of C/C composites were observed in reflection polarized light microscope, where the analyzer was rotated instead of the stage, and the polarizer was taken out. The bireflectance of like-graphite negative uniaxial crystal was analyzed. It was the theoretic foundation of image collection and data processing. The analyzer was rotated through 36 × 10° intervals without any movement of the specimen. The polished cross-section of C/C composites took micrographs at each analyzer orientation. All image data collected from the same field of view were processed by image registration and image fusion. The synthesized images were obtained by calculating the maximum and minimum gray values and their differences at each point of the million pixels at 18 orientations of the analyzer. They are unique and quite reliable to be applied to analyze the microstructure of C/C composites. Subsequently, image segmentation was performed, and the feature parameters of each component were calculated. Good agreement was found between the results from image analysis and experimental data.

  19. Improvement of three-dimensional microstructure contour accuracy using maskless lithography technique based on DMD

    NASA Astrophysics Data System (ADS)

    Huang, Shengzhou; Li, Mujun; Shen, Lianguan; Qiu, Jinfeng; Zhou, Youquan

    2016-10-01

    A novel method is proposed to improve contour accuracy of three-dimensional (3D) microstructure in real-time maskless lithography technique based on a digital micro-mirror device (DMD). In this paper, firstly according to the study of theory and experiment on exposure doses and exposure thickness relation, the spatial distribution of the photo-resist exposure doses was derived, which could predict the resulting 3D contour. Secondly, an equal-arc slicing strategy was adopted, in which arc lengths between adjacent slicing point are kept constant while layer heights become variant. And an equal-arc-mean slicing strategy that takes the average of adjacent layers height was also proposed to further optimize the quality of contour and reduce the contour error on the basis of the equal-arc slicing. Finally, to estimate the validity of the method and as a study case, aspheric micro-lens array were fabricated with proposed method in experiments. Our results showed that the proposed method is feasible for improving and enhancing the 3D microstructure contour accuracy and smoothness.

  20. [Titanium joints welded with laser and infrared techniques: comparative analysis of its microstructure].

    PubMed

    Manicone, P; Valentini, G; Raffaelli, L; Raffaelli, R

    2000-10-01

    Aim of the study is to compare microstructure of Titanium joints soldered with Laser and Infrared methods by performing SEM analysis, metallography and microhardness evaluation. Wax specimens were separated in the middle area corresponding to the joint region, machined and then soldered. 40 Titanium samples were fused and divided in 2 groups of 20 samples each. First group was soldered by laser welding, second one by infrared brazing. SEM analysis and standard metallography were carried out at joined areas and unsoldered surfaces. Microhardness test was performed on longitudinally sectioned samples with 150 g load for 15 second up to 7 mm distance from the joined area. SEM photomicrographs revealed for group 1 a homogeneous metal-joint interface, without microporosities; for group 2 exhibited a distinct demarcation of metal joint interface. Metallography evaluation showed for laser joined samples only the presence of Titanium; infrared joined samples showed in soldered regions also Ni and Cu. Microhardness values detected at the joined surfaces seem to be higher for both considered groups. Laser joining method with exclusive presence of Titanium seems to be ideal for monometallism; both techniques exhibited microstructural changes in the heated surface layer.

  1. Study of microstructure and electrical properties of bulk YBCO prepared by melt textured growth technique

    SciTech Connect

    Gonal, M. R.; Krishnan, Madangopal; Tewari, R.; Tyagi, A. K.; Gyore, A.; Vajda, I.

    2015-06-24

    Bulk YBCO components were prepared using Melt Texture Growth (MTG) technique. Components were fabricated using MTG by addition of Y{sub 2}BaCuO{sub 5} (Y211) and Ag to YBCO, which leads to improved grain size without affecting superconducting properties. Green compacts prepared by cold isostatic pressing were pre-sintered at 930°C before subjecting melt texturing. Cooling rates lower than 1 °C.h{sup −1} was used, in between (peritectic) temperature of about 995 and 1025°C, to obtain large grained components. Microstructure studies in details were carried out by Scanning Electron Microscope (SEM), Electron Probe Micro Analysis (EPMA), Orientation Imaging Microscope (OIM) and TEM correlated with electrical properties like Critical current density (J{sub c})

  2. Microstructural Examination to Aid in Understanding Friction Bonding Fabrication Technique for Monolithic Nuclear Fuel

    SciTech Connect

    Karen L. Shropshire

    2008-04-01

    Monolithic nuclear fuel is currently being developed for use in research reactors, and friction bonding (FB) is a technique being developed to help in this fuel’s fabrication. Since both FB and monolithic fuel are new concepts, research is needed to understand the impact of varying FB fabrication parameters on fuel plate characteristics. This thesis research provides insight into the FB process and its application to the monolithic fuel design by recognizing and understanding the microstructural effects of varying fabrication parameters (a) FB tool load, and (b) FB tool face alloy. These two fabrication parameters help drive material temperature during fabrication, and thus the material properties, bond strength, and possible formation of interface reaction layers. This study analyzed temperatures and tool loads measured during those FB processes and examined microstructural characteristics of materials and bonds in samples taken from the resulting fuel plates. This study shows that higher tool load increases aluminum plasticization and forging during FB, and that the tool face alloy helps determine the tool’s heat extraction efficacy. The study concludes that successful aluminum bonds can be attained in fuel plates using a wide range of FB tool loads. The range of tool loads yielding successful uranium-aluminum bonding was not established, but it was demonstrated that such bonding can be attained with FB tool load of 48,900 N (11,000 lbf) when using a FB tool faced with a tungsten alloy. This tool successfully performed FB, and with better results than tools faced with other materials. Results of this study correlate well with results reported for similar aluminum bonding techniques. This study’s results also provide support and validation for other nuclear fuel development studies and conclusions. Recommendations are offered for further research.

  3. Mold: Cleanup and Remediation

    MedlinePlus

    ... Program in Brief Related Issues Resources Quick Links Air Pollution & Respiratory Health Air Quality Asthma Mold What's New ... and mold problems in schools ... more Quick Links Air Pollution & Respiratory Health Air Quality Asthma Mold What's New ...

  4. Allergies, asthma, and molds

    MedlinePlus

    ... carpets, stuffed animals, books, and wallpaper can contain mold spores if they are in damp places. Outdoors, mold ... at less than 30% to 50% will keep mold spores down. Empty dehumidifiers daily and clean them often ...

  5. Comparison of different sample preparation techniques in TEM observation of microstructure of INCONEL alloy 783 subjected to prolonged isothermal exposure.

    PubMed

    Ma, Longzhou

    2004-01-01

    INCONEL alloy 783 was annealed and aged following the standard heat treatment procedure. One set of specimens was then isothermally exposed at 500 degrees C for 3000 h. Mechanical properties were measured at room temperature and 650 degrees C, and the results showed the prolonged exposure increased the strength and decreased elongation of alloy 783. The microstructures of as-produced and exposed material were examined using optical microscope, SEM and TEM, respectively. Three techniques, jet electro-polishing, ion milling, and focused ion beam, were employed to prepare the TEM samples to observe the variation of microstructure of alloy 783 due to isothermal exposure. TEM images of samples prepared by different methods were analyzed and compared. The results indicate that the jet electro-polishing technique allows the detail microstructure of alloy 783 subjected to different treatments to be well revealed, and thereby the TEM images can be used to explain the enhancement of strength of alloy 783 caused by isothermal exposure.

  6. Thermochemical micro imprinting of single-crystal diamond surface using a nickel mold under high-pressure conditions

    NASA Astrophysics Data System (ADS)

    Imoto, Yuji; Yan, Jiwang

    2017-05-01

    Single-crystal diamond is an important material for cutting tools, micro electro mechanical systems, optical devices, and semiconductor substrates. However, the techniques for producing microstructures on diamond surface with high efficiency and accuracy have not been established. This paper proposes a thermochemical imprinting method for transferring microstructures from a nickel (Ni) mold onto single-crystal diamond surface. The Ni mold was micro-structured by a nanoindenter and then pressed against the diamond surface under high temperature and pressure in argon atmosphere. Results show that microstructures on the Ni mold were successfully transferred onto the diamond surface, and their depth increased with both pressure and temperature. Laser micro-Raman spectroscopy, transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) analyses indicate that a graphite layer was formed over the contact area between diamond and Ni during pressing, and after washing by a mixed acid, the graphite layer could be completely removed. This study demonstrated the feasibility of a cost-efficient fabrication method for large-area microstructures on single-crystal diamond.

  7. Vacuum isostatic micro molding of microfluidic structures into polytetrafluoroethylene (PTFE) materials

    NASA Astrophysics Data System (ADS)

    Lizotte, Todd E.

    2008-04-01

    Polytetrafluoroethylene (PTFE) is an ideal material for use in microfluidic applications, such as industrial inkjet and biomedical analysis devices. PTFE has outstanding physical properties; such as chemical inertness and resistance to chemical corrosion, even when exposed to a strong acid, alkali and oxidants. Its properties provide for superior electrical insulation and thermal stability, which is not affected by wide ranges in temperature and frequency. Its non-absorption of moisture makes it a perfect material for consideration in micro-fluidic devices used in chemical analysis, fluidic photonic sensors and biomedical diagnostics. This paper presents an overview of a unique fabrication method that incorporates a variety of elements to establish a processing technique that can form micro channels, complex filter arrays and reflective micro mirror structures into PTFE materials for such applications. Using a modified isostatic compression molding process, this new technique incorporates the addition of a vacuum to assist in the reliable molding of micron structures and further densification of the fused or semi-fused PTFE. Various micro-structured electroformed and micro-machined shims are demonstrated to form small microstructures into the surface of the PTFE material. The combination of the vacuum and the electroformed shim within the molding process noticeably increases the precision, reproducibility and resolution of microstructures that can be realized. The paper will describe the molding hardware involved, process parameters and the resulting microfluidic channels and complex filter and capillary structures formed. Function testing and metrology of the micro-structure geometry formed on each sample will be compared to the original design mandrel geometry.

  8. High-Resolution PFPE-based Molding Techniques for Nanofabrication of High-Pattern Density, Sub-20 nm Features: A Fundamental Materials Approach

    SciTech Connect

    Williams, Stuart S.; Retterer, Scott; Lopez, Rene; Ruiz, Ricardo; Samulski, Edward T.; DeSimone, Joseph M.

    2010-04-14

    Several perfluoropolyether (PFPE)-based elastomers for high-resolution replica molding applications are explored. The modulus of the elastomeric materials was increased through synthetic and additive approaches while maintaining relatively low surface tension values (<25 mN/m). Using large area (>4 in.{sup 2}) master templates, we experimentally show the relationship between mold resolution and material properties such as modulus and surface tension for materials used in this study. A composite mold approach was used to form flexible molds out of stiff, high modulus materials that allow for replication of sub-20 nm post structures. Sub-100 nm line grating master templates, formed using e-beam lithography, were used to determine the experimental stability of the molding materials. It was observed that as the feature spacing decreased, high modulus PFPE tetramethacrylate (TMA) composite molds were able to effectively replicate the nanograting structures without cracking or tear-out defects that typically occur with high modulus elastomers.

  9. High-resolution PFPE-based molding techniques for nanofabrication of high-pattern density, sub-20 nm features: a fundamental materials approach.

    PubMed

    Williams, Stuart S; Retterer, Scott; Lopez, Rene; Ruiz, Ricardo; Samulski, Edward T; DeSimone, Joseph M

    2010-04-14

    Several perfluoropolyether (PFPE)-based elastomers for high-resolution replica molding applications are explored. The modulus of the elastomeric materials was increased through synthetic and additive approaches while maintaining relatively low surface tension values (<25 mN/m). Using large area (>4 in.(2)) master templates, we experimentally show the relationship between mold resolution and material properties such as modulus and surface tension for materials used in this study. A composite mold approach was used to form flexible molds out of stiff, high modulus materials that allow for replication of sub-20 nm post structures. Sub-100 nm line grating master templates, formed using e-beam lithography, were used to determine the experimental stability of the molding materials. It was observed that as the feature spacing decreased, high modulus PFPE tetramethacrylate (TMA) composite molds were able to effectively replicate the nanograting structures without cracking or tear-out defects that typically occur with high modulus elastomers.

  10. Characterization of Microstructure and Molecular Dynamics with High Frequency Oscillatory Techniques

    NASA Astrophysics Data System (ADS)

    Remmler, Torsten; Amin, Samiul; Ferrante, Andrea; Pechhold, Wolfgang

    2009-07-01

    To characterize the rheological behaviour of complex viscoelastic fluids, polymer melts and other soft materials, motor-drive controlled rheometers are mainly used, either at constant stress or strain rate, or in the oscillatory mode. The latter has proved advantageous to discover the viscoelastic functions G*, η*, J* as fingerprints of the material under investigation, it's composition, molecular modelling and applicability. A conclusive analysis of such a viscoelastic spectrum can only be achieved if the amplitudes chosen guarantee linearity and if the frequency range covers more than 6 decades to reach the low kHz-domain. Investigations of many materials with motor-drive controlled rheometers are limited at higher frequencies and reach the above mentioned goal by applying the time-temperature superposition principle, i.e. the mastercurve technique. Since this method is restricted to rheologically simple materials (e.g. some polymer melts), but exclude those of small activation energies and others with temperature-sensitive chemical/physical structures including phase transitions, oscillating rheometry should be extended into higher real-frequency ranges, to establish useful linear viscoelastic spectroscopy. Since complex fluids can have structural arrangement over a wide range of lengthscales and their relaxation mechanisms can impact the dynamics over a wide range of timescales, multiple techniques need to be employed in order to accurately and fully establish the links between rheology, microstructure & dynamics. This is also critical information, required for fully validating developed theory and models. In this talk, advantages and limits of classical oscillatory rheometry will be covered, handling and principle of operation of two high frequency options are introduced and typical examples for real frequency spectra on soft matter, such as polymer melts, polymer solutions and weak gels will be shown. A xanthum gum based system has been investigated not only

  11. High-rate production of micro- and nanostructured surfaces: Injection molding and novel process for metal tooling manufacturing

    NASA Astrophysics Data System (ADS)

    De Jesus Vega, Marisely

    rapidly processed via liquid injection molding. LSR with its excellent mechanical properties, transparency, non-toxicity and rapid molding capabilities can bring the production of micro and nanostructured surfaces from laboratory research facilities to high-rate manufacturing. However, previous research on microstructured surfaces made off LSR does not focus on the processing aspect of this material. Therefore, there is a lack of understanding of how different processing conditions affect the replication of microstructures. Additionally, there are no reports molding nanostructures of LSR. Features between 115 microm and 0.250 microm were molded in this work and the effect of different processing conditions and features sizes were studied. For the last part of this work, a novel metal additive manufacturing technique was used for the production of microstructured surfaces to be used as tooling for injection molding. The printing method consists of metal pastes printed through a tip onto a steel substrate. Prior work has shown spreading and swelling of features when metal pastes extrude out of the printing tip. PDMS was studied as a binder material to minimize spreading and swelling of the features by curing right after printing. In addition, prior work has shown durability of this metal printed tool up to 5000 injection molding cycles. This work compares this durability to durability of commercially available selective laser sintering metal tools. Furthermore, surface roughness was studied as this is one of the most important things to consider when molding microchannels for certain applications.

  12. Comparison of three‐dimensional analysis and stereological techniques for quantifying lithium‐ion battery electrode microstructures

    PubMed Central

    TAIWO, OLUWADAMILOLA O.; FINEGAN, DONAL P.; EASTWOOD, DAVID S.; FIFE, JULIE L.; BROWN, LEON D.; DARR, JAWWAD A.; LEE, PETER D.; BRETT, DANIEL J.L.

    2016-01-01

    Summary Lithium‐ion battery performance is intrinsically linked to electrode microstructure. Quantitative measurement of key structural parameters of lithium‐ion battery electrode microstructures will enable optimization as well as motivate systematic numerical studies for the improvement of battery performance. With the rapid development of 3‐D imaging techniques, quantitative assessment of 3‐D microstructures from 2‐D image sections by stereological methods appears outmoded; however, in spite of the proliferation of tomographic imaging techniques, it remains significantly easier to obtain two‐dimensional (2‐D) data sets. In this study, stereological prediction and three‐dimensional (3‐D) analysis techniques for quantitative assessment of key geometric parameters for characterizing battery electrode microstructures are examined and compared. Lithium‐ion battery electrodes were imaged using synchrotron‐based X‐ray tomographic microscopy. For each electrode sample investigated, stereological analysis was performed on reconstructed 2‐D image sections generated from tomographic imaging, whereas direct 3‐D analysis was performed on reconstructed image volumes. The analysis showed that geometric parameter estimation using 2‐D image sections is bound to be associated with ambiguity and that volume‐based 3‐D characterization of nonconvex, irregular and interconnected particles can be used to more accurately quantify spatially‐dependent parameters, such as tortuosity and pore‐phase connectivity. PMID:26999804

  13. Comparison of three-dimensional analysis and stereological techniques for quantifying lithium-ion battery electrode microstructures.

    PubMed

    Taiwo, Oluwadamilola O; Finegan, Donal P; Eastwood, David S; Fife, Julie L; Brown, Leon D; Darr, Jawwad A; Lee, Peter D; Brett, Daniel J L; Shearing, Paul R

    2016-09-01

    Lithium-ion battery performance is intrinsically linked to electrode microstructure. Quantitative measurement of key structural parameters of lithium-ion battery electrode microstructures will enable optimization as well as motivate systematic numerical studies for the improvement of battery performance. With the rapid development of 3-D imaging techniques, quantitative assessment of 3-D microstructures from 2-D image sections by stereological methods appears outmoded; however, in spite of the proliferation of tomographic imaging techniques, it remains significantly easier to obtain two-dimensional (2-D) data sets. In this study, stereological prediction and three-dimensional (3-D) analysis techniques for quantitative assessment of key geometric parameters for characterizing battery electrode microstructures are examined and compared. Lithium-ion battery electrodes were imaged using synchrotron-based X-ray tomographic microscopy. For each electrode sample investigated, stereological analysis was performed on reconstructed 2-D image sections generated from tomographic imaging, whereas direct 3-D analysis was performed on reconstructed image volumes. The analysis showed that geometric parameter estimation using 2-D image sections is bound to be associated with ambiguity and that volume-based 3-D characterization of nonconvex, irregular and interconnected particles can be used to more accurately quantify spatially-dependent parameters, such as tortuosity and pore-phase connectivity.

  14. Review on Microstructure Analysis of Metals and Alloys Using Image Analysis Techniques

    NASA Astrophysics Data System (ADS)

    Rekha, Suganthini; Bupesh Raja, V. K.

    2017-05-01

    The metals and alloys find vast application in engineering and domestic sectors. The mechanical properties of the metals and alloys are influenced by their microstructure. Hence the microstructural investigation is very critical. Traditionally the microstructure is studied using optical microscope with suitable metallurgical preparation. The past few decades the computers are applied in the capture and analysis of the optical micrographs. The advent of computer softwares like digital image processing and computer vision technologies are a boon to the analysis of the microstructure. In this paper the literature study of the various developments in the microstructural analysis, is done. The conventional optical microscope is complemented by the use of Scanning Electron Microscope (SEM) and other high end equipments.

  15. EBSD: a powerful microstructure analysis technique in the field of solidification.

    PubMed

    Boehm-Courjault, E; Gonzales, F; Jacot, A; Kohler, F; Mariaux, A; Niederberger, C; Salgado-Ordorica, M A; Rappaz, M

    2009-01-01

    This paper presents a few examples of the application of electron back-scatter diffraction (EBSD) to solidification problems. For directionally solidified Al-Zn samples, this technique could reveal the change in dendrite growth directions from <100> to <110> as the composition of zinc increases from 5 to 90 wt%. The corresponding texture evolution and grain selection mechanisms were also examined. Twinned dendrites that form under certain solidification conditions in Al-X specimens (with X = Zn, Mg, Ni, Cu) were clearly identified as <110> dendrite trunks split in their centre by a (111) twin plane. In Zn-0.2 wt% Al hot-dip galvanized coatings on steel sheets, EBSD clearly revealed the preferential basal orientation distribution of the nuclei as well as the reinforcement of this distribution by the faster growth of <1010> dendrites. Moreover, in Al-Zn-Si coatings, misorientations as large as 10 degrees mm(-1) have been measured within individual grains. Finally, the complex band and lamellae microstructures that form in the Cu-Sn peritectic system at low growth rate could be shown to constitute a continuous network initiated from a single nucleus. EBSD also showed that the alpha and beta phases had a Kurdjumov-Sachs crystallographic relationship.

  16. Microstructural study of codeposited pentacene:perfluoropentacene grown on KCl by TEM techniques

    NASA Astrophysics Data System (ADS)

    Félix, Rocío; Breuer, Tobias; Witte, Gregor; Volz, Kerstin; Gries, Katharina I.

    2017-08-01

    Transmission electron microscopy techniques have been used as a research tool to derive information on structure and orientation of organic semiconductor blends. Within this work, we have studied the structure and morphology of pentacene (PEN, C22H14) and perfluoropentacene (PFP, C22F14) blends grown with [2:1] and [1:2] mixing ratios on KCl substrates. The [2:1] mixture exhibits a uniform layer on the substrate with domains that are rotated in-plane by 90° towards each other. Electron diffraction experiments revealed that these domains are formed by a crystalline mixed phase (consisting of PEN and PFP) and a PEN phase in excess whose lattice parameters are rather similar. By contrast, in the [1:2] blend, two different arrangements were found. The majority of the sample exhibits some spicular fibers on a background layer lying on top of the KCl substrate. The microstructural characterization revealed that these fibers consist of pure PFP in excess while the background layer is formed by the mixed phase. The other arrangement, which is present to a lesser extent, consists of a PFP film that is in direct contact with the KCl substrate. Using electron diffraction experiments, the orientation of the different phases with respect to each other and in some cases relative to the KCl substrate has been determined.

  17. Fabrication of balloon-expandable self-lock drug-eluting polycaprolactone stents using micro-injection molding and spray coating techniques.

    PubMed

    Liu, Shih-Jung; Chiang, Fu-Jun; Hsiao, Chao-Ying; Kau, Yi-Chuan; Liu, Kuo-Sheng

    2010-10-01

    The purpose of this report was to develop novel balloon-expandable self-lock drug-eluting poly(ε-caprolactone) stents. To fabricate the biodegradable stents, polycaprolactone (PCL) components were first fabricated by a lab-scale micro-injection molded machine. They were then assembled and hot-spot welded into mesh-like stents of 3 and 5 mm in diameters. A special geometry of the components was designed to self-lock the assembled stents and to resist the external pressure of the blood vessels after being expanded by balloons. Characterization of the biodegradable PCL stents was carried out. PCL stents exhibited comparable mechanical property to that of metallic stents. No significant collapse pressure reduction and weight loss of the stents were observed after being submerged in PBS for 12 weeks. In addition, the developed stent was coated with paclitaxel by a spray coating technique and the release characteristic of the drug was determined by an in vitro elution method. The high-performance liquid chromatography analysis showed that the biodegradable stents could release a high concentration of paclitaxel for more than 60 days. By adopting the novel techniques, we will be able to fabricate biodegradable drug-eluting PCL stents of different sizes for various cardiovascular applications.

  18. 21ST CENTURY MOLD ANALYSIS IN FOOD

    EPA Science Inventory

    Traditionally, the indoor air community has relied on mold analysis performed by either microscopic observations or the culturing of molds on various media to assess indoor air quality. These techniques were developed in the 19th century and are very laborious and time consumin...

  19. 21ST CENTURY MOLD ANALYSIS IN FOOD

    EPA Science Inventory

    Traditionally, the indoor air community has relied on mold analysis performed by either microscopic observations or the culturing of molds on various media to assess indoor air quality. These techniques were developed in the 19th century and are very laborious and time consumin...

  20. Damage Tolerance of Resin Transfer Molded Composite Sandwich Constructions

    DTIC Science & Technology

    1999-05-01

    cost manufacturing techniques to produce panels included; resin transfer molding ( RTM ), vacuum assisted resin infusion/transfer molding ( VARTM ), co...analysis conducted revealed that in terms of failure characteristics, the RTM / VARTM processed sandwich composites yielded similar performance as those...injection VARTM and vacuum assisted compression molding (VACM). Detailed experimental impact studies were performed under three scenarios low velocity

  1. Effects of adding injection-compression to rapid heat cycle molding on the structure of a light guide plate

    NASA Astrophysics Data System (ADS)

    Hong, Seokkwan; Min, Inki; Yoon, Kyunghwan; Kang, Jeongjin

    2014-01-01

    This study investigates the effects of adding injection-compression to rapid heat cycle molding (RHCM) (rapid heat cycle injection-compression molding (RICM)) on the physical quality and optical anisotropy of a molded light guide plate (LGP). Transcription ratio of microstructure, uniformity of part thickness and birefringence were experimentally evaluated on a 7 inch LGP of nominal thickness of 1.12 mm (including a microstructure array of 30 µm diameter and 14 µm height). The designed mold was equipped with rapid heating and compressing facilities and a microstructured nickel stamper was fabricated by UV LIGA process. In addition, to investigate the efficacy of RICM, experiments involving conventional injection molding (CIM), ICM, and RHCM were conducted in parallel with RICM using the same mold. RHCM and RICM yielded excellent transcription ratios for the microstructure, while CIM and RICM provided high thickness uniformity and low birefringence. Thus, RICM obtains high transcription ratio of microstructure, uniform thickness and low birefringence.

  2. Floods and Mold Growth

    EPA Pesticide Factsheets

    Mold growth may be a problem after flooding. Excess moisture in the home is cause for concern about indoor air quality primarily because it provides breeding conditions for pests, molds and other microorganisms.

  3. QUANTIFYING INDOOR MOLDS

    EPA Science Inventory

    There is growing awareness that indoor molds/fungi may be connected to such conditions as asthma, allergies, hemorrhaging, chronic rhinosinusitis, memory loss, and a symptom complex called sick-building-syndrome. In addition, molds cause frequently fatal nosocomical infections. ...

  4. QUANTIFYING INDOOR MOLDS

    EPA Science Inventory

    There is growing awareness that indoor molds/fungi may be connected to such conditions as asthma, allergies, hemorrhaging, chronic rhinosinusitis, memory loss, and a symptom complex called sick-building-syndrome. In addition, molds cause frequently fatal nosocomical infections. ...

  5. Mold After a Disaster

    MedlinePlus

    ... or other health care provider. Safely Preventing Mold Growth Clean up and dry out the building quickly ( ... Systems: A Guide for Building Owners and Managers Population-Specific Recommendations for Protection From Exposure to Mold ...

  6. Adaptive bonding technique for precise assembly of three-dimensional microstructures

    NASA Astrophysics Data System (ADS)

    Park, Sang-Hu; Jeong, Jun-Ho; Choi, Dae-Geun; Kim, Ki-Don; Altun, Ali Ozhan; Lee, Eung-Sug; Yang, Dong-Yol; Lee, Kwang-Sup

    2007-06-01

    Precise fabrication of three-dimensional (3D) self-standing microstructures on thin glass plates via two-photon induced polymerization (TPP) has been an important issue for innovative 3D nanodevices and microdevices. However, there are still issues remaining to be solved, such as building 3D microstructures on opaque materials via TPP and being able to implant them as functional parts onto practical systems. To settle these issues simply and effectively, the authors propose a contact print lithography (CPL) method using an ultraviolet-curable polymer layer. They report some of the possibilities and potential of CPL by presenting their results for transplanting 3D microstructures onto large-area substrates and also their examination of some of the effects of the process parameters on CPL.

  7. A Combined Experimental and Computational Approach for the Design of Mold Topography that Leads to Desired Ingot Surface and Microstructure in Aluminum Casting.

    SciTech Connect

    Dr. Zabaras, N.; Tan, L.

    2005-07-12

    A method combining features of front-tracking methods and fixed-domain methods is presented to model dendritic solidification of pure materials. To explicitly track the interface growth and shape of the solidifying crystals, a fronttracking approach based on the level set method is implemented. To easily model the heat and momentum transport, a fixed-domain method is implemented assuming a diffused freezing front where the liquid fraction is defined in terms of the level set function. The fixed-domain approach, by avoiding the explicit application of essential boundary conditions on the freezing front, leads to an energy conserving methodology that is not sensitive to the mesh size. To compute the freezing front morphology, an extended Stefan condition is considered. Applications to several classical Stefan problems and two- and three-dimensional crystal growth of pure materials in an undercooled melt including the effects of melt flow are considered. The computed results agree very well with available analytical solutions as well as with results obtained using front-tracking techniques and the phase-field method.

  8. Mold-Resistant Construction.

    ERIC Educational Resources Information Center

    Huckabee, Christopher

    2003-01-01

    Asserts that one of the surest ways to prevent indoor air quality and mold issues is to use preventive construction materials, discussing typical resistance to dealing with mold problems (usually budget-related) and describing mold-resistant construction, which uses concrete masonry, brick, and stone and is intended to withstand inevitable…

  9. Bleach Neutralizes Mold Allergens

    ERIC Educational Resources Information Center

    Science Teacher, 2005

    2005-01-01

    Researchers at National Jewish Medical and Research Center have demonstrated that dilute bleach not only kills common household mold, but may also neutralize the mold allergens that cause most mold-related health complaints. The study, published in the Journal of Allergy and Clinical Immunology, is the first to test the effect on allergic…

  10. Molds for cable dielectrics

    DOEpatents

    Roose, L.D.

    1996-12-10

    Molds for use in making end moldings for high-voltage cables are described wherein the dielectric insulator of a cable is heated and molded to conform to a desired shape. As a consequence, high quality substantially bubble-free cable connectors suitable for mating to premanufactured fittings are made. 5 figs.

  11. Molds for cable dielectrics

    DOEpatents

    Roose, Lars D.

    1996-01-01

    Molds for use in making end moldings for high-voltage cables are described wherein the dielectric insulator of a cable is heated and molded to conform to a desired shape. As a consequence, high quality substantially bubble-free cable connectors suitable for mating to premanufactured fittings are made.

  12. Molds in the Environment

    MedlinePlus

    ... so that your employer can take action to clean up and prevent mold growth. To find out more about mold, remediation of mold, or workplace safety and health guidelines and regulations, you may also want to contact your local (city, county, or state) health department. You should also ...

  13. Interactive Mold House Tour

    EPA Pesticide Factsheets

    Get a quick glimpse of some of the most important ways to protect your home from mold by this interactive tour of the Mold House. Room-by-room, you'll learn about common mold issues and how to address them.

  14. Mold and Children's Health.

    ERIC Educational Resources Information Center

    Tuscano, Antoinette

    1998-01-01

    Mold can seriously affect the health of children with asthma or allergies. Indoor air problems related to mold can be difficult to identify, but when several students who spend time in the same classroom area show allergic symptoms, it is important to consider mold and air quality. Failure to respond promptly can have serious consequences. (SM)

  15. Mold-Resistant Construction.

    ERIC Educational Resources Information Center

    Huckabee, Christopher

    2003-01-01

    Asserts that one of the surest ways to prevent indoor air quality and mold issues is to use preventive construction materials, discussing typical resistance to dealing with mold problems (usually budget-related) and describing mold-resistant construction, which uses concrete masonry, brick, and stone and is intended to withstand inevitable…

  16. Bleach Neutralizes Mold Allergens

    ERIC Educational Resources Information Center

    Science Teacher, 2005

    2005-01-01

    Researchers at National Jewish Medical and Research Center have demonstrated that dilute bleach not only kills common household mold, but may also neutralize the mold allergens that cause most mold-related health complaints. The study, published in the Journal of Allergy and Clinical Immunology, is the first to test the effect on allergic…

  17. Fast prototyping of injection molded polymer microfluidic chips

    NASA Astrophysics Data System (ADS)

    Steen Hansen, Thomas; Selmeczi, David; Larsen, Niels B.

    2010-01-01

    We present fast prototyping of injection molding tools by the definition of microfluidic structures in a light-curable epoxy (SU-8) directly on planar nickel mold inserts. Optimized prototype mold structures could withstand injection molding of more than 300 replicas in cyclic olefin copolymer (COC) without any signs of failure or release. The key parameters to avoid mold failure are maximum adhesion strength of the epoxy to the nickel insert and minimum interfacial energy of the epoxy pattern to the molded polymer. Optimal molding of microstructures with vertical sidewalls was found for nickel inserts pre-coated by silicon oxide before applying the structured epoxy, followed by coating of the epoxy by a fluorocarbon layer prior to injection molding. Further improvements in the mold stability were observed after homogeneous coating of the patterned epoxy by a second reflowed layer of epoxy, likely due to the resulting reduction in sidewall steepness. We employed the latter method for injection molding bondable polymer microfluidic chips with integrated conducting polymer electrode arrays that permitted the culture and on-chip analysis of cell spreading by impedance spectroscopy.

  18. A Combined Experimental and Computational Approach for the Design of Mold Topography that Leads to Desired Ingot Surface and Microstructure in Aluminum Casting.

    SciTech Connect

    Dr. Zabaras, N.; Samanta, D.

    2005-04-27

    Solidification of dendritic alloys is modeled using stabilized finite element techniques to study convection and macrosegregation driven by buoyancy and shrinkage. The adopted governing macroscopic conservation equations of momentum, energy and species transport are derived from their microscopic counterparts using the volume-averaging method. A single domain model is considered with a fixed numerical grid and without boundary conditions applied explicitly on the freezing front. The mushy zone is modeled here as a porous medium with either an isotropic or an anisotropic permeability. The stabilized finite-element scheme, previously developed by authors for modeling flows with phase change, is extended here to include effects of shrinkage, density changes and anisotropic permeability during solidification. The fluid flow scheme developed includes streamline-upwind/Petrov-Galerkin (SUPG), pressure stabilizing/Petrov-Galerkin, Darcy stabilizing/Petrov-Galerkin and other stabilizing terms arising from changes in density in the mushy zone. For the energy and species equations a classical SUPG-based finite element method is employed with minor modifications. The developed algorithms are first tested for a reference problem involving solidification of lead-tin alloy where the mushy zone is characterized by an isotropic permeability. Convergence studies are performed to validate the simulation results. Solidification of the same alloy in the absence of shrinkage is studied to observe differences in macrosegregation. Vertical solidification of a lead-tin alloy, where the mushy zone is characterized by an anisotropic permeability, is then simulated. The main aim here is to study convection and demonstrate formation of freckles and channels due to macrosegregation. The ability of stabilized finite element methods to model a wide variety of solidification problems with varying underlying phenomena in two and three dimensions is demonstrated through these examples.

  19. Determination of the Microstructure of Powder Tool Steels by Different Etching Techniques

    NASA Astrophysics Data System (ADS)

    Atapek, Ş. H.; Polat, Ş.; Gümüş, S.; Erişir, E.; Altuğ, G. S.

    2014-07-01

    The microstructure of three powder high-speed steels is studied in quenched and tempered conditions by methods of light and scanning electron microscopy. Several types of carbides with different morphology are detected by using various methods of etching of specimens. The composition of the carbide phases is determined by the method of energy dispersive local analysis.

  20. IC chip stress during plastic package molding

    SciTech Connect

    Palmer, D.W.; Benson, D.A.; Peterson, D.W.; Sweet, J.N.

    1998-02-01

    Approximately 95% of the world`s integrated chips are packaged using a hot, high pressure transfer molding process. The stress created by the flow of silica powder loaded epoxy can displace the fine bonding wires and can even distort the metalization patterns under the protective chip passivation layer. In this study the authors developed a technique to measure the mechanical stress over the surface of an integrated circuit during the molding process. A CMOS test chip with 25 diffused resistor stress sensors was applied to a commercial lead frame. Both compression and shear stresses were measured at all 25 locations on the surface of the chip every 50 milliseconds during molding. These measurements have a fine time and stress resolution which should allow comparison with computer simulation of the molding process, thus allowing optimization of both the manufacturing process and mold geometry.

  1. Development and evaluation of P/M processing techniques to improve and control the mechanical properties of metal injection molded parts

    NASA Astrophysics Data System (ADS)

    Sago, James Alan

    Metal Injection Molding (MIM) is one of the most rapidly growing areas of powder metallurgy (P/M) but the growth of MIM into new markets and more demanding applications is limited by two fundamental barriers, the availability of low cost metal powders and a lack of knowledge and understanding of how mechanical properties, especially toughness, are affected by the many parameters in the MIM process. The goals of this study were to investigate solutions to these challenges for MIM. Mechanical alloying (MA) is a technique which can produce a wide variety of powder compositions in a size range suited to MIM and in smaller batches. However MA typically suffers from low production volumes and long milling times. This study will show that a saucer mill can produce sizable volumes of MA powders in times typically less than an hour. The MA process was also used to produce powders of 17-4PH stainless steel and the NiTi shape memory alloy for a MIM feedstock. This study shows that the MA powder characteristics led to successful MIM processing of parts. Previous studies have shown that the toughness of individual MIM parts can vary widely within a single production run and from one producer to another. In the last part of the study a Design of Experiments (DOE) approach was used to evaluate the effects of MIM processing parameters on the mechanical properties. Analysis of Variance produced mathematical models for Charpy impact toughness, hardness, density, and carbon content. Tensile properties did not produce a good model due to processing problems. The models and recommendations for improving both toughness and reproducibility of toughness are presented.

  2. Hybrid approach combining multiple characterization techniques and simulations for microstructural analysis of proton exchange membrane fuel cell electrodes

    NASA Astrophysics Data System (ADS)

    Cetinbas, Firat C.; Ahluwalia, Rajesh K.; Kariuki, Nancy; De Andrade, Vincent; Fongalland, Dash; Smith, Linda; Sharman, Jonathan; Ferreira, Paulo; Rasouli, Somaye; Myers, Deborah J.

    2017-03-01

    The cost and performance of proton exchange membrane fuel cells strongly depend on the cathode electrode due to usage of expensive platinum (Pt) group metal catalyst and sluggish reaction kinetics. Development of low Pt content high performance cathodes requires comprehensive understanding of the electrode microstructure. In this study, a new approach is presented to characterize the detailed cathode electrode microstructure from nm to μm length scales by combining information from different experimental techniques. In this context, nano-scale X-ray computed tomography (nano-CT) is performed to extract the secondary pore space of the electrode. Transmission electron microscopy (TEM) is employed to determine primary C particle and Pt particle size distributions. X-ray scattering, with its ability to provide size distributions of orders of magnitude more particles than TEM, is used to confirm the TEM-determined size distributions. The number of primary pores that cannot be resolved by nano-CT is approximated using mercury intrusion porosimetry. An algorithm is developed to incorporate all these experimental data in one geometric representation. Upon validation of pore size distribution against gas adsorption and mercury intrusion porosimetry data, reconstructed ionomer size distribution is reported. In addition, transport related characteristics and effective properties are computed by performing simulations on the hybrid microstructure.

  3. Microstructural evolution with various Ti contents in Fe-based hardfacing alloys using a GTAW technique

    NASA Astrophysics Data System (ADS)

    Hsieh, Chih-Chun; Liu, Yi-Chia; Wang, Jia-Siang; Wu, Weite

    2014-07-01

    The aim of this study is to discuss the effect of microstructural development with different Ti contents in Fe-based hardfacing alloys. A series of Fe-Cr-C-Si-Mn-xTi alloy fillers was deposited on SS400 low carbon steel substrate using oscillating gas tungsten arc welding. The microstructure in the Fe-based hardfacing alloy without Ti content addition included: the primary γ, eutectic γ+(Fe,Cr)3C, eutectic γ+(Fe,Cr)2C and martensite. With increasing Ti contents, the microstructures showed the primary TiC carbide, γ phase and eutectic γ+(Fe,Cr,Ti)3C. The amount and size of TiC carbide in the hardfacing layers increased as the Ti content increased. However, the eutectic γ+(Fe,Cr,Ti)3C content decreased as the Ti content increased. According to the results of the hardness test, the lowest hardness value (HRC 54.93) was found with 0% wt% Ti and the highest hardness (HRC 60.29) was observed with 4.87 wt% Ti.

  4. Injection molded polymeric micropatterns for bone regeneration study.

    PubMed

    Zanchetta, Erika; Guidi, Enrica; Della Giustina, Gioia; Sorgato, Marco; Krampera, Mauro; Bassi, Giulio; Di Liddo, Rosa; Lucchetta, Giovanni; Conconi, Maria Teresa; Brusatin, Giovanna

    2015-04-08

    An industrially feasible process for the fast mass-production of molded polymeric micro-patterned substrates is here presented. Microstructured polystyrene (PS) surfaces were obtained through micro injection molding (μIM) technique on directly patterned stamps realized with a new zirconia-based hybrid spin-on system able to withstand 300 cycles at 90 °C. The use of directly patterned stamps entails a great advantage on the overall manufacturing process as it allows a fast, flexible, and simple one-step process with respect to the use of milling, laser machining, electroforming techniques, or conventional lithographic processes for stamp fabrication. Among the different obtainable geometries, we focused our attention on PS replicas reporting 2, 3, and 4 μm diameter pillars with 8, 9, 10 μm center-to-center distance, respectively. This enabled us to study the effect of the substrate topography on human mesenchymal stem cells behavior without any osteogenic growth factors. Our data show that microtopography affected cell behavior. In particular, calcium deposition and osteocalcin expression enhanced as diameter and interpillar distance size increases, and the 4-10 surface was the most effective to induce osteogenic differentiation.

  5. Immunotherapy for mold allergy.

    PubMed

    Coop, Christopher A

    2014-12-01

    The objective of this article is to review the available studies regarding mold immunotherapy. A literature search was conducted in MEDLINE to identify peer-reviewed articles related to mold immunotherapy using the following keywords: mold, allergy, asthma, and immunotherapy. In addition, references cited within these articles were also reviewed. Articles were selected based on their relevance to the topic. Allergic responses to inhaled mold antigens are a recognized factor in allergic rhinitis and asthma. There are significant problems with respect to the production of relevant allergen material for the diagnosis and treatment of mold allergy with immunotherapy. Mold allergens contain proteases and should not be mixed with other allergens for immunotherapy. Most of the immunotherapy studies focus on two molds, Alternaria and Cladosporium. There is a lack of randomized placebo-controlled trials when evaluating the efficacy of mold immunotherapy with trials only focusing on immunotherapy to Alternaria and Cladosporium. Additional studies are needed regarding mold allergy and immunotherapy focusing on which molds are important for causing allergic disease.

  6. 53. PRODUCTION MOLDS. THESE MOLDS ARE COPIES OF THE ORIGINAL ...

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

    53. PRODUCTION MOLDS. THESE MOLDS ARE COPIES OF THE ORIGINAL MOLDS IN THE MORAVIAN POTTERY AND TILE WORKS COLLECTION, AND ARE USED TO PRESS TILES. THE FACTORY KEEPS TEN PRODUCTION MOLDS FOR EACH IMAGE. THE ORIGINAL MOLDS ARE NOT USED IN PRODUCTION. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  7. Mold Simulator Study of the Initial Solidification of Molten Steel in Continuous Casting Mold: Part II. Effects of Mold Oscillation and Mold Level Fluctuation

    NASA Astrophysics Data System (ADS)

    Zhang, Haihui; Wang, Wanlin

    2016-04-01

    The surface quality of the continuous casting strands is closely related to the initial solidification of liquid steel in the vicinity of the mold meniscus, and thus the clear understanding of the behavior of molten steel initial solidification would be of great importance for the control of the quality of final slab. With the development of the mold simulator techniques, the complex interrelationship between the solidified shell surface profile, heat flux, shell thickness, mold level fluctuation, and the infiltrated slag film was well illustrated in our previous study. As the second part, this article investigated the effect of the mold oscillation frequency, stroke, and mold level fluctuation on the initial solidification of the molten steel through the conduction of five different experiments. Results suggested that in the case of the stable mold level, the oscillation marks (OMs) exhibit equally spaced horizon depressions on the shell surface, where the heat flux at the meniscus area raises rapidly during negative strip time (NST) period and the presence of each OMs on the shell surface is corresponding to a peak value of the heat flux variation rate. Otherwise, the shell surface is poorly defined by the existence of wave-type defects, such as ripples or deep depressions, and the heat flux variation is irregular during NST period. The rising of the mold level leads to the longer-pitch and deeper OMs formation; conversely, the falling of mold level introduces shorter-pitch and shallower OMs. With the increase of the mold oscillation frequency, the average value of the low-frequency heat flux at the meniscus increases; however, it decreases when the mold oscillation stroke increases. Additionally, the variation amplitude of the high-frequency temperature and the high-frequency heat flux decreases with the increase of the oscillation frequency and the reduction of the oscillation stroke.

  8. Quantitative assessment of lung microstructure in healthy mice using an MR-based 3He lung morphometry technique

    PubMed Central

    Osmanagic, E.; Sukstanskii, A. L.; Quirk, J. D.; Woods, J. C.; Pierce, R. A.; Conradi, M. S.; Weibel, E. R.

    2010-01-01

    The recently developed technique of lung morphometry using hyperpolarized 3He diffusion magnetic resonance (MR) (Yablonskiy DA, Sukstanskii AL, Woods JC, Gierada DS, Quirk JD, Hogg JC, Cooper JD, Conradi MS. J Appl Physiol 107: 1258–1265, 2009) permits in vivo study of lung microstructure at the alveolar level. Originally proposed for human lungs, it also has the potential to study small animals. The technique relies on theoretical developments in the area of gas diffusion in lungs linking the diffusion attenuated MR signal to the lung microstructure. To adapt this technique to small animals, certain modifications in MR protocol and data analysis are required, reflecting the smaller size of mouse alveoli and acinar airways. This is the subject of the present paper. Herein, we established empirical relationships relating diffusion measurements to geometrical parameters of lung acinar airways with dimensions typical for mice and rats by using simulations of diffusion in the airways. We have also adjusted the MR protocol to acquire data with much shorter diffusion times compared with humans to accommodate the substantially smaller acinar airway length. We apply this technique to study mouse lungs ex vivo. Our MR-based measurements yield mean values of lung surface-to-volume ratio of 670 cm−1, alveolar density of 3,200 per mm3, alveolar depth of 55 μm, and mean chord length of 62 μm, all consistent with published data obtained histologically in mice by unbiased methods. The proposed technique can be used for in vivo experiments, opening a door for longitudinal studies of lung morphometry in mice and other small animals. PMID:20798272

  9. Heat transfer through mold fluxes: A new approach to measure thermal properties of slags

    NASA Astrophysics Data System (ADS)

    Assis, Karina

    been made to substitute regular industrial mold powders with fluorine-free versions. In chapter 7, two different samples of fluoride-free mold powders were tested with the new Cold Finger technique approach. The results indicate that, although these samples can substitute low basicity mold powders, the lack of crystallization observed might be a problem to substitute mold powders used in the casting of crack sensitive steel where, in order to prevent surface defects, heat withdrawn in the caster needs to be reduced. In chapter 8 of the document, for two of the regular samples, a comparison between SEM images of slag rims recovered during the continuous casting of steel and slag films recovered after the Cold Finger tests showed similar microstructure and phase formation. In the same way, for the same samples, the thermal properties estimated using data from the casting process and the results from the Cold Finger test are quite similar, indicating that the new technique presented is a suitable tool to estimate the thermal properties of mold fluxes. In summary, the new approach proposed in the present work enables better characterization of the thermal properties of silicate melts and can be a useful tool to deeper understand the thermal behavior of mold fluxes.

  10. Three-dimensional pattern transfer and nanolithography: modified soft molding

    NASA Astrophysics Data System (ADS)

    Kim, Y. S.; Park, Joonhyung; Lee, Hong H.

    2002-08-01

    One-step transfer of molded three-dimensional polymer structures into underlying substrate is reported. The one-step transfer is made possible by a molding technique presented here in the form of modified soft molding. Formation of a desired three-dimensional structure in a polymer film by this method, followed by one-step reactive ion etching, is utilized for the transfer. The technique is also shown to be effective in transferring sub-100-nm features.

  11. Preparation and laser properties of Yb3+-doped microstructure fiber based on hydrolysis-melting technique

    NASA Astrophysics Data System (ADS)

    Wang, Chao

    2017-01-01

    The Yb3+-doped silica glass was prepared by the SiCl4 hydrolysis doping and powder melting technology based on high frequency plasma. The absorption and emission characteristics of the Yb3+-doped silica glass are studied at room temperature. The integrated absorption cross section, stimulated emission cross section and fluorescence lifetime are calculated to be 8.56×104 pm3, 1.39 pm2 and 0.56 ms, respectively. The Yb3+-doped microstructure fiber (MSF) was also fabricated by using the Yb3+-doped silica glass as fiber core. What's more, the laser properties of the Yb3+-doped MSF are studied.

  12. Guide to Molds at School.

    ERIC Educational Resources Information Center

    Healthy Schools Network, Inc., Albany, NY.

    Asserting that molds growing in schools can be harmful to children's health and learning, this guide offers information about the issue. It provides an overview of the basics, then addresses testing, types of molds, molds and health, monitoring schools for mold, mold prevention and clean-up tips for schools, and what parents should do if they…

  13. Guide to Molds at School.

    ERIC Educational Resources Information Center

    Healthy Schools Network, Inc., Albany, NY.

    Asserting that molds growing in schools can be harmful to children's health and learning, this guide offers information about the issue. It provides an overview of the basics, then addresses testing, types of molds, molds and health, monitoring schools for mold, mold prevention and clean-up tips for schools, and what parents should do if they…

  14. Molded Magnetic Article

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor); Namkung, Min (Inventor); Wincheski, Russell A. (Inventor); Fulton, James P. (Inventor); Fox, Robert L. (Inventor)

    2000-01-01

    A molded magnetic article and fabrication method are provided. Particles of ferromagnetic material embedded in a polymer binder are molded under heat and pressure into a geometric shape. Each particle is an oblate spheroid having a radius-to-thickness aspect ratio approximately in the range of 15-30. Each oblate spheroid has flattened poles that are substantially in perpendicular alignment to a direction of the molding pressure throughout the geometric shape.

  15. Microstructure and wear properties of Al-20Si alloy prepared by spray deposition with following continuous extrusion forming technique

    NASA Astrophysics Data System (ADS)

    Liu, Yingli; Yin, Jiancheng; Zhong, Yi

    2016-10-01

    Spray deposition with following continuous extrusion forming technique (SD-CE) is an innovative manufacturing technique to produce high alloy net-shape products. Al-20Si alloy rods have been fabricated by SD-CE at different extrusion ratio. Microstructure, hardness and wear resistance of the alloy have been investigated in details. The results show that Al-20Si alloy can be refined effectively by SD-CE, and the size and shape of Si particles become fine and spherical with the increasing extrusion ratio. When the extrusion ratio reaches 20:1, fully dense material with uniform distribution of Si particles can be obtained. The Al-20Si alloys fabricated by SD-CE exhibit excellent wear resistance, which can be further improved by large extrusion ratio, due to increasing hardness and density. A mechanically mixed layer containing a considerable amount of oxygen and iron was formed on the worn surface.

  16. Microstructure Characterization and Corrosion Resistance Behavior of New Cobalt-Free Maraging Steel Produced Through ESR Techniques

    NASA Astrophysics Data System (ADS)

    Seikh, Asiful H.; Halfa, Hossam; Baig, Muneer; Khan, Sohail M. A.

    2017-03-01

    In this study, two different grades (M23 and M29) of cobalt-free low nickel maraging steel have been produced through electroslag remelting (ESR) process. The corrosion resistance of these ESR steels was investigated in 1 M H2SO4 solution using linear potentiodynamic polarization (LPP) and electrochemical impedance spectroscopy (EIS) techniques. The experiments were performed for different immersion time and solution temperature. To evaluate the corrosion resistance of the ESR steels, some significant characterization parameters from LPP and EIS curves were analyzed and compared with that of conventional C250 maraging steel. Irrespective of measurement techniques used, the results show that the corrosion resistance of the ESR steels was higher than the C250 steel. The microstructure of ESR steels was composed of uniform and well-distributed martensite accompanied with little amount of retained austenite in comparison with C250 steel.

  17. BRITISH MOLDING MACHINE, PBQ AUTOMATIC COPE AND DRAG MOLDING MACHINE ...

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

    BRITISH MOLDING MACHINE, PBQ AUTOMATIC COPE AND DRAG MOLDING MACHINE MAKES BOTH MOLD HALVES INDIVIDUALLY WHICH ARE LATER ROTATED, ASSEMBLED, AND LOWERED TO POURING CONVEYORS BY ASSISTING MACHINES. - Southern Ductile Casting Company, Casting, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  18. BRITISH MOLDING MACHINE, PBQ AUTOMATIC COPE AND DRAG MOLDING MACHINE ...

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

    BRITISH MOLDING MACHINE, PBQ AUTOMATIC COPE AND DRAG MOLDING MACHINE MAKES BOTH MOLD HALVES INDIVIDUALLY WHICH ARE LATER ROTATED, ASSEMBLED, AND LOWERED TO POURING CONVEYORS BY ASSISTING MACHINES. - Southern Ductile Casting Company, Casting, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  19. Characterization of airborne fungal levels after mold remediation.

    PubMed

    Kleinheinz, G T; Langolf, B M; Englebert, E

    2006-01-01

    The overall objective of this project was to evaluate levels of airborne fungi present after a mold remediation project and determine the effectiveness of this remediation using airborne mold levels to determine the success of these projects. Andersen N6 (viable) and Air-O-Cell (non-viable) sampling techniques were utilized. Both test methodologies demonstrated that levels of mold in the successfully remediated portions of buildings were significantly different (p<0.05) from the levels found in non-complaint and outdoor samples from the same building, respectively. Conversely, levels in unsuccessful remediation projects were not significantly different (p>0.05) to non-complaint and outdoor samples. Both techniques showed high variability in the overall mold levels found between sites; however, the ratios of specific mold groups in each area tested, within the same site, were remarkably similar. The use of either viable or non-viable mold sampling techniques after mold remediation is essential for determining the success of such projects. This project demonstrates the relationship between mold levels and the success of a mold remediation projects, and will assist in the interpretation of data collected at the conclusion of a mold remediation project.

  20. Microstructure investigations of streak formation in 6063 aluminum extrusions by optical metallographic techniques.

    PubMed

    Vander Voort, George; Suárez-Peña, Beatriz; Asensio-Lozano, Juan

    2013-04-01

    The present study investigates the effect of the solidification strategy for AA 6063 alloy on the surface appearance of anodized extrusions. The microstructure of the samples was analyzed using both light optical microscopy and scanning electron microscopy. Results show that if heavy segregation occurs from rapid solidification, coarse Mg2Si particles form, thus reducing the potential for precipitation strengthening by the finer β-Mg2Si developed in the solid state. Differentially-strained regions formed during hot extrusion induce differences in particle size for magnesium silicide (Mg2Si) precipitates. Anodizing generates surface roughness due to Mg2Si particle dissolution and AlFeSi decohesion, which is related to both particle size and deformation. During anodizing, an oxide layer forms on the surface of the extruded products, which can lead to streak formation, usually a subject of rejection due to unacceptable heterogeneous reflectivity.

  1. New methods and materials for molding and casting ice formations

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew L.; Richter, G. Paul

    1987-01-01

    This study was designed to find improved materials and techniques for molding and casting natural or simulated ice shapes that could replace the wax and plaster method. By utilizing modern molding and casting materials and techniques, a new methodology was developed that provides excellent reproduction, low-temperature capability, and reasonable turnaround time. The resulting casts are accurate and tough.

  2. Mold design with simulation for chalcogenide glass precision molding

    NASA Astrophysics Data System (ADS)

    Zhang, Yunlong; Wang, Zhibin; Li, Junqi; Zhang, Feng; Su, Ying; Wang, Zhongqiang

    2016-10-01

    Compare with the manufacturing of the traditional infrared material, such as signal crystal germanium, zinc sulfide, zinc selenide etc, chalcogenide infrared glass is suitable for precision molding for the low soften temperature to have large mass industry production. So the researches of precision glass molding are necessary, especially for the fast development of infrared product. The mold design is one of the key technologies of precision glass molding. In this paper, the mold processing of a sample chalcogenide glass from the technical drawing, mold design, molding to the lens are introduced. From the result of the precision molding, the technology of finite element simulation is a useful way to guiding the mold design. The molded lens by using mold process fit the design requirement.

  3. Silicon micro-mold

    DOEpatents

    Morales, Alfredo M.

    2006-10-24

    The present invention describes a method for rapidly fabricating a robust 3-dimensional silicon-mold for use in preparing complex metal micro-components. The process begins by depositing a conductive metal layer onto one surface of a silicon wafer. A thin photoresist and a standard lithographic mask are then used to transfer a trace image pattern onto the opposite surface of the wafer by exposing and developing the resist. The exposed portion of the silicon substrate is anisotropically etched through the wafer thickness down to conductive metal layer to provide an etched pattern consisting of a series of rectilinear channels and recesses in the silicon which serve as the silicon micro-mold. Microcomponents are prepared with this mold by first filling the mold channels and recesses with a metal deposit, typically by electroplating, and then removing the silicon micro-mold by chemical etching.

  4. Microstructure and phase composition of Fe-B-Al coatings on low carbon steel prepared by using mechanical alloying technique

    NASA Astrophysics Data System (ADS)

    Sundawa, R. Y.; Aryanto, D.; Wismogroho, A. S.; Sudiro, T.

    2017-04-01

    In the present study, varying composition of FeB-Al was coated on low carbon steel by using mechanical alloying technique for 4 hours and followed by heat treatment in vacuum atmosphere of 5.9 Pa at 700 °C. The microstructure and formed phases of FeB-50 at.%Al, FeB-25 at.%Al, FeB-12.5 at.%Al and FeB coatings were intensively discussed. The cross sectional observation indicates that the coating thickness tends to increase with increasing Al content. Before heat treatment, the coatings are composed of FeB and Al phases, depending on coating composition.. After heat treatment, the intermetallic phases were identified. Interdifussion layer was also formed in the FeB-50 at.%Al coating after heat treatment.

  5. Experimental analysis of viscous and material damping in microstructures through the interferometric microscopy technique with climatic chamber

    NASA Astrophysics Data System (ADS)

    De Pasquale, Giorgio

    2013-09-01

    This study describes an experimental analysis of energy dissipation due to damping sources in microstructures and micro-electromechanical systems (MEMS) components using interferometric microscopy techniques. Viscous damping caused by the surrounding air (squeeze film damping) and material damping are measured using variable geometrical parameters of samples and under different environmental conditions. The equipment included a self-made climatic chamber which was used to modify the surrounding air pressure. Results show the relationship between damping coefficients and sample geometry caused by variation in airflow resistance and the relationship between quality factor and air pressure. The experimental results will provide a useful data source for validating analytic models and calibrating simulations. A thorough discussion about interferometry applied to experimental mechanics of MEMS will also contribute to the reduction of the knowledge gap between specialists in optical methods and microsystem designers.

  6. Glass molding process with mold lubrication

    DOEpatents

    Davey, Richard G.

    1978-06-27

    Improvements are provided in glass forming processes of the type wherein hot metal blank molds are employed by using the complementary action of a solid film lubricant layer, of graphite dispersed in a cured thermoset organopolysiloxane, along with an overspray of a lubricating oil.

  7. Microstructure and electrochemical properties of nitrogen-doped DLC films deposited by PECVD technique

    NASA Astrophysics Data System (ADS)

    Zhou, Kai; Ke, Peiling; Li, Xiaowei; Zou, Yousheng; Wang, Aiying

    2015-02-01

    Nitrogen-doped diamond-like carbon (N-DLC) films were synthesized by glow discharge plasma enhanced chemical vapor deposition (PECVD) using a hybrid ion beam system. The influence of nitrogen incorporation on the microstructure and electrochemical properties of N-DLC films was investigated by scanning probe microscopy, Raman spectroscopy, X-ray photoemission spectroscopy and cycle voltammetry. Regardless of the deposition parameters, the surface of all the deposited films is very smooth. Raman spectra show that ID/IG increases from 0.6 to 1.04 with the substrate bias voltage increases. XPS results identify that carbon is bonded with nitrogen and the substrate bias makes no distinct contribution to the N content in the films, even the N-DLC film at bias of -550 V has the lowest N-O bonds concentration and the highest C-N bonds concentration. The film electrodes show the wide potential windows range over 4 V, lower background currents in strong acid media. At the bias of -550 V, the N-DLC film electrode not only exhibits the ΔEp at 209 mV and Ipox / Ipred at 0.8778 in K3Fe(CN)6 solution, respectively, but also illustrates a nearly reversible electrode reaction. The mechanism of electroproperties is discussed in terms of the atomic bond structures and diffusion process.

  8. Resin film infusion mold tooling and molding method

    NASA Technical Reports Server (NTRS)

    Burgess, Roger (Inventor); Grossheim, Brian (Inventor); Mouradian, Karbis (Inventor); Thrash, Patrick J. (Inventor)

    1999-01-01

    A mold apparatus and method for resin film infusion molding including an outer mold tool having a facing sheet adapted to support a resin film and preform assembly. The facing sheet includes attachment features extending therefrom. An inner mold tool is positioned on the facing sheet to enclose the resin film and preform assembly for resin film infusion molding. The inner mold tool includes a plurality of mandrels positioned for engagement with the resin film and preform assembly. Each mandrel includes a slot formed therein. A plurality of locating bars cooperate with the slots and with the attachment features for locating the mandrels longitudinally on the outer mold tool.

  9. 92. PRODUCTION MOLDS. THESE MOLDS ARE COPIES OF THE ORIGINAL ...

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

    92. PRODUCTION MOLDS. THESE MOLDS ARE COPIES OF THE ORIGINAL MOLDS IN THE MORAVIAN POTTERY AND TILE WORKS COLLECTION, AND ARE USED TO PRESS TILES. THE FACTORY KEEPS TEN PRODUCTION MOLDS FOR EACH IMAGE. THE ORIGINAL MOLDS ARE NOT USED IN PRODUCTION. SAME VIEW AS PA-107-53. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  10. Study of Single-Power, Two-Circuit ESR Process with Current-Carrying Mold: Development of the Technique and Its Physical Simulation

    NASA Astrophysics Data System (ADS)

    Dong, Yanwu; Jiang, Zhouhua; Cao, Haibo; Hou, Zhiwen; Yao, Kean

    2016-12-01

    Physical simulation of a single-power, two-circuit electroslag remelting (ESR) process with current conductive mold (ESR-STCCM) is carried out in this paper. Wood alloy and sodium chloride solution are used to study the current distribution ratio of passing electrode and conductive part of current carrying mold (conductor). A conventional ESR (CESR) process has been studied as a comparison. The total current of ESR-STCCM is larger than the CESR process, which indicates that the resistance in ESR-STCCM is smaller than in CESR. Results show that the ratio of I electrode/ I conductor changes with filling ratio, electrode immersion depth, and effective conductor height. Electrode immersion depth plays an important role on the current distribution ratio. Nevertheless, the effective conductor height has a little influence on the current distribution ratio. A larger filling ratio has an obvious effect on the current distribution ratio in ESR-STCCM. Current flowing through the electrode increases with the increasing of electrode immersion depth under a certain filling ratio. The physical model established can provide an important direction to real ESR-STCCM.

  11. Progress in Titanium Metal Powder Injection Molding

    PubMed Central

    German, Randall M.

    2013-01-01

    Metal powder injection molding is a shaping technology that has achieved solid scientific underpinnings. It is from this science base that recent progress has occurred in titanium powder injection molding. Much of the progress awaited development of the required particles with specific characteristics of particle size, particle shape, and purity. The production of titanium components by injection molding is stabilized by a good understanding of how each process variable impacts density and impurity level. As summarized here, recent research has isolated the four critical success factors in titanium metal powder injection molding (Ti-MIM) that must be simultaneously satisfied—density, purity, alloying, and microstructure. The critical role of density and impurities, and the inability to remove impurities with sintering, compels attention to starting Ti-MIM with high quality alloy powders. This article addresses the four critical success factors to rationalize Ti-MIM processing conditions to the requirements for demanding applications in aerospace and medical fields. Based on extensive research, a baseline process is identified and reported here with attention to linking mechanical properties to the four critical success factors. PMID:28811458

  12. Application of Cathodoluminescence in Analyzing Mold Flux Films

    NASA Astrophysics Data System (ADS)

    Nolte, Elizabeth; Smith, Jeffrey D.; Frazee, Michael; Sutcliffe, Neil; O'Malley, Ronald J.

    Mold fluxes are used in continuous casting of steel to control heat transfer from the steel shell to the copper mold based on their structure and properties. Structures observed in mold flux film samples extracted from conventional and thin slab continuous casters at the end of a cast were examined using cathodoluminescence (CL) imaging in conjunction with XRD and SEM/EDS analysis. Glassy and crystalline structures in the flux films varied greatly depending on sampling location in the mold, distance from the mold wall and the mold flux being examined. Temperature data collected from thermocouple arrays in a thin slab funnel mold indicated sawtooth temperature fluctuations in the lower area of the funnel region, presumably due to cyclic fracture and regrowth of the mold flux crystalline layer in that region of the mold. The temperature observations correlate well with the structures observed in the flux film samples from the region. CL microscopy clearly distinguishes glassy regions from regions with devitrified and dendritic crystal growth, as well as continuous and fractured crystallite layers and cuspidine and nepheline phases that are present. The technique also highlights small variations in Mn oxide content in the glassy region of the flux that results from exchange reactions with the steel, making flow lines in the previously liquid portion of the flux film clearly visible. The benefits of applying cathodoluminescence imaging to the analysis of mold flux films in continuous casting are discussed.

  13. Metal Injection Molding of Alloy 718 for Aerospace Applications

    NASA Astrophysics Data System (ADS)

    Ott, Eric A.; Peretti, Michael W.

    2012-02-01

    The metal injection molding process, used in the automotive, medical, and consumer markets for several decades, was investigated for application to superalloys for small, complex-shaped, aerospace components. With sufficient control on processing, inclusion risks, and chemistry, the process can successfully be applied to superalloy 718 components. Assessments included tensile and fatigue property evaluation, characterization of microstructure, and development of an AMS specification.

  14. Fast and cheap fabrication of molding tools for polymer replication

    NASA Astrophysics Data System (ADS)

    Richter, Christiane; Kirschner, Nadine; Worgull, Matthias; Rapp, Bastian E.

    2017-02-01

    Polymer replication is a prerequisite for low-cost microstructure components for consumer and end user market. The production of cost-effective microstructure in polymers requires metal molding tools which are often fabricated by direct structuring methods like milling or laser machining both of which are time-consuming and cost-intensive. We present an alternative fabrication method based on replication processes which allows the cheap ( 50 €) and fast ( 12 h) replication of complex microstructures into metal. The process comprises three steps: 1. Generation of the microstructure in a photoresist via lithography. 2. Casting of the structure into a high-temperature silicone which serves as original mold for creation of the metal molding tool. 3. Melting of an eutectic alloy of Sn, Ag and Cu under light pressure directly inside of the silicone within an oven. After cooling to room temperature the metal molding tool can be used for polymer replication into conventional thermoplastic polymers. As a first example we structured polymethylmethacrylate (PMMA) foils with a thickness of 1 mm via hot embossing and feature sizes of 100 μm could be replicated with high fidelity.

  15. THE COMPARISON OF SEVERAL STANDARD MATERIALS AND TECHNIQUES FOR THE WARREN-AVERBACH DETERMINATION OF MICRO-STRUCTURE CHARACTERISTICS OF CALCIUM HYDROXIDE SORBENT MATERIALS

    EPA Science Inventory

    The paper gives results of a comparison of several standard materials and techniques for the Warren-Averbach determination of microstructure characteristics of calcium hydroxide--Ca(OH)2--sorbent materials. The comparison is part of an investigation of the injection of dry Ca(OH)...

  16. THE COMPARISON OF SEVERAL STANDARD MATERIALS AND TECHNIQUES FOR THE WARREN-AVERBACH DETERMINATION OF MICRO-STRUCTURE CHARACTERISTICS OF CALCIUM HYDROXIDE SORBENT MATERIALS

    EPA Science Inventory

    The paper gives results of a comparison of several standard materials and techniques for the Warren-Averbach determination of microstructure characteristics of calcium hydroxide--Ca(OH)2--sorbent materials. The comparison is part of an investigation of the injection of dry Ca(OH)...

  17. Breaking the Mold.

    ERIC Educational Resources Information Center

    Huckabee, Christopher

    2003-01-01

    Using the example of a Texas elementary school, describes how to eliminate mold and mildew from school facilities, including discovering the problem, responding quickly, reconstructing the area, and crisis planning and prevention. (EV)

  18. Breaking the Mold.

    ERIC Educational Resources Information Center

    Huckabee, Christopher

    2003-01-01

    Using the example of a Texas elementary school, describes how to eliminate mold and mildew from school facilities, including discovering the problem, responding quickly, reconstructing the area, and crisis planning and prevention. (EV)

  19. Ultrasound Imaging Techniques for Spatiotemporal Characterization of Composition, Microstructure, and Mechanical Properties in Tissue Engineering.

    PubMed

    Deng, Cheri X; Hong, Xiaowei; Stegemann, Jan P

    2016-08-01

    Ultrasound techniques are increasingly being used to quantitatively characterize both native and engineered tissues. This review provides an overview and selected examples of the main techniques used in these applications. Grayscale imaging has been used to characterize extracellular matrix deposition, and quantitative ultrasound imaging based on the integrated backscatter coefficient has been applied to estimating cell concentrations and matrix morphology in tissue engineering. Spectral analysis has been employed to characterize the concentration and spatial distribution of mineral particles in a construct, as well as to monitor mineral deposition by cells over time. Ultrasound techniques have also been used to measure the mechanical properties of native and engineered tissues. Conventional ultrasound elasticity imaging and acoustic radiation force imaging have been applied to detect regions of altered stiffness within tissues. Sonorheometry and monitoring of steady-state excitation and recovery have been used to characterize viscoelastic properties of tissue using a single transducer to both deform and image the sample. Dual-mode ultrasound elastography uses separate ultrasound transducers to produce a more potent deformation force to microscale characterization of viscoelasticity of hydrogel constructs. These ultrasound-based techniques have high potential to impact the field of tissue engineering as they are further developed and their range of applications expands.

  20. A high-brightness light guide plate with high precise double-sided microstructures fabricated using the fixed boundary hot embossing technique

    NASA Astrophysics Data System (ADS)

    Yang, Cheng-Huan; Yang, Sen-Yeu

    2013-03-01

    In recent years, microstructures have been widely applied in many key optical elements and bio-elements. The effective and efficient fabrication of optical elements and bio-elements with superior performance has become an essential challenge. This requires very accurate shape replication of microstructures. The plate-to-plate hot embossing process is the most likely method of mass production for the replication of double-sided micro/nano structures with high precision and quality. However, the traditional uniform heating hot embossing process as the free boundary of open die forging leads to variation. In this research, three techniques are implemented; the conventional uniform heating technique, the non-uniform pressure compensating technique and the fixed boundary hot embossing technique. The temperature distribution of the hot-plates of the fixed boundary hot embossing technique are designed to keep the temperature in the center part higher than the outer part on the surface of the substrates. This phenomenon changes free boundary in conventional uniform heating into fixed boundary. The results demonstrate the potential of the fixed boundary hot embossing technique for the fabrication of large-area high brightness LGPs with double-sided microstructures. The results are also helpful for enhancing the performance of optical elements and bio-elements fabricated using the fixed boundary hot embossing technique.

  1. 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)

  2. Scanning electron microscopy combined with image processing technique: Microstructure and texture analysis of legumes and vegetables for instant meal.

    PubMed

    Pieniazek, Facundo; Messina, Valeria

    2016-04-01

    Development and innovation of new technologies are necessary especially in food quality; due that most instrumental technique for measuring quality properties involves a considerable amount of manual work. Image analysis is a technique that allows to provide objective evaluations from digitalized images that can estimate quality parameters for consumer's acceptance. The aim of the present research was to study the effect of freeze drying on the microstructure and texture of legume and vegetables using scanning electron microscopy at different magnifications' combined with image analysis. Cooked and cooked freeze dried rehydrated legumes and vegetables were analyzed individually by scanning electron microscopy at different magnifications' (250, 500, and 1000×).Texture properties were analyzed by texture analyzer and image analysis. Significant differences (P < 0.05) were obtained for image and instrumental texture parameters. A linear trend with a linear correlation was applied for instrumental and image features. Results showed that image features calculated from Grey level co-occurrence matrix at 1,000× had high correlations with instrumental features. In rice, homogeneity and contrast can be applied to evaluate texture parameters gumminess and adhesiviness; Lentils: contrast, correlation, energy, homogeneity, and entropy for hardness, adhesiviness, gumminess, and chewiness; Potato and carrots: contrast, energy, homogeneity and entropy for adhesiviness, chewiness, hardness, cohesiviness, and resilence. Results revealed that combing scanning electron microscopy with image analysis can be a useful tool to analyze quality parameters in legumes and vegetables.

  3. Physicochemical and Microstructural Characterization of Corn Starch Edible Films Obtained by a Combination of Extrusion Technology and Casting Technique.

    PubMed

    Fitch-Vargas, Perla Rosa; Aguilar-Palazuelos, Ernesto; de Jesús Zazueta-Morales, José; Vega-García, Misael Odín; Valdez-Morales, Jesús Enrique; Martínez-Bustos, Fernando; Jacobo-Valenzuela, Noelia

    2016-09-01

    Starch edible films (EFs) have been widely studied due to their potential in food preservation; however, their application is limited because of their poor mechanical and barrier properties. Because of that, the aim of this work was to use the extrusion technology (Ex T) as a pretreatment of casting technique to change the starch structure in order to obtain EFs with improved physicochemical properties. To this, corn starch and a mixture of plasticizers (sorbitol and glycerol, in different ratios) were processed in a twin screw extruder to generate the starch modification and subsequently casting technique was used for EFs formation. The best conditions of the Ex T and plasticizers concentration were obtained using response surface methodology. All the response variables evaluated, were affected significatively by the Plasticizers Ratio (Sorbitol:Glycerol) (PR (S:G)) and Extrusion Temperature (ET), while the Screw Speed (SS) did not show significant effect on any of these variables. The optimization study showed that the appropriate conditions to obtain EFs with the best mechanical and barrier properties were ET = 89 °C, SS = 66 rpm and PR (S:G) = 79.7:20.3. Once the best conditions were obtained, the optimal treatment was characterized according to its microstructural properties (X-ray diffraction, Scanning Electron Microscopy and Atomic Force Microscopy) to determine the damage caused in the starch during Ex T and casting technique. In conclusion, with the combination of Ex T and casting technique were obtained EFs with greater breaking strength and deformation, as well as lower water vapor permeability than those reported in the literature. © 2016 Institute of Food Technologists®

  4. An Elastic-Plastic and Strength Prediction Model for Injection-Molded Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Phelps, Jay; Tucker III, Charles L.; Bapanapalli, Satish K.

    2008-09-01

    This paper applies a recently developed model to predict the elastic-plastic stress/strain response and strength of injection-molded long-fiber thermoplastics (LFTs). The model combines a micro-macro constitutive modeling approach with experimental characterization and modeling of the composite microstructure to determine the composite stress/strain response and strength. Specifically, it accounts for elastic fibers embedded in a thermoplastic resin that exhibits the elastic-plastic behavior obeying the Ramberg-Osgood relation and J-2 deformation theory of plasticity. It also accounts for fiber length, orientation and volume fraction distributions in the composite formed by the injection-molding process. Injection-molded-long-glass-fiber/polypropylene (PP) specimens were prepared for mechanical characterization and testing. Fiber length, orientation, and volume fraction distributions were then measured at some selected locations for use in the computation. Fiber orientations in these specimens were also predicted using an anisotropic rotary diffusion model developed for LFTs. The stress-strain response of the as-formed composite was computed by an incremental procedure that uses the Eshelby’s equivalent inclusion method, the Mori-Tanaka assumption and a fiber orientation averaging technique. The model has been validated against the experimental stress-strain results obtained for these long-glass-fiber/PP specimens.

  5. Topographic design and application of hierarchical polymer surfaces replicated by microinjection compression molding

    NASA Astrophysics Data System (ADS)

    Guan, Wei-Sheng; Huang, Han-Xiong; Wang, Bin

    2013-10-01

    In recent years, the fast growing demand for biomimetic surfaces featuring unique wettability and functionality in various fields highlights the necessity of developing a reliable technique for mass production. In this work, hierarchical topography designs of templates were applied to prepare superhydrophobic surfaces via microinjection compression molding, comprehensively considering the feasibility of mechanical demolding and the superhydrophobicity and mechanical robustness of the molded polypropylene parts. Mimicking the wettability of a lotus leaf or rose petal, superhydrophobic surfaces were replicated. An unstable wetting state formed on the surface exhibiting the petal effect. On such a surface, the increased water pressure could cause water penetration into the micro gaps between the hierarchical asperities featuring low-roughness sidewalls and bottom surface; the resultant water membrane led to drastically increased water adhesion of the surface. Moreover, the low-adhesion superhydrophobicity of the molded surface was changed into superhydrophilicity, by means of introducing carbonyl groups via ultraviolet/ozone treatment and the subsequent water membrane preserved in microstructures via the pre-wetting process. Patterning the superhydrophilic micro channel on the superhydrophobic surface developed the surface microfluidic devices for micro-liter fluid pumping and mixing processes driven by surface tension.

  6. Differences in time-dependent mechanical properties between extruded and molded hydrogels

    PubMed Central

    Ersumo, N; Witherel, CE; Spiller, KL

    2016-01-01

    The mechanical properties of hydrogels used in biomaterials and tissue engineering applications are critical determinants of their functionality. Despite the recent rise of additive manufacturing, and specifically extrusion-based bioprinting, as a prominent biofabrication method, comprehensive studies investigating the mechanical behavior of extruded constructs remain lacking. To address this gap in knowledge, we compared the mechanical properties and swelling properties of crosslinked gelatin-based hydrogels prepared by conventional molding techniques or by 3D bioprinting using a BioBots Beta pneumatic extruder. A preliminary characterization of the impact of bioprinting parameters on construct properties revealed that both Young's modulus and optimal extruding pressure increased with polymer content, and that printing resolution increased with both printing speed and nozzle gauge. High viability (>95%) of encapsulated NIH 3T3 fibroblasts confirmed the cytocompatibility of the construct preparation process. Interestingly, the Young's moduli of extruded and molded constructs were not different, but extruded constructs did show increases in both the rate and extent of time-dependent mechanical behavior observed in creep. Despite similar polymer densities, extruded hydrogels showed greater swelling over time compared to molded hydrogels, suggesting that differences in creep behavior derived from differences in microstructure and fluid flow. Because of the crucial roles of time-dependent mechanical properties, fluid flow, and swelling properties on tissue and cell behavior, these findings highlight the need for greater consideration of the effects of the extrusion process on hydrogel properties. PMID:27550945

  7. Deterministic embedding of a single gold nanoparticle into polymeric microstructures by direct laser writing technique

    NASA Astrophysics Data System (ADS)

    Nguyen, Dam Thuy Trang; Pelissier, Aurélien; Montes, Kevin; Tong, Quang Cong; Ngo, Hoang Minh; Ledoux-Rak, Isabelle; Lai, Ngoc Diep

    2016-04-01

    We have precisely positioned and embedded a single gold nanoparticle (Au NP) into a desired polymeric photonic structure (PS) using a simple and low-cost technique called low one-photon absorption direct laser writing (LOPA DLW), with a two-step process: identification and fabrication. First, the position of the Au NP was identified with a precision of 20 nm by using DLW technique with ultralow excitation laser power (μW). This power did not induce the polymerization of the photoresist (SU8) due to its low absorption at the excitation wavelength (532 nm). Then, the structure containing the NP was fabricated by using the same DLW system with high excitation power (mW). Different 2D photonic structures have been fabricated, which contain a single Au NP at desired position. In particular, we obtained a microsphere instead of a micropillar at the position of the Au NP. The formation of such microsphere was explained by the thermal effect of the Au NP at the wavelength of 532 nm, which induced thermal polymerization of surrounding photoresist. The effect of the post-exposure bake on the quality of structures was taken into account, revealing a more efficient fabrication way by exploiting the local thermal effect of the laser. We studied further the influence of the NP size on the NP/PS coupling by investigating the fabrication and fluorescence measurement of Au NPs of different sizes: 10, 30, 50, 80, and 100 nm. The photon collection enhancements in each case were 12.9 +/- 2.5, 12.6 +/- 5.6, 3.9 +/- 2.7, 5.9 +/- 4.4, and 6.6 +/- 5.1 times, respectively. The gain in fluorescence could reach up to 36.6 times for 10-nm gold NPs.

  8. [IR/UV spectroscopic analysis of gangliosides and their microstructures of polymeric aggregates observed by AFM technique].

    PubMed

    Wang, Hai-long; Sun, Run-guang; Zhang, Jing; Hao, Chang-chun

    2009-04-01

    Gangliosides, a kind of acid glycosphingolipid containing sialic acid, plays a very important physiological role in biomembrane as one of the important components of neurocyte membrane. They were extracted from bovine brain by the Folch method and purified by silica gel and DEAE-Sephadex A-25 column chromatograph. Their molecular functional groups and microstructures of polymeric aggregates were studied by infrared spectrum (IR), ultraviolet spectrum (UV) and atomic force microscope (AFM). The experimental results indicate that: 55.2 mg of Gls from 100 g of wet bovine brain had a certain purity, 62.84%. And their UV absorption spectra appeared at 195 nm, near to the results reported by other peoples. Compared with the IR spectra of sialic acid, the experimental results showed that the structures of the products had the units of sialic acid. In order to investigate the aggregate structures of ganglioside. AFM technique was applied in water, and the results showed that gangliosides can form spherical or ellipsoidal structures in water. It was determined that the size of polymeric aggregates of gangliosides varies between 55 and 380 nm, the average size is (148.9+/-66.7) nm; the height is between 1.0 and 5.0 nm, and the average height is (3.25+/-1.01) nm. The experimental results provide a theoretical and experimental basis for investigating biological activity and the exploitation and utilization of neural drugs.

  9. Microstructural, nanomechanical, and microtribological properties of Pb thin films prepared by pulsed laser deposition and thermal evaporation techniques

    SciTech Connect

    Broitman, Esteban; Flores-Ruiz, Francisco J.; Di Giulio, Massimo; Gontad, Francisco; Lorusso, Antonella; Perrone, Alessio

    2016-03-15

    In this work, the authors compare the morphological, structural, nanomechanical, and microtribological properties of Pb films deposited by thermal evaporation (TE) and pulsed laser deposition (PLD) techniques onto Si (111) substrates. Films were investigated by scanning electron microscopy, surface probe microscopy, and x-ray diffraction in θ-2θ geometry to determine their morphology, root-mean-square (RMS) roughness, and microstructure, respectively. TE films showed a percolated morphology with densely packed fibrous grains while PLD films had a granular morphology with a columnar and tightly packed structure in accordance with the zone growth model of Thornton. Moreover, PLD films presented a more polycrystalline structure with respect to TE films, with RMS roughness of 14 and 10 nm, respectively. Hardness and elastic modulus vary from 2.1 to 0.8 GPa and from 14 to 10 GPa for PLD and TE films, respectively. A reciprocal friction test has shown that PLD films have lower friction coefficient and wear rate than TE films. Our study has demonstrated for first time that, at the microscale, Pb films do not show the same simple lubricious properties measured at the macroscale.

  10. Selective disordering of InAs/InGaAs dots-in-a-well structure patterned with sol-gel derived SiO{sub 2} strips imprinted by soft mold technique

    SciTech Connect

    Chia, C. K.; Suryana, M.; Low, H. Y.; Zhao, W.; Hopkinson, M.

    2008-08-18

    Selective impurity free vacancy disordering of InAs/InGaAs quantum dot (QD) structures imprinted with sol-gel derived SiO{sub 2} strips via a polyethylene terepthalate soft mold has been investigated. Wavelength blueshift of up to 220 nm for areas capped with the sol-gel derived SiO{sub 2} is demonstrated. The imprinted SiO{sub 2} strips were used as hard mask for plasma etching of GaAs ridge waveguide structures and were found to have similar hardness as the SiO{sub 2} prepared by plasma-enhanced chemical vapor deposition. QD intermixing using sol-gel derived SiO{sub 2} with step-thickness profile was demonstrated, and a one-step SiO{sub 2} imprinting technique for multiple band gap QD intermixing is proposed.

  11. FILLING MOLDS MADE ON THE BRITISH MOLDING MACHINE, AUTOMATIC COPE ...

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

    FILLING MOLDS MADE ON THE BRITISH MOLDING MACHINE, AUTOMATIC COPE AND DRAG (BMM) FROM MOBILE LADLE. EMPTY BULL LADLE IN FOREGROUND. - Southern Ductile Casting Company, Casting, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  12. TENDING THE MOLD, DURING THE TRANSFER FROM TUNDISH TO MOLD ...

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

    TENDING THE MOLD, DURING THE TRANSFER FROM TUNDISH TO MOLD TO CONTAINMENT CHAMBER IS CONTINUOUS CASTING OPERATOR, CALVIN ANDERS. - U.S. Steel, Fairfield Works, Continuous Caster, Fairfield, Jefferson County, AL

  13. Photorefractive polymer composites fabricated by injection molding

    NASA Astrophysics Data System (ADS)

    Herlocker, J. A.; Fuentes-Hernandez, C.; Wang, J. F.; Peyghambarian, N.; Kippelen, B.; Zhang, Q.; Marder, S. R.

    2002-02-01

    We report on the fabrication of bulk samples of photorefractive polymers using the injection molding technique. The photorefractive properties of these materials are evaluated by four-wave mixing and two-beam coupling experiments. Samples with good optical quality, high diffraction efficiency, and net optical gain are obtained.

  14. Improvement of Billet Quality by Use of a Hot Top Mold with a Two Phase Lubrication

    NASA Astrophysics Data System (ADS)

    Schneider, W.; Lossack, E.

    Based on the cast shop proved conventional VAW Hot Top Mold system for billets a more advanced billet casting process was developed. The mold of this casting process applies a special defined mixture of oil and air for lubrication. This two phase lubrication mixture reduces significantly the heat extraction through the cooled mold wall. This paper will give the presentation of the new mold, the discussion of suitable casting conditions and the achieved billet quality improvements with this more advanced casting technique.

  15. Innovative molding technologies for the fabrication of components for microsystems

    NASA Astrophysics Data System (ADS)

    Piotter, Volker; Benzler, Tobias; Hanemann, Thomas; Woellmer, Heinz; Ruprecht, Robert; Hausselt, Juergen H.

    1999-03-01

    Economic success of microsystems technology requires a wide range of materials as well as the related manufacturing processes. A suitable technology for medium/large scale production is micro injection molding which actually allows the manufacturing of plastic microstructures with 20 microns minimum thickness, structural details of approximately 0.2 microns or maximum aspect ratios of more than 20. These microstructures are, for example, applied as components in micro optics, micro fluidics or minimally invasive surgery. This is demonstrated by microparts that are currently available or will be available soon. For higher economic efficiency and cost reduction, fully electrical injection modeling machines of higher accuracy have been applied. Also, micro insert injection molding reduces mounting costs. Manufacturing of metal or ceramic microparts by powder injection modeling allows large-scale production of complex shaped microstructures with a wide range of materials. Typical examples are sintered structured like stepped LIGA- gear wheels with minimal dimensions of 50 microns in different metal and ceramic materials. Micro Precision Casting originating from conventional investment casting is a suitable process for small/medium-scale production. Examples are microturbine housings made of precious metal alloys. An approach similar to rapid prototyping applies photocurable reactive resins. Photoinduced molding of low viscous resins under ambient conditions leads to significantly reduced cycle times. Additionally, rapid testing of new composite materials can be performed easily. Microcomponents molded from polymers and different composites like dyes with nonlinear optical properties and nanosized ceramic powders will be presented.

  16. The research of UV curing injection molding

    NASA Astrophysics Data System (ADS)

    Xie, Pengcheng; Chang, Le; Song, Le; Cai, Tianze; Ding, Yumei; Yang, Weimin

    2015-05-01

    The micro-injection molding technology and the UV (ultraviolet) curing technique are combined to bring about a new plastic forming method, UV curing injection molding. The mean weight of micro-product is an important process characteristic for UV curing injection molding as well as the surface quality of micro-features is another important process characteristic for this new plastic forming method. This research investigates three effects of processing factors on the mass-change rate of micro-product and the surface quality of micro-features. In every particular, the following two factors are considered: UV material system temperature and the packing pressure. The study revealed that as usual, the micro-products gain weight with the imported increasing UV material system temperature and the improved packing pressure. Meanwhile, the increasing packing pressure also improves the surface quality, yet, warming the UV system temperature up has no effect on the quality of the product.

  17. Ultrasonically-assisted Polymer Molding: An Evaluation

    NASA Astrophysics Data System (ADS)

    Moles, Matthew; Roy, Anish; Silberschmidt, Vadim

    Energy reduction in extrusion and injection molding processes can be achieved by the introduction of ultrasonic energy. Polymer flow can be enhanced on application of ultrasonic vibration, which can reduce the thermal and pressure input requirements to produce the same molding; higher productivity may also be achieved. In this paper, a design of an ultrasound-assisted injection mold machine is explored. An extrusion-die design was augmented with a commercial 1.5 kW ultrasonic transducer and sonotrode designed to resonate close to 20 kHz with up to 100 μm vibration amplitude. The design was evaluated with modal and thermal analysis using finite-element analysis software. The use of numerical techniques, including computational fluid dynamics, fluid-structure interaction and coupled Lagrangian-Eulerian method, to predict the effect of ultrasound on polymer flow was considered. A sonotrode design utilizing ceramic to enhance thermal isolation was also explored.

  18. Grinding aspheric and freeform micro-optical molds

    NASA Astrophysics Data System (ADS)

    Tohme, Yazid E.

    2007-02-01

    Fueled by the need for better performing optics, glass optics are now replacing plastic optics in many industrial and consumer electronic devices. One of these devices is the mobile phone camera. The optical sub-assembly in a mobile phone includes several micro lenses that are spherical and/or aspherical in shape and require form tolerances in the submicron range. These micro glass lenses are mass produced by a replication process known as glass press molding. The process entails the compression of a glass gob between two precise optical quality molds at an elevated temperature, usually near the transition temperature of the glass material. The elevated forces and temperatures required in the glass molding process limits the materials of the molds to very tough materials such as tungsten carbide or silicon carbide. These materials can withstand large pressing forces at high temperatures without any significant deformation. These materials offer great mechanical properties for glass press molding but they are also a challenge to machine to submicron accuracy. The work in this paper discusses a deterministic micro grinding manufacturing process referred to as wheel normal grinding, which is utilized to produce these optical quality molds. Wheel normal grinding is more accurate and more deterministic than most other grinding techniques and can produce molds to the form and finish tolerances required for optical molding. This method relies on the ability to recognize and compensate for grinding wheel wear and machine repeatable errors. Results will be presented to illustrate the accuracy of this micro grinding technique.

  19. Molding process for imidazopyrrolone polymers

    NASA Technical Reports Server (NTRS)

    Johnson, C. L. (Inventor)

    1973-01-01

    A process is described for producing shaped articles of imidazopyrrolone polymers comprising molding imidazopyrrolone polymer molding power under pressure and at a temperature greater than 475 C. Moderate pressures may be employed. Preferably, prior to molding, a preform is prepared by isostatic compression. The preform may be molded at a relatively low initial pressure and temperature; as the temperature is increased to a value greater than 475 C., the pressure is also increased.

  20. End moldings for cable dielectrics

    DOEpatents

    Roose, Lars D.

    2000-01-01

    End moldings for high-voltage cables are described wherein the dielectric insulator of the cable is heated and molded to conform to a desired shape. As a consequence, high quality substantially bubble-free cable connectors suitable for mating to premanufactured fittings are made. Disclosed is a method for making the cable connectors either in the field or in a factory, molds suitable for use with the method, and the molded cable connectors, themselves.

  1. Effect of cross sectional geometry on PDMS micro peristaltic pump performance: comparison of SU-8 replica molding vs. micro injection molding.

    PubMed

    Graf, Neil J; Bowser, Michael T

    2013-10-07

    Two different fabrication methods were employed to fabricate micropumps with different cross-sectional channel geometries. The first was to fabricate rectangular cross-sectional microchannel geometries using the well known fabrication method of replica molding (REM). The second, and far less utilized fabrication technique, was to create microchannel molds using an in-house fabricated handheld micro injection molding apparatus. The injection mold apparatus was designed for use with elastomeric room temperature vulcanization (RTV) polymers, as opposed to most other injection molding machines, which are designed for use with thermoplastic polymers. The injection mold's bottom plate was used as a microchannel molding template. The molding template was created by threading a small-diameter wire (150 μm or less) through the injection mold's bottom plate, with subsequent adhesion and smoothing of a thin piece of aluminum foil over the wire-raised injection mold template. When molded against, the template produced a rounded/Gaussian-shaped PDMS microchannel. The design of the injection mold will be presented, along with a direct comparison for micropump performance metrics such as flow rate, valving characteristics, and maximum backpressures attainable for each of the respective micropump channel geometries.

  2. Technique for Automated Extraction of Symmetric Microstructural Features: Application to Dendritic Cores in Single Crystal Ni-Based Superalloys

    DTIC Science & Technology

    2010-06-14

    microstructure in Ni alloys [4, 22, 23], the intermetallic particles in Sn -rich solder [24], and the pore morphology in die-cast magnesium alloys [25], to name...alloys [11, 12], and Pb- Sn alloys [13, 14], the reinforcement particle for particle-reinforced metal-matrix composites [15, 16], microstructure...stitching multiple individual images together. Occasionally, an individual image may be out-of-focus or the im- age contrast may change slightly in the

  3. REFRACTORY COATING FOR GRAPHITE MOLDS

    DOEpatents

    Stoddard, S.D.

    1958-06-24

    Refractory coating for graphite molds used in the casting of uranium is described. The coating is an alumino-silicate refractory composition which may be used as a mold surface in solid form or as a coating applied to the graphite mold. The composition consists of a mixture of ball clay, kaolin, alumina cement, alumina, water, sodium silicate, and sodium carbonate.

  4. Mold Allergy: Proper Humidifier Care

    MedlinePlus

    ... can be a major source of mold and mold spores. Learn how to keep a humidifier clean and reduce or eliminate this common allergen. CAUTION: Use of a humidifier or vaporizer can increase dust mite and mold growth. Frequent use of a humidifier or vaporizer ...

  5. Hybrid EB-writing technique with a 50 kV-VSB writer and a 100 kV-SB writer for nanoimprint mold fabrication

    NASA Astrophysics Data System (ADS)

    Ishikawa, Mikio; Sakaki, Masashi; Kuwahara, Naoko; Fujita, Hiroshi; Takikawa, Tadahiko; Sano, Hisatake; Hoga, Morihisa; Hayashi, Naoya

    2007-05-01

    Nanoimprint lithography is a candidate for lithography for the hp32nm and hp22nm nodes. Molds or templates for it are being developed on the basis of the process of making phase-shift photomasks. The combination of a 50 kV-VSB (variable shaped beam) EB writer and a chemically amplified resist (CAR) does not have a resolution sufficient for 1X patterning. On the other hand, a combination of a 100 kV-SB (spot beam) EB writer and a non-CAR satisfies the resolution requirement, but this combination leads to an extremely low throughput due to low resist sensitivity. To increase the throughput, we have examined double patterning and double exposure with hybrid use of two different types of writers, a 50 kV-VSB writer, JBX-9000MV, for delineating fine features and a 100 kV-SB writer, JBX-9300FS, for delineating rough features. Overlay accuracy is a key item in such hybrid writing. The results of an overlay accuracy evaluation together with a throughput improvement will be reported in this paper. An estimation of the time for writing a gate layer has given a good example; the writing time for hybrid writing is reduced to about half of the time for 100kV-SB writing. The overlay accuracy for double patterning is found to be 20nm (3σ). However, we are confident that we will be able obtain an overlay accuracy of 10nm (3σ) by improving the image placement accuracy of the JBX-9300FS. An example of double exposure is also shown.

  6. MOLDED SEALING ELEMENT

    DOEpatents

    Bradford, B.W.; Skinner, W.J.

    1959-03-24

    Molded sealing elements suitable for use under conditions involving exposure to uranium hexafluoride vapor are described. Such sealing elements are made by subjecting graphitic carbons to a preliminary treatment with uranium hexafluoride vapor, and then incorporating polytetrafluorethylene in them. The resulting composition has good wear resistant and frictional properties and is resistant to disintegration by uranium hexafluoride over long periods of exposure.

  7. Novel Techniques for Examining Detailed Microstructure of Two-phase Lower Mantle Mineral Analogs with SEM and EBSD

    NASA Astrophysics Data System (ADS)

    Kaercher, P. M.; Mariani, E.; Dawson, K.

    2015-12-01

    We examined deformation microstructures of an analog two-phase system of the lower mantle using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Halite (NaCl) and neighborite (NaMgF3) were used as analogs to lower mantle minerals ferropericlase (Mg,Fe)O and bridgmanite MgSiO3, respectively, and deformed to 30% strain at 4 GPa in the D-DIA. We have adapted techniques previously used for EBSD preparation of halite (NaCl) (e.g. Pennock et al. 2002, Journal of Microscopy, v205; Staiger et al. 2010, Materials Characterization, v61) to prepare halite and neighborite for EBSD. Because halite is soft and hydrophilic, it is tricky to prepare for high quality EBSD. On the other hand, neighborite is much harder than halite (with a bulk modulus 5 times that of halite) and requires high quality polishing for longer and through various polishing-medium sizes. EBSD maps were obtained by polishing with very fine colloidal alumina, followed by etching or a final polish in a precision ion polishing system (PIPS). Distribution of phases, grain size and shape, and crystallographic preferred orientation were examined to determine which phase controls the deformation and which deformation mechanisms dominate. Preliminary results show the softer halite is likely interconnected at just 25 volume % or less and controls the deformation through a mechanism that does not promote development of crystallographic preferred orientation. This suggests that periclase may control deformation in the lower mantle resulting in a weaker, more viscous lower mantle and may help to explain why the bulk of the lower mantle is mostly isotropic.

  8. Selective area bandgap engineering of InGaAsP/InP quantum well microstructures with an infrared laser rapid thermal annealing technique

    NASA Astrophysics Data System (ADS)

    Stanowski, R.; Bouaziz, S.; Dubowski, J. J.

    2008-02-01

    Fabrication of wafers with built-in areas of different bandgap materials is of paramount importance for the technology of monolithically integrated devices. Numerous approaches have been proposed and investigated in literature to address this problem especially in III-V basedsemiconductor microstructures. We report on an innovative technique of post-growth selective area bandgap engineering of InGaAsP/InP quantum well (QW) microstructures that is based on infrared laser rapid thermal annealing (Laser-RTA). The method makes use of a 150 W 980 nm laser for background heating of wafers to just below the threshold for quantum well intermixing (QWI) temperatures. Another infrared source, a 30 W TEM00 Nd:YAG laser, is used to increase the temperature above the QWI threshold that leads to the fabrication of different bandgap material. The Laser-RTA technique allows for a significant reduction in the risk of damaging the surface of a semiconductor wafer heated to high temperature with one laser source. Also, it has the potential to fabricate almost arbitrary shaped lines of bandgap engineered material. For the investigated GaInAsP/InP QW microstructures, we have achieved bandgap shifts in excess of 200 nm. We discuss advantages that the proposed Laser-RTA technique offers in the fabrication of monolithically integrated photonic devices.

  9. Mold behavior and its influence on quality in the continuous casting of steel slabs: Part i. Industrial trials, mold temperature measurements, and mathematical modeling

    NASA Astrophysics Data System (ADS)

    Mahapatra, R. B.; Brimacombe, J. K.; Samarasekera, I. V.; Walker, N.; Paterson, E. A.; Young, J. D.

    1991-12-01

    An extensive study has been conducted to elucidate mold behavior and its influence on quality during the continuous casting of slabs. The study combined industrial measurements, mathe matical modeling, and metallographic examination of cast slab samples. The industrial mea surements involved instrumenting an operating slab mold with 114 thermocouples in order to determine the axial mold wall temperature profiles for a wide range of casting conditions. A three-dimensional (3-D) heat-flow model of the mold wall was developed to characterize the heat fluxes in the mold quantitatively from the measured mold temperature data. Furthermore, heat-flow models were developed to examine steel solidification phenomena and mold flux behavior at the meniscus. Slab samples collected during the industrial trials were examined metallographically to evaluate the cast structure and defects. Owing to the length of the study, it is presented in two parts, the first of which describes the experimental techniques employed in the instrumentation of the mold together with the details of the industrial trials and mold temperature measurements. Also, the mathematical modeling technique applied to determine the axial heat-flux profiles from the measured mold temperature data is presented. It is shown that a fully 3-D model of the mold wall is needed to convert the measured temperatures to heat-flux profiles properly.

  10. High Cost/High Risk Components to Chalcogenide Molded Lens Model: Molding Preforms and Mold Technology

    SciTech Connect

    Bernacki, Bruce E.

    2012-10-05

    This brief report contains a critique of two key components of FiveFocal's cost model for glass compression molding of chalcogenide lenses for infrared applications. Molding preforms and mold technology have the greatest influence on the ultimate cost of the product and help determine the volumes needed to select glass molding over conventional single-point diamond turning or grinding and polishing. This brief report highlights key areas of both technologies with recommendations for further study.

  11. Nonpost mold cure compound

    NASA Astrophysics Data System (ADS)

    Hirata, Akihiro

    1997-08-01

    The recent low price trend of electronic products has made IC manufacturing efficiency a top priority in the semiconductor industry. Post mold cure (PMC) process, which generally involves heating the packages in the oven at 175 C for 4 to 8 hours, takes up much longer time than most other assembly processes. If this PMC process can be reduced or eliminated, semiconductor makers will be rewarded with a much higher cost merit. We define the purpose of Non-PMC as 'to get high reliability with suitable physical and electrical properties without PMC'. We compared carious properties of molding compound before and after PMC. We found that curing reaction has almost complete through DSC and C-NMR measurement, but several properties have not stabilized yet, and that not all properties after PMC were better than before PMC. We developed new grade of molding compound considering these facts. And we found that main factors to accomplish non-PMC compound are curability and flowability, and more, increasing of fundamental properties. To accomplish non-PMC, at first, molding compound need to have very high curability. Generally speaking, too high curability causes low flowability, and causes incomplete filing, wire sweep, pad shift, and weak adhesion to inner parts of IC packages. To prevent these failures, various compound properties were studied, and we achieved in adding good flowability to very high curable molding compound. Finally, anti-popcorn property was improved by adding low moisture, high adhesion, high Tg, and high flexural strengths at high temperature. Through this study, we developed new compound grade for various package, especially large QFP using standard ECN resin.

  12. THE DURABILITY OF LARGE-SCALE ADDITIVE MANUFACTURING COMPOSITE MOLDS

    SciTech Connect

    Post, Brian K; Love, Lonnie J; Duty, Chad; Vaidya, Uday; Pipes, R. Byron; Kunc, Vlastimil

    2016-01-01

    Oak Ridge National Laboratory s Big Area Additive Manufacturing (BAAM) technology permits the rapid production of thermoplastic composite molds using a carbon fiber filled Acrylonitrile-Butadiene-Styrene (ABS) thermoplastic. Demonstration tools (i.e. 0.965 m X 0.559 m X 0.152 m) for composite part fabrication have been printed, coated, and finished with a traditional tooling gel. We present validation results demonstrating the stability of thermoplastic printed molds for room temperature Vacuum Assisted Resin Transfer Molding (VARTM) processes. Arkema s Elium thermoplastic resin was investigated with a variety of reinforcement materials. Experimental results include dimensional characterization of the tool surface using laser scanning technique following demolding of 10 parts. Thermoplastic composite molds offer rapid production compared to traditionally built thermoset molds in that near-net deposition allows direct digital production of the net geometry at production rate of 45 kg/hr.

  13. Advanced crystallization techniques of 'solar grade' silicon

    NASA Astrophysics Data System (ADS)

    Gasparini, M.; Calligarich, C.; Rava, P.; Sardi, L.; Alessandri, M.; Redaelli, F.; Pizzini, S.

    Microstructural, electrical and photo-voltaic characteristics of polycrystal line silicon solar cells fabricated with silicon ingots containing 5, 100 and 500 ppmw iron are reported and discussed. All silicon ingots were grown by the directional solidification technique in graphite or special quartz molds and doped intentionally with iron, in order to evaluate the potentiality of the D.S. technique when employed with solar silicon feedstocks. Results indicate that structural breakdown limits the amount of the ingot which is usable for solar cells fabrication, but also that efficiencies in excess of 10 percent are obtained using the 'good' region of the ingot.

  14. Precision lens molding of asphero diffractive surfaces in chalcogenide materials

    NASA Astrophysics Data System (ADS)

    Nelson, J.; Scordato, M.; Schwertz, K.; Bagwell, J.

    2015-10-01

    Finished lens molding, and the similar process of precision lens molding, have long been practiced for high volume, accurate replication of optical surfaces on oxide glass. The physics surrounding these processes are well understood, and the processes are capable of producing high quality optics with great fidelity. However, several limitations exist due to properties inherent with oxide glasses. Tooling materials that can withstand the severe environmental conditions of oxide glass molding cannot easily be machined to produce complex geometries such as diffractive surfaces, lens arrays, and off axis features. Current machining technologies coupled with a limited selection of tool materials greatly limits the type of structures that can be molded into the finished optic. Tooling for chalcogenide glasses are not bound by these restrictions since the molding temperatures required are much lower than for oxide glasses. Innovations in tooling materials and manufacturing techniques have enabled the production of complex geometries to optical quality specifications and have demonstrated the viability of creating tools for molding diffractive surfaces, off axis features, datums, and arrays. Applications for optics having these features are found in automotive, defense, security, medical, and industrial domains. This paper will discuss results achieved in the study of various molding techniques for the formation of positive diffractive features on a concave spherical surface molded from As2Se3 chalcogenide glass. Examples and results of molding with tools having CTE match with the glass and non CTE match will be reviewed. The formation of stress within the glass during molding will be discussed, and methods of stress management will also be demonstrated and discussed. Results of process development methods and production of good diffractive surfaces will be shown.

  15. Numerical recipes for mold filling simulation

    SciTech Connect

    Kothe, D.; Juric, D.; Lam, K.; Lally, B.

    1998-07-01

    Has the ability to simulate the filling of a mold progressed to a point where an appropriate numerical recipe achieves the desired results? If results are defined to be topological robustness, computational efficiency, quantitative accuracy, and predictability, all within a computational domain that faithfully represents complex three-dimensional foundry molds, then the answer unfortunately remains no. Significant interfacial flow algorithm developments have occurred over the last decade, however, that could bring this answer closer to maybe. These developments have been both evolutionary and revolutionary, will continue to transpire for the near future. Might they become useful numerical recipes for mold filling simulations? Quite possibly. Recent progress in algorithms for interface kinematics and dynamics, linear solution methods, computer science issues such as parallelization and object-oriented programming, high resolution Navier-Stokes (NS) solution methods, and unstructured mesh techniques, must all be pursued as possible paths toward higher fidelity mold filling simulations. A detailed exposition of these algorithmic developments is beyond the scope of this paper, hence the authors choose to focus here exclusively on algorithms for interface kinematics. These interface tracking algorithms are designed to model the movement of interfaces relative to a reference frame such as a fixed mesh. Current interface tracking algorithm choices are numerous, so is any one best suited for mold filling simulation? Although a clear winner is not (yet) apparent, pros and cons are given in the following brief, critical review. Highlighted are those outstanding interface tracking algorithm issues the authors feel can hamper the reliable modeling of today`s foundry mold filling processes.

  16. Injection molded polymer optics in the 21st Century

    NASA Astrophysics Data System (ADS)

    Beich, William S.

    2005-08-01

    Precision polymer optics, manufactured by injection molding techniques, has been a key enabling technology for several decades now. The technology, which can be thought of as a subset of the wider field of precision optics manufacturing, was pioneered in the United States by companies such as Eastman Kodak, US Precision Lens, and Polaroid. In addition to suppliers in the U.S. there are several companies worldwide that design and manufacture precision polymer optics, for example Philips High Tech Plastics in Europe and Fujinon in Japan. Designers who are considering using polymer optics need a fundamental understanding of exactly how the optics are created. This paper will survey the technology and processes that are employed in the successful implementation of a polymer optic solution from a manufacturer's perspective. Special emphasis will be paid to the unique relationship between the molds and the optics that they produce. We will discuss the key elements of production: molding resins, molds and molding equipment, and metrology. Finally we will offer a case study to illustrate just how the optics designer carries a design concept through to production. The underlying theme throughout the discussion of polymer optics is the need for the design team to work closely with an experienced polymer optics manufacturer with a solid track record of success in molded optics. As will be seen shortly, the complex interaction between thermoplastics, molds, and molding machines dictates the need for working closely with a supplier who has the critical knowledge needed to manage all aspects of the program.

  17. Rapid and low-cost prototyping of medical devices using 3D printed molds for liquid injection molding.

    PubMed

    Chung, Philip; Heller, J Alex; Etemadi, Mozziyar; Ottoson, Paige E; Liu, Jonathan A; Rand, Larry; Roy, Shuvo

    2014-06-27

    Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using traditional liquid injection molding processes can be an expensive process due to tooling and equipment costs. As a result, it has traditionally been impractical to use liquid injection molding for low-cost, rapid prototyping applications. We have devised a method for rapid and low-cost production of liquid elastomer injection molded devices that utilizes fused deposition modeling 3D printers for mold design and a modified desiccator as an injection system. Low costs and rapid turnaround time in this technique lower the barrier to iteratively designing and prototyping complex elastomer devices. Furthermore, CAD models developed in this process can be later adapted for metal mold tooling design, enabling an easy transition to a traditional injection molding process. We have used this technique to manufacture intravaginal probes involving complex geometries, as well as overmolding over metal parts, using tools commonly available within an academic research laboratory. However, this technique can be easily adapted to create liquid injection molded devices for many other applications.

  18. Rapid and Low-cost Prototyping of Medical Devices Using 3D Printed Molds for Liquid Injection Molding

    PubMed Central

    Chung, Philip; Heller, J. Alex; Etemadi, Mozziyar; Ottoson, Paige E.; Liu, Jonathan A.; Rand, Larry; Roy, Shuvo

    2014-01-01

    Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using traditional liquid injection molding processes can be an expensive process due to tooling and equipment costs. As a result, it has traditionally been impractical to use liquid injection molding for low-cost, rapid prototyping applications. We have devised a method for rapid and low-cost production of liquid elastomer injection molded devices that utilizes fused deposition modeling 3D printers for mold design and a modified desiccator as an injection system. Low costs and rapid turnaround time in this technique lower the barrier to iteratively designing and prototyping complex elastomer devices. Furthermore, CAD models developed in this process can be later adapted for metal mold tooling design, enabling an easy transition to a traditional injection molding process. We have used this technique to manufacture intravaginal probes involving complex geometries, as well as overmolding over metal parts, using tools commonly available within an academic research laboratory. However, this technique can be easily adapted to create liquid injection molded devices for many other applications. PMID:24998993

  19. Rapid production of polymer microstructures

    NASA Astrophysics Data System (ADS)

    Nagarajan, Pratapkumar

    The goal of this research is to develop an integrated polymer embossing module, with which difficult-to-emboss polymer microstructures and microparts can be fabricated in a cost-effective manner. In particular, the research addresses three major limitations of the hot embossing process, namely, long cycle time, difficulty in producing shell patterns, and difficulty in building up a high embossing pressure on thick substrates. To overcome these limitations, three new technical approaches - two-station embossing, rubber-assisted embossing, and through-thickness embossing - were developed and investigated. Fundamental understanding of these new embossing techniques were achieved through extensive experimental and theoretical studies involving parametric experiments, rheological characterization, surface investigation, mathematical modeling, and computer simulation. A two-station embossing process was developed to reduce the hot embossing cycle time, accomplished by decoupling the heating and cooling stations. For this purpose, the standard hot embossing mold was replaced by a shell type mold, and separate hot and cold stations were used to selectively heat and cool the shell mold during the process. With this method, microlens arrays and micro channels were fabricated onto ABS and HDPE substrates with a cycle time of approximately 10 s. Numerical simulations were performed to study the effect of different design parameters, including thermal contact resistance, shell material and shell thickness, on the thermal response at the mold surface. Furthermore, the polymer flow during the two-station embossing process for the microlens was numerically studied. The simulated filling behavior agreed with the experimental observation, and the predicted thermal and deformation history of the polymer offers a good explanation on the experimentally observed process characteristics. The second technique, rubber-assisted embossing, involving a rubber pad as a soft counter tool, was

  20. Modeling white matter microstructure

    PubMed Central

    Duval, Tanguy; Stikov, Nikola; Cohen-Adad, Julien

    2016-01-01

    Summary Quantitative magnetic resonance imaging can be combined with advanced biophysical models to measure microstructural features of white matter. Non-invasive microstructural imaging has the potential to revolutionize neuroscience, and acquiring these measures in clinically feasible times would greatly improve patient monitoring and clinical studies of drug efficacy. However, a good understanding of microstructural imaging techniques is essential to set realistic expectations and to prevent over-interpretation of results. This review explains the methodology behind microstructural modeling and imaging, and gives an overview of the breakthroughs and challenges associated with it. PMID:28072382

  1. An isotropic suspension system for a biaxial accelerometer using electroplated thick metal with a HAR SU-8 mold

    NASA Astrophysics Data System (ADS)

    Lee, Jin Seung; Lee, Seung S.

    2008-02-01

    In this paper, a novel approach is developed to design an isotropic suspension system using thick metal freestanding micro-structures combining bulk micro-machining with electroplating based on a HAR SU-8 mold. An omega-shape isotropic suspension system composed of circular curved beams that have free switching of imaginary boundary conditions is proposed. This novel isotropic suspension design is not affected by geometric dimensional parameters and always achieves matching stiffness along the principle axes of elasticity. Using the finite element method, the isotropic suspension system was compared with an S-shaped meandering suspension system. In order to realize the suggested isotropic suspension system, a cost-effective fabrication process using electroplating with the SU-8 mold was developed to avoid expensive equipment and materials such as deep reactive-ion etching (DRIE) or a silicon-on-insulator (SOI) wafer. The fabricated isotropic suspension system was verified by electromagnetic actuation experiments. Finally, a biaxial accelerometer with isotropic suspension system was realized and tested using a vibration generator system. The proposed isotropic suspension system and the modified surface micro-machining technique based on electroplating with an SU-8 mold can contribute towards minimizing the system size, simplifying the system configuration, reducing the system price of and facilitating mass production of various types of low-cost sensors and actuators.

  2. Microstructure evolution of zinc oxide films derived from dip-coating sol-gel technique: formation of nanorods through orientation attachment.

    PubMed

    Huang, Nan; Sun, Chao; Zhu, Mingwei; Zhang, Bin; Gong, Jun; Jiang, Xin

    2011-07-01

    ZnO:Al thin films with Al incorporation of 0-20 at.% were deposited through the sol-gel technique. Such a film undergoes a significant microstructure development, from columnar to granular structures and then nanorod arrays with increasing Al content. The important role of Al incorporation level in the microstructure evolution was determined using scanning electron microscopy, x-ray photoelectron spectroscopy and transmission electron microscopy. At low Al level, the transition from columnar to granular grains can be attributed to the coarsening barrier resulting from the introduction of Al into the matrix. However, oriented structures of ZnO nanorod arrays are formed at a high Al level. TEM investigation reveals that a nanorod with smooth morphology at the top and rough morphology at the bottom has a single-crystalline wurtzite structure, which is the aggregation of nanoparticles of a few nanometers in size formed through the orientation attachment mechanism followed by epitaxial growth on the aggregated particles. Finally, the physical properties of the ZnO films with different degrees of Al concentration are discussed. Such detailed microstructure studies may aid the understanding of the doping effect process on the growth of a film, which is essential to altering its physical or chemical properties.

  3. Stimuli-responsive topological change of microstructured surfaces and the resultant variations of wetting properties.

    PubMed

    Wu, Zi Liang; Wei, Renbo; Buguin, Axel; Taulemesse, Jean-Marie; Le Moigne, Nicolas; Bergeret, Anne; Wang, Xiaogong; Keller, Patrick

    2013-08-14

    It is now well established that topological microstructures play a key role in the physical properties of surfaces. Stimulus-induced variations of topological microstructure should therefore lead to a change in the physical properties of microstructured responsive surfaces. In this paper, we demonstrate that roughness changes alter the wetting properties of responsive organic surfaces. Oriented nematic liquid crystalline elastomers (LCEs) are used to construct the microstructured surfaces via a replica molding technique. The topological microstructure of the surfaces covered with micropillars changes with temperature, due to the reversible contraction of the LCE pillars along the long axis at the nematic-to-isotropic phase transition. This is directly observed for the first time under environmental scanning electron microscopy (E-SEM). A high boiling point liquid, glycerol, is used to continuously monitor the contact angle change with temperature. The glycerol contact angle of the microstructured surfaces covered with small pillars decreases from 118° at room temperature to 80° at 140 °C, corresponding to a transition from Cassie state to Wenzel state.

  4. Fabrication of Molded Magnetic Article

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor); Namkung, Min (Inventor); Wincheski, Russell A. (Inventor); Fox, Robert L. (Inventor)

    2001-01-01

    A molded magnetic article and fabrication method are provided. Particles of ferromagnetic material embedded in a polymer binder are molded under heat and pressure into a geometric shape. Each particle is an oblate spheroid having a radius-to-thickness aspect ratio approximately in the range of 15-30. Each oblate spheroid has flattened poles that are substantially in perpendicular alignment to a direction of the molding pressure throughout the geometric shape.

  5. Development of a low cost permanent mold casting process for TiAl automotive valves

    SciTech Connect

    Jones, P.E.; Porter, W.J. III; Eylon, D.; Colvin, G.

    1995-12-31

    This paper reviews progress made in the development of a low cost permanent mold casting process for TiAl automotive valves. The issues studied include mold life, mold/metal reaction, shrinkage void control, dimensional control, and post casting processes. More than 800 Ti-47Al-2Nb-1.75 Cr (at%) valves were produced by gravity, centrifugal, and pressure assisted casting methods on a laboratory scale. Microstructures, tensile, creep, and fatigue properties of as-HIP and as-heat treated valves are described. Process scale up challenges identified in this work are also discussed.

  6. Evaluation of Additive Manufacturing for Composite Part Molds

    SciTech Connect

    Duty, Chad E.; Springfield, Robert M.

    2015-02-01

    The ORNL Manufacturing Demonstration Facility (MDF) collaborated with Tru-Design to test the quality and durability of molds used for making fiber reinforced composites using additive manufacturing. The partners developed surface treatment techniques including epoxy coatings and machining to improve the quality of the surface finish. Test samples made using the printed and surface finished molds demonstrated life spans suitable for one-of-a-kind and low-volume applications, meeting the project objective.

  7. Method for molding ceramic powders

    DOEpatents

    Janney, M.A.

    1990-01-16

    A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, where after the product may be sintered.

  8. Method for molding ceramic powders

    DOEpatents

    Janney, Mark A.

    1990-01-01

    A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered.

  9. Microstructural analysis of an epitaxial AlN thick film/trench-patterned template by three-dimensional reciprocal lattice space mapping technique

    NASA Astrophysics Data System (ADS)

    Kamada, Shohei; Takeuchi, Shotaro; Thanh Khan, Dinh; Miyake, Hideto; Hiramatsu, Kazumasa; Imai, Yasuhiko; Kimura, Shigeru; Sakai, Akira

    2016-11-01

    Three-dimensional (3D) lattice plane microstructures were investigated at local regions in an epitaxial AlN thick film grown on a trench-patterned AlN/sapphire template. A 3D reciprocal lattice space mapping technique combined with cross-sectional X-ray microdiffraction using an appropriate Bragg reflection quantitatively revealed the inhomogeneity of the lattice structures in the AlN film without loss of spatial resolution. The results showed a strong correlation of the lattice plane tilt/twist and variations with respect to the void configuration, the patterning structure of the template, and the dislocation morphologies confirmed by transmission electron microscopy.

  10. Permanent Mold Casting of JIS-AC4C Aluminum Alloy Using a Low-Temperature Mold

    SciTech Connect

    Yamagata, Hiroshi; Nikawa, Makoto

    2011-01-17

    Permanent mold casting using mold temperatures below 200 deg. C was conducted to obtain a high-strength, thin-walled casting. Al-7.36 mass% Si -0.18 Cu- 0.27Mg-0.34Fe alloy JIS-AC4C was cast using a bottom pouring cast plan. The product had a rectangular tube shape (70 mm W x 68 mm D x 180 mm H) with wall thicknesses of 1, 3 and 5 mm. The effect of heat insulation at the melt path was compared when using a sand runner insert and when using a steel runner insert as well as a powder mold release agent. Fine microstructures were observed in the casting. The smaller the thickness, the higher the hardness with smaller secondary dendrite arm spacing (SDAS). However, the hardness and the SDAS were unaffected by the mold temperature. It was proposed that the avoidance of the formation of primary {alpha} dendrite at the melt path generates a higher strength casting with adequate mold filling.

  11. Indoor Mold, Toxigenic Fungi, and Stachybotrys chartarum: Infectious Disease Perspective

    PubMed Central

    Kuhn, D. M.; Ghannoum, M. A.

    2003-01-01

    Damp buildings often have a moldy smell or obvious mold growth; some molds are human pathogens. This has caused concern regarding health effects of moldy indoor environments and has resulted in many studies of moisture- and mold-damaged buildings. Recently, there have been reports of severe illness as a result of indoor mold exposure, particularly due to Stachybotrys chartarum. While many authors describe a direct relationship between fungal contamination and illness, close examination of the literature reveals a confusing picture. Here, we review the evidence regarding indoor mold exposure and mycotoxicosis, with an emphasis on S. chartarum. We also examine possible end-organ effects, including pulmonary, immunologic, neurologic, and oncologic disorders. We discuss the Cleveland infant idiopathic pulmonary hemorrhage reports in detail, since they provided important impetus for concerns about Stachybotrys. Some valid concerns exist regarding the relationship between indoor mold exposure and human disease. Review of the literature reveals certain fungus-disease associations in humans, including ergotism (Claviceps species), alimentary toxic aleukia (Fusarium), and liver disease (Aspergillys). While many papers suggest a similar relationship between Stachybotrys and human disease, the studies nearly uniformly suffer from significant methodological flaws, making their findings inconclusive. As a result, we have not found well-substantiated supportive evidence of serious illness due to Stachybotrys exposure in the contemporary environment. To address issues of indoor mold-related illness, there is an urgent need for studies using objective markers of illness, relevant animal models, proper epidemiologic techniques, and examination of confounding factors. PMID:12525430

  12. Indoor mold, toxigenic fungi, and Stachybotrys chartarum: infectious disease perspective.

    PubMed

    Kuhn, D M; Ghannoum, M A

    2003-01-01

    Damp buildings often have a moldy smell or obvious mold growth; some molds are human pathogens. This has caused concern regarding health effects of moldy indoor environments and has resulted in many studies of moisture- and mold-damaged buildings. Recently, there have been reports of severe illness as a result of indoor mold exposure, particularly due to Stachybotrys chartarum. While many authors describe a direct relationship between fungal contamination and illness, close examination of the literature reveals a confusing picture. Here, we review the evidence regarding indoor mold exposure and mycotoxicosis, with an emphasis on S. chartarum. We also examine possible end-organ effects, including pulmonary, immunologic, neurologic, and oncologic disorders. We discuss the Cleveland infant idiopathic pulmonary hemorrhage reports in detail, since they provided important impetus for concerns about Stachybotrys. Some valid concerns exist regarding the relationship between indoor mold exposure and human disease. Review of the literature reveals certain fungus-disease associations in humans, including ergotism (Claviceps species), alimentary toxic aleukia (Fusarium), and liver disease (Aspergillys). While many papers suggest a similar relationship between Stachybotrys and human disease, the studies nearly uniformly suffer from significant methodological flaws, making their findings inconclusive. As a result, we have not found well-substantiated supportive evidence of serious illness due to Stachybotrys exposure in the contemporary environment. To address issues of indoor mold-related illness, there is an urgent need for studies using objective markers of illness, relevant animal models, proper epidemiologic techniques, and examination of confounding factors.

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

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

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

  14. MOLD SPECIFIC QUANTITATIVE PCR: THE EMERGING STANDARD IN MOLD ANALYSIS

    EPA Science Inventory

    Today I will talk about the use of quantitative or Real time PCR for the standardized identification and quantification of molds. There are probably at least 100,000 species of molds or fungi. But there are actually about 100 typically found indoors. Some pose a threat to human...

  15. MOLD SPECIFIC QUANTITATIVE PCR: THE EMERGING STANDARD IN MOLD ANALYSIS

    EPA Science Inventory

    Today I will talk about the use of quantitative or Real time PCR for the standardized identification and quantification of molds. There are probably at least 100,000 species of molds or fungi. But there are actually about 100 typically found indoors. Some pose a threat to human...

  16. Mold Materials For Permanent Molding of Aluminum Alloys

    SciTech Connect

    John F Wallace; David Schwam; Wen Hong dxs11@po.cwru.edu

    2001-09-14

    A test that involves immersion of the potential mod materials for permanent molds has been developed that provides a thermal cycle that is similar to the experienced during casting of aluminum in permanent molds. This test has been employed to determine the relative thermal fatigue resistance of several different types of mold materials. Four commercial mold coatings have been evaluated for their insulating ability, wear resistance and roughness. The results indicate that composition and structure of the mold materials have considerable effect on their thermal fatigue cracking behavior. Irons with a gray iron structure are the most prone to thermal fatigue cracking followed by compacted graphite irons with the least thermal fatigue cracking of the cast irons experienced by ductile iron. The composition of these various irons affects their behavior.

  17. Effect of Cross Sectional Geometry on PDMS Micro Peristaltic Pump Performance: Comparison of SU-8 Replica Molding vs. Micro Injection Molding

    PubMed Central

    Graf, Neil J.

    2013-01-01

    Two different fabrication methods were employed to fabricate micropumps with different cross-sectional channel geometries. The first was to fabricate rectangular cross-sectional microchannel geometries using the well known fabrication method of replica molding (REM).1 The second, and far less utilized fabrication technique, was to create microchannel molds using an in-house fabricated handheld micro injection molding apparatus. The injection mold apparatus was designed for use with elastomeric room temperature vulcanization (RTV) polymers, as opposed to most other injection molding machines, which are designed for use with thermoplastic polymers. The injection mold’s bottom plate was used as a microchannel molding template. The molding template was created by threading a small-diameter wire (150 μm or less) through the injection mold’s bottom plate, with subsequent adhesion and smoothing of a thin piece of aluminum foil over the wire-raised injection mold template. When molded against, the template produced a rounded/Gaussian-shaped PDMS microchannel. The design of the injection mold will be presented, along with a direct comparison for micropump performance metrics such as flow rate, valving characteristics, and maximum backpressures attainable for each of the respective micropump channel geometries. PMID:23917263

  18. Thermophilic molds: Biology and applications.

    PubMed

    Singh, Bijender; Poças-Fonseca, Marcio J; Johri, B N; Satyanarayana, Tulasi

    2016-11-01

    Thermophilic molds thrive in a variety of natural habitats including soils, composts, wood chip piles, nesting materials of birds and other animals, municipal refuse and others, and ubiquitous in their distribution. These molds grow in simple media containing carbon and nitrogen sources and mineral salts. Polyamines are synthesized in these molds and the composition of lipids varies considerably, predominantly containing palmitic, oleic and linoleic acids with low levels of lauric, palmiotoleic and stearic acids. Thermophilic molds are capable of efficiently degrading organic materials by secreting thermostable enzymes, which are useful in the bioremediation of industrial wastes and effluents that are rich in oil, heavy metals, anti-nutritional factors such as phytic acid and polysaccharides. Thermophilic molds synthesize several antimicrobial substances and biotechnologically useful miscellaneous enzymes. The analysis of genomes of thermophilic molds reveals high G:C contents, shorter introns and intergenic regions with lesser repetitive sequences, and further confirms their ability to degrade agro-residues efficiently. Genetic engineering has aided in ameliorating the characteristics of the enzymes of thermophilic molds. This review is aimed at focusing on the biology of thermophilic molds with emphasis on recent developments in the analysis of genomes, genetic engineering and potential applications.

  19. INDOOR MOLDS AND ALLERGIC POTENTIAL

    EPA Science Inventory

    Rationale: Damp/moldy environments have been associated with asthma exacerbation, but mold¿s role in allergic asthma induction is less clear. Recently, 5 molds were statistically associated with water-damaged asthmatic homes in the Cleveland area. The asthma exacerbation...

  20. Twistable mold for helicopter blades

    NASA Technical Reports Server (NTRS)

    Carter, E. S.; Kiely, E. F.

    1972-01-01

    Design is described of mold for fabrication of blades composed of sets of aerodynamic shells having same airfoil section characteristics but different distributions. Mold consists of opposing stacks of thin templates held together by long bolts. When bolts are loosened, templates can be set at different positions with respect to each other and then locked in place.

  1. INDOOR MOLDS AND ALLERGIC POTENTIAL

    EPA Science Inventory

    Rationale: Damp/moldy environments have been associated with asthma exacerbation, but mold¿s role in allergic asthma induction is less clear. Recently, 5 molds were statistically associated with water-damaged asthmatic homes in the Cleveland area. The asthma exacerbation...

  2. Microcellular nanocomposite injection molding process

    Treesearch

    Mingjun Yuan; Lih-Sheng Turng; Rick Spindler; Daniel Caulfield; Chris Hunt

    2003-01-01

    This study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The molded parts produced based on the Design of Experiments (DOE) matrices were subjected to tensile testing, impact testing, and Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Dynamic Mechanical...

  3. STANDARDIZED MOLD IDENTIFICATION AND ENUMERATION

    EPA Science Inventory

    There are probably at least 100,000 species of molds or fungi. But there are actually about 100 typically found indoors. Some pose a threat to humans and animals and others don't. We need to know what molds are present indoors and their concentrations. The older methods of cult...

  4. The effect of mold materials on the overlay accuracy of a roll-to-roll imprinting system using UV LED illumination within a transparent mold

    NASA Astrophysics Data System (ADS)

    Choi, Sungwoo; Kook, YunHo; Kim, ChulHo; Yoo, SoonSung; Park, Kwon-Shik; Kim, Seok-min; Kang, Shinill

    2016-06-01

    Although several studies on the roll-to-roll (R2R) imprinting process have reported achieving flexible electronics, improving the alignment accuracy in the overlay process of R2R imprinting is recognized as the biggest problem for the commercialization of this technology. For an overlay technique with high alignment accuracy, it is essential to develop a roll mold with high positional accuracy. In this study, a method for fabricating a roll mold with high positional accuracy is proposed by wrapping a thin glass substrate flexible mold around the transparent roll base, because it can provide higher mechanical strength and thermal stability than a conventional polymer substrate. To confirm the usability of the proposed process, the prepared roll mold was used to fabricate a test pattern of thin-film transistor backplane for a rollable display. The positional and overlay accuracy of the roll mold with the proposed thin glass substrate flexible mold were compared with the roll mold with a conventional polymer substrate flexible mold. Large-area transparent flexible molds with a size of 470  ×  370 mm were fabricated by an ultraviolet (UV) imprinting process on thin glass and polyethylene terephthalate substrates, and these flexible molds were wrapped around a roll base of 125 mm radius through a precision alignment process. After an anti-adhesion treatment and the wrapping process, the roll mold with the polymer substrate showed a ~180 μm positional error, whereas the thin glass substrate showed a ~30 μm positional error. After the overlay process using the R2R imprinting system with the alignment system, an average overlay error of ~3 μm was obtained when the thin glass flexible wrapped roll mold was used, whereas a ~22 μm overlay error was obtained when the polymer substrate flexible wrapped roll mold was used.

  5. Characterization of transition carbides in quench and partitioned steel microstructures by Mössbauer spectroscopy and complementary techniques

    SciTech Connect

    Pierce, D. T.; Coughlin, D. R.; Williamson, D. L.; Clarke, K. D.; Clarke, A. J.; Speer, J. G.; De Moor, E.

    2015-05-01

    Quenching and partitioning (Q&P) produces steel microstructures with martensite and austenite that exhibit promising property combinations for third generation advanced high strength steels. Understanding the kinetics of reactions that compete for available carbon, such as carbide formation, is critical for alloying and processing design and achieving austenite enrichment and retention during Q&P. Mössbauer effect spectroscopy (MES) was used to characterize Q&P microstructures in a 0.38C-1.54Mn-1.48Si wt.% steel after quenching to 225 °C and partitioning at 400 °C for 10 or 300 s, with an emphasis on transition carbides. The recoilless fraction for η-carbide was calculated and a correction for saturation of the MES absorption spectrum was applied, making quantitative measurements of small amounts of η-carbide, including non-stoichiometric η-carbide, possible in Q&P microstructures. Complementary transmission electron microscopy confirmed the presence of η-carbides, and MES and X-ray diffraction were used to characterize the austenite. The amount of η-carbide formed during Q&P ranged from 1.4 to 2.4 at.%, accounting for a substantial portion (~24% to 41%) of the bulk carbon content of the steel. The amount (5.0 at.%) of η-carbide that formed after quenching and tempering (Q&T) at 400 °C for 300 s was significantly greater than after partitioning at 400 °C for 300 s (2.4 at.%), suggesting that carbon partitioning from martensite to austenite occurs in conjunction with η-carbide formation during Q&P in these specimens.

  6. Characterization of transition carbides in quench and partitioned steel microstructures by Mössbauer spectroscopy and complementary techniques

    DOE PAGES

    Pierce, D. T.; Coughlin, D. R.; Williamson, D. L.; ...

    2015-05-01

    Quenching and partitioning (Q&P) produces steel microstructures with martensite and austenite that exhibit promising property combinations for third generation advanced high strength steels. Understanding the kinetics of reactions that compete for available carbon, such as carbide formation, is critical for alloying and processing design and achieving austenite enrichment and retention during Q&P. Mössbauer effect spectroscopy (MES) was used to characterize Q&P microstructures in a 0.38C-1.54Mn-1.48Si wt.% steel after quenching to 225 °C and partitioning at 400 °C for 10 or 300 s, with an emphasis on transition carbides. The recoilless fraction for η-carbide was calculated and a correction for saturationmore » of the MES absorption spectrum was applied, making quantitative measurements of small amounts of η-carbide, including non-stoichiometric η-carbide, possible in Q&P microstructures. Complementary transmission electron microscopy confirmed the presence of η-carbides, and MES and X-ray diffraction were used to characterize the austenite. The amount of η-carbide formed during Q&P ranged from 1.4 to 2.4 at.%, accounting for a substantial portion (~24% to 41%) of the bulk carbon content of the steel. The amount (5.0 at.%) of η-carbide that formed after quenching and tempering (Q&T) at 400 °C for 300 s was significantly greater than after partitioning at 400 °C for 300 s (2.4 at.%), suggesting that carbon partitioning from martensite to austenite occurs in conjunction with η-carbide formation during Q&P in these specimens.« less

  7. Theory and application of ultrasonic microstructural characterization

    NASA Astrophysics Data System (ADS)

    Thompson, R. Bruce

    1992-10-01

    Ultrasonic microstructural characterization techniques have been developed for a variety of reasons ranging from process control to life extension. The techniques are based on principles of wave propagation and scattering from inhomogeneities. Applications of ultrasonic techniques include predicting sheet metal formability, controlling microstructure in metal-matrix composites, monitoring diffusion bonding, measuring porosity in castings and composites, and designing microstructures for enhanced inspectability.

  8. Effect of sandblasting intensity on microstructures and properties of pure titanium micro-arc oxidation coatings in an optimized composite technique

    NASA Astrophysics Data System (ADS)

    Wang, Hong-Yuan; Zhu, Rui-Fu; Lu, Yu-Peng; Xiao, Gui-Yong; He, Kun; Yuan, Y. F.; Ma, Xiao-Ni; Li, Ying

    2014-02-01

    Sandblasting is one of the most effective methods to modify a metal surface and improve its properties for application. Micro-arc oxidation (MAO) could produce a ceramic coating on a dental implant, facilitating cellular differentiation and osseocomposite on it. This study aims to deposit bioceramic Ca- and P-containing coatings on sandblasted commercially pure titanium by an optimum composite technique to improve the bioactive performance. The effect of sandblasting intensity on microstructures and properties of the implant coatings is examined, and the modified surfaces are characterized in terms of their topography, phase, chemical composition, mechanical properties and hydroxyapatite (HA)-inducing ability. The results show that a moderate sandblasting micromachines the substrate in favorable combination of rough and residual stresses; its MAO coating deposits nano-hydroxyapatite after immersion in simulated body fluid (SBF) for 5 days exhibiting better bioactivity. The further improvement of the implant surface performance is attributed to an optimized composite technique.

  9. Effect of injection-molding-induced residual stress on microchannel deformation irregularity during thermal bonding

    NASA Astrophysics Data System (ADS)

    Yu, H.; Tor, S. B.; Loh, N. H.; Asundi, A. K.

    2013-01-01

    Micro injection molding offers a promising approach to rapidly produce thermoplastic microfluidic substrates in large volumes. Many research works have been focused on the replication fidelity of microstructures by injection molding. However, there has not been any investigation on the effect of molded-in residual stress on microchannel deformation during the subsequent thermal bonding process. These effects could be important, because the residual stress developed due to anisotropic polymer flow orientation and inhomogeneous cooling may lead to abnormal microchannel distortion. In the direct thermal bonding process, asymmetric cross-sectional distortion was observed in well-formed microchannels aligned perpendicular to the polymer melt injection direction. This asymmetric distortion is attributed to the residual stress introduced into the substrates during molding, particularly in the surface region where microchannels are molded. Design of experiment on injection molding was carried out to reduce the residual stress in order to achieve the lowest microchannel deformation irregularity, which is a new term defined in this study. The direct thermal bonding was utilized as a feasible non-destructive indirectly quantitative method to evaluate the effect of residual stress around microchannel regarding deformation irregularity. The dominant molding parameters with positive effects were found to be melt temperature, mold temperature as well as cooling time after packing. The presence of the residual stress was also demonstrated through photoelastic stress analysis in terms of phase retardation. With improved molding condition, the absolute retardation difference around microchannels aligned parallel and perpendicular to the molding direction could be tuned to the same level, which indicates that the molded-in residual stresses have been moderated.

  10. Further Insight into the Depth-Dependent Microstructural Response of Cartilage to Compression Using a Channel Indentation Technique

    PubMed Central

    Thambyah, Ashvin; Broom, Neil D.

    2013-01-01

    Stress relaxation and structural analysis were used to investigate the zonally differentiated microstructural response to compression of the integrated cartilage-on-bone tissue system. Fifteen cartilage-on-bone samples were divided into three equal groups and their stress relaxation responses obtained at three different levels of axial compressive strain defined as low (~20%), medium (~40%) and high (~60%). All tests were performed using a channel indenter which included a central relief space designed to capture the response of the matrix adjacent to the directly loaded regions. On completion of each stress relaxation test and while maintaining the imposed axial strain, the samples were formalin fixed, decalcified, and then sectioned for microstructural analysis. Chondron aspect ratios were used to determine the extent of relative strain at different zonal depths. The stress relaxation response of cartilage to all three defined levels of axial strain displayed an initial highly viscous response followed by a significant elastic response. Chondron aspect ratio measurements showed that at the lowest level of compression, axial deformation was confined to the superficial cartilage layer, while in the medium and high axial strain samples the deformation extended into the midzone. The cells in the deep zone remained undeformed for all compression levels. PMID:24023589

  11. Microstructure and Mechanical Properties of Al356/SiCp Cast Composites Fabricated by a Novel Technique

    NASA Astrophysics Data System (ADS)

    Amirkhanlou, Sajjad; Niroumand, Behzad

    2013-01-01

    In this study, SiCp containing composite powders were used as the reinforcement carrier media for manufacturing cast Al356/5 vol.% SiCp composites. Untreated SiCp, milled particulate Al-SiCp composite powder, and milled particulate Al-SiCp-Mg composite powder were injected into Al356 melt. The resultant composite slurries were then cast from either a fully liquid state (stir casting) or semisolid state (compocasting). The results revealed that by injection of composite powders, the uniformity of the SiCp in the Al356 matrix was greatly improved, the particle-free zones in the matrix were disappeared, the SiC particles became smaller, the porosity was decreased, and the matrix microstructure became finer. Compocasting changed the matrix dendritic microstructure to a finer non-dendritic one and also slightly improved the distribution of the SiCp. Simultaneous utilization of Al-SiCp-Mg composite powder and compocasting method increased the macro- and micro-hardness, impact energy, bending strength, and bending strain of Al356/SiCp composite by 35, 63, 20, 20, and 40%, respectively, as compared with those of the composite fabricated by injection of untreated SiCp and stir casting process.

  12. Chemistry in microstructured reactors.

    PubMed

    Jähnisch, Klaus; Hessel, Volker; Löwe, Holger; Baerns, Manfred

    2004-01-16

    The application of microstructured reactors in the chemical process industry has gained significant importance in recent years. Companies that offer not only microstructured reactors, but also entire chemical process plants and services relating to them, are already in existence. In addition, many institutes and universities are active within this field, and process-engineering-oriented reviews and a specialized book are available. Microstructured systems can be applied with particular success in the investigation of highly exothermic and fast reactions. Often the presence of temperature-induced side reactions can be significantly reduced through isothermal operations. Although microstructured reaction techniques have been shown to optimize many synthetic procedures, they have not yet received the attention they deserve in organic chemistry. For this reason, this Review aims to address this by providing an overview of the chemistry in microstructured reactors, grouped into liquid-phase, gas-phase, and gas-liquid reactions.

  13. INJECTION-MOLDING APPARATUS

    DOEpatents

    Lobell, G.M.

    1958-02-11

    This patent is drawn to an injection molding apparatus for producing a tube closed at one end wherein the normally unsupported end of the core located in the cavity during the injection of the molten material to fill the space between the core and cavity wall, which supporting means is automatically removed from operation during the forming of the closed end of the tube. This support means is a plug extending through the end of the core into a recess in the bottom of the cavity where the closed end of the tube is to be formed. The plug is spring pressed into said recess and is forced out of the recess by a slidable bushing at the top of the cavity which is moved against the force of the spring by the molten material when it fills the uppormost open end portion of the cavity, thereby permitting the closed end of the tube to be formed.

  14. Molding single DNA molecules in metals and sample preparation for electronic sequencing.

    PubMed

    Lund, John A; Parviz, Babak A

    2009-01-01

    We demonstrate the molding of single DNA molecules in 8 nm thin platinum molds. The molded structures have an apparent depth of 1 nm under STM imaging, and closely follow the contours of the DNA molecules. We have confirmed the presence of the embedded molecules and have verified the ability of this technique to scale down to single molecules. Additionally, we have utilized this method to perform electron tunneling analysis on embedded DNA molecules.

  15. FIBER LENGTH DISTRIBUTION MEASUREMENT FOR LONG GLASS AND CARBON FIBER REINFORCED INJECTION MOLDED THERMOPLASTICS

    SciTech Connect

    Kunc, Vlastimil; Frame, Barbara J; Nguyen, Ba N.; TuckerIII, Charles L.; Velez-Garcia, Gregorio

    2007-01-01

    Procedures for fiber length distribution (FLD) measurement of long fiber reinforced injection molded thermoplastics were refined for glass and carbon fibers. Techniques for sample selection, fiber separation, digitization and length measurement for both fiber types are described in detail. Quantitative FLD results are provided for glass and carbon reinforced polypropylene samples molded with a nominal original fiber length of 12.7 mm (1/2 in.) using equipment optimized for molding short fiber reinforced thermoplastics.

  16. Reduction of birefringence in a skin-layer of injection molded polymer strips using CO{sub 2} laser irradiation

    SciTech Connect

    Kurosaki, Yasuo; Satoh, Isao; Saito, Takushi

    1995-12-31

    Injection molding of polymers is currently utilized for numerous industrial applications. Because of high productivity and stable quality of molded products, the injection-molding process makes the production costs lower, and therefore, is expected to spread more widely in the future. This paper deals with a technique for improving the optical quality of injection molded polymer products using radiative heating. The birefringence frozen in a skin-layer of the molded part was reduced by CO{sub 2} laser heating, and the efficiency of this technique was investigated experimentally. Namely, a simple numerical calculation was performed to estimate the heating efficiency of CO{sub 2} laser in the polymer, effects of radiation heating on the skin-layer of the molded polymer were observed by using a mold with transparent windows, and the residual birefringence frozen in the final molded specimen was measured. The results clearly showed that the birefringence in the skin-layer of injection molded polymer strips was reduced with CO{sub 2} laser heating. The authors believe that the proposed method for reducing the birefringence frozen in injection-molded polymer products is suitable for practical molding, because process time required for the injection-molding is only slightly increased with this method.

  17. Microstructural study of as sprayed and heat treated Ni3Al coatings deposited by air plasma spraying technique

    NASA Astrophysics Data System (ADS)

    Mehmood, K.; Rafiq, M. A.; Nusair Khan, A.; Rauf, M. M.

    2016-08-01

    Air plasma spraying system was utilized to deposit Ni3Al coatings on AISI 321 steel samples. After plasma spraying the coatings were heat treated at different temperatures i.e. 500 °C to 800 °C for 10 to 100 hours. The characterization tools such as, X-Ray diffraction analysis, optical and scanning electron microscopy were used. By comparing the XRD scan data of as sprayed and heat treated coating, it was observed that the formation of NiO increases drastically with time and temperature. Due to the formation of NiO, hardness was also enhanced. The oxidation behavior was observed by using optical microscope and when it was studied that the oxidation was increasing with time and temperature. Further, the SEM tool was utilized to study the detail microstructural behavior such as shrinkage cavity and oxide particles. The other phases like alumina and spinel phases were determined by using Energy dispersive spectrometer method.

  18. ZnO nanoparticles obtained by ball milling technique: Structural, micro-structure, optical and photo-catalytic properties

    SciTech Connect

    Balamurugan, S. Joy, Josny; Godwin, M. Anto; Selvamani, S.; Raja, T. S. Gokul

    2016-05-23

    The ZnO nanoparticles were obtained by ball milling of commercial grade ZnO powder at 250 rpm for 20 h and studied their structural, micro-structure, optical and photo-catalytic properties. Due to ball milling significant decrease in lattice parameters and average crystalline size is noticed for the as-milled ZnO nano powder. The HRSEM images of the as-milled powder consist of agglomerated fine spherical nanoparticles in the range of ~10-20 nm. The room temperature PL spectrum of as-milled ZnO nano powder excited under 320 nm reveals two emission bands at ~406 nm (violet emission) and ~639 nm (green emission). Interestingly about 98 % of photo degradation of methylene (MB) by the ZnO catalyst is achieved at 100 minutes of solar light irradiation.

  19. On the thickness uniformity of micropatterns of hyaluronic acid in a soft lithographic molding method

    NASA Astrophysics Data System (ADS)

    Jeong, Hoon Eui; Suh, Kahp Y.

    2005-06-01

    A soft lithographic molding is a simple and yet robust method for fabricating well-defined microstructures of a hydrophilic biopolymer such as polyethylene glycol and polysaccharide over a large area. The method consists of three steps: placing a polydimethylsiloxane mold with a bas-relief pattern onto a drop-dispensed polymer solution typically dissolved in water, letting the mold and the solution undisturbed in contact until solvent evaporates completely, and leaving behind a polymer replica after mold removal. In such a molding process, water can only evaporate from the edges of the mold due to impermeable nature of polydimethylsiloxane to water, resulting in a nonuniform distribution of film thickness or pattern height. Here we examine systematically how the evaporation rate affects the thickness distribution of the resulting microstructures by evaporating the solution of hyaluronic acid in various conditions. To compare with a theory, we also present a simple theoretical model based on one-dimensional conservation equation for a liquid film, which is in good agreement with the experimental data.

  20. Precision grinding of tungsten carbide mold insert for molding of sub-millimeter glass aspheric lenses

    NASA Astrophysics Data System (ADS)

    Chao, Choung-Lii; Chang, Chia-Jung; Chen, Chun-Chieh; Chou, Wen-Chen; Ma, Kung-Jeng

    2013-06-01

    As the demand for precision optical components with sub-millimeter feature size steadily increasing, numerous efforts have been made in developing new techniques and in improving the existing approaches to efficiently and economically produce those components. Glass molding process (GMP) is one of these methods to enable mass production of precision glass optical components in recent years. One of the key issues in GMP is precision mold insert fabrication. Since the mould are normally made of hard and brittle materials such as tungsten carbide (WC) and silicon carbide (SiC), precision diamond grinding is by far the principal choice used to machine the GMP mould. As the feature size of optical component gets smaller, the size of mould and grinding wheel used to fabricate the mould gets smaller too. This makes the grinding process a very time consuming and expensive task. This research aimed to improve the small mold fabrication processes by developing an effective way of producing small diamond wheels and in-process monitoring wheel profile. Diamond wheels of around 0.2mm to 0.5mm in diameter after truing and WC aspheric mold insert of form accuracy around 0.47μm were successfully produced in this research.

  1. The effect of boron powder on the microstructure of MgB2 filaments prepared by the modified internal magnesium diffusion technique

    NASA Astrophysics Data System (ADS)

    Rosová, A.; Kulich, M.; Kováč, P.; Brunner, B.; Scheiter, J.; Häßler, W.

    2017-05-01

    We have analyzed the microstructure of MgB2 prepared by the modified internal magnesium diffusion technique resulting in filaments without a central hole. Three different amorphous boron powders with a nominal purity of 98.5%-99.0% and a different particle size were used. It was shown that the real purity of the powders was different from the nominal purity, and the microstructure as well as the critical current densities of the MgB2 were affected by using boron. Larger B particles with a size of 400-500 nm led to the presence of large B-rich grains inside the MgB2 matrix. For one wire series, boron powder containing residual chlorine from the boron preparation process was used. It was found that just a small quantity of chlorine in the B powder caused significant MgB2 filament inhomogeneity, an apparent decrease in the critical current density and high reactivity with air. We estimated the ideal packing density for achieving a large volume of dense MgB2.

  2. Transfer molding of PMR-15 polyimide resin

    NASA Technical Reports Server (NTRS)

    Reardon, J. P.; Moyer, D. W.; Nowak, B. E.

    1985-01-01

    Transfer molding is an economically viable method of producing small shapes of PMR-15 polyimide. It is shown that with regard to flexural, compressive, and tribological properties transfer-molded PMR-15 polyimide is essentially equivalent to PMR-15 polyimide produced by the more common method of compression molding. Minor variations in anisotropy are predictable effects of molding design and secondary finishing operations.

  3. ILLUSTRATED HANDBOOK OF SOME COMMON MOLDS.

    ERIC Educational Resources Information Center

    CHANDLER, MARION N.

    THIS DOCUMENT IS A PICTURE GUIDE FOR THE IDENTIFICATION OF TEN COMMON MOLDS. IT IS DESIGNED FOR USE WITH THE ELEMENTARY SCIENCE STUDY UNIT "MICROGARDENING" AND IS SUGGESTED FOR UPPER ELEMENTARY GRADES. INCLUDED FOR EACH MOLD ARE COLOR PHOTOGRAPHS AND PHOTOMICROGRAPHS OF THE INTACT MOLD MASS AND OF THE MOLD'S SPORE PRODUCING STRUCTURES.…

  4. Classification of buildings mold threat using electronic nose

    NASA Astrophysics Data System (ADS)

    Łagód, Grzegorz; Suchorab, Zbigniew; Guz, Łukasz; Sobczuk, Henryk

    2017-07-01

    Mold is considered to be one of the most important features of Sick Building Syndrome and is an important problem in current building industry. In many cases it is caused by the rising moisture of building envelopes surface and exaggerated humidity of indoor air. Concerning historical buildings it is mostly caused by outdated raising techniques among that is absence of horizontal isolation against moisture and hygroscopic materials applied for construction. Recent buildings also suffer problem of mold risk which is caused in many cases by hermetization leading to improper performance of gravitational ventilation systems that make suitable conditions for mold development. Basing on our research there is proposed a method of buildings mold threat classification using electronic nose, based on a gas sensors array which consists of MOS sensors (metal oxide semiconductor). Used device is frequently applied for air quality assessment in environmental engineering branches. Presented results show the interpretation of e-nose readouts of indoor air sampled in rooms threatened with mold development in comparison with clean reference rooms and synthetic air. Obtained multivariate data were processed, visualized and classified using a PCA (Principal Component Analysis) and ANN (Artificial Neural Network) methods. Described investigation confirmed that electronic nose - gas sensors array supported with data processing enables to classify air samples taken from different rooms affected with mold.

  5. Rapid control of mold temperature during injection molding process

    SciTech Connect

    Liparoti, Sara; Titomanlio, Giuseppe; Hunag, Tsang Min; Cakmak, Mukerrem; Sorrentino, Andrea

    2015-05-22

    The control of mold surface temperature is an important factor that determines surface morphology and its dimension in thickness direction. It can also affect the frozen molecular orientation and the mold surface replicability in injection molded products. In this work, thin thermally active films were used to quickly control the mold surface temperature. In particular, an active high electrical conductivity carbon black loaded polyimide composites sandwiched between two insulating thin polymeric layers was used to condition the mold surface. By controlling the heating time, it was possible to control precisely the temporal variation of the mold temperature surface during the entire cycle. The surface heating rate was about 40°C/s and upon contact with the polymer the surface temperature decreased back to 40°C within about 5 s; the overall cycle time increased only slightly. The effect on cross section sample morphology of samples of iPP were analyzed and discussed on the basis of the recorded temperature evolution.

  6. Corrosion, microstructure, and metallography

    SciTech Connect

    Northwood, D.O.; White, W.E.; Vander Voort, G.F.

    1985-01-01

    Of the forty-one papers presented, nearly half of them deal with microstructural aspects of corrosion, corrosion control and corrosion failure analysis. They describe various analytical approaches for studying corrosion and for diagnosing corrosion failure mechanisms. Details include microstructural features of corrosion on a wide range of materials or coatings and in environments ranging from within the human body to outer space. Another series of papers handles microstructure-property relationships and contains reports on hydrogen embrittlement of AISI 316 stainless steel, shell and detail cracking in railroad rails, and the precipitation of martensitic Fe-Ni-W alloys. A third grouping looks at microstructure-fracture relationships. Coverage of advancements in metal-lographic techniques includes the use of microcomputers, applied techniques of inplace analysis, and use of the Tandem Van de Graff accelerator facility.

  7. Replication and molding of optical components; Proceedings of the Meeting, Los Angeles, CA, Jan. 13, 14, 1988

    NASA Astrophysics Data System (ADS)

    Riedl, Max J.

    1988-01-01

    Various papers on the replication and molding of optical components are presented. Individual topics discussed include: advantages and limitations of epoxy replication, protecting optical replication models with hard carbon, aspheric optics made by thin film epoxy replication, replication of transmissive optical surfaces, stability of lightweight replicated mirrors, replication of optical components, novel ultraviolet light-absorbing polymers for optical applications, improved acrylic resins for optical applications, novel acrylic resin for injection-molded precision lenses, and birefringence control in optical disk molding. Also addressed are: development of prototype plastic optics, molded acrylic retroreflector, injection molding of optical components, coating of plastics, problems and solutions for coating plastic optics, abrasion testing of coated plastic lenses, surface enhancement for optical plastics, survey of present lens-molding techniques, new directions in glass and plastic aspherics, characterization of molded glass and plastic aspheric lenses, and precision glass microlens array by a photothermal technique.

  8. Mold Cleanup in Your Home

    EPA Pesticide Factsheets

    If you found mold in your household, you will want to clean it up. Some considerations on how you will clean it up depend on the size of the area, the contaminated materials, and any additional health concerns.

  9. White mold of Jerusalem artichoke

    USDA-ARS?s Scientific Manuscript database

    Jerusalem artichoke (Helianthus tuberosus) is a Native American food plant closely related to the common sunflower (Helianthus annuus). Tubers of Jerusalem artichoke are increasingly available in retail grocery outlets. White mold (Sclerotinia stem rot), caused by the fungus, Sclerotinia sclerotioru...

  10. Mold remediation in a hospital.

    PubMed

    Lee, Tang G

    2009-01-01

    As occupants in a hospital, patients are susceptible to air contaminants that can include biological agents dispersed throughout the premise. An exposed patient can become ill and require medical intervention. A consideration for patients is that they may have become environmentally sensitive and require placement in an environment that does not compromise their health. Unfortunately, the hospital environment often contains more biological substances than can be expected in an office or home environment. When a hospital also experiences water intrusion such as flooding or water leaks, resulting mold growth can seriously compromise the health of patients and others such as nursing staff and physicians (Burge, Indoor Air and Infectious Disease. Occupational Medicine: State of the Art Reviews, 1980; Lutz et al., Clinical Infectious Diseases 37: 786-793, 2003). Micro-organism growth can propagate if the water is not addressed quickly and effectively. Immunocompromised patients are particularly at risk when subjected to fungal infection such that the US Center for Disease Control issued guideline for building mold in health care facilities (Centers for Disease and Control [CDC], Centers for Disease and Control: Questions and Answers on Stachybotrys chartarum and Other Molds, 2000). This paper is based on mold remediation of one portion of a hospital unit due to water from construction activity and inadequate maintenance, resulting in mold growth. A large proportion of the hospital staff, primarily nurses in the dialysis unit, exhibited health symptoms consistent with mold exposure. Unfortunately, the hospital administrators did not consider the mold risk to be serious and refused an independent consultant retained by the nurse's union to examine the premise (Canadian Broadcasting Corporation [CBC], Nurses file complaints over mold at Foothills. Canadian Broadcasting Corporation, 2003). The nurse's union managed to have the premise examined by submitting a court order of

  11. A review on preparation techniques for synthesis of nanocrystalline soft magnetic ferrites and investigation on the effects of microstructure features on magnetic properties

    NASA Astrophysics Data System (ADS)

    Hajalilou, Abdollah; Mazlan, Saiful Amri

    2016-07-01

    Soft magnetic materials have been used in many applications, i.e., electrical and electronic industries, due to their desirable electromagnetic characteristics. The performance of these materials in bulk form, where the size of grains is in micrometer scale, is only limited to a few megahertz frequencies due to their higher conductivity and domain wall resonance. Synthesizing the ferrite particles in nanometer scales before compacting them for sintering would be one way to solve using these materials at higher frequencies. The properties of ferrite depend mainly on the technique and conditions of preparation, which, in turn, affect the cation distribution over the tetrahedral and octahedral sites. Thus, the aim of this study was to introduce some methods used for synthesizing nanocrystalline soft magnetic ferrites. Furthermore, the microstructure features, i.e., grain sizes and porosities, which are influenced by the types of method used for preparation, playing key role on the magnetic properties of the sample, are also highlighted.

  12. Comparison of rose bengal-chloramphenicol and modified aureomycin-rose bengal-glucose-peptone agar as media for the enumeration of molds and yeasts in water by membrane filtration techniques.

    PubMed

    Albaum, Silva; Masaphy, Segula

    2009-03-01

    The present study compares the suitability of rose bengalchloramphenicol (RBCh) and modified aureomycin-rose bengal glucose-peptone agar for enumerating fungi recovered from diverse water sources using the membrane filtration method. Both mold and yeast colonies were established more rapidly, with more intensified colony colors and higher RBCh counts.

  13. Molded polymer solar water heater

    DOEpatents

    Bourne, Richard C.; Lee, Brian E.

    2004-11-09

    A solar water heater has a rotationally-molded water box and a glazing subassembly disposed over the water box that enhances solar gain and provides an insulating air space between the outside environment and the water box. When used with a pressurized water system, an internal heat exchanger is integrally molded within the water box. Mounting and connection hardware is included to provide a rapid and secure method of installation.

  14. Grain Refinement of Permanent Mold Cast Copper Base Alloys

    SciTech Connect

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

    2005-04-01

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

  15. Microstructure characterization of a food-grade U-type microemulsion system by differential scanning calorimetry and electrical conductivity techniques.

    PubMed

    Zhang, Hui; Taxipalati, Maierhaba; Que, Fei; Feng, Fengqin

    2013-12-01

    The microstructure transitions of a food-grade U-type microemulsion system containing glycerol monolaurate and propionic acid at a 1:1 mass ratio as oil phase and Tween 80 as surfactant were investigated along a water dilution line at a ratio of 80:20 mass% surfactant/oil phase, based on a previously studied phase diagram. From the water thermal behaviours detected by differential scanning calorimetry, three structural regions are identified along the dilution line. In the first region, all water molecules are confined to the water core of the reverse micelles, leading to the formation of w/o microemulsion. As the water content increases, the water gains mobility, transforms into bicontinuous in the second region, and finally the microemulsion become o/w in the third region. The thermal transition points coincide with the structural phase transitions by electrical conductivity measurements, indicating that the structural transitions occur at 35 and 65 mass% of water along the dilution line.

  16. Effects of process parameters on the molding quality of the micro-needle array

    NASA Astrophysics Data System (ADS)

    Qiu, Z. J.; Ma, Z.; Gao, S.

    2016-07-01

    Micro-needle array, which is used in medical applications, is a kind of typical injection molded products with microstructures. Due to its tiny micro-features size and high aspect ratios, it is more likely to produce short shots defects, leading to poor molding quality. The injection molding process of the micro-needle array was studied in this paper to find the effects of the process parameters on the molding quality of the micro-needle array and to provide theoretical guidance for practical production of high-quality products. With the shrinkage ratio and warpage of micro needles as the evaluation indices of the molding quality, the orthogonal experiment was conducted and the analysis of variance was carried out. According to the results, the contribution rates were calculated to determine the influence of various process parameters on molding quality. The single parameter method was used to analyse the main process parameter. It was found that the contribution rate of the holding pressure on shrinkage ratio and warpage reached 83.55% and 94.71% respectively, far higher than that of the other parameters. The study revealed that the holding pressure is the main factor which affects the molding quality of micro-needle array so that it should be focused on in order to obtain plastic parts with high quality in the practical production.

  17. Injection Molding and its application to drug delivery.

    PubMed

    Zema, Lucia; Loreti, Giulia; Melocchi, Alice; Maroni, Alessandra; Gazzaniga, Andrea

    2012-05-10

    Injection Molding (IM) consists in the injection, under high pressure conditions, of heat-induced softened materials into a mold cavity where they are shaped. The advantages the technique may offer in the development of drug products concern both production costs (no need for water or other solvents, continuous manufacturing, scalability, patentability) and technological/biopharmaceutical characteristics of the molded items (versatility of the design and composition, possibility of obtaining solid molecular dispersions/solutions of the active ingredient). In this article, process steps and formulation aspects relevant to IM are discussed, with emphasis on the issues and advantages connected with the transfer of this technique from the plastics industry to the production of conventional and controlled-release dosage forms. Moreover, its pharmaceutical applications thus far proposed in the primary literature, intended as either alternative manufacturing strategies for existing products or innovative systems with improved design and performance characteristics, are critically reviewed.

  18. Producing Zirconium Diboride Components with Complex, Near-Net Shape Geometries by Aqueous Room-Temperature Injection Molding

    NASA Technical Reports Server (NTRS)

    Wiesner, Valerie L.; Youngblood, Jeffrey; Trice, Rodney

    2014-01-01

    Room-temperature injection molding is proposed as a novel, low-cost and more energy efficient manufacturing process capable of forming complex-shaped zirconium diboride (ZrB2) parts. This innovative processing method utilized aqueous suspensions with high powder loading and a minimal amount (5 vol.) of water-soluble polyvinylpyrrolidone (PVP), which was used as a viscosity modifier. Rheological characterization was performed to evaluate the room-temperature flow properties of ZrB2-PVP suspensions. ZrB2 specimens were fabricated with high green body strength and were machinable prior to binder removal despite their low polymer content. After binder burnout and pressureless sintering, the bulk density and microstructure of specimens were characterized using Archimedes technique and scanning electron microscopy. X-Ray Diffraction was used to determine the phase compositions present in sintered specimens. Ultimate strength of sintered specimens will be determined using ASTM C1323-10 compressive C-ring test.

  19. Investigation of Heat Transfer at the Mold/Metal Interface in Permanent Mold Casting of Light Alloys

    SciTech Connect

    Robert D. Pehlke; John T. Berry

    2005-12-16

    Accurate modeling of the metal casting process prior to creating a mold design demands reliable knowledge of the interfacial heat transfer coefficient at the mold metal interface as a function of both time and location. The phenomena concerned with the gap forming between the mold and the solidifying metal are complex but need to be understood before any modeling is attempted. The presence of mold coatings further complicates the situation. A commercial casting was chosen and studied in a gravity permanent mold casting process. The metal/mold interfacial heat transfer coefficient (IHTC) was the focus of the research. A simple, direct method has been used to evaluate the IHTC. Both the simulation and experiments have shown that a reasonably good estimate of the heat transfer coefficient could be made in the case studied. It has been found that there is a good agreement between experiments and simulations in the temperature profiles during the solidification process, given that the primary mechanism of heat transfer across the gap in permanent mold casting of light alloys is by conduction across the gap. The procedure utilized to determine the interfacial heat transfer coefficient can be applied to other casting processes. A recently completed project involving The University of Michigan and Mississippi State University, together with several industrial partners, which was supported by the USDOE through the Cast Metals Coalition, examined a number of cases of thermal contact. In an investigation which gave special consideration to the techniques of measurement, several mold coatings were employed and results presented as a function of time. Realistic conditions of coating thickness and type together with an appropriate combination of mold preheat and metal pouring temperature were strictly maintained throughout the investigation. Temperature sensors, in particular thermocouples, play an important part in validating the predictions of solidification models. Cooling

  20. Effect of volatile removal during molding on the properties of two phenolic-fiber composites

    NASA Technical Reports Server (NTRS)

    Price, H. L.; Lucy, M. H.

    1974-01-01

    A comparison has been made of the effect of three volatile-removing techniques during molding on the properties of phenolic-fiber composites. The first technique involved heating the molding compound from one side, initiating the volatile-producing reactions, and driving these volatiles through the compound toward the cooler side. The second technique involved the application of a vacuum to the molding cavity before and during the cure cycle. The third technique was a combination of the first two. These techniques were used in the compression molding of phenolic-asbestos and phenolic-glass composites. The effects of both the individual and combined techniques on the mechanical, thermal, and sorption properties of the composites are reported.

  1. Microstructural study of the nickel-base alloy WAZ-20 using qualitative and quantitative electron optical techniques

    NASA Technical Reports Server (NTRS)

    Young, S. G.

    1973-01-01

    The NASA nickel-base alloy WAZ-20 was analyzed by advanced metallographic techniques to qualitatively and quantitatively characterize its phases and stability. The as-cast alloy contained primary gamma-prime, a coarse gamma-gamma prime eutectic, a gamma-fine gamma prime matrix, and MC carbides. A specimen aged at 870 C for 1000 hours contained these same constituents and a few widely scattered high W particles. No detrimental phases (such as sigma or mu) were observed. Scanning electron microscope, light metallography, and replica electron microscope methods are compared. The value of quantitative electron microprobe techniques such as spot and area analysis is demonstrated.

  2. Rotationally Molded Liquid Crystalline Polymers

    NASA Technical Reports Server (NTRS)

    Rogers, Martin; Scribben, Eric; Baird, Donald; Hulcher, Bruce

    2002-01-01

    Rotational molding is a unique process for producing hollow plastic parts. Rotational molding offers low cost tooling and can produce very large parts with complicated shapes. Products made by rotational molding include water tanks with capacities up to 20,000 gallons, truck bed liners, playground equipment, air ducts, Nylon fuel tanks, pipes, toys, stretchers, kayaks, pallets, and many others. Thermotropic liquid crystalline polymers are an important class of engineering resins employed in a wide variety of applications. Thermotropic liquid crystalline polymers resins are composed of semirigid, nearly linear polymeric chains resulting in an ordered mesomorphic phase between the crystalline solid and the isotropic liquid. Ordering of the rigid rod-like polymers in the melt phase yields microfibrous, self-reinforcing polymer structures with outstanding mechanical and thermal properties. Rotational molding of liquid crystalline polymer resins results in high strength and high temperature hollow structures useful in a variety of applications. Various fillers and reinforcements can potentially be added to improve properties of the hollow structures. This paper focuses on the process and properties of rotationally molded liquid crystalline polymers. This paper will also highlight the interactions between academia and small businesses in developing new products and processes.

  3. Rotationally Molded Liquid Crystalline Polymers

    NASA Technical Reports Server (NTRS)

    Rogers, Martin; Scribben, Eric; Baird, Donald; Hulcher, Bruce

    2002-01-01

    Rotational molding is a unique process for producing hollow plastic parts. Rotational molding offers low cost tooling and can produce very large parts with complicated shapes. Products made by rotational molding include water tanks with capacities up to 20,000 gallons, truck bed liners, playground equipment, air ducts, Nylon fuel tanks, pipes, toys, stretchers, kayaks, pallets, and many others. Thermotropic liquid crystalline polymers are an important class of engineering resins employed in a wide variety of applications. Thermotropic liquid crystalline polymers resins are composed of semirigid, nearly linear polymeric chains resulting in an ordered mesomorphic phase between the crystalline solid and the isotropic liquid. Ordering of the rigid rod-like polymers in the melt phase yields microfibrous, self-reinforcing polymer structures with outstanding mechanical and thermal properties. Rotational molding of liquid crystalline polymer resins results in high strength and high temperature hollow structures useful in a variety of applications. Various fillers and reinforcements can potentially be added to improve properties of the hollow structures. This paper focuses on the process and properties of rotationally molded liquid crystalline polymers. This paper will also highlight the interactions between academia and small businesses in developing new products and processes.

  4. Rotationally Molded Liquid Crystalline Polymers

    NASA Technical Reports Server (NTRS)

    Rogers, Martin; Stevenson, Paige; Scribben, Eric; Baird, Donald; Hulcher, Bruce

    2002-01-01

    Rotational molding is a unique process for producing hollow plastic parts. Rotational molding offers advantages of low cost tooling and can produce very large parts with complicated shapes. Products made by rotational molding include water tanks with capacities up to 20,000 gallons, truck bed liners, playground equipment, air ducts, Nylon fuel tanks, pipes, toys, stretchers, kayaks, pallets, and many others. Thermotropic liquid crystalline polymers are an important class of engineering resins employed in a wide variety of applications. Thermotropic liquid crystalline polymers resins are composed of semi-rigid, nearly linear polymeric chains resulting in an ordered mesomorphic phase between the crystalline solid and the isotropic liquid. Ordering of the rigid rod-like polymers in the melt phase yields microfibrous, self-reinforcing polymer structures with outstanding mechanical and thermal properties. Rotational molding of liquid crystalline polymer resins results in high strength and high temperature hollow structures useful in a variety of applications. Various fillers and reinforcements can potentially be added to improve properties of the hollow structures. This paper focuses on the process and properties of rotationally molded liquid crystalline polymers.

  5. Correlation Between Microstructure and Optical Properties of Cu (In0.7, Ga0.3) Se2 Grown by Electrodeposition Technique

    NASA Astrophysics Data System (ADS)

    Chihi, Adel; Bessais, Brahim

    2017-01-01

    Polycrystalline thin films Cu (In0.7, Ga0.3) Se2 (CIGSe) were grown on copper foils at various cathodic potentials by using an electrodeposition technique. Scanning electron microscopy showed that the average diameter of CIGSe grains increase from 0.1 μm to 1 μm when the cathodic potential decreases. The structure and surface morphology were investigated by x-ray diffraction and atomic force microscopy (AFM) techniques. This structure study shows that the thin films were well crystallized in a chalcopyrite structure without unwanted secondary phases with a preferred orientation along (112) plane. Energy-dispersive x-ray analyses confirms the existence of CIGSe single phase on a copper substrate. AFM analysis indicated that the root mean square roughness decreases from 64.28 to 27.42 when the potential deposition increases from -0.95 V to -0.77 V. Using Raman scattering spectroscopy, the A1 optical phonon mode was observed in 173 cm-1 and two other weak peaks were detected at 214 cm-1 and 225 cm-1 associated with the B2 and E modes of the CIGSe phase. Through spectroscopy ellipsometry analysis, a three-layer optical model was exploited to derive the optical properties and layer thickness of the CIGSe film by least-squares fitting the measured variation in polarization light versus the obtained microstructure.

  6. Application of an acoustoelectronic technique to study ordered microstructured disperse systems with biological objects in a hydrogel

    NASA Astrophysics Data System (ADS)

    Anisimkin, V. I.; Pokusaev, B. G.; Skladnev, D. A.; Sorokin, V. V.; Tyupa, D. V.

    2016-11-01

    Using acoustoelectronic sensors not containing sensitive coatings, we studied a series of microbiological preparations: yeast cells and bacteria, as well as virus particles, immobilized in hydrogels of different concentration. The obtained measurement data on the acoustic characteristics make it possible to (1) reveal the presence of biological objects in both fluid media and agarose-based hydrogels of various concentration; (2) establish the physical mechanism that results in acoustoelectronic detection; (3) evaluate changes in the concentration of biological objects and their electric conductivity. The data confirm the possibility of applying the acoustoelectronic technique to detect microbiological objects and observe their growth in hydrogel media. We discus the limitations and drawbacks of the acoustoelectronic technique.

  7. Microstructural evolution and surface properties of nanostructured Cu-based alloy by ultrasonic nanocrystalline surface modification technique

    NASA Astrophysics Data System (ADS)

    Amanov, Auezhan; Cho, In-Sik; Pyun, Young-Sik

    2016-12-01

    A nanostructured surface layer with a thickness of about 180 μm was successfully produced in Cu-based alloy using an ultrasonic nanocrystalline surface modification (UNSM) technique. Cu-based alloy was sintered onto low carbon steel using a powder metallurgy (P/M) method. Transmission electron microscope (TEM) characterization revealed that the severe plastic deformation introduced by UNSM technique resulted in nano-sized grains in the topmost surface layer and deformation twins. It was also found by atomic force microscope (AFM) observations that the UNSM technique provides a significant reduction in number of interconnected pores. The effectiveness of nanostructured surface layer on the tribological and micro-scratch properties of Cu-based alloy specimens was investigated using a ball-on-disk tribometer and micro-scratch tester, respectively. Results exhibited that the UNSM-treated specimen led to an improvement in tribological and micro-scratch properties compared to that of the sintered specimen, which may be attributed to the presence of nanostructured surface layer having an increase in surface hardness and reduction in surface roughness. The findings from this study are expected to be implemented to the automotive industry, in particular connected rod bearings and bushings in order to increase the efficiency and performance of internal combustion engines (ICEs).

  8. Long-Fiber Thermoplastic Injection Molded Composites: from Process Modeling to Property Prediction

    SciTech Connect

    Nguyen, Ba Nghiep; Holbery, Jim D.; Johnson, Kenneth I.; Smith, Mark T.

    2005-09-01

    Recently, long-fiber filled thermoplastics have become a great interest to the automotive industry since these materials offer much better property performance (e.g. elastic moduli, strength, durability…) than their short-fiber analogues, and they can be processed through injection molding with some specific tool design. However, in order that long-fiber thermoplastic injection molded composites can be used efficiently for automotive applications, there is a tremendous need to develop process and constitutive models as well as computational tools to predict the microstructure of the as-formed composite, and its resulting properties and macroscopic responses from processing to the final product. The microstructure and properties of such a composite are governed by i) flow-induced fiber orientation, ii) fiber breakage during injection molding, and iii) processing conditions (e,g. pressure, mold and melt temperatures, mold geometries, injection speed, etc.). This paper highlights our efforts to address these challenging issues. The work is an integrated part of a research program supported by the US Department of Energy, which includes • The development of process models for long-fiber filled thermoplastics, • The construction of an interface between process modeling and property prediction as well as the development of new constitutive models to perform linear and nonlinear structural analyses, • Experimental characterization of model parameters and verification of the model predictions.

  9. Staged mold for encapsulating hazardous wastes

    DOEpatents

    Unger, Samuel L.; Telles, Rodney W.; Lubowitz, Hyman R.

    1990-01-01

    A staged mold for stabilizing hazardous wastes for final disposal by molding an agglomerate of the hazardous wastes and encapsulating the agglomerate. Three stages are employed in the process. In the first stage, a first mold body is positioned on a first mold base, a mixture of the hazardous wastes and a thermosetting plastic is loaded into the mold, the mixture is mechanically compressed, heat is applied to cure the mixture to form a rigid agglomerate, and the first mold body is removed leaving the agglomerate sitting on the first mold base. In the second stage, a clamshell second mold body is positioned around the agglomerate and the first mold base, a powdered thermoplastic resin is poured on top of the agglomerate and in the gap between the sides of the agglomerate and the second mold body, the thermoplastic is compressed, heat is applied to melt the thermoplastic, and the plastic is cooled jacketing the agglomerate on the top and sides. In the third stage, the mold with the jacketed agglomerate is inverted, the first mold base is removed exposing the former bottom of the agglomerate, powdered thermoplastic is poured over the former bottom, the first mold base is replaced to compress the thermoplastic, heat is applied to melt the new thermoplastic and the top part of the jacket on the sides, the plastic is cooled jacketing the bottom and fusing with the jacketing on the sides to complete the seamless encapsulation of the agglomerate.

  10. Staged mold for encapsulating hazardous wastes

    DOEpatents

    Unger, Samuel L.; Telles, Rodney W.; Lubowitz, Hyman R.

    1988-01-01

    A staged mold for stabilizing hazardous wastes for final disposal by molding an agglomerate of the hazardous wastes and encapsulating the agglomerate. Three stages are employed in the process. In the first stage, a first mold body is positioned on a first mold base, a mixture of the hazardous wastes and a thermosetting plastic is loaded into the mold, the mixture is mechanically compressed, heat is applied to cure the mixture to form a rigid agglomerate, and the first mold body is removed leaving the agglomerate sitting on the first mold base. In the second stage, a clamshell second mold body is positioned around the agglomerate and the first mold base, a powdered thermoplastic resin is poured on top of the agglomerate and in the gap between the sides of the agglomerate and the second mold body, the thermoplastic is compressed, heat is applied to melt the thermoplastic, and the plastic is cooled jacketing the agglomerate on the top and sides. In the third stage, the mold with the jacketed agglomerate is inverted, the first mold base is removed exposing the former bottom of the agglomerate, powdered thermoplastic is poured over the former bottom, the first mold base is replaced to compress the thermoplastic, heat is applied to melt the new thermoplastic and the top part of the jacket on the sides, the plastic is cooled jacketing the bottom and fusing with the jacketing on the sides to complete the seamless encapsulation of the agglomerate.

  11. Flow behavior in liquid molding

    NASA Technical Reports Server (NTRS)

    Hunston, D.; Phelan, F.; Parnas, R.

    1992-01-01

    The liquid molding (LM) process for manufacturing polymer composites with structural properties has the potential to significantly lower fabrication costs and increase production rates. LM includes both resin transfer molding and structural reaction injection molding. To achieve this potential, however, the underlying science base must be improved to facilitate effective process optimization and implementation of on-line process control. The National Institute of Standards and Technology (NIST) has a major program in LM that includes materials characterization, process simulation models, on-line process monitoring and control, and the fabrication of test specimens. The results of this program are applied to real parts through cooperative projects with industry. The key feature in the effort is a comprehensive and integrated approach to the processing science aspects of LM. This paper briefly outlines the NIST program and uses several examples to illustrate the work.

  12. Fabrication of a roller type PDMS stamp using SU-8 concave molds and its application for roll contact printing

    NASA Astrophysics Data System (ADS)

    Park, Jongho; Kim, Beomjoon

    2016-03-01

    Continuous fabrication of micropatterns at low-cost is attracting attention in various applications within industrial fields. To meet such demands, we have demonstrated a roll contact printing technique, using roller type polydimethylsiloxane (PDMS) stamps with roll-to-flat and roll-to-roll stages. Roller type PDMS stamps for roll contact printing were fabricated using a custom-made metal support and SU-8 microstructures fabricated on concave substrates as a mold. The molding/casting method which we developed here provided faster and easier fabrication than conventional methods for roller type stamps. Next, roll contact printing was performed using fabricated roller type PDMS stamps with roll-to-flat and roll-to-roll stages. Patterns with minimum widths of 3 μm and 2.1 μm were continuously fabricated for each stage, respectively. In addition, the relationship between applied pressures and dimensional changes of roll contact printed patterns was investigated. Finally, we confirmed that roll contact printing and the new fabrication method for roller stamps presented in this study demonstrated the feasibility for industrial applications.

  13. Fabrication of rigid microstructures with thiol-ene-based soft lithography for continuous-flow cell lysis.

    PubMed

    Burke, Jeffrey M; Pandit, Kunal R; Goertz, John P; White, Ian M

    2014-09-01

    In this work, we introduce a method for the soft-lithography-based fabrication of rigid microstructures and a new, simple bonding technique for use as a continuous-flow cell lysis device. While on-chip cell lysis techniques have been reported previously, these techniques generally require a long on-chip residence time, and thus cannot be performed in a rapid, continuous-flow manner. Microstructured microfluidic devices can perform mechanical lysis of cells, enabling continuous-flow lysis; however, rigid silicon-based devices require complex and expensive fabrication of each device, while polydimethylsiloxane (PMDS), the most common material used for soft lithography fabrication, is not rigid and expands under the pressures required, resulting in poor lysis performance. Here, we demonstrate the fabrication of microfluidic microstructures from off-stoichiometry thiol-ene (OSTE) polymer using soft-lithography replica molding combined with a post-assembly cure for easy bonding. With finite element simulations, we show that the rigid microstructures generate an energy dissipation rate of nearly 10(7), which is sufficient for continuous-flow cell lysis. Correspondingly, with the OSTE device we achieve lysis of highly deformable MDA-MB-231 breast cancer cells at a rate of 85%, while a comparable PDMS device leads to a lysis rate of only 40%.

  14. Fabricating microfluidic valve master molds in SU-8 photoresist

    NASA Astrophysics Data System (ADS)

    Dy, Aaron J.; Cosmanescu, Alin; Sluka, James; Glazier, James A.; Stupack, Dwayne; Amarie, Dragos

    2014-05-01

    Multilayer soft lithography has become a powerful tool in analytical chemistry, biochemistry, material and life sciences, and medical research. Complex fluidic micro-circuits require reliable components that integrate easily into microchips. We introduce two novel approaches to master mold fabrication for constructing in-line micro-valves using SU-8. Our fabrication techniques enable robust and versatile integration of many lab-on-a-chip functions including filters, mixers, pumps, stream focusing and cell-culture chambers, with in-line valves. SU-8 created more robust valve master molds than the conventional positive photoresists used in multilayer soft lithography, but maintained the advantages of biocompatibility and rapid prototyping. As an example, we used valve master molds made of SU-8 to fabricate PDMS chips capable of precisely controlling beads or cells in solution.

  15. Contamination Barrier For Contour-Molding Material

    NASA Technical Reports Server (NTRS)

    Adams, James F.

    1988-01-01

    Release agent prevents molding compound from adhering to or contaminating surface. Cleaning agent, Turco 4215 NCLT, forms barrier preventing silicone molding compound from sticking to surface and leaving contaminating residue. Also see MFS-29243.

  16. National Allergy Bureau Pollen and Mold Report

    MedlinePlus

    ... Search Search AAAAI National Allergy Bureau Pollen and Mold Report Date: April 12, 2017 Location: San Antonio ( ... Service can automatically email you daily pollen and mold reports. Click here sign up! Return to Map ...

  17. Microstructural analysis of 800H steel exposed at test operation in HTHL by using FIB-SEM and HRTEM techniques

    NASA Astrophysics Data System (ADS)

    Marušáková, Daniela; Bublíková, Petra; Berka, Jan; Vávrovcová, Zuzana; Burda, Jaroslav

    2017-09-01

    To understand the degradation process of metal materials which are used in power engineering, appropriate evaluation procedure is necessary to ensure. In that order, the degradation of alloy 800H during the first period of test operation in High Temperature Helium Loop (HTHL) was tested. Experiment was carried out in atmosphere of pure technical helium with purity 4.6 containing only residual concentration of moisture up to 300 vppm. Parameters during the operation test were not constant, process was interrupted several times. The maximum temperature on specimens during this period was 750 °C, average temperature was 460 °C, gas pressure ranged from 3 to 6 MPa and gas flow from 3 to 9 gs-1. Total duration of the test was 264 h. After the exposure the degradation of specimens was investigated by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Using the technique of Focused Ion Beam (FIB) integrated within SEM the transparent samples with quality surface parameters were obtained for TEM analysis. FIB technique in combination with High Resolution TEM ensured the guaranteed methodology of exposed sample preparation and precise description of changes in this kind of material.

  18. 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.

  19. 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.

  20. Breath Figure Micromolding Approach for Regulating the Microstructures of Polymeric Films for Triboelectric Nanogenerators.

    PubMed

    Gong, Jianliang; Xu, Bingang; Tao, Xiaoming

    2017-02-08

    A triboelectric nanogenerator (TENG) is an innovative kind of energy harvester recently developed on the basis of organic materials for converting mechanical energy into electricity through the combined use of the triboelectric effect and electrostatic induction. Polymeric materials and their microstructures play key roles in the generation, accumulation, and retainment of triboelectric charges, which decisively determines the final electric performance of TENGs. Herein we report a simple and efficient breath figure (BF) micromolding approach to rapidly regulate the surface microstructures of polymeric films for the assembly of TENGs. Honeycomb porous films with adjustable pore size and dimensional architectures were first prepared by the BF technique through simply adjusting the concentration of the polymer solution. They were then used as negative molds for straightforward synthesis of polydimethylsiloxane (PDMS) films with different microlens arrays (MLAs) and lens sizes, which were further assembled for TENGs to investigate the influence of film microstructures. All MLA-based TENGs were found to have an obviously enhanced electric performance in comparison with a flat-PDMS-film-based TENG. Specifically, up to 3 times improvement in the electric performance can be achieved by the MLA-based TENG with optimal surface microstructures over flat-PDMS-film-based TENG under the same triggering conditions. A MLA-based TENG was further successfully used to harvest the waste mechanical energy generated by different human body motions, including finger tapping, hand clapping, and walking with a frequency ranging from 0.5 to 5.5 Hz.

  1. MOLD-SPECIFIC QUANTITATIVE PCR: THE EMERGING STANDARD IN MOLD ANALYSIS

    EPA Science Inventory

    Molds can cause health problems like infections and allergies, destroy crops, and contaminate our food or pharmaceuticals. We can't avoid molds. Molds are essential players in the biological processes on earth, but we can now identify and quantify the molds that will be most pr...

  2. MOLD-SPECIFIC QUANTITATIVE PCR: THE EMERGING STANDARD IN MOLD ANALYSIS

    EPA Science Inventory

    Molds can cause health problems like infections and allergies, destroy crops, and contaminate our food or pharmaceuticals. We can't avoid molds. Molds are essential players in the biological processes on earth, but we can now identify and quantify the molds that will be most pr...

  3. Blow molding of melt processible rubber

    SciTech Connect

    Abell, W.R.; Stuart, R.E.; Myrick, R.E.

    1991-07-01

    This article discusses the advantages of making hollow rubber parts by blow molding thermoplastic elastomers (TPEs) versus conventional rubber processing. It describes the various types of blow molding processes and it provides some insight into the rheological properties of melt processible rubber (MPR) and how MPR should be molded by each of these processes. A number of blow molded applications for MPR are also discussed.

  4. Making Internal Molds Of Long, Curved Tubes

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.

    1989-01-01

    Mold material carried to internal weld joint and removed after impression taken. Remotely operated device makes impression mold of interior surface of tube at weld joint. Mold provides indication of extent of mismatch between members at joint. Maneuvered to weld inspected through curved tube 3 in. in diameter by 50 in. long. Readily adapted to making molds to measure depth of corrosion in boiler tubes or other pipes.

  5. Making Internal Molds Of Long, Curved Tubes

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.

    1989-01-01

    Mold material carried to internal weld joint and removed after impression taken. Remotely operated device makes impression mold of interior surface of tube at weld joint. Mold provides indication of extent of mismatch between members at joint. Maneuvered to weld inspected through curved tube 3 in. in diameter by 50 in. long. Readily adapted to making molds to measure depth of corrosion in boiler tubes or other pipes.

  6. Processing-microstructure models for short- and long-fiber thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Phelps, Jay H.

    The research for this thesis has explored the important microstructural variables for injection-molded thermoplastic composites with discontinuous fiber reinforcement. Two variables, the distributions of fiber orientation and fiber length after processing, have proven to be not only important for correct material property prediction but also difficult to predict using currently available modeling and simulation techniques. In this work, we develop new models for the prediction of these two microstructural variables. Previously, the Folgar-Tucker model has been widely used to predict fiber orientation in injection molded SFT composites. This model accounts for the effects of both hydrodynamics and fiber-fiber interactions in order to give a prediction for a tensorial measure of fiber orientation. However, when applied to at least some classes of LFTs, this model does not match all components of experimental fiber orientation tensor data. In order to address this shortcoming of the model, we hypothesize that Folgar and Tucker's phenomenological treatment of the effects of fiber-fiber interactions with an isotropic rotary diffusion contribution to the rate of change of orientation is insufficient for materials with longer fibers. Instead, this work develops a fiber orientation model that incorporates anisotropic rotary diffusion (ARD). From kinetic theory we derive a general family of evolution equations for the second-order orientation tensor, correcting errors in earlier treatments, and identify a specific equation that is useful for predicting orientation in LFTs. The amount of diffusivity in this model used to approximate the effect of fiber-fiber interactions in each direction is assumed to depend on a second-order space tensor, which is taken to be a function of the orientation state and the rate of deformation. Also, concentrated fiber suspensions align more slowly with respect to strain than the Folgar-Tucker model predicts. Here, we borrow the technique of

  7. Improved compression molding technology for continuous fiber reinforced composite laminates. Part 2: AS-4/Polyimidesulfone prepreg system

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M.; Hou, Tan-Hung; Kidder, Paul W.; Reddy, Rakasi M.

    1991-01-01

    AS-4/polyimidesulfone (PISO2) composite prepreg was utilized for the improved compression molding technology investigation. This improved technique employed molding stops which advantageously facilitate the escape of volatile by-products during the B-stage curing step, and effectively minimize the neutralization of the consolidating pressure by intimate interply fiber-fiber contact within the laminate in the subsequent molding cycle. Without the modifying the resin matrix properties, composite panels with both unidirectional and angled plies with outstanding C-scans and mechanical properties were successfully molded using moderate molding conditions, i.e., 660 F and 500 psi, using this technique. The size of the panels molded were up to 6.00 x 6.00 x 0.07 in. A consolidation theory was proposed for the understanding and advancement of the processing science. Processing parameters such as vacuum, pressure cycle design, prepreg quality, etc. were explored.

  8. Mold inhibition on unseasoned southern pine

    Treesearch

    Carol A. Clausen; Vina W. Yang

    2003-01-01

    Concerns about indoor air quality due to mold growth have increased dramatically in the United States. In the absence of moisture management, fungicides need to be developed for indoor use to control mold establishment. An ideal fungicide for prevention of indoor mold growth on wood-based materials needs to specifically prevent spore germination and provide long-term...

  9. HOW to Recognize and Control Sooty Molds

    Treesearch

    Kenneth J. Jr. Kessler

    1992-01-01

    Sooty molds are dark fungi that grow on honeydew excreted by sucking insects or on exudates from leaves of certain plants. Typically, sooty mold growths are composed of fungal complexes made up of ascomycetes and fungi imperfecti. Some of the common genera of fungi found in sooty mold complexes are Cladosporium, Aureobasidium, Antennariella, Limacinula, Scorias, and...

  10. The Mold that Almost Ate the Principal

    ERIC Educational Resources Information Center

    Barry, Wayne; Bishop, Chuck; Byars, Jennifer

    2006-01-01

    New-building mold was a bane for many home construction companies and new homeowners during the 1990s. It was not unusual to read or watch the news and see the tragedy played out in one's local community. Untold, however, is the story of the toll new-building mold can take on school systems and their principals, especially as these mold problems…

  11. Planning an Injection Mold Design Training Program.

    ERIC Educational Resources Information Center

    Allyn, Edward P.

    With the increased use of plastics worldwide the shortage of trained personnel in moldmaking and design for plastic injection molds is becoming critical. Local schools and community colleges should provide courses in mold design and mold making, since most workers presently learn while working under experienced designers on the job. Following this…

  12. Snow Mold Investigations in Eastern Washington

    Treesearch

    T. H. Filer; A. G. Law

    1961-01-01

    "Snow mold of turf" in the Pacific Northwest must include both Fusarium Patch caused by Calonectria graminicola (Berk and Br.) (conidial stage Fusarium nivale (Fr. ) CES.), and Gray snow mold caused by Typhula itoana Imai, which occur together to give a disease complex. Snow mold of turf is the most...

  13. The Mold that Almost Ate the Principal

    ERIC Educational Resources Information Center

    Barry, Wayne; Bishop, Chuck; Byars, Jennifer

    2006-01-01

    New-building mold was a bane for many home construction companies and new homeowners during the 1990s. It was not unusual to read or watch the news and see the tragedy played out in one's local community. Untold, however, is the story of the toll new-building mold can take on school systems and their principals, especially as these mold problems…

  14. Injection Molding of Plastics from Agricultural Materials

    SciTech Connect

    Bhattacharya, M.; Ruan, R.

    2001-02-22

    The objective of this research was to conduct a systematic study to relate injection molding parameters to properties of blends of starch and synthetic polymer. From this study, we wished to develop a thorough understanding of the injection molding process and gain significant insight into designing molds and aiding in developing products cheaply and efficiently.

  15. Attack of the Killer Mold Spores.

    ERIC Educational Resources Information Center

    Moore, Mary

    1999-01-01

    Describes experiences at the Arkansas State University at Jonesboro library when mold was discovered in a large portion of the monograph collection. Discusses causes of mold formation, equipment needed, news media coverage, staff involvement in the cleanup, and possible health hazards from mold. (LRW)

  16. Investigation of Properties of Powder Injection-Molded Steatites

    NASA Astrophysics Data System (ADS)

    Urtekin, L.; Uslan, I.; Tuc, B.

    2012-03-01

    In this study, the mechanical and micro-structural properties of injection-molded steatites were investigated experimentally. Initially, steatite powders and binders of polyethylene glycol (PEG), polypropylene (PP), and stearic aside (SA) were mixed to prepare the feedstock. The mixing powders were granulated using the extruder. The short granules in cylindrical shapes were used as the feedstock in the injection-molding operations. Solvent- and thermal-debinding processes were applied to the green samples after the molding. The samples were sintered at 1300 °C for 4 h, and a theoretical density of 98-99% was achieved. Three-point bending and tensile tests were performed on the samples which were sintered at 1200-1300 °C. The maximum three-point bending and tensile strength values were found as 154 and 47 MPa, respectively. The morphology of fractured surface was done by scanning electron microscopy whereas porosity investigations were carried out using the same microscopy. Grain growth and structure on the specimens were also investigated using transmission electron microscopy.

  17. Absorptivity of molded soil-improving agents based on brown coals and zeolites

    SciTech Connect

    Aleksandrov, I.V.; Kossov, I.I.

    1993-12-31

    The objective of this work was to create a new technique for producing molded soil-improving agents based on brown coal from the Adunchulun deposit, and to determine the soil-improving properties of the obtained compositions.

  18. Influence of the local morphology on the surface tension of injection molded polypropylene

    NASA Astrophysics Data System (ADS)

    Gomes, M.; Pontes, A. J.; Viana, J. C.

    2014-05-01

    In this work, we investigate the development of the morphology of an injection molding polypropylene under the local thermomechanical environment imposed during processing, and its effect on the contact angle and, hence, on the surface tension of the moldings. Melt and mold temperatures were varied in two levels. The local thermomechanical environment was characterized by mold filling computational simulations that allow the calculation of thermomechanical variables (e.g., local temperatures, shear stresses) and indices (related to the local morphology development). In order to investigate the structural hierarchy variations of the moldings in the thickness direction, samples from skin to core were used. The molecular orientation and degree of crystallinity were determined as function of the thickness, as well as the contact angle. The variations of the degree of crystallinity were assessed by differential scanning calorimetry. The level of molecular orientation was evaluated by birefringence measurements. The contact angles were measured in deionized water by sessile drop (needle in) method at room temperature, to determine the wettability of the samples. The contact angles were found to vary along the molding thickness in the skin, transition and core layers. These variations are related to the local morphologies developed. Results suggest that water contact angle increases with the level of molecular orientation and for finer microstructures.

  19. ALLERGIC POTENTIAL OF INDOOR MOLDS

    EPA Science Inventory

    Many fungi have been associated with allergic lung disease, but few are well studied and even fewer allergens of fungal origin are well characterized. Exposure to damp moldy environments has been associated with the exacerbation of asthma, but the role of molds in the induction o...

  20. ALLERGIC POTENTIAL OF INDOOR MOLDS

    EPA Science Inventory

    Many fungi have been associated with allergic lung disease, but few are well studied and even fewer allergens of fungal origin are well characterized. Exposure to damp moldy environments has been associated with the exacerbation of asthma, but the role of molds in the induction o...

  1. Molded Concrete Center Mine Wall

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1987-01-01

    Proposed semiautomatic system forms concrete-foam wall along middle of coal-mine passage. Wall helps support roof and divides passage into two conduits needed for ventilation of coal face. Mobile mold and concrete-foam generator form sections of wall in place.

  2. Mold production for polymer optics

    NASA Astrophysics Data System (ADS)

    Boerret, Rainer; Raab, Jonas; Speich, Marco

    2014-09-01

    The fields of application for polymer optics are huge and thus the need for polymer optics is steadily growing. Most polymer optics are produced in high numbers by injection molding. Therefore molds and dies that fulfill special requirements are needed. Polishing is usually the last process in the common process chain for production of molds for polymer optics. Usually this process step is done manually by experienced polishers. Due to the small number of skilled professionals and health problems because of the monotonous work the idea was to support or probably supersede manual polishing. Polishing using an industrial robot as movement system enables totally new possibilities in automated polishing. This work focuses on the surface generation with a newly designed polishing setup and on the code generation for the robot movement. The process starts on ground surfaces and with different tools and polishing agents surfaces that fulfill the requirements for injection molding of optics can be achieved. To achieve this the attention has to be focused not only on the process itself but also on tool path generation. A proprietary software developed in the Centre for Optical Technologies in Aalen University allows the tool path generation on almost any surface. This allows the usage of the newly developed polishing processes on different surfaces and enables an easy adaption. Details of process and software development will be presented as well as results from different polishing tests on different surfaces.

  3. Is Mold the New Asbestos?

    ERIC Educational Resources Information Center

    Colgan, Craig

    2003-01-01

    Mold and indoor air quality (IAQ) are matters of major concern to architects and their educational clients. The Environmental Protection Agency's Indoor Air Quality Tools for Schools program offers help to districts seeking to tackle IAQ issues. Strengthening community relations is one way to be ready in case of a bad environmental or IAQ report.…

  4. ANIMAL MODELS OF MOLD ALLERGY

    EPA Science Inventory

    The concept of molds as causative agents for allergy/asthma is not new. In fact many fungal genera have been associated with allergic lung disease, but only a few fungi are well studied and even fewer fungal allergens well characterized. The complexity and variety of fungal pro...

  5. Molded Concrete Center Mine Wall

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1987-01-01

    Proposed semiautomatic system forms concrete-foam wall along middle of coal-mine passage. Wall helps support roof and divides passage into two conduits needed for ventilation of coal face. Mobile mold and concrete-foam generator form sections of wall in place.

  6. Is Mold the New Asbestos?

    ERIC Educational Resources Information Center

    Colgan, Craig

    2003-01-01

    Mold and indoor air quality (IAQ) are matters of major concern to architects and their educational clients. The Environmental Protection Agency's Indoor Air Quality Tools for Schools program offers help to districts seeking to tackle IAQ issues. Strengthening community relations is one way to be ready in case of a bad environmental or IAQ report.…

  7. ANIMAL MODELS OF MOLD ALLERGY

    EPA Science Inventory

    The concept of molds as causative agents for allergy/asthma is not new. In fact many fungal genera have been associated with allergic lung disease, but only a few fungi are well studied and even fewer fungal allergens well characterized. The complexity and variety of fungal pro...

  8. Application of the multi-step EPD technique to fabricate thick TiO2 layers: effect of organic medium viscosity on the layer microstructure.

    PubMed

    Sadeghi, A A; Ebadzadeh, T; Raissi, B; Ghashghaie, S; Fateminia, S M A

    2013-02-14

    In the present study, electrophoretic deposition (EPD) was used to obtain dense layers of TiO(2) in four organic media-methanol, ethanol, 1-propanol, and butanol-with different TiO(2) nanoparticle concenterations of 1-8 g/L. Microstructural study of the obtained layers by scanning electron (SEM) and optical microscope (OM) revealed that the multistep EPD technique could effectively prevent crack formation across the layer compared with the single-step method and will consequently increase the critical cracking thickness (CCT). The quality of EPD layers was also affected by viscosity. According to SEM and atomic force microscope (AFM) results, as the viscosity of the medium increased, more compact layers were formed which can be attributed to the lower deposition rates in heavier alcohols. High deposition rate in methanol and ethanol was also confirmed by zeta potential results. Suspension viscosity was interestingly observed to control the threshold concentration above which crack formation would occur. These values were measured to be 3 and 5 g/L for methanol and ethanol, respectively. However, in suspensions based on more viscous alcohols, the threshold concentration increased to 8 g/L which implied the decisive role of medium on concentration limits. It indicates that by employing organic vehicles of higher viscosity it is possible to maintain the CCT values obtained in less viscous media with no need to decrease the colloidal concentration of the suspension.

  9. Effect of C2H2 flow rate on microstructure and properties of nc-Cu/a-C:H nanocomposite films prepared by filtered cathodic vaccum arc technique

    NASA Astrophysics Data System (ADS)

    Zhang, Haiqiang; Chen, Yiming; Liao, Bin; Wu, Xianying; Zhang, Huixing; Zhang, Xu

    2013-07-01

    Nc-Cu/a-C:H nanocomposite films are deposited by filtered cathodic vaccum arc (FCVA) technique using C2H2 as the precursor. The effects of C2H2 flow rate on the microstructure, composition and properties of nc-Cu/a-C:H films have been studied by Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and nanoindentation test. In these films, copper nanoparticles (3.5-15 nm) are embedded in the amorphous carbon matrix, which could be confirmed by XRD analysis. Raman spectroscopy and XPS results confirm the decrease of sp3 content with the increasing copper fraction, which could be a result of more severe thermalization on carbon matrix owing to the presence of copper. The compressive stresses of these films, calculated by Stoney's equation, are found to be as low as 0.5 Gpa, declining with the increasing copper content. Nanoindentation measurements reveal that the film hardness falls monotonically as the Cu content in the films increases.

  10. Investigation of microstructural and physical characteristics of nano composite tin oxide-doped Al3+ in Zn2+ based composite coating by DAECD technique

    NASA Astrophysics Data System (ADS)

    Anawe, P. A. L.; Fayomi, O. S. I.; Popoola, A. P. I.

    In other to overcome the devastating deterioration of mild steel in service, Zn-based embedded Al/SnO2 composite coatings have been considered as reinforcing alternative replacements to the more traditional deposition for improved surface properties by using Dual Anode Electrolytic Co-deposition (DAECD) technique from chloride bath. The structural characterization of the starting materials and deposited coating are evaluated using scanning electron microscopy (SEM), equipped with energy dispersive X-ray spectroscopy (EDX) elemental analysis and atomic force microscope (AFM). The hardness behaviour, wear and intermetallic distribution was examined by diamond based microhardness tester, CETR reciprocating sliding test rig and X-ray diffractometer (XRD) respectively. The corrosion properties of the developed coating were examined in 3.5% NaCl. The microstructure of the deposited sample obtained at 7% SnO2, revealed fine-grains deposit of the Al/SnO2 on the mild steel surface. The results showed that the Al/SnO2 strengthening alloy plays a significant role in impelling the wear and corrosion behaviour of Zn-Al/SnO2 coatings in an aggressive saline environment. Interestingly Zn-30Al-7Sn-chloride showed the highest wear and improved corrosion resistance due to Al/SnO2 oxide passive film that forms during anodic polarization. This work established that co-deposition of mild steel with Al/SnO2 is auspicious in increasing the anti-wear and corrosion progression.

  11. Micro-structural characterization of black crust and laser cleaning of building stones by micro-Raman and SEM techniques.

    PubMed

    Potgieter-Vermaak, S S; Godoi, R H M; Grieken, R Van; Potgieter, J H; Oujja, M; Castillejo, M

    2005-09-01

    Research concerning the formation and removal of black crusts on various historical objects is approached from many different angles. The so-called "yellowing effect", observed after laser treatment for cleaning purposes, has also received a lot of attention. Evidence regarding this phenomenon differs considerably and the actual mechanisms are still speculated on by researchers. In an attempt to elucidate the processes involved in the yellowing effect associated with laser cleaning, a new analytical technique has been used to investigate the black crust, a region of the sample cleaned by laser irradiation at 1064 nm and another region of the same sample subjected to further laser irradiation at 355 nm, on a limestone sample from the cathedral of Seville in Spain. Micro-Raman spectrometry offers the advantage of spatial chemical characterization of the stone, based upon its molecular makeup and was performed on the bulk body of the stone. Raman and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDXS) results indicate that the surfaces cleaned by irradiation at 1064 nm and by double irradiation at 1064 and 355 nm differed in terms of their calcium sulphate, calcium oxalate and iron oxide content, and that this could contribute to the difference in colour observed.

  12. Development in corrosion resistance by microstructural refinement in Zr-16 SS 304 alloy using suction casting technique

    SciTech Connect

    Das, N. Sengupta, P.; Abraham, G.; Arya, A.; Kain, V.; Dey, G.K.

    2016-08-15

    Highlights: • Grain refinement was made in Zr–16 wt.% SS alloy while prepared by suction casting process. • Distribution of Laves phase, e.g., Zr{sub 2}(Fe, Cr) was raised in suction cast (SC) Zr–16 wt.% SS. • Corrosion resistance was improved in SC alloy compared to that of arc-melt-cast alloy. • Grain refinement in SC alloy assisted for an increase in its corrosion resistance. - Abstract: Zirconium (Zr)-stainless steel (SS) hybrid alloys are being considered as baseline alloys for developing metallic-waste-form (MWF) with the motivation of disposing of Zr and SS base nuclear metallic wastes. Zr–16 wt.% SS, a MWF alloy optimized from previous studies, exhibit significant grain refinement and changes in phase assemblages (soft phase: Zr{sub 2}(Fe, Cr)/α-Zr vs. hard phase: Zr{sub 3}(Fe, Ni)) when prepared by suction casting (SC) technique in comparison to arc-cast-melt (AMC) route. Variation in Cr-distribution among different phases are found to be low in suction cast alloy, which along with grain refinement restricted Cr-depletion at the Zr{sub 2}(Fe, Cr)/Zr interfaces, prone to localized attack. Hence, SC alloy, compared to AMC alloy, showed lower current density, higher potential at the breakdown of passivity and higher corrosion potential during polarization experiments (carried out under possible geological repository environments, viz., pH 8, 5 and 1) indicating its superior corrosion resistance.

  13. Micro-structural characterization of black crust and laser cleaning of building stones by micro-Raman and SEM techniques

    NASA Astrophysics Data System (ADS)

    Potgieter-Vermaak, S. S.; Godoi, R. H. M.; Grieken, R. Van; Potgieter, J. H.; Oujja, M.; Castillejo, M.

    2005-09-01

    Research concerning the formation and removal of black crusts on various historical objects is approached from many different angles. The so-called "yellowing effect", observed after laser treatment for cleaning purposes, has also received a lot of attention. Evidence regarding this phenomenon differs considerably and the actual mechanisms are still speculated on by researchers. In an attempt to elucidate the processes involved in the yellowing effect associated with laser cleaning, a new analytical technique has been used to investigate the black crust, a region of the sample cleaned by laser irradiation at 1064 nm and another region of the same sample subjected to further laser irradiation at 355 nm, on a limestone sample from the cathedral of Seville in Spain. Micro-Raman spectrometry offers the advantage of spatial chemical characterization of the stone, based upon its molecular makeup and was performed on the bulk body of the stone. Raman and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDXS) results indicate that the surfaces cleaned by irradiation at 1064 nm and by double irradiation at 1064 and 355 nm differed in terms of their calcium sulphate, calcium oxalate and iron oxide content, and that this could contribute to the difference in colour observed.

  14. High-precision micromilling for low-cost fabrication of metal mold masters

    NASA Astrophysics Data System (ADS)

    Hupert, Mateusz L.; Guy, W. J.; Llopis, Shawn D.; Situma, Catherine; Rani, Sudheer; Nikitopoulos, Dimitris E.; Soper, Steven A.

    2006-01-01

    High-precision micromilling was employed as a cost-efficient method preparation of metal masters useful in fabrication of polymer microfluidic devices through replication techniques. In first application, a brass mold master was used for hot embossing of microchip electrophoresis devices in poly(methyl methacrylate) (PMMA). The sidewalls of the milled microstructures were characterized by a maximum average roughness (R a) of 110 nm and mean peak height (R pm) of 320 nm. SEM imaging showed a transfer of the sidewall roughness from the molding tool to the polymer microdevice. The electroosmotic flow (EOF) values for micromilled-based microchannels were comparable to ones in the LiGA-prepared devices (sidewall R a = 20 nm) with values of ca. 3.7 x 10 -4 cm2V -1s -1 (20 mM TBE buffer, pH 8.2), indicating insignificant effects of wall roughness on the bulk EOF. Numerical simulations showed that the additional volumes present in an injection cross due to curvature of the corners produced by micromilling lead to elongated sample plugs. PMMA microchip electrophoresis devices were used for a separation of pUC19 Sau3AI double-stranded DNA. The plate numbers achieved exceeded 1 million m -1 and were comparable to the plate numbers for the LiGA-based devices of similar geometry. In second application brass master was used as tool for preparation of poly(dimethylsiloxane) PDMS stencils for patterning of DNA microarrays onto a PMMA substrate. Four zip code probes immobilized onto the PMMA surface directed allele-specic ligation products containing mutations in the KRAS2 gene (12.2D, 12.2A, 12.2V, and 13.4D) to the appropriate address of a universal array with minimal amounts of crosshybridization or misligation.

  15. Analysis of shell thickness irregularity in continuously cast middle carbon steel slabs using mold thermocouple data

    SciTech Connect

    Suni, J.P.; Henein, H.

    1996-12-01

    Thermocouples buried in the mold wall of a continuous caster are used to investigate the nature and source of shell thickness irregularity in middle carbon steel slabs. Fourier analysis is used in conjunction with digital filters to determine the power spectra of time series mold temperature and mold level measurements. Direct evidence is obtained on the physical dimension of irregularity, as well as the phase relationships between neighboring thermocouples in both the transverse and longitudinal directions. In addition, mold thermocouple readings are used to set the boundary heat flux conditions for use in self-consistent mathematical modeling of mold thermal profiles. Temperature readings--average, minimum, and maximum--allow for the calculation of an envelope of shell thicknesses around the average distribution. These techniques are used to help explain a mechanism for the occurrence of shell thickness irregularity, in terms of both meniscus disturbances and shell deflections in response to such disturbances.

  16. Method for collecting spores from a mold

    DOEpatents

    Au, Frederick H. F.; Beckert, Werner F.

    1977-01-01

    A technique and apparatus used therewith for determining the uptake of plutonium and other contaminants by soil microorganisms which, in turn, gives a measure of the plutonium and/or other contaminants available to the biosphere at that particular time. A measured quantity of uncontaminated spores of a selected mold is added to a moistened sample of the soil to be tested. The mixture is allowed to sit a predetermined number of days under specified temperature conditions. An agar layer is then applied to the top of the sample. After three or more days, when spores of the mold growing in the sample have formed, the spores are collected by a miniature vacuum collection apparatus operated under preselected vacuum conditions, which collect only the spores with essentially no contamination by mycelial fragments or culture medium. After collection, the fungal spores are dried and analyzed for the plutonium and/or other contaminants. The apparatus is also suitable for collection of pollen, small insects, dust and other small particles, material from thin-layer chromatography plates, etc.

  17. The cellular slime mold: eukaryotic model microorganism.

    PubMed

    Urushihara, Hideko

    2009-04-01

    Cellular slime molds are eukaryotic microorganisms in the soil. They feed on bacteria as solitary amoebae but conditionally construct multicellular forms in which cell differentiation takes place. Therefore, they are attractive for the study of fundamental biological phenomena such as phagocytosis, cell division, chemotactic movements, intercellular communication, cell differentiation, and morphogenesis. The most widely used species, Dictyostelium discoideum, is highly amenable to experimental manipulation and can be used with most recent molecular biological techniques. Its genome and cDNA analyses have been completed and well-annotated data are publicly available. A larger number of orthologues of human disease-related genes were found in D. discoideum than in yeast. Moreover, some pathogenic bacteria infect Dictyostelium amoebae. Thus, this microorganism can also offer a good experimental system for biomedical research. The resources of cellular slime molds, standard strains, mutants, and genes are maintained and distributed upon request by the core center of the National BioResource Project (NBRP-nenkin) to support Dictyostelium community users as well as new users interested in new platforms for research and/or phylogenic consideration.

  18. Precision injection molding of freeform optics

    NASA Astrophysics Data System (ADS)

    Fang, Fengzhou; Zhang, Nan; Zhang, Xiaodong

    2016-08-01

    Precision injection molding is the most efficient mass production technology for manufacturing plastic optics. Applications of plastic optics in field of imaging, illumination, and concentration demonstrate a variety of complex surface forms, developing from conventional plano and spherical surfaces to aspheric and freeform surfaces. It requires high optical quality with high form accuracy and lower residual stresses, which challenges both optical tool inserts machining and precision injection molding process. The present paper reviews recent progress in mold tool machining and precision injection molding, with more emphasis on precision injection molding. The challenges and future development trend are also discussed.

  19. HIGH TEMPERATURE REFRACTORY COATING FOR GRAPHITE MOLDS

    DOEpatents

    Stoddard, S.D.

    1958-10-21

    An improved foundry mold coating for use with graphite molds used in the casting of uranium is presented. The refractory mold coating serves to keep the molten uranium from contact with graphite of the mold and thus prevents carbon pickup by the molten metal. The refractory coating is made by dry mixing certain specific amounts of aluminum oxide, bentonite, Tennessee ball clay, and a soluble silicate salt. Water is then added to the mixture and the suspension thus formed is applied by spraying onto the mold.

  20. Heat transfer and microstructure during the early stages of metal solidification

    NASA Astrophysics Data System (ADS)

    Muojekwu, C. A.; Samarasekera, I. V.; Brimacombe, J. K.

    1995-04-01

    Transient heat transfer in the early stages of solidification of an alloy on a water-cooled chill and the consequent evolution of microstructure, quantified in terms of secondary dendrite arm spacing (SDAS), have been studied. Based on dip tests of the chill, instrumented with thermocouples, into Al-Si alloys, the influence of process variables such as mold surface roughness, mold material, metal superheat, alloy composition, and lubricant on heat transfer and cast structure has been determined. The heat flux between the solidifying metal and substrate, computed from measurements of transient temperature in the chill by the inverse heat-transfer technique, ranged from low values of 0.3 to 0.4 MW/m2 to peak values of 0.95 to 2.0 MW/m2. A onedimensional, implicit, finite-difference model was applied to compute heat-transfer coefficients, which ranged from 0.45 to 4.0 kW/m2 °C, and local cooling rates of 10 °C/s to 100 °C/s near the chill surface, as well as growth of the solidifying shell. Near the chill surface, the SDAS varied from 12 to 22 ( µm while at 20 mm from the chill, values of up to 80 /smm were measured. Although the SDAS depended on the cooling rate and local solidification time, it was also found to be a direct function of the heat-transfer coefficient at distances very near to the casting/chill interface. A three-stage empirical heat-flux model based on the thermophysical properties of the mold and casting has been proposed for the simulation of the mold/casting boundary condition during solidification. The applicability of the various models proposed in the literature relating the SDAS to heat-transfer parameters has been evaluated and the extension of these models to continuous casting processes pursued.

  1. Characterization of thermoplastic polyurethane/polylactic acid (TPU/PLA) tissue engineering scaffolds fabricated by microcellular injection molding

    PubMed Central

    Mi, Hao-Yang; Salick, Max R.; Jing, Xin; Jacques, Brianna R.; Crone, Wendy C.; Peng, Xiang-Fang; Turng, Lih-Sheng

    2015-01-01

    Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. PLA has rigid mechanical properties while TPU possesses flexible mechanical properties. Blended TPU/PLA tissue engineering scaffolds at different ratios for tunable properties were fabricated via twin screw extrusion and microcellular injection molding techniques for the first time. Multiple test methods were used to characterize these materials. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of the two components in the blends; differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between the TPU and PLA. Scanning electron microscopy (SEM) images verified that, at the composition ratios studied, PLA was dispersed as spheres or islands inside the TPU matrix and that this phase morphology further influenced the scaffold’s microstructure and surface roughness. The blends exhibited a large range of mechanical properties that covered several human tissue requirements. 3T3 fibroblast cell culture showed that the scaffolds supported cell proliferation and migration properly. Most importantly, this study demonstrated the feasibility of mass producing biocompatible PLA/TPU scaffolds with tunable microstructures, surface roughnesses, and mechanical properties that have the potential to be used as artificial scaffolds in multiple tissue engineering applications. PMID:24094186

  2. Characterization of thermoplastic polyurethane/polylactic acid (TPU/PLA) tissue engineering scaffolds fabricated by microcellular injection molding.

    PubMed

    Mi, Hao-Yang; Salick, Max R; Jing, Xin; Jacques, Brianna R; Crone, Wendy C; Peng, Xiang-Fang; Turng, Lih-Sheng

    2013-12-01

    Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. PLA has rigid mechanical properties while TPU possesses flexible mechanical properties. Blended TPU/PLA tissue engineering scaffolds at different ratios for tunable properties were fabricated via twin screw extrusion and microcellular injection molding techniques for the first time. Multiple test methods were used to characterize these materials. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of the two components in the blends; differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between the TPU and PLA. Scanning electron microscopy (SEM) images verified that, at the composition ratios studied, PLA was dispersed as spheres or islands inside the TPU matrix and that this phase morphology further influenced the scaffold's microstructure and surface roughness. The blends exhibited a large range of mechanical properties that covered several human tissue requirements. 3T3 fibroblast cell culture showed that the scaffolds supported cell proliferation and migration properly. Most importantly, this study demonstrated the feasibility of mass producing biocompatible PLA/TPU scaffolds with tunable microstructures, surface roughnesses, and mechanical properties that have the potential to be used as artificial scaffolds in multiple tissue engineering applications.

  3. [Mold infections in lung transplants].

    PubMed

    Solé, Amparo; Ussetti, Piedad

    2014-01-01

    Invasive infections by molds, mainly Aspergillus infections, account for more than 10% of infectious complications in lung transplant recipients. These infections have a bimodal presentation: an early one, mainly invading bronchial airways, and a late one, mostly focused on lung or disseminated. The Aspergillus colonization at any time in the post-transplant period is one of the major risk factors. Late colonization, together with chronic rejection, is one of the main causes of late invasive forms. A galactomannan value of 0.5 in bronchoalveolar lavage is currently considered a predictive factor of pulmonary invasive infection. There is no universal strategy in terms of prophylaxis. Targeted prophylaxis and preemptive treatment instead of universal prophylaxis, are gaining more followers. The therapeutic drug monitoring level of azoles is highly recommended in the treatment. Monotherapy with voriconazole is the treatment of choice in invasive aspergillosis; combined antifungal therapies are only recommended in severe, disseminated, and other infections due to non-Aspergillus molds.

  4. Compression molding of aerogel microspheres

    DOEpatents

    Pekala, R.W.; Hrubesh, L.W.

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner is disclosed. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50--800 kg/m{sup 3} (0.05--0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization. 4 figs.

  5. Compression molding of aerogel microspheres

    DOEpatents

    Pekala, Richard W.; Hrubesh, Lawrence W.

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50-800 kg/m.sup.3 (0.05-0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization.

  6. High Temperature Transfer Molding Resins

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor); Hergenrother, Paul M. (Inventor)

    2000-01-01

    High temperature resins containing phenylethynyl groups that are processable by transfer molding have been prepared. These phenylethynyl containing oligomers were prepared from aromatic diamines containing phenylethynyl groups and various ratios of phthalic anhydride and 4-phenylethynlphthalic anhydride in glacial acetic acid to form a mixture of imide compounds in one step. This synthetic approach is advantageous since the products are a mixture of compounds and consequently exhibit a relatively low melting temperature. In addition, these materials exhibit low melt viscosities which are stable for several hours at 210-275 C, and since the thermal reaction of the phenylethynyl group does not occur to any appreciable extent at temperatures below 300 C, these materials have a broad processing window. Upon thermal cure at approximately 300-350 C, the phenylethynyl groups react to provide a crosslinked resin system. These new materials exhibit excellent properties and are potentially useful as adhesives, coatings, films, moldings and composite matrices.

  7. Onychomycosis due to opportunistic molds*

    PubMed Central

    Martínez-Herrera, Erick Obed; Arroyo-Camarena, Stefanie; Tejada-García, Diana Luz; Porras-López, Carlos Francisco; Arenas, Roberto

    2015-01-01

    BACKGROUND: Onychomycosis are caused by dermatophytes and Candida, but rarely by non- dermatophyte molds. These opportunistic agents are filamentous fungi found as soil and plant pathogens. OBJECTIVES: To determine the frequency of opportunistic molds in onychomycosis. METHODS: A retrospective analysis of 4,220 cases with onychomycosis, diagnosed in a 39-month period at the Institute of Dermatology and Skin surgery "Prof. Dr. Fernando A. Cordero C." in Guatemala City, and confirmed with a positive KOH test and culture. RESULTS: 32 cases (0.76%) of onychomycosis caused by opportunistic molds were confirmed. The most affected age group ranged from 41 to 65 years (15 patients, 46.9%) and females were more commonly affected (21 cases, 65.6%) than males. Lateral and distal subungual onychomycosis (OSD-L) was detected in 20 cases (62.5%). The microscopic examination with KOH showed filaments in 19 cases (59.4%), dermatophytoma in 9 cases (28.1%), spores in 2 cases (6.25%), and filaments and spores in 2 cases (6.25%). Etiologic agents: Aspergillus sp., 11 cases (34.4%); Scopulariopsis brevicaulis, 8 cases (25.0%); Cladosporium sp., 3 cases (9.4%); Acremonium sp., 2 cases (6.25%); Paecilomyces sp., 2 cases (6.25%); Tritirachium oryzae, 2 cases (6.25%); Fusarium sp., Phialophora sp., Rhizopus sp. and Alternaria alternate, 1 case (3.1%) each. CONCLUSIONS: We found onychomycosis by opportunistic molds in 0.76% of the cases and DLSO was present in 62.5%. The most frequent isolated etiological agents were: Aspergillus sp. and Scopulariopsis brevicaulis. PMID:26131862

  8. Soft molding lithography of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Pisignano, Dario; Persano, Luana; Cingolani, Roberto; Gigli, Giuseppe; Babudri, Francesco; Farinola, Gianluca M.; Naso, Francesco

    2004-02-01

    We report on the nanopatterning of conjugated polymers by soft molding, and exploit the glass transition of the organic compound in conformal contact with an elastomeric element. We succeeded in printing different compounds with resolution down to 300 nm at temperatures up to 300 °C in vacuum. No significant variation of the photoluminescence (PL) spectra nor heavy degradation of the PL quantum yield was observed after the lithography process. Based on the high resolution achieved and on the well-retained luminescence properties of the patterned compounds, we conclude that high-temperature soft lithography is a valid, flexible and straightforward technique for one-step realization of organic-based devices.

  9. Capillarity in metal casting mold filling

    NASA Astrophysics Data System (ADS)

    Hilden, Jon L.

    In metal casting processes, surface tension of the molten metal typically resists filling of the metal into the mold. The effects are greater for smaller mold cavities, and ultimately, the smallest cavities may not be filled. Surface tension forces can be overcome by applying pressure (head) to the molten metal, thus forcing metal into the cavities. However, a pressure-window will exist, too little pressure resulting in non-filled cavities and too much pressure resulting in penetration of the mold, which is itself porous. Filling-pressure windows are investigated for cylindrical-shaped mold cavities on both a theoretical and experimental basis. The lower bound of the filling pressure window is examined by treating cylindrical mold cavities as cylinders lined with packed spheres representing mold particles. The upper bound is examined by treating the mold as a 3-D array of close-packed spheres. The experimental work concerns industrial-scale vacuum investment casting of superalloy IN718 into molds containing various cylindrical mold cavities at various heights (heads). The experimental results are found to be in good agreement with the numerical modeling predictions for filling of rough (sphere-lined) cylindrical mold cavities.

  10. Microelectronics plastic molded packaging

    SciTech Connect

    Johnson, D.R.; Palmer, D.W.; Peterson, D.W.

    1997-02-01

    The use of commercial off-the-shelf (COTS) microelectronics for nuclear weapon applications will soon be reality rather than hearsay. The use of COTS for new technologies for uniquely military applications is being driven by the so-called Perry Initiative that requires the U.S. Department of Defense (DoD) to accept and utilize commercial standards for procurement of military systems. Based on this philosophy, coupled with several practical considerations, new weapons systems as well as future upgrades will contain plastic encapsulated microelectronics. However, a conservative Department of Energy (DOE) approach requires lifetime predictive models. Thus, the focus of the current project is on accelerated testing to advance current aging models as well as on the development of the methodology to be used during WR qualification of plastic encapsulated microelectronics. An additional focal point involves achieving awareness of commercial capabilities, materials, and processes. One of the major outcomes of the project has been the definition of proper techniques for handling and evaluation of modern surface mount parts which might be used in future systems. This program is also raising the familiarity level of plastic within the weapons complex, allowing subsystem design rules accommodating COTS to evolve. A two year program plan is presented along with test results and commercial interactions during this first year.

  11. Materials processing research opportunities in powder injection molding

    SciTech Connect

    German, R.M.

    1995-12-31

    Materials processing is an active area with many research opportunities for advanced instrumentation, control, and modeling. Among new materials processing routes, powder injection molding (PIM) has rapidly grown from a curiosity to a viable production technique over just a few years. This manufacturing technique is applicable to all materials, and is the preferred fabrication route for many complex-shaped, high-performance components for surgical tools, computer hardware, automotive systems, consumer products, and turbine components. This presentation introduces the use of a computer controlled injection molding machine to shape powders (metal, carbide, composite, and ceramic) in a high productivity setting. After molding the organic is extracted and the powder structure is sintered to full density. Much research is needed in process modeling, control, inspection, and optimization. This presentation summarizes the basic technology and several important factors relevant to manufacturing. An important development is in minimization of molding defects via closed-loop feedback control using pressure, temperature, and optical sensors. Recent progress has occurred using in situ guided waves for ultrasonic inspection of the molded part. Neural networks are being generated to allow assessment of processing changes as required from the integrated robot, visual imaging, pressure, and ultrasonic sensors. Similar, but less refined efforts are occurring in die compaction technology. As another example, computer simulation of heat transfer is needed during sintering to understand sources of component warpage during densification. A furnace equipped with visual imaging and residual gas analysis is being used to assist in verification of such computer simulations. These tools are still in the research stage, so future integration into the manufacturing environment will bring new challenges.

  12. Effects of Mold Temperature and Pouring Temperature on the Hot Tearing of Cast Al-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Li, Shimin; Sadayappan, Kumar; Apelian, Diran

    2016-10-01

    The effects of mold temperature and pouring temperature on hot tearing formation and contraction behavior of a modified Al-Cu alloy 206 (M206) have been studied. The experiments were conducted using a newly developed Constrained Rod Mold, which simultaneously measures the contraction force/time/temperature during solidification for the restrained casting or linear contraction/time/temperature for a relaxed casting. Three mold temperatures [473 K, 573 K, and 643 K (200 °C, 300 °C, and 370 °C)] and three pouring temperatures [superheat of 50 K, 100 K, and 150 K (50 °C, 100 °C, and 150 °C)] were studied, and alloy A356 was used as reference for comparison. The results confirm that alloy A356 has high resistance to hot tearing. Hot tearing did not occur for the three mold temperatures evaluated, whereas alloy M206 exhibited significant hot tearing for the same casting and mold temperature conditions. Hot tearing severity and linear contraction in alloy 206 decreased significantly with increasing mold temperature. Increasing pouring temperature increases hot tearing in alloy M206, but the effect is not as significant as that of mold temperature. The results and underlying mechanism of these effects are discussed in correlation with the thermomechanical properties and microstructures.

  13. Professional judgment and the interpretation of viable mold air sampling data.

    PubMed

    Johnson, David; Thompson, David; Clinkenbeard, Rodney; Redus, Jason

    2008-10-01

    Although mold air sampling is technically straightforward, interpreting the results to decide if there is an indoor source is not. Applying formal statistical tests to mold sampling data is an error-prone practice due to the extreme data variability. With neither established exposure limits nor useful statistical techniques, indoor air quality investigators often must rely on their professional judgment, but the lack of a consensus "decision strategy" incorporating explicit decision criteria requires professionals to establish their own personal set of criteria when interpreting air sampling data. This study examined the level of agreement among indoor air quality practitioners in their evaluation of airborne mold sampling data and explored differences in inter-evaluator assessments. Eighteen investigators independently judged 30 sets of viable mold air sampling results to indicate: "definite indoor mold source," "likely indoor mold source," "not enough information to decide," "likely no indoor mold source," or "definitely no indoor mold source." Kappa coefficient analysis indicated weak inter-observer reliability, and comparison of evaluator mean scores showed clear inter-evaluator differences in their overall scoring patterns. The responses were modeled on indicator "traits" of the data sets using a generalized, linear mixed model approach and showed several traits to be associated with respondents' ratings, but they also demonstrated distinct and divergent inter-evaluator response patterns. Conclusions were that there was only weak overall agreement in evaluation of the mold sampling data, that particular traits of the data were associated with the conclusions reached, and that there were substantial inter-evaluator differences that were likely due to differences in the personal decision criteria employed by the individual evaluators. The overall conclusion was that there is a need for additional work to rigorously explore the constellation of decision criteria

  14. Revealing the microstructure of materials

    NASA Technical Reports Server (NTRS)

    Nelson, James A.

    1990-01-01

    The objectives are to demonstrate how the microstructure of materials may be revealed by abrasive polishing and chemical etching, and to illustrate how microstructural information is used to monitor manufacturing processes, provide in-depth inspection, and perform failure analysis. Microstructural analysis is the procedure used to reveal the internal microstructural details of a material or part by sectioning and polishing the cut surface so that it may be examined under a suitable microscope. A printed wiring board was selected as the test material because it contains both metals and nonmetals that have distinctive microstructures, and because this technique is used throughout the electronic industry as a key quality control tool. The three principle component materials in printed circuit boards are glass/epoxy laminates faced with copper foil; copper, deposited by both electroless and electrolytic plating; and tin/lead solder. Sample preparation, mounting, grinding, polishing, and examination and analysis are discussed.

  15. Revealing the microstructure of materials

    NASA Technical Reports Server (NTRS)

    Nelson, James A.

    1990-01-01

    The objectives are to demonstrate how the microstructure of materials may be revealed by abrasive polishing and chemical etching, and to illustrate how microstructural information is used to monitor manufacturing processes, provide in-depth inspection, and perform failure analysis. Microstructural analysis is the procedure used to reveal the internal microstructural details of a material or part by sectioning and polishing the cut surface so that it may be examined under a suitable microscope. A printed wiring board was selected as the test material because it contains both metals and nonmetals that have distinctive microstructures, and because this technique is used throughout the electronic industry as a key quality control tool. The three principle component materials in printed circuit boards are glass/epoxy laminates faced with copper foil; copper, deposited by both electroless and electrolytic plating; and tin/lead solder. Sample preparation, mounting, grinding, polishing, and examination and analysis are discussed.

  16. Sub-nanometer Replica Molding of Molecular Steps on Ionic Crystals

    PubMed Central

    Elhadj, Selim; Rioux, Robert M.; Dickey, Michael D.; DeYoreo, James J.; Whitesides, George M.

    2010-01-01

    Replica molding with elastomeric polymers has been used routinely to replicate features less than 10 nm in size. Because the theoretical limit of this technique is set by polymer-surface interactions, atomic radii and accessible volumes, replication at sub-nm length scales should be possible. Using PDMS to create a mold and polyurethane to form the replica, we demonstrate replication of elementary steps 3-5 Å in height that define the minimum separation between molecular layers in the lattices of the ionic crystals potassium dihydrogen phosphate (KDP) and calcite (CaCO3). This work establishes the operation of replica molding at the molecular scale. PMID:20843061

  17. Nanoimprint mold fabrication and replication by room-temperature conformal chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Murphy, Patrick F.; Morton, Keith J.; Fu, Zengli; Chou, Stephen Y.

    2007-05-01

    The authors present a technique for the replication of molds for nanoimprint lithography (NIL) without solvents or etching. A thin hard amorphous silicon film is deposited onto imprinted or self-assembled polymer nanostructures by room-temperature conformal plasma-enhanced chemical vapor deposition. After attachment to another substrate and separation from the polymer original, the thin hard film forms a NIL mold that is the inverse of the polymer original. Using this technology, the authors demonstrate the replication of a 200nm pitch grating mold and sub-50-nm features over wafer-scale areas without introducing additional line edge roughness associated with conventional replication methods.

  18. The Effect of Mold Flux on Reheat Scale -- Austenitic Stainless Steel Slabs

    NASA Astrophysics Data System (ADS)

    Cheung, Kelvin H.

    mixtures at 1250°C, for two hours. The post-oxidation microstructures were investigated by scanning electron microscopy (SEM) with backscattered electron (BSE) imaging and the energy dispersive spectroscopy (EDS) technique was used to measure chemical compositions. X-ray diffraction (XRD) was also used to verify the dominant phases present. A binary Fe-15Ni alloy was also tested in air at 1280°C to test for any direct effect mold flux might have (in the absence of chromium) on elimination of the network of nickel enriched metal inherent in subscale. For oxidized Fe-15Ni, the presence of mold flux worsened the oxidation attack, supporting the idea that the effect of mold flux is not to promote oxidation of nickel (from the unoxidized metallic networks) as such. Fe-Cr alloys oxidized in wet air revealed the formation of a continuous external eskolaite layer for an 18%Cr and 19%Cr steel in the flux treated case, where none was observed in the non-flux treated case, supporting the proposed mechanism regarding the ability of the molten flux to promote the growth of a protective Cr2O3 layer. Dry gas oxidation tests reveal that volatilization of chromium oxide is likely a major contributor in preventing protective continuous eskolaite formation at high temperature. This was shown when deep subscale formation was avoided for a 304L sample oxidized in a dry N2-20%O2 mixture, resulting in the formation of a continuous external eskolaite layer. Furthermore, eskolaite formation was observed for Fe-14Cr and Fe-18Cr alloys oxidized in dry gas where none formed in wet air. The change in chromium depletion profiles in wet environments versus dry environments supports the idea of increased chromium loss due to volatilization. Results from this work support the proposed mechanism explaining how enhanced chromium loss can occur due to volatilization in water containing gas and how mold flux affects this behavior. Mold flux serves to prevent chromium loss by acting as a solubility barrier

  19. Injection-molded replication of binary optic structures

    NASA Astrophysics Data System (ADS)

    Nisper, Jon K.

    1995-12-01

    Application of molded plastics to precision optical systems has required significant advances in both the design and fabrication of these optical components. Tighter fabrication tolerances and improved transmitted wavefront quality are being achieved with each passing year. Recently, interest has focused on the particular challenge of injection molded diffractive optic structures. Binary optics are generated using VLSI techniques of microlithography and dry etching to produce a diffractive structure with submicron accuracy. The cost incurred in wafer scale fabrication of individual elements is quite high. By precise mastering, detailed mold design and careful process control, binary optics can be successfully replicated in plastic materials allowing significantly lower costs. This paper will address three specific applications of mass produced diffractive structures. A hybrid refractive/diffractive lens has been designed and produced in acrylic; a set of complex diffractive fanout gratings has been produced in acrylic, polycarbonate, polymethylpentene, and cyclic olefin copolymer; and a diode laser collimator/corrector has recently been successfully molded in polycarbonate. Detailed results highlighting the fidelity of the replicated surface will be included.

  20. Thermal modeling of wafer-based precision glass molding process

    NASA Astrophysics Data System (ADS)

    Hu, Yang; Shen, Lianguan; Zhou, Jian; Li, Mujun

    2016-10-01

    Wafer based precision glass optics manufacturing has been an innovative approach for combining high accuracy with mass production. However, due to the small ratio of thickness and diameter of the glass wafer, deformation and residual stress would be induced for the nonuniform temperature distribution in the glass wafer after molding. Therefore, thermal modelling of the heating system in the wafer based precision glass molding (PGM) process is of great importance in optimizing the heating system and the technique of the process. The current paper deals with a transient thermal modelling of a self-developed heating system for wafer based PGM process. First, in order to investigate the effect of radiation from the surface and interior of the glass wafer, the thermal modeling is simulated with a discrete ordinates radiation model in the CFD software FLUENT. Temperature distribution of the glass wafer obtained from the simulations is then used to evaluate the performance of heating system and investigate some importance parameters in the model, such as interior and surface radiation in glass wafer, thermal contact conductance between glass wafer and molds, thickness to diameter ratio of glass wafer. Finally, structure modification in the molding chamber is raised to decrease the temperature gradient in the glass wafer and the effect is significant.

  1. Direct fabrication of rigid microstructures on a metallic roller using a dry film resist

    NASA Astrophysics Data System (ADS)

    Jiang, Liang-Ting; Huang, Tzu-Chien; Chang, Chih-Yuan; Ciou, Jian-Ren; Yang, Sen-Yeu; Huang, Po-Hsun

    2008-01-01

    This paper presents a novel method to fabricate a metallic roller mold with microstructures on its surface using a dry film resist (DFR). The DFR is laminated uniformly onto the curvy surface of a copper roller. After that, the micro-scale photoresist on the surface of the roller can be patterned by non-planar lithography using a flexible film photomask, followed by ferric chloride wet etching to obtain the desired microstructures. This method overcomes the uniformity issue of photoresist coating on rollers, and solves the molds sliding problem during the embossing process because the microstructures are fabricated directly on the roller surface. Furthermore, the rigid metallic roller mold has excellent strength durability and temperature endurance, which can be used in roller hot embossing with a high embossing pressure. The fabricated microstructure roller mold is used as a mold in the hybrid extrusion roller embossing process and successfully fabricates uniform micro-scale prominent line arrays on PC films. This result proves that the roller fabricated by this method can be successfully used in roller embossing for microstructure mass production. The excellent flatness of dry film resist laminating is the key in this fabrication process. The flexible film photomask can be easily designed using CAD software; this roller fabrication method enhances the design flexibility and reduces the cost and time.

  2. The medical effects of mold exposure.

    PubMed

    Bush, Robert K; Portnoy, Jay M; Saxon, Andrew; Terr, Abba I; Wood, Robert A

    2006-02-01

    Exposure to molds can cause human disease through several well-defined mechanisms. In addition, many new mold-related illnesses have been hypothesized in recent years that remain largely or completely unproved. Concerns about mold exposure and its effects are so common that all health care providers, particularly allergists and immunologists, are frequently faced with issues regarding these real and asserted mold-related illnesses. The purpose of this position paper is to provide a state-of-the-art review of the role that molds are known to play in human disease, including asthma, allergic rhinitis, allergic bronchopulmonary aspergillosis, sinusitis, and hypersensitivity pneumonitis. In addition, other purported mold-related illnesses and the data that currently exist to support them are carefully reviewed, as are the currently available approaches for the evaluation of both patients and the environment.

  3. 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.

  4. Amorphous materials molded IR lens progress report

    NASA Astrophysics Data System (ADS)

    Hilton, A. R., Sr.; McCord, James; Timm, Ronald; Le Blanc, R. A.

    2008-04-01

    Amorphous Materials began in 2000 a joint program with Lockheed Martin in Orlando to develop molding technology required to produce infrared lenses from chalcogenide glasses. Preliminary results were reported at this SPIE meeting by Amy Graham1 in 2003. The program ended in 2004. Since that time, AMI has concentrated on improving results from two low softening glasses, Amtir 4&5. Both glasses have been fully characterized and antireflection coatings have been developed for each. Lenses have been molded from both glasses, from Amtir 6 and from C1 Core glass. A Zygo unit is used to evaluate the results of each molded lens as a guide to improving the molding process. Expansion into a larger building has provided room for five production molding units. Molded lens sizes have ranged from 8 mm to 136 mm in diameter. Recent results will be presented

  5. Hydrogen silsesquioxane mold coatings for improved replication of nanopatterns by injection molding

    NASA Astrophysics Data System (ADS)

    Hobæk, Thor Christian; Matschuk, Maria; Kafka, Jan; Pranov, Henrik J.; Larsen, Niels B.

    2015-03-01

    We demonstrate the replication of nanosized pillars in polymer (cyclic olefin copolymer) by injection molding using nanostructured thermally cured hydrogen silsesquioxane (HSQ) ceramic coatings on stainless steel mold inserts with mold nanostructures produced by a simple embossing process. At isothermal mold conditions, the average pillar height increases by up to 100% and a more uniform height distribution is observed compared to a traditional metal mold insert. Thermal heat transfer simulations predict that the HSQ film retards the cooling of the polymer melt during the initial stages of replication, thus allowing more time to fill the nanoscale cavities compared to standard metal molds. A monolayer of a fluorinated silane (heptadecafluorotrichlorosilane) deposited on the mold surface reduces the mold/polymer interfacial energy to support demolding of the polymer replica. The mechanical stability of thermally cured HSQ makes it a promising material for nanopattern replication on an industrial scale without the need for slow and energy intensive variotherm processes.

  6. Mold in My School: What Do I Do?

    ERIC Educational Resources Information Center

    National Clearinghouse for Educational Facilities, Washington, DC.

    This publication provides information on the most important indoor mold-related health concerns and discusses how school districts can keep school facilities mold-free and avoid these problems. The document addresses when to be concerned, how molds cause health problems, symptoms caused by mold allergies, indoor molds that form toxins, who is most…

  7. Mold For Casting Radius-Inspection Specimens

    NASA Technical Reports Server (NTRS)

    Ball, Robert N.

    1988-01-01

    Thin replicas viewed on comparator without sectioning. New mold machined from piece of transparent poly(methyl methacrylate). Fits around base of post. Two slots machined into inner surface form channels for casting inspection sections. Bottom of mold fits flush against surface around bottom of post. When surface slanted, mold automatically aligns in proper orientation. Time required to inspect elliptical radii located at bottoms of series of small posts reduced from 18 hours to 3 hours.

  8. Mold For Casting Radius-Inspection Specimens

    NASA Technical Reports Server (NTRS)

    Ball, Robert N.

    1988-01-01

    Thin replicas viewed on comparator without sectioning. New mold machined from piece of transparent poly(methyl methacrylate). Fits around base of post. Two slots machined into inner surface form channels for casting inspection sections. Bottom of mold fits flush against surface around bottom of post. When surface slanted, mold automatically aligns in proper orientation. Time required to inspect elliptical radii located at bottoms of series of small posts reduced from 18 hours to 3 hours.

  9. Lost Mold Rapid Infiltration Forming of Mesoscale Ceramics: Part 1, Fabrication

    PubMed Central

    Antolino, Nicholas E.; Hayes, Gregory; Kirkpatrick, Rebecca; Muhlstein, Christopher L.; Frecker, Mary I.; Mockensturm, Eric M.; Adair, James H.

    2009-01-01

    Free-standing mesoscale (340 μm × 30 μm × 20 μm) bend bars with an aspect ratio over 15:1 and an edge resolution as fine as a single grain diameter (∼400 nm) have been fabricated in large numbers on refractory ceramic substrates by combining a novel powder processing approach with photoresist molds and an innovative lost-mold thermal process. The colloid and interfacial chemistry of the nanoscale zirconia particulates has been modeled and used to prepare highly concentrated suspensions. Engineering solutions to challenges in mold fabrication and casting have yielded free-standing, crack-free parts. Molds are fabricated using high-aspect-ratio photoresist on ceramic substrates. Green parts are formed using a rapid infiltration method that exploits the shear thinning behavior of the highly concentrated ceramic suspension in combination with gelcasting. The mold is thermally decomposed and the parts are sintered in place on the ceramic substrate. Chemically aided attrition milling disperses and concentrates the as-received 3Y-TZP powder to produce a dense, fine-grained sintered microstructure. Initial three-point bend strength data are comparable to that of conventional zirconia; however, geometric irregularities (e.g., trapezoidal cross sections) are present in this first generation and are discussed with respect to the distribution of bend strength. PMID:19809595

  10. 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.

  11. Effect of Different Molding Materials on the Thin-Walled Compacted Graphite Iron Castings

    NASA Astrophysics Data System (ADS)

    Górny, Marcin; Dańko, Rafał; Lelito, Janusz; Kawalec, Magdalena; Sikora, Gabriela

    2016-10-01

    This article addresses the effects of six mold materials used for obtaining thin-walled compacted graphite iron castings with a wall thickness of 3 mm. During this research, the following materials were analyzed: fine silica sand, coarse silica sand, cerabeads, molohite and also insulated materials in the shape of microspheres, including low-density alumina/silica ceramic sand. Granulometric and SEM observations indicate that the sand matrix used in these studies differs in terms of size, homogeneity and shape. This study shows that molds made with insulating sands (microspheres) possess both: thermal conductivity and material mold ability to absorb heat, on average to be more than five times lower compared to those of silica sand. In addition to that, the resultant peak of heat transfer coefficient at the mold/metal interface for microspheres is more than four times lower in comparison with fine silica sand. This is accompanied by a significant decrease in the cooling rate of metal in the mold cavity which promotes the development of compacted graphite in thin-walled castings as well as ferrite fractions in their microstructure.

  12. Thermoelastic Stability Analysis of Solidification of Pure Metals on a Coated Planar Mold of Finite Thickness

    NASA Astrophysics Data System (ADS)

    Demir, Mehmet Hakan; Yigit, Faruk

    2016-12-01

    A theoretical model for investigating the thermoelastic instability/mechanism during pure metal solidification on a coated mold of finite thickness is developed. This study extends the previous theoretical works on growth instability during solidification process by investigating the effects of an added coating layer. Mold coating is one of the most important factors controlling the heat transfer rate, and hence it has a very important role on the solidification rate and the development of microstructure. In this model, thermal and mechanical problems are coupled through the pressure-dependent contact resistances at mold/coating and coating/shell interfaces. The thermal diffusivities of solidified shell, coating, and mold materials are assumed to be zero. This assumption provides us to solve heat transfer problem analytically. A linear perturbation method is used to simplify complexity of the modeled solidification problem, and governing equations are solved numerically using a variable step variable order predictor-corrector algorithm. The effects of coating layer thickness and coupling rates at shell/coating and coating/mold interfaces are investigated in detail. The results show that coating thickness has destabilizing effect on the growth instability when the coupling rates are small. However, when these coupling rates are increased individually or together, the destabilizing effect of coating thickness turns to be stabilizing. On the other hand, coupling rates have generally destabilizing effects on the process, but an increase in the thickness of coating leads to diminishing coupling rates effect in some cases.

  13. Thermoelastic Stability Analysis of Solidification of Pure Metals on a Coated Planar Mold of Finite Thickness

    NASA Astrophysics Data System (ADS)

    Demir, Mehmet Hakan; Yigit, Faruk

    2017-04-01

    A theoretical model for investigating the thermoelastic instability/mechanism during pure metal solidification on a coated mold of finite thickness is developed. This study extends the previous theoretical works on growth instability during solidification process by investigating the effects of an added coating layer. Mold coating is one of the most important factors controlling the heat transfer rate, and hence it has a very important role on the solidification rate and the development of microstructure. In this model, thermal and mechanical problems are coupled through the pressure-dependent contact resistances at mold/coating and coating/shell interfaces. The thermal diffusivities of solidified shell, coating, and mold materials are assumed to be zero. This assumption provides us to solve heat transfer problem analytically. A linear perturbation method is used to simplify complexity of the modeled solidification problem, and governing equations are solved numerically using a variable step variable order predictor-corrector algorithm. The effects of coating layer thickness and coupling rates at shell/coating and coating/mold interfaces are investigated in detail. The results show that coating thickness has destabilizing effect on the growth instability when the coupling rates are small. However, when these coupling rates are increased individually or together, the destabilizing effect of coating thickness turns to be stabilizing. On the other hand, coupling rates have generally destabilizing effects on the process, but an increase in the thickness of coating leads to diminishing coupling rates effect in some cases.

  14. Chalcogenide-mold interactions during precision glass molding (PGM) of GeAsSe glasses

    NASA Astrophysics Data System (ADS)

    Gleason, B.; Wachtel, P.; Musgraves, J. D.; Steinkopf, R.; Eberhardt, R.; Richardson, K.

    2013-09-01

    Five chalcogenide glasses in the GeAsSe ternary glass system were melted, fabricated into flats, and molded between planar, uncoated, binderless WC molds using a laboratory-scale precision glass molding machine. The five glasses originate at the binary arsenic triselenide (As40Se60) and are modified by replacing As with Se in 5 mol% increments, or by locking the As:Se ratio and adding Ge, also in 5 mol% increments. The glasses are separated into two groups, one for the Ge-free compositions and the other for the Ge-containing compositions. This effort analyzes the differences between the Ge-containing and the Ge-free glasses on the post-molded glass and mold surface behavior, as well as the mold lifetime. Fabrication features, such as scratch and/or dig marks were present on the glass and mold surfaces prior to the PGM process. White light interferometry analysis of the surfaces shows an overall reduction in the RMS roughness of the glass after molding, and an increase of the roughness of the molds, after 15 molding cycles. After molding, the quantity of observable defects, primarily deposits and dig marks are increased for both the glass and mold surfaces. Deposits found on the WC molds and glasses were analyzed using Electron Dispersive X-ray Spectroscopy (EDS) and showed no evidence of being due to material transfer between the WC molds and the glass constituents. In general the main observable difference in the analysis of the two post molded sets, despite the changes in chemistry, is the quantity of molding induced defects near the edge of the GeAsSe samples.

  15. Review on Sintering Process of WC-Co Cemented Carbide in Metal Injection Molding Technology

    NASA Astrophysics Data System (ADS)

    Prathabrao, M.; Amin, Sri Yulis M.; Ibrahim, M. H. I.

    2017-01-01

    The objective of this paper is to give an overview on sintering process of WC-Co cemented carbides in metal injection molding technology. Metal injection molding is an advanced and promising technology in producing cemented nanostructured carbides. Cemented tungsten carbide (WC-Co) hard metal is known for its high hardness and wear resistance in various applications. Moreover, areas include fine grained materials, alternative binders, and alternative sintering techniques has been discussed in this paper.

  16. A New Fast and Simple Border Molding Process for Complete Dentures Using a Compound Stick Gun.

    PubMed

    Park, Chan; Yang, Hong-So; Lim, Hyun-Pil; Yun, Kwi-Dug; Oh, Gye-Jeong; Park, Sang-Won

    This article describes the use of a newly invented compound stick gun to take impressions for complete denture. The border molding process involves loading the modeling compound in an electric heating device and applying an even thickness of compound on the flange of a custom tray at a proper temperature without hot water tempering. This method provides a quicker and easier border molding process alternative to conventional techniques.

  17. Wetting Behavior of Mold Flux Droplet on Steel Substrate With or Without Interfacial Reaction

    NASA Astrophysics Data System (ADS)

    Zhou, Lejun; Li, Jingwen; Wang, Wanlin; Sohn, Il

    2017-08-01

    The slag entrapment in mold tends to cause severe defects on the slab surface, especially for casting steels containing active alloy elements such as Al, Ti, and Mn. The wetting behavior of molten mold flux on the initial solidified shell is considered to be a key factor to determine the entrapment of mold slag on the shell surface. Therefore, the wetting behavior of mold flux droplet on the steel substrate with or without interfacial reaction was investigated by the sessile drop method. The results indicated that the melting process of mold flux has a significant influence on the variation of contact angle, and the final contact angle for Flux1 droplet on 20Mn23AlV is only 15 deg, which is lower than the other two cases due to the intensive interracial reactions occurring in this case. In addition, the thickness of the interaction layer for the case of Flux1 on 20Mn23AlV is 10- μm greater than the other two cases, which confirms that the most intensive reactions occurred at the interface area. The microstructure and element distribution at the interface analyzed by a scanning electron microscope (SEM) and energy dispersive spectrum (EDS) suggested that the increase of wettability of mold flux droplet on the steel substrate is caused by the migration of Al, Mn, and Si elements occurring in the vicinity of the interface. The results obtained in this article can reveal the mechanism of flux entrapment by hook or shell and provide theoretic guidance for mold flux design and optimization.

  18. New alnico magnets fabricated from pre-alloyed gas-atomized powder through diverse consolidation techniques

    SciTech Connect

    Tang, W.; Zhou, L.; Kassen, A. G.; Palasyuk, A.; White, E. M.; Dennis, K. W.; Kramer, M. J.; McCallum, R. W.; Anderson, I. E.

    2015-05-25

    Fine Alnico 8 spherical powder produced by gas atomization was consolidated through hot pressing (HP), hot isostatic pressing (HIP), and compression molding and subsequent sintering (CMS) techniques. The effects of different fabrication techniques and processing parameters on microstructure and magnetic properties were analyzed and compared. The HP, HIP, and CMS magnets exhibited different features in microstructures and magnetic properties. Magnetically annealed at 840°C for 10 min and subsequently tempered at 650°C for 5h and 580°C for 15h, the HIP sample achieved the best coercivity (Hcj =1845 Oe) due to spinodally decomposed (SD) phases with uniform and well-faceted mosaic morphology. As a result, the CMS sample had a lower Hcj than HIP and HP samples, but a higher remanence and thus the best energy product (6.5 MGOe) due to preferential grain alignment induced by abnormal grain growth.

  19. New alnico magnets fabricated from pre-alloyed gas-atomized powder through diverse consolidation techniques

    DOE PAGES

    Tang, W.; Zhou, L.; Kassen, A. G.; ...

    2015-05-25

    Fine Alnico 8 spherical powder produced by gas atomization was consolidated through hot pressing (HP), hot isostatic pressing (HIP), and compression molding and subsequent sintering (CMS) techniques. The effects of different fabrication techniques and processing parameters on microstructure and magnetic properties were analyzed and compared. The HP, HIP, and CMS magnets exhibited different features in microstructures and magnetic properties. Magnetically annealed at 840°C for 10 min and subsequently tempered at 650°C for 5h and 580°C for 15h, the HIP sample achieved the best coercivity (Hcj =1845 Oe) due to spinodally decomposed (SD) phases with uniform and well-faceted mosaic morphology. Asmore » a result, the CMS sample had a lower Hcj than HIP and HP samples, but a higher remanence and thus the best energy product (6.5 MGOe) due to preferential grain alignment induced by abnormal grain growth.« less

  20. Porous media heat transfer for injection molding

    DOEpatents

    Beer, Neil Reginald

    2016-05-31

    The cooling of injection molded plastic is targeted. Coolant flows into a porous medium disposed within an injection molding component via a porous medium inlet. The porous medium is thermally coupled to a mold cavity configured to receive injected liquid plastic. The porous medium beneficially allows for an increased rate of heat transfer from the injected liquid plastic to the coolant and provides additional structural support over a hollow cooling well. When the temperature of the injected liquid plastic falls below a solidifying temperature threshold, the molded component is ejected and collected.

  1. Mold Infections of the Central Nervous System

    PubMed Central

    McCarthy, Matthew; Rosengart, Axel; Schuetz, Audrey N.; Kontoyiannis, Dimitrios P.; Walsh, Thomas J.

    2016-01-01

    The recent outbreak of exserohilum rostratum meningitis linked to epidural injections of methylprednisolone acetate has brought renewed attention to mold infections of the central nervous system (CNS).1 Although uncommon, these infections are often devastating and difficult to treat. This focused review of the epidemiologic aspects, clinical characteristics, and treatment of mold infections of the CNS covers a group of common pathogens: aspergillus, fusarium, and scedosporium species, molds in the order Mucorales, and dematiaceous molds. Infections caused by these pathogen groups have distinctive epidemiologic profiles, clinical manifestations, microbiologic characteristics, and therapeutic implications, all of which clinicians should understand. PMID:25006721

  2. Mold and Human Health: a Reality Check.

    PubMed

    Borchers, Andrea T; Chang, Christopher; Eric Gershwin, M

    2017-06-01

    There are possibly millions of mold species on earth. The vast majority of these mold spores live in harmony with humans, rarely causing disease. The rare species that does cause disease does so by triggering allergies or asthma, or may be involved in hypersensitivity diseases such as allergic bronchopulmonary aspergillosis or allergic fungal sinusitis. Other hypersensitivity diseases include those related to occupational or domiciliary exposures to certain mold species, as in the case of Pigeon Breeder's disease, Farmer's lung, or humidifier fever. The final proven category of fungal diseases is through infection, as in the case of onchomycosis or coccidiomycosis. These diseases can be treated using anti-fungal agents. Molds and fungi can also be particularly important in infections that occur in immunocompromised patients. Systemic candidiasis does not occur unless the individual is immunodeficient. Previous reports of "toxic mold syndrome" or "toxic black mold" have been shown to be no more than media hype and mass hysteria, partly stemming from the misinterpreted concept of the "sick building syndrome." There is no scientific evidence that exposure to visible black mold in apartments and buildings can lead to the vague and subjective symptoms of memory loss, inability to focus, fatigue, and headaches that were reported by people who erroneously believed that they were suffering from "mycotoxicosis." Similarly, a causal relationship between cases of infant pulmonary hemorrhage and exposure to "black mold" has never been proven. Finally, there is no evidence of a link between autoimmune disease and mold exposure.

  3. Lightweight sheet molding compound (SMC) composites containing cellulose nanocrystals

    Treesearch

    Amir Asadi; Mark Miller; Arjun V. Singh; Robert J. Moon; Kyriaki Kalaitzidou

    2017-01-01

    A scalable technique was introduced to produce high volume lightweight composites using sheet molding compound (SMC) manufacturing method by replacing 10 wt% glass fibers (GF) with a small amount of cellulose nanocrystals (CNC). The incorporation of 1 and 1.5 wt% CNC by dispersing in the epoxy matrix of short GF/epoxy SMC composites with 25 wt% GF content (25GF/CNC-...

  4. Analysis of optical properties in injection-molded and compression-molded optical lenses.

    PubMed

    Wang, Chung Yen; Wang, Pei Jen

    2014-04-10

    Numerical mold-flow simulations and experimental measurements for injection-molded lenses have been investigated in form accuracy on a two-cavity mold with various process conditions. First, form profiles of the molded lenses have been measured together with the corresponding simulated mold-temperature distribution and displacement distribution of the lens in the z direction. A flow-through type layout of cooling channels has been devised for balance of mold-temperature distribution in mold cavities with various parametric distances for assessments in uniformity of temperature distribution. Finally, a compression-molding process is proposed for the post-process of birefringence relaxation as well as adequate form accuracy of lenses. In conclusion, optimization of process parameters to achieve good form accuracy in a multicavity mold with symmetric geometry but nonuniform cooling conditions is difficult. A good design of cooling channels plus optimized process conditions could provide uniform mold-temperature distribution so that molded lenses of good quality would be possible. Then, the profile deviation of lenses could be further compensated by profile geometry corrections. In conclusion, the post-compression-molding process could make birefringence-free plastic lenses with good form accuracy.

  5. Testing of molded high temperature plastic actuator road seals for use in advanced aircraft hydraulic systems

    NASA Technical Reports Server (NTRS)

    Waterman, A. W.; Huxford, R. L.; Nelson, W. G.

    1976-01-01

    Molded high temperature plastic first and second stage rod seal elements were evaluated in seal assemblies to determine performance characteristics. These characteristics were compared with the performance of machined seal elements. The 6.35 cm second stage Chevron seal assembly was tested using molded Chevrons fabricated from five molding materials. Impulse screening tests conducted over a range of 311 K to 478 K revealed thermal setting deficiencies in the aromatic polyimide molding materials. Seal elements fabricated from aromatic copolyester materials structurally failed during impulse cycle calibration. Endurance testing of 3.85 million cycles at 450 K using MIL-H-83283 fluid showed poorer seal performance with the unfilled aromatic polyimide material than had been attained with seals machined from Vespel SP-21 material. The 6.35 cm first stage step-cut compression loaded seal ring fabricated from copolyester injection molding material failed structurally during impulse cycle calibration. Molding of complex shape rod seals was shown to be a potentially controllable technique, but additional molding material property testing is recommended.

  6. Holistic microstructural techniques reveal synchronous and alternating andalusite and staurolite growth during three tectonic events resulted from shifting partitioning of growth vs deformation

    NASA Astrophysics Data System (ADS)

    Bell, T. H.; Fay, C.

    2016-10-01

    Excellent inclusion trails in a sample containing both staurolite and andalusite porphyroblasts are used to demonstrate techniques that allow the intimate relationships between deformation and porphyroblast growth to be recognized, described in detail and understood. This approach reveals three main phases of growth of both mineral phases, some of which was demonstrably synchronous, during three tectonic events. Each main period of growth occurred during the early stages of three deformations that were successively near orthogonal. However, extra periods are distinguishable in andalusite in some of these events because this phase occurs as clusters of large crystals that vary in orientation by 2° to > 10°. All foliations defined by all inclusion trails within every porphyroblast inflect/intersect about an axis trending at 025° (called a FIA). This indicates that the direction of the horizontal component of bulk shortening was identical for the first and third of the three deformations recorded by porphyroblast growth. Portions of sigmoidal to slightly spiral-shaped inclusion trails in most porphyroblast clusters locally diverge in opposite directions due to overprinting orthogonal bulk shortening typical of that which forms millipede geometries. These microstructures confirm the role of coaxial bulk shortening in initiating porphyroblast growth in an environment that locally becomes strongly non-coaxial as the deformation intensifies in the same event. In this sample, increasing non-coaxiality as the deformation intensified resulted in the same asymmetry for each of the three events and thus an overall spiral-like shape. Differing stages in the development of these bulk-shortening geometries preserved in adjacent or touching phases negate any role for porphyroblast rotation during ductile deformation. Andalusite and staurolite grew without any inter-reaction in locations where they lie in contact. This multiply repeated growth behaviour initiated within zones of

  7. Diamond turning microstructure optical components

    NASA Astrophysics Data System (ADS)

    Jiang, Wenda

    2009-05-01

    Microstructure optical components in the form of Fresnel, TIR, microgroove, micro lens array provide a lot design freedom for high compact optical systems. It is a key factor which enables the cutting edge technology for telecommunication, surveillance and high-definition display system. Therefore, the demand of manufacturing such element is rapidly increasing. These elements usually contain high precision, tiny structure and complex form, which have posed many new challenges for tooling, programming as well as ultra-precision machining. To cope with the fast development of the technology and meet the increasing demand of the market, we have developed our own manufacturing process to fabricate microstructure optical components by way of Diamond tuning, Shaping, Raster cutting, Slow Slide Servo (SSS), Diamond milling and Post polishing. This paper is to focus on how we employed these methods to produce complex prototype of microstructure optical components and precision mold inserts which either contains aspheric lens array or freeform V grooves. The high quality finish of these surfaces meets application requirements. Measurement results are presented. Advantages and disadvantages of these methods are compared and discussed in the paper.

  8. Wafer-level microstructuring of glassy carbon

    NASA Astrophysics Data System (ADS)

    Hans, Loïc. E.; Prater, Karin; Kilchoer, Cédric; Scharf, Toralf; Herzig, Hans Peter; Hermerschmidt, Andreas

    2014-03-01

    Glassy carbon is used nowadays for a variety of applications because of its mechanical strength, thermal stability and non-sticking adhesion properties. One application is glass molding that allows to realize high resolution diffractive optical elements on large areas and at affordable price appropriate for mass production. We study glassy carbon microstructuring for future precision compression molding of low and high glass-transition temperature. For applications in optics the uniformity, surface roughness, edge definition and lateral resolution are very important parameters for a stamp and the final product. We study different methods of microstructuring of glassy carbon by etching and milling. Reactive ion etching with different protection layers such as photoresists, aluminium and titanium hard masks have been performed and will be compare with Ion beam etching. We comment on the quality of the structure definition and give process details as well as drawbacks for the different methods. In our fabrications we were able to realize optically flat diffractive structures with slope angles of 80° at typical feature sizes of 5 micron and 700 nm depth qualified for high precision glass molding.

  9. Commercial and Residential Water Damage: The Mold Connection.

    ERIC Educational Resources Information Center

    Williams, Del

    2002-01-01

    Describes the problem of toxic mold in residential and commercial property resulting from excess moisture. Includes common sources of unwanted moisture, design and construction flaws, determining the presence of mold, and advice for identifying and hiring reputable mold remediators. (PKP)

  10. Plastic molds reduce cost of encapsulating electric cable connectors

    NASA Technical Reports Server (NTRS)

    Knott, D.

    1964-01-01

    Resin casting of the aluminum master pattern forms a plastic mold for encapsulating a cable connector. An elastomer is injected into the mold and cured. The mold is disassembled leaving an elastomeric encapsulation around the connector.

  11. Commercial and Residential Water Damage: The Mold Connection.

    ERIC Educational Resources Information Center

    Williams, Del

    2002-01-01

    Describes the problem of toxic mold in residential and commercial property resulting from excess moisture. Includes common sources of unwanted moisture, design and construction flaws, determining the presence of mold, and advice for identifying and hiring reputable mold remediators. (PKP)

  12. Mold

    MedlinePlus

    ... Health Study to assess the levels of fungal sensitization among farmers. 11 Another example of NIEHS’ efforts ... Freeman LE, Hoppin JA. 2012. Fungal and atopic sensitization are low among farmers in the Agricultural Health ...

  13. The use of a directional solidification technique to investigate the interrelationship of thermal parameters, microstructure and microhardness of Bi–Ag solder alloys

    SciTech Connect

    Spinelli, José Eduardo; Silva, Bismarck Luiz; Cheung, Noé; Garcia, Amauri

    2014-10-15

    Bi–Ag alloys have been stressed as possible alternatives to replace Pb-based solder alloys. Although acceptable melting temperatures and suitable mechanical properties may characterize such alloys, as referenced in literature, there is a lack of comprehension regarding their microstructures (morphologies and sizes of the phases) considering a composition range from 1.5 to 4.0 wt.%Ag. In order to better comprehend such aspects and their correlations with solidification thermal parameters (growth rate, v and cooling rate, T-dot), directional solidification experiments were carried out under transient heat flow conditions. The effects of Ag content on both cooling rate and growth rate during solidification are examined. Microstructure parameters such as eutectic/dendritic spacing, interphase spacing and diameter of the Ag-rich phase were determined by optical microscopy and scanning electron microscopy. The competition between eutectic cells and dendrites in the range from 1.5 to 4.0 wt.%Ag is explained by the coupled zone concept. Microhardness was determined for different microstructures and alloy Ag contents with a view to permitting correlations with microstructure parameters to be established. Hardness is shown to be directly affected by both solute macrosegregation and morphologies of the phases forming the Bi–Ag alloys, with higher hardness being associated with the cellular morphology of the Bi-2.5 and 4.0 wt.%Ag alloys. - Highlights: • Asymmetric zone of coupled growth for Bi–Ag is demonstrated. • Faceted Bi-rich dendrites have been characterized for Bi–1.5 wt.%Ag alloy. • Eutectic cells were shown for the Bi-2.5 and 4.0 wt.%Ag solder alloys. • Interphase spacing relations with G × v are able to represent the experimental scatters. • Hall-Petch type equations are proposed relating microstructural spacings to hardness.

  14. Microstructural lines involving luminescence

    NASA Astrophysics Data System (ADS)

    Shimada, Kazuhiko

    2004-06-01

    Japanese National Printing Bureau has been focused upon the development of anti-copy lines for many years. The basic concept with regard to security measure lies in the merge of art and technology. On this basis, our originally developed anti-copy lines show flexibility to various security designs. Our newest anti-copy lines comprising from the Tri-Branched and Divided Lines shows clearer latent image effect compared to that of our other developed anti-copy lines. However, the anti-copy effect of security printing lines with microstructure is deteriorating due to the emergence of digital image techniques with higher resolution. In this situation, this paper introduces a new security measure comprising from luminescence and security printing lines with microstructure. It gives rise to a latent image effect under UV light due to the characteristic microstructure while visually same density. The principle advantage is that the combination of the anti-copy and luminescent feature strongly enhances its secure effect in documents. There is no necessity of two kinds of inks and any specially designed equipment to produce security documents with microstructural lines involving luminescence.

  15. Process for Making Ceramic Mold

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    An improved process for slip casting molds that can be more economically automated and that also exhibits greater dimensional stability is disclosed. The process involves subjecting an investment pattern, preferably made from wax, to successive cycles of wet-dipping in a slurry of colloidal, silica-based binder and dry powder-coating, or stuccoing with plaster of Paris or calcium sulfate mixtures to produce a multi-layer shell over the pattern. The invention as claimed entails applying a primary and a secondary coating to the investment pattern. At least two wet-dipping on in a primary slurry and dry-stuccoing cycles provide the primary coating, and an additional two wet-dippings and dry-stuccoing cycles provide the secondary, or back-up, coating. The primary and secondary coatings produce a multi-layered shell pattern. The multi-layered shell pattern is placed in a furnace first to cure and harden, and then to vaporize the investment pattern, leaving a detailed, high precision shell mold.

  16. Microstructure and properties of Fe-base alloy fabricated using selective laser melting

    NASA Astrophysics Data System (ADS)

    Sun, Manlong; Lu, Li; Fuh, Jerry Y. H.

    2002-02-01

    This paper studies recent advances in rapid tooling (RT) of high performance components via selective laser melting (SLM). The present study of SLM focuses on the development of materials used in injection molding. In the process, the pre-alloyed iron-base alloy powder was used to fabricate parts using a 3KW CO2 laser machine. Iron components with nearly full density have been directly produced under suitable laser parameters. The result of the SLM processed parts showed very fine dendrite microstructure. The surface hardness measured is 35-40 HRC, which is comparable to that of the AISI P20 steel (30-35 HRC). The advantages of this technique include elimination of a secondary infiltration process used by former selective laser sintering technology, reduced pre-processing time, and reduction in post- processing steps. The SLM process has a great potential in the field of RT.

  17. Quality of Plaster Molding for Distal Radius Fractures Is Improved Through Focused Tuition of Junior Surgeons.

    PubMed

    Ramoutar, Darryl N; Silk, Robert; Rodrigues, Jeremy N; Hatton, Mark

    2014-08-01

    Successful nonoperative management of distal radius fractures requires an adequately reduced fracture held in a well-molded cast. The purpose of this study was to determine whether a targeted teaching session to the same group of junior doctors led to objective improvement in fracture reduction and plaster molding and hence a decrease in the redisplacement of these fractures. Retrospective review. Level I academic trauma center. A retrospective review of all dorsally angulated distal radius fractures treated in plaster that presented to our plaster room over a 4-week period (group 1, n = 52). This was followed by the intervention and a subsequent 4-week prospective review (group 2, n = 36). Radiographs were reviewed before manipulation, after manipulation, and at follow-up by a single senior orthopaedic trainee using predetermined criteria. A targeted teaching session on fracture reduction and cast molding to the same group of junior doctors involved in managing all these cases. Adequate fracture reduction, plaster molding, redisplacement, and further intervention before and after the targeted intervention. In group 1, 85% had adequate fracture reduction but only 36% showed adequate molding. This was improved in group 2%-94% adequate reduction and 65% adequate molding (P = 0.022). The rate of redisplacement was improved from 65% to 44% in group 2. In both groups, the rate of redisplacement was around 20% for adequately reduced and molded fractures, compared with around 90% for adequately reduced but inadequately molded cases (P < 0.001). The rate of further intervention improved from 27% to 8% (P = 0.052). We recommend that specific teaching focusing on fracture reduction and molding techniques is included in orthopaedic juniors' induction teaching or as a separate session. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

  18. "Estudio tribologico de aceros para moldes. Aplicacion al moldeo por inyeccion de polibutilentereftalato reforzado con fibra de vidrio"

    NASA Astrophysics Data System (ADS)

    Martinez Mateo, Isidoro Jose

    Mould materials for injection moulding of polymers and polymer-matrix composites represent a relevant industrial economic sector due to the large quantity of pieces and components processed. The material selection for mould manufacturing, its composition and heat treatment, the hardening procedures and machining and finishing processes determine the service performance and life of the mould. In the first part of the present study, the relationship between the hardness and microstructure and the wear resistance of mould steels from large blocks has been studied by pin-on-disc tests, studying the main wear mechanisms. In order to determine the surface damage on mould steels under real injection conditions, different commercial steels have been studied by measuring the variation of surface roughness with the number of injected pieces with different reinforcement percentages and different mould geometries, by using optical profilometry and scanning electron microscopy techniques. It was important to determine the variation of surface roughness of the moulded pieces with the number of injection operations. The materials used were polybutyleneterephthalate pure and reinforced with either 20% or 50% glass fibre. For the different mould designs, the evolution of the glass fibre orientation with injection flow has been determined by image analysis and related to roughness changes and surface damage, both of the composite parts and of the mould steel surface. Finally, the abrasion resistance of the composite parts has been studied by scratch tests as a function of the number of injected parts and of the scratch direction with respect to injection flow and glass fibre orientation. Los materiales para moldes de inyeccion de polimeros y materiales compuestos representan un sector economicamente muy relevante debido al gran aumento del numero de componentes fabricados a partir de materiales polimericos obtenidos mediante moldeo por inyeccion. La seleccion del material para la

  19. The Thermal Distortion of a Funnel Mold

    NASA Astrophysics Data System (ADS)

    Hibbeler, Lance C.; Thomas, Brian G.; Schimmel, Ronald C.; Abbel, Gert

    2012-10-01

    This article investigates the thermal distortion of a funnel mold for continuous casting of thin slabs and explores the implications on taper and solidification of the steel shell. The three-dimensional mold temperatures are calculated using shell-mold heat flux and cooling water profiles that were calibrated with plant measurements. The thermal stresses and distorted shape of the mold are calculated with a detailed finite-element model of a symmetric fourth of the entire mold and waterbox assembly, and they are validated with plant thermocouple data and measurements of the wear of the narrow-face copper mold plates. The narrow-face mold distorts into the typical parabolic arc, and the wide face distorts into a "W" shape owing to the large variation in bolt stiffnesses. The thermal expansion of the wide face works against the applied narrow-face taper and funnel effects, so the effect of thermal distortion must be considered to accurately predict the ideal mold taper.

  20. Mold Remediation in Schools and Commercial Buildings.

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Washington, DC. Office of Radiation and Indoor Air.

    This document describes how to investigate and evaluate moisture and mold problems in educational facilities, and presents the key steps for implementing a remediation plan. A checklist is provided for conducting mold remediation efforts along with a resource list of helpful organizations and governmental agencies. Appendices contain a glossary,…

  1. EXPOSURE OF CHILDREN TO INDOOR MOLDS

    EPA Science Inventory

    Children now spend more than 90% of their time indoors. Thus, any exposure to indoor pollutants may be critical to their health. Molds are one of the most important pollutants children are exposed to indoors. Molds produce hundreds of allergens and toxins. These products ha...

  2. Dynamic Feed Control For Injection Molding

    DOEpatents

    Kazmer, David O.

    1996-09-17

    The invention provides methods and apparatus in which mold material flows through a gate into a mold cavity that defines the shape of a desired part. An adjustable valve is provided that is operable to change dynamically the effective size of the gate to control the flow of mold material through the gate. The valve is adjustable while the mold material is flowing through the gate into the mold cavity. A sensor is provided for sensing a process condition while the part is being molded. During molding, the valve is adjusted based at least in part on information from the sensor. In the preferred embodiment, the adjustable valve is controlled by a digital computer, which includes circuitry for acquiring data from the sensor, processing circuitry for computing a desired position of the valve based on the data from the sensor and a control data file containing target process conditions, and control circuitry for generating signals to control a valve driver to adjust the position of the valve. More complex embodiments include a plurality of gates, sensors, and controllable valves. Each valve is individually controllable so that process conditions corresponding to each gate can be adjusted independently. This allows for great flexibility in the control of injection molding to produce complex, high-quality parts.

  3. The use of IR thermography to show the mold and part temperature evolution in injection molding

    NASA Astrophysics Data System (ADS)

    Bula, Karol; Różański, Leszek; Marciniak-Podsadna, Lidia; Wróbel, Dawid

    2016-12-01

    This study concerns the application of infrared camera for injection molding analysis by measuring temperatures of both injection molded parts and injection mold cavities in a function of injection cycles. The mold with two cavities, differing in thickness (1 and 3 mm), and a cold direct runner was used. Isotactic polypropylene homopolymer was utilized to produce parts. Mold temperature was set at 22°C and controlled by a water chiller. Five measuring points were determined: SP1, SP2 (placed in the 3 mm cavity), SP3, SP4 (located in the 1 mm cavity) and SP5 around an injection molding gate. Our investigations showed that the highest temperature is localized around SP2 point and the lowest at SP4. Also, it was proved that even after 62 injection molding cycles, temperatures of cavities were not stable, revealing their further increase with each cycle.

  4. Grinding technologies of small optical element molds

    NASA Astrophysics Data System (ADS)

    Katsuki, Masahide; Urushibata, Kazunori

    2003-05-01

    The high-precision grinding technology is making contribution in every field, which is especially remarkable in the optics-related field. Lenses for digital camera and projector, which are mass-produced, for instance, are molded by the injection molding machine and glass molding-press machine. Concerning materials of high-precision molds, nickel alloy is mainly used in plastic-molding. And brittle material such as tungsten carbide and ceramic is used in glass-molding because the molding temperature is generally high. High-precision machining of nickel alloy is possible with a single-crystal diamond tool. Brittle material is ground by means of a diamond wheel, etc. Glass is being widely used for the lenses and other optical elements due to its favorable characteristics and life. As a result, needs for advancement of the high-precision grinding technology are being heightened. In grinding of small, fine and complex profiles, consideration for wheel truing and wear is a key point. Also, as many optical mold products are convex, mold profile is mainly concave. Especially, grinding of a small-aperture mold with small radius of curvature is difficult. In other words, a wheel whose diameter is larger than the radius of curvature of a mold to be ground cannot be used, and use of a small-diameter wheel is required inevitably. Influence of wheel wear and wheel diameter input errors at creation of grinding program becomes large. To eliminate such errors, a cycle of grinding, measurement and compensation grinding is normally repeated in mold machining until the target accuracy is obtained. Recently, needs for molding optical elements of small body of non-revolution such as prism and cylinder lens are on the increase, in addition to the body of revolution including lens. As one example, we introduce the compensation grinding and its results when grinding molds for an extremely small-aperture lens used for optical communication and a cylindrical lens array used for semi

  5. Immune Response among Patients Exposed to Molds

    PubMed Central

    Edmondson, David A.; Barrios, Christy S.; Brasel, Trevor L.; Straus, David C.; Kurup, Viswanath P.; Fink, Jordan N.

    2009-01-01

    Macrocyclic trichothecenes, mycotoxins produced by Stachybotrys chartarum, have been implicated in adverse reactions in individuals exposed to mold-contaminated environments. Cellular and humoral immune responses and the presence of trichothecenes were evaluated in patients with mold-related health complaints. Patients underwent history, physical examination, skin prick/puncture tests with mold extracts, immunological evaluations and their sera were analyzed for trichothecenes. T-cell proliferation, macrocyclic trichothecenes, and mold specific IgG and IgA levels were not significantly different than controls; however 70% of the patients had positive skin tests to molds. Thus, IgE mediated or other non-immune mechanisms could be the cause of their symptoms. PMID:20054481

  6. Castable plastic mold with electroplatable base

    DOEpatents

    Domeier, Linda A.; Morales, Alfredo M.; Gonzales, Marcela G.; Keifer, Patrick M.

    2004-01-20

    A sacrificial plastic mold having an electroplatable backing is provided as are methods of making such a mold via the infusion of a castable liquid formulation through a porous metal substrate (sheet, screen, mesh or foam) and into the features of a micro-scale master mold. Upon casting and demolding, the porous metal substrate is embedded within the cast formulation and projects a plastic structure with features determined by the mold tool. The plastic structure provides a sacrificial plastic mold mechanically bonded to the porous metal substrate, which provides a conducting support suitable for electroplating either contiguous or non-contiguous metal replicates. After electroplating and lapping, the sacrificial plastic can be dissolved, leaving the desired metal structure bonded to the porous metal substrate. Optionally, the electroplated structures may be debonded from the porous substrate by selective dissolution of the porous substrate or a coating thereon.

  7. Application of Artificial Vision in flow redirection during filling of Liquid Composite Molding processes

    NASA Astrophysics Data System (ADS)

    Montés, N.; Sanchez, F.; García, J. A.; Falcó, A.; Tornero, J.; Chinesta, F.

    2007-04-01

    The control techniques applied in Liquid Composite Molding processes have been extensively worked out by many different research groups abroad. In this work, the original use of artificial vision technology in order to redirect the flow path during mold filling appears as a major objective of online control strategy. In this study, a process performance index developed in a previous work is used to define the mold gate opening sequence. The Vacuum Assisted Resin Transfer Molding (VARTM) and Vacuum Assisted Resin Infusion (VARI) have been selected as the main processes of study. The expert system will make use of numerical simulation in order to obtain a previous physical understanding of the flow behaviour in different manufacturing conditions. Some examples of the installation are presented and discussed.

  8. Replication molds having nanometer-scale shape control fabricated by means of oxidation and etching.

    PubMed

    Kim, G M; Kovalgin, A; Holleman, J; Brugger, J

    2002-02-01

    A means of accurate control of the curvature radius of molds that are used in nanostructure replication techniques is presented. The local non-uniform growth of SiO2 at regions with high curvature is used to fabricate molds with a curvature radius ranging anywhere between 10 and 250 nm. The mold radius is predicted by numerical simulation as a function of oxidation temperature and time and confirmed by a series of oxidation and etching experiments. The silicon, silicon dioxide, and polymer nanostructures are analyzed by scanning electron microscopy and compared with the theory. Replication into photo-plastic polymer from various sharp and round molds is performed, and their properties are discussed. Our results are useful for designing nanostructures in the area of soft lithography and nanoprobe engineering.

  9. Controlled study of mold growth and cleaning procedure on treated and untreated wet gypsum wallboard in an indoor environment.

    PubMed

    Krause, Michael; Geer, William; Swenson, Lonie; Fallah, Payam; Robbins, Coreen

    2006-08-01

    The basis for some common gypsum wallboard mold remediation practices was examined. The bottom inch of several gypsum wallboard panels was immersed in bottled drinking water; some panels were coated and others were untreated. The panels were examined and tested for a period of 8 weeks. This study investigated: (a) whether mold growth, detectable visually or with tape lift samples, occurs within 1 week on wet gypsum wallboard; (b) the types, timing, and extent of mold growth on wet gypsum wallboard; (c) whether mold growth is present on gypsum wallboard surfaces 6 inches from visible mold growth; (d) whether some commonly used surface treatments affect the timing of occurrence and rate of mold growth; and (e) if moldy but dried gypsum wallboard can be cleaned with simple methods and then sealed with common surface treatments so that residual mold particles are undetectable with typical surface sampling techniques. Mold growth was not detected visually or with tape lift samples after 1 week on any of the wallboard panels, regardless of treatment, well beyond the 24-48 hours often mentioned as the incubation period. Growth was detected at 2 weeks on untreated gypsum. Penicillium, Cladosporium, and Acremonium were early colonizers of untreated panels. Aspergillus, Epicoccum, Alternaria, and Ulocladium appeared later. Stachybotrys was not found. Mold growth was not detected more than 6 inches beyond the margin of visible mold growth, suggesting that recommendations to remove gypsum wallboard more than 1 foot beyond visible mold are excessive. The surface treatments resulted in delayed mold growth and reduced the area of mold growth compared with untreated gypsum wallboard. Results showed that simple cleaning of moldy gypsum wallboard was possible to the extent that mold particles beyond "normal trapping" were not found on tape lift samples. Thus, cleaning is an option in some situations where removal is not feasible or desirable. In cases where conditions are not

  10. Comparing suppository mold variability which can lead to dosage errors for suppositories prepared with the same or different molds.

    PubMed

    Alexander, Kenneth S; Baki, Gabriella; Hart, Christine; Hejduk, Courtney; Chillas, Stephanie

    2013-01-01

    Suppository molds must be properly calibrated to ensure accurate dosing. There are often slight differences between molds and even in the cavities within a mold. A method is presented for the calibration of standard aluminum 6-, 12-, 50-, or 100-well suppository molds. Ten different molds were tested using water for volume calibration, and cocoa butter for standardization involving establishing the density factor. This method is shown to be straightforward and appropriate for calibrating suppository molds.

  11. Fabrication of metallic nanodots in large-area arrays by mold-to-mold cross imprinting (MTMCI).

    PubMed

    Kwon, Sunghoon; Yan, Xiaoming; Contreras, Anthony M; Liddle, J Alexander; Somorjai, Gabor A; Bokor, Jeffrey

    2005-12-01

    We have developed a mold-to-mold cross imprint (MTMCI) process, which redefines an imprint mold with another imprint mold. By performing MTMCI on two identical imprint molds with silicon spacer nanowires in a perpendicular arrangement, we fabricated a large array of sub-30-nm silicon nanopillars. Large-area arrays of Pt dots are then produced using nanoimprint lithography with the silicon nanopillar mold.

  12. 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.

  13. Investigation on overplating high-aspect-ratio microstructure

    NASA Astrophysics Data System (ADS)

    Guo, Yuhua; Liu, Gang; Tian, Yangchao

    2006-01-01

    Most previous research on electroplating in LIGA has focused on electrodeposition of metal into high aspect ratio resist molds. In overplating process how the metal grows up across the top of resist molds has been relatively neglected. Typical defects like holes formation at the top of cavities of electroplated metal mold usually occur due to improper process control especially when the space/linewidth ratio of microstructure increases. To help understand these problems, overplating process has been investigated. A model is developed to compute current density distribution based on LIGA mold feature using electroplating simulation tools. Results show that it is almost an isotropic growing model at the first stage of overplating. As the deposited metal grows bigger the space between electrodes is shortened and the current density distribution along electrode may be modulated by neighbor electrode. It doesn't show an isotropic growing model any more. The deposition rate in inward lateral direction is smaller than in vertical direction. The growing model based on calculation shows that the trench feature aspect ratio can reach a considerable magnitude especially when the LIGA mold feature space/linewidth ratio increases. In poor transport situation, ion depletion becomes significant and a stopped deposition may occur thus holes can be formed at the bottom of overlapped neighbor electrodes. An optimized experiment has been performed using low overpotentials at the stage before the overlapping of neighbor electrodes and a rigorous stirring of electrolyte. A nickel mold insert without holes-formation defects can be obtained.

  14. A Review of Metal Injection Molding- Process, Optimization, Defects and Microwave Sintering on WC-Co Cemented Carbide

    NASA Astrophysics Data System (ADS)

    Shahbudin, S. N. A.; Othman, M. H.; Amin, Sri Yulis M.; Ibrahim, M. H. I.

    2017-08-01

    This article is about a review of optimization of metal injection molding and microwave sintering process on tungsten cemented carbide produce by metal injection molding process. In this study, the process parameters for the metal injection molding were optimized using Taguchi method. Taguchi methods have been used widely in engineering analysis to optimize the performance characteristics through the setting of design parameters. Microwave sintering is a process generally being used in powder metallurgy over the conventional method. It has typical characteristics such as accelerated heating rate, shortened processing cycle, high energy efficiency, fine and homogeneous microstructure, and enhanced mechanical performance, which is beneficial to prepare nanostructured cemented carbides in metal injection molding. Besides that, with an advanced and promising technology, metal injection molding has proven that can produce cemented carbides. Cemented tungsten carbide hard metal has been used widely in various applications due to its desirable combination of mechanical, physical, and chemical properties. Moreover, areas of study include common defects in metal injection molding and application of microwave sintering itself has been discussed in this paper.

  15. Medical diagnostics for indoor mold exposure.

    PubMed

    Hurraß, Julia; Heinzow, Birger; Aurbach, Ute; Bergmann, Karl-Christian; Bufe, Albrecht; Buzina, Walter; Cornely, Oliver A; Engelhart, Steffen; Fischer, Guido; Gabrio, Thomas; Heinz, Werner; Herr, Caroline E W; Kleine-Tebbe, Jörg; Klimek, Ludger; Köberle, Martin; Lichtnecker, Herbert; Lob-Corzilius, Thomas; Merget, Rolf; Mülleneisen, Norbert; Nowak, Dennis; Rabe, Uta; Raulf, Monika; Seidl, Hans Peter; Steiß, Jens-Oliver; Szewszyk, Regine; Thomas, Peter; Valtanen, Kerttu; Wiesmüller, Gerhard A

    2017-04-01

    In April 2016, the German Society of Hygiene, Environmental Medicine and Preventative Medicine (Gesellschaft für Hygiene, Umweltmedizin und Präventivmedizin (GHUP)) together with other scientific medical societies, German and Austrian medical societies, physician unions and experts has provided an AWMF (Association of the Scientific Medical Societies) guideline 'Medical diagnostics for indoor mold exposure'. This guideline shall help physicians to advise and treat patients exposed indoors to mold. Indoor mold growth is a potential health risk, even without a quantitative and/or causal association between the occurrence of individual mold species and health effects. Apart from the allergic bronchopulmonary aspergillosis (ABPA) and the mycoses caused by mold, there is only sufficient evidence for the following associations between moisture/mold damages and different health effects: Allergic respiratory diseases, asthma (manifestation, progression, exacerbation), allergic rhinitis, exogenous allergic alveolitis and respiratory tract infections/bronchitis. In comparison to other environmental allergens, the sensitizing potential of molds is estimated to be low. Recent studies show a prevalence of sensitization of 3-10% in the total population of Europe. The evidence for associations to mucous membrane irritation and atopic eczema (manifestation, progression, exacerbation) is classified as limited or suspected. Inadequate or insufficient evidence for an association is given for COPD, acute idiopathic pulmonary hemorrhage in children, rheumatism/arthritis, sarcoidosis, and cancer. The risk of infections from indoor molds is low for healthy individuals. Only molds that are capable to form toxins can cause intoxications. The environmental and growth conditions and especially the substrate determine whether toxin formation occurs, but indoor air concentrations are always very low. In the case of indoor moisture/mold damages, everyone can be affected by odor effects and

  16. Mold management of wetted carpet.

    PubMed

    Ong, Kee-Hean; Dixit, Anupma; Lewis, Roger D; MacDonald Perkins, Maureen; Backer, Denis; Condoor, Sridhar; Emo, Brett; Yang, Mingan

    2014-01-01

    This study evaluated the growth and removal of fungi on wetted carpet using newly designed technologies that rely on physical principles of steam, heat, and fluid flow. Sixty samples of carpet were embedded with heat-treated house dust, followed by embedding, wearing with a hexapod, and wetting. Samples were inoculated using a liquid suspension of Cladosporium sphaerospermum prior to placement over a water-saturated foam pad. Incubation times were 24 hr, 7 days, and 30 days. Cleaning was performed using three methods; high-flow hot water extraction, hot water and detergent, and steam. Fungal loading increased from approximately 1500 colony forming units per area (CFU/cm(2)) in 24 hr to a maximum of approximately 10,200 CFU/cm(2) after 7 days with a slight decline to 9700 CFU/cm(2) after 30 days incubation. Statistically significant differences were found among all three methods for removal of fungi for all three time periods (p < 0.05). Steam-vapor was significantly better than the alternative methods (p <0.001) with over 99% efficiency in mold spore decline from wetted carpet after 24 hr and 30 days, and over 92% efficiency after 7 days. The alternative methods exhibited lower efficiencies with a decline over time, from a maximum of 82% and 81% at 24 hr down to 60% and 43% at 30 days for detergent-hot water and high-flow, hot water extraction, respectively. The net effect of the mold management study demonstrates that while steam has a consistent fungal removal rate, the detergent and high-flow, hot water methods decline in efficiency with increasing incubation time.

  17. Challenges in mold manufacturing for high precision molded diffractive optical elements

    NASA Astrophysics Data System (ADS)

    Pongs, Guido; Bresseler, Bernd; Schweizer, Klaus; Bergs, Thomas

    2016-09-01

    Isothermal precision glass molding of imaging optics is the key technology for mass production of precise optical elements. Especially for numerous consumer applications (e.g. digital cameras, smart phones, …), high precision glass molding is applied for the manufacturing of aspherical lenses. The usage of diffractive optical elements (DOEs) can help to further reduce the number of lenses in the optical systems which will lead to a reduced weight of hand-held optical devices. But today the application of molded glass DOEs is limited due to the technological challenges in structuring the mold surfaces. Depending on the application submicrometer structures are required on the mold surface. Furthermore these structures have to be replicated very precisely to the glass lens surface. Especially the micro structuring of hard and brittle mold materials such as Tungsten Carbide is very difficult and not established. Thus a multitude of innovative approaches using diffractive optical elements cannot be realized. Aixtooling has investigated in different mold materials and different suitable machining technologies for the micro- and sub-micrometer structuring of mold surfaces. The focus of the work lays on ultra-precision grinding to generate the diffractive pattern on the mold surfaces. This paper presents the latest achievements in diffractive structuring of Tungsten Carbide mold surfaces by ultra-precision grinding.

  18. Rotational molding of pultruded profiles reinforced polyethylene

    NASA Astrophysics Data System (ADS)

    Greco, Antonio; Maffezzoli, Alfonso; Romano, Giorgio

    2014-05-01

    The aim of this paper is the production of fiber reinforced LLDPE components by rotational molding. To this purpose, a process upgrade was developed, for the incorporation of pultruded tapes in the rotational molding cycle. Pultruded tapes, made of 50% by weight of glass fibers dispersed in a high density polyethylene(HDPE) matrix, were glued on the internal surface of a cubic mold, and rotational molding process was run using the same processing conditions used for conventional LLDPE processing. During processing, melting of LLDPE powders and of HDPE allowed to incorporate the tapes inside rotational molded LLDPE. The glass fiber reinforced prototypes were characterized in terms of mechanical properties. Plate bending tests were performed on the square faces extracted from the rotational molded product. The rotational molding products were also subjected to internal hydrostatic pressure tests up to 10 bar. In any case, no failure of the cubic samples was observed. In both cases, it was found that addition of a single pultruded strips, which corresponds to addition of about 0.6% by weight of glass fibers, involved an increase of the stiffness of the faces by about 25%.

  19. Tracing the Origin of Non-ferrous Oxides in Lamination Defects on Hot-Rolled Coils: Mold Slag Entrainment vs Submerged Entry Nozzle Reaction Products

    NASA Astrophysics Data System (ADS)

    Sengo, Sabri; Romano Triguero, Patricia; Zinngrebe, Enno; Mensonides, Fokko

    2017-06-01

    In this work, lamination defects (slivers) on hot-rolled coils of Ca-treated steel were investigated for microstructure and composition using optical and scanning electron microscopy combined with microanalysis (SEM/EDS). The goal was to identify possible origins for the observed defects which contain a complex assemblage of phases, such as different types of calcium aluminates (CA, CA2, CA6), melilite (C2AS), spinel (MA), and a newly identified phase, CNA2. Mold slag similar to that employed during the cast was absent. Analysis of the bulk composition of some of the defects indicated these to be too rich in alumina to be derived from mold slag through steel-slag redox exchange. In contrast, microstructural observation of the inner side of the submerged entry nozzles (SEN) used during casting showed deposits with compositions comparable to those of the defect material. Based on an estimation of the chemical evolution of mold slag interacting with steel, it is found that the defects are not likely to be entrained mold slag but remobilized SEN deposits, as supported by several microstructural and trace phase criteria. However, it should be noted that extensive reduction of mold slag by steel can lead to compositions rich in sodic-calcic aluminates (CNA2). Therefore, differentiation between specific locations of the defect materials within a casting system requires detailed analysis from the potential sources of origin as well as from the materials found in the defects.

  20. Tracing the Origin of Non-ferrous Oxides in Lamination Defects on Hot-Rolled Coils: Mold Slag Entrainment vs Submerged Entry Nozzle Reaction Products

    NASA Astrophysics Data System (ADS)

    Sengo, Sabri; Romano Triguero, Patricia; Zinngrebe, Enno; Mensonides, Fokko

    2017-02-01

    In this work, lamination defects (slivers) on hot-rolled coils of Ca-treated steel were investigated for microstructure and composition using optical and scanning electron microscopy combined with microanalysis (SEM/EDS). The goal was to identify possible origins for the observed defects which contain a complex assemblage of phases, such as different types of calcium aluminates (CA, CA2, CA6), melilite (C2AS), spinel (MA), and a newly identified phase, CNA2. Mold slag similar to that employed during the cast was absent. Analysis of the bulk composition of some of the defects indicated these to be too rich in alumina to be derived from mold slag through steel-slag redox exchange. In contrast, microstructural observation of the inner side of the submerged entry nozzles (SEN) used during casting showed deposits with compositions comparable to those of the defect material. Based on an estimation of the chemical evolution of mold slag interacting with steel, it is found that the defects are not likely to be entrained mold slag but remobilized SEN deposits, as supported by several microstructural and trace phase criteria. However, it should be noted that extensive reduction of mold slag by steel can lead to compositions rich in sodic-calcic aluminates (CNA2). Therefore, differentiation between specific locations of the defect materials within a casting system requires detailed analysis from the potential sources of origin as well as from the materials found in the defects.

  1. Micromachining using a focused MeV proton beam for the production of high-precision 3D microstructures with vertical sidewalls of high orthogonality

    NASA Astrophysics Data System (ADS)

    van Kan, Jeroen A.; Bettiol, Andrew A.; Ansari, K.; Watt, Frank

    2001-08-01

    The production of high aspect ratio microstructures requires a lithographic technique capable of producing microstructures with vertical sidewalls. There are few techniques (eg proton beam micromachining, LIGA and Stereolithoghaphy) capable of producing high aspect ratio microstructures at sub-micron dimensions. In Proton Beam Micromachining (PBM), a high energy (eg 2 MeV) proton beam is focused to a sub-micron spot size and scanned over a resist material (eg SU-8 and PMMA). When a proton beam interacts with matter it follows an almost straight path, the depth of which is dependent on the proton beam energy. These features enable the production of multilevel microstructures with vertical sidewalls of high orthogonality. Proton beam micromachining is a fast direct write lithographic technique; in a few seconds a complicated pattern in an area of 400 x 400 micrometers 2 can be exposed down to a depth of 150 micrometers . These features make proton beam micromachining a technique of high potential for the production of high-aspect-ratio-structures at a much lower total cost than the LIGA process, which requires a synchrotron radiation source and precision masks. Research is currently under way to improve the process that employs the SU-8 negative photo-resist as a mold to electroplate Ni. Experiments have shown that post-bake and curing steps are not required in this SU-8 process, reducing the effects of cracking and internal stress in the resist. Plated Ni structures can be easily produced which are high quality negative copies of the SU-8 produced microstructures.

  2. Study of Double-Side Ultrasonic Embossing for Fabrication of Microstructures on Thermoplastic Polymer Substrates

    PubMed Central

    Luo, Yi; Yan, Xu; Qi, Na; Wang, Xiaodong; Wang, Liangjiang

    2013-01-01

    Double-side replication of polymer substrates is beneficial to the design and the fabrication of 3-demensional devices. The ultrasonic embossing method is a promising, high efficiency and low cost replication method for thermoplastic substrates. It is convenient to apply silicon molds in ultrasonic embossing, because microstructures can be easily fabricated on silicon wafers with etching techniques. To reduce the risk of damaging to silicon molds and to improve the replication uniformity on both sides of the polymer substrates, thermal assisted ultrasonic embossing method was proposed and tested. The processing parameters for the replication of polymethyl methacrylate (PMMA), including ultrasonic amplitude, ultrasonic force, ultrasonic time, and thermal assisted temperature were studied using orthogonal array experiments. The influences of the substrate thickness, pattern style and density were also investigated. The experiment results show that the principal parameters for the upper and lower surface replication are ultrasonic amplitude and thermal assisted temperature, respectively. As to the replication uniformity on both sides, the ultrasonic force has the maximal influence. Using the optimized parameters, the replication rate reached 97.5% on both sides of the PMMA substrate, and the cycle time was less than 50 s. PMID:23630605

  3. Study of double-side ultrasonic embossing for fabrication of microstructures on thermoplastic polymer substrates.

    PubMed

    Luo, Yi; Yan, Xu; Qi, Na; Wang, Xiaodong; Wang, Liangjiang

    2013-01-01

    Double-side replication of polymer substrates is beneficial to the design and the fabrication of 3-demensional devices. The ultrasonic embossing method is a promising, high efficiency and low cost replication method for thermoplastic substrates. It is convenient to apply silicon molds in ultrasonic embossing, because microstructures can be easily fabricated on silicon wafers with etching techniques. To reduce the risk of damaging to silicon molds and to improve the replication uniformity on both sides of the polymer substrates, thermal assisted ultrasonic embossing method was proposed and tested. The processing parameters for the replication of polymethyl methacrylate (PMMA), including ultrasonic amplitude, ultrasonic force, ultrasonic time, and thermal assisted temperature were studied using orthogonal array experiments. The influences of the substrate thickness, pattern style and density were also investigated. The experiment results show that the principal parameters for the upper and lower surface replication are ultrasonic amplitude and thermal assisted temperature, respectively. As to the replication uniformity on both sides, the ultrasonic force has the maximal influence. Using the optimized parameters, the replication rate reached 97.5% on both sides of the PMMA substrate, and the cycle time was less than 50 s.

  4. Slimeware: engineering devices with slime mold.

    PubMed

    Adamatzky, Andrew

    2013-01-01

    The plasmodium of the acellular slime mold Physarum polycephalum is a gigantic single cell visible to the unaided eye. The cell shows a rich spectrum of behavioral patterns in response to environmental conditions. In a series of simple experiments we demonstrate how to make computing, sensing, and actuating devices from the slime mold. We show how to program living slime mold machines by configurations of repelling and attracting gradients and demonstrate the workability of the living machines on tasks of computational geometry, logic, and arithmetic.

  5. Mucormycosis, Pseudallescheriasis, and Other Uncommon Mold Infections

    PubMed Central

    Quan, Clifford; Spellberg, Brad

    2010-01-01

    Serious infections due to non-Aspergillus molds are being encountered with increasing frequency. Factors likely responsible for the rise of these infections include aging populations in countries with advanced medical technologies, the resultant increase in incidence of many cancers, increasingly intensive myeloablative therapies for these cancers, increasingly intensive care for critically ill patients, and increases in the frequency of solid organ and hematopoietic stem cell transplantation. Although diagnostic and therapeutic modalities have improved, mortality rates for invasive mold infections remain high. In this review, we summarize current knowledge about non-Aspergillus mold infections of the chest, with a focus on risk factors, clinical features, diagnosis, and treatment. PMID:20463250

  6. Mold contamination of automobile air conditioner systems.

    PubMed

    Kumar, P; Lopez, M; Fan, W; Cambre, K; Elston, R C

    1990-02-01

    Eight cars belonging to patients who were found to have exacerbation of allergic rhinitis and bronchial asthma after turning on the air conditioner in their cars were examined. Mold concentrations inside the passenger compartment with the a/c turned off and at different climate control settings were lower than concentrations in the outside air. After turning on the air conditioner to "Max", cultures obtained at various intervals revealed that mold concentrations decreased significantly with time. Furthermore, placement of a filter at the portal of entry of outside air significantly reduced the mold concentration in the passenger compartment.

  7. Controlling Radiative Heat Transfer Across the Mold Flux Layer by the Scattering Effect of the Borosilicate Mold Flux System with Metallic Iron

    NASA Astrophysics Data System (ADS)

    Yoon, Dae-Woo; Cho, Jung-Wook; Kim, Seon-Hyo

    2017-08-01

    The present study proposes a countermeasure for regulating total heat flux through the mold flux layer by designed mold flux with additive metallic iron particles. The heat flux through the B2O3-CaO-SiO2-Na2O-CaF2-Fe system was investigated using the infrared emitter technique to evaluate total flux density across the mold flux film. Both scanning electron microscope (SEM) and X-ray diffraction analysis were employed in order to identify the morphological and compositional changes of the crystalline phase, according to increasing iron contents in the mold flux. It was confirmed that the crystalline layer of studied mold fluxes does not have a meaningful effect on the total heat flux density due to the similar structure and fraction of the crystalline phase. The extinction coefficient was measured for glassy mold fluxes using an ultraviolet/visible and a Fourier transformation-infrared ray spectrometer in the range of 0.5 to 5 μm. For analyzing the scattering behavior of iron particles on the extinction coefficient, the number density and diameter of particles were observed by an automated SEM (auto-SEM). With these data, Mie scattering theory is adopted to define the scattering behavior of dispersed iron droplets in glassy matrix. It was found that the theoretical scattering coefficient demonstrated about 1623 to 3295 m-1, which is in accordance with the experimental results. In doing so, this study successfully achieves the strong scattering behavior that would contribute greatly to the optimization of overall heat flux through the mold flux film during the casting process.

  8. Metal Injection Molding of Tungsten Heavy Alloys: SBIR Phase 1

    DTIC Science & Technology

    1991-10-01

    Huntington Beach, CA). Task 7: Injection Molding Injection Molding was performed in a Arburg (Model 305-211-700) with test specimens provided for both solid... Arburg Injection Molding machine (Model 305-211-700). The molding conditions were: Temperature: Nozzle - 177°C (350°F) Front - 177 0 C (350°F) Middle

  9. INTERIOR VIEW, GRAY IRON MOLDING MACHINE WITH MOLDER, R. L. ...

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

    INTERIOR VIEW, GRAY IRON MOLDING MACHINE WITH MOLDER, R. L. BRANDY MOLDING A RAIL CASTING (LAWLER NO. 1337, A 16' x 35' MOLD WITH A 5' COPE AND A 4' DRAG). DRAG IS FILLED WITH SAND. - Lawler Machine & Foundry Company, Molding Area, 760 North Forty-fourth Street, Birmingham, Jefferson County, AL

  10. RUN OUTS OCCUR WHEN IRON HAS UNSEATED MOLDING SAND AND ...

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

    RUN OUTS OCCUR WHEN IRON HAS UNSEATED MOLDING SAND AND RUN OUT OF THE MOLD UNDER POURING JACKETS AND SPILLS ONTO THE MOLDING PLATFORM. WORKERS GENERALLY WAIT SEVERAL MINUTES FOR THE IRON TO SOLIDIFY AND, WHILE IT IS STILL RED-HOT, REMOVE IT FROM THE PLATFORM AND SCRAP THE MOLD. - Southern Ductile Casting Company, Centerville Foundry, 101 Airport Road, Centreville, Bibb County, AL

  11. RUN OUTS OCCUR WHEN IRON HAS UNSEATED MOLDING SAND AND ...

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

    RUN OUTS OCCUR WHEN IRON HAS UNSEATED MOLDING SAND AND RUN OUT OF THE MOLD UNDER POURING JACKETS AND SPILLS ONTO THE MOLDING PLATFORM. WORKERS GENERALLY WAIT SEVERAL MINUTES FOR THE IRON TO SOLIDIFY AND, WHILE IT IS STILL RED-HOT, REMOVE IT FROM THE PLATFORM AND SCRAP THE MOLD. - Southern Ductile Casting Company, Centerville Foundry, 101 Airport Road, Centreville, Bibb County, AL

  12. Tissue engineering of a human sized and shaped auricle using a mold.

    PubMed

    Kamil, S H; Vacanti, M P; Aminuddin, B S; Jackson, M J; Vacanti, C A; Eavey, R D

    2004-05-01

    The creation of a tissue-engineered auricle was initially successful in an immunocompromised nude mouse model. Subsequently, an immunocompetent porcine model successfully generated a helical construct. We wished to evaluate the novel technique of using a mold to create a complete, anatomically refined auricle in a large animal model. Mixtures of autogenous chondrocytes and biodegradable polymers were used inside a perforated, auricle shaped hollow gold mold. Three biodegradable polymers (calcium alginate, pluronic F-127, and polyglycolic acid) were used to retain the seeded chondrocytes inside the mold. These molds, along with a control, were implanted subcutaneously in the abdominal area of 10 animals (pigs and sheep). The constructs were removed after 8 to 20 weeks and were assessed by gross morphology and histology. All the gold implants were well tolerated by the animals. The implants using calcium alginate (n = 3) generated constructs of the exact shape and size of a normal human ear; the histology demonstrated mostly normal cartilage with some persistent alginate. The implants with pluronic F-127 (n = 3) resulted in cartilage with essentially normal histology, although leakage outside the molds and external cartilage generation was noted. Polyglycolic acid implants (n = 3) produced no useful cartilage because of an inflammatory reaction with fibrosis. The empty control mold (n = 1) demonstrated only a very small amount of fibrous tissue inside. A tissue-engineered human sized auricle of normal anatomic definition can be generated in an immunocompetent large-animal model using a mold technique. Although further refinements will be necessary, the technique appears promising for potential use in patients with microtia.

  13. Fabrication of Microfluidic Valves Using a Hydrogel Molding Method

    PubMed Central

    Sugiura, Yusuke; Hirama, Hirotada; Torii, Toru

    2015-01-01

    In this paper, a method for fabricating a microfluidic valve made of polydimethylsiloxane (PDMS) using a rapid prototyping method for microchannels through hydrogel cast molding is discussed. Currently, the valves in microchannels play an important role in various microfluidic devices. The technology to prototype microfluidic valves rapidly is actively being developed. For the rapid prototyping of PDMS microchannels, a method that uses a hydrogel as the casting mold has been recently developed. This technique can be used to prepare a three-dimensional structure through simple and uncomplicated methods. In this study, we were able to fabricate microfluidic valves easily using this rapid prototyping method that utilizes hydrogel cast molding. In addition, we confirmed that the valve displacement could be predicted within a range of constant pressures. Moreover, because microfluidic valves fabricated using this method can be directly observed from a cross-sectional direction, we anticipate that this technology will significantly contribute to clarifying fluid behavior and other phenomena in microchannels and microfluidic valves with complex structures. PMID:26300303

  14. Low cost energy storage flywheels from structural sheet molding compound

    NASA Astrophysics Data System (ADS)

    Kay, J. F.

    Compression molded structural sheet molding compound (SMC) composed of S-2 Glass and polyester resin has been used to fabricate energy storage flywheel rotors. This technique has the potential of low cost, high throughput production of rotors for the automobile industry. An isophthalic polyester resin and chopped S-2 Glass were used to mold flat, constant cross section discs 53.3 cm (21 innches) in diameter, 2.54 cm (1.0 inches) thick, and 49.5 kg (22.5 pounds) in weight. Materials characterizations have shown a tensile strength of 337 MPa (49 ksi) for the S-2 Glass reinforced rotors, which would allow the rotor to store 28.6 watt-hours per kilogram (13 watt-hours per pound) at 330 hertz when a filament wound carbon fiber/epoxy ring is fitted around the SMC core. A dynamic test of an SMC flywheel has shown an energy storage density of 27.7 watt-hours per kilogram (12.6 watt-hours per pound) at 330 hertz.

  15. Semiautomatic registration of digital histopathology images to in vivo MR images in molded and unmolded prostates.

    PubMed

    Starobinets, Olga; Guo, Richard; Simko, Jeffry P; Kuchinsky, Kyle; Kurhanewicz, John; Carroll, Peter R; Greene, Kirsten L; Noworolski, Susan M

    2014-05-01

    To evaluate a semiautomatic software-based method of registering in vivo prostate MR images to digital histopathology images using two approaches: (i) in which the prostates were molded to simulate distortion due to the endorectal imaging coil before fixation, and (ii) in which the prostates were not molded. T2-weighted MR images and digitized whole-mount histopathology images were acquired for 26 patients with biopsy-confirmed prostate cancer who underwent radical prostatectomy. Ten excised prostates were molded before fixation. A semiautomatic method was used to align MR images to histopathology. Percent overlap between MR and histopathology images, as well as distances between corresponding anatomical landmarks were calculated and used to evaluate the registration technique for molded and unmolded cases. The software successfully morphed histology-based prostate images into corresponding MR images. Percent overlap improved from 80.4 ± 5.8% before morphing to 99.7 ± 0.62% post morphing. Molded prostates had a smaller distance between landmarks (1.91 ± 0.75 mm) versus unmolded (2.34 ± 0.68 mm), P < 0.08. Molding a prostate before fixation provided a better alignment of internal structures within the prostate, but this did not reach statistical significance. Software-based morphing allowed for nearly complete overlap between the pathology slides and the MR images. Copyright © 2013 Wiley Periodicals, Inc.

  16. Development of a PCR protocol to detect aflatoxigenic molds in food products.

    PubMed

    Luque, M Isabel; Rodríguez, Alicia; Andrade, María J; Martín, Alberto; Córdoba, Juan J

    2012-01-01

    Aflatoxins are secondary metabolites produced mainly by Aspergillus species growing in foodstuffs. Because aflatoxins have important health effects, the detection of early contamination of foods by aflatoxigenic molds should be useful. In the present work, a reliable conventional PCR method for detecting aflatoxigenic molds of various species was developed. Fifty-six aflatoxigenic and nonaflatoxigenic strains commonly reported in foodstuffs were tested. Aflatoxin production was first confirmed by micellar electrokinetic capillary electrophoresis or/and high-pressure liquid chromatography-mass spectrometry. Based on the conserved regions of the O-methyltransferase gene (omt-1) involved in the aflatoxin biosynthetic pathway, six primer pairs were designed. With only the designed primer pair AFF1-AFR3, the expected PCR product (381 bp) was obtained in all of the tested aflatoxigenic strains of various species and genera. Amplification products were not obtained with this primer pair for any of the nonaflatoxigenic reference molds. However, an amplicon of 453 bp was obtained for all aflatoxigenic and nonaflatoxigenic mold reference strains with a PCR protocol based on the constitutive fungal β-tubulin gene, which was used as a positive fungal control. The PCR protocol based on omt-1 detected as little as 15 pg of DNA from aflatoxigenic molds and 10(2) to 10(3) CFU/g in contaminated food samples. This PCR protocol should be used as a routine technique to detect aflatoxigenic molds in foods.

  17. Local mechanical properties of LFT injection molded parts: Numerical simulations versus experiments

    NASA Astrophysics Data System (ADS)

    Desplentere, F.; Soete, K.; Bonte, H.; Debrabandere, E.

    2014-05-01

    In predictive engineering for polymer processes, the proper prediction of material microstructure from known processing conditions and constituent material properties is a critical step forward properly predicting bulk properties in the finished composite. Operating within the context of long-fiber thermoplastics (LFT, length < 15mm) this investigation concentrates on the prediction of the local mechanical properties of an injection molded part. To realize this, the Autodesk Simulation Moldflow Insight 2014 software has been used. In this software, a fiber breakage algorithm for the polymer flow inside the mold is available. Using well known micro mechanic formulas allow to combine the local fiber length with the local orientation into local mechanical properties. Different experiments were performed using a commercially available glass fiber filled compound to compare the measured data with the numerical simulation results. In this investigation, tensile tests and 3 point bending tests are considered. To characterize the fiber length distribution of the polymer melt entering the mold (necessary for the numerical simulations), air shots were performed. For those air shots, similar homogenization conditions were used as during the injection molding tests. The fiber length distribution is characterized using automated optical method on samples for which the matrix material is burned away. Using the appropriate settings for the different experiments, good predictions of the local mechanical properties are obtained.

  18. The Study of Deep Lithography and Moulding Process of LIGA Technique

    NASA Astrophysics Data System (ADS)

    Guo, Yuhua; Liu, Gang; Kan, Ya; Tian, Yangchao

    2007-01-01

    The knowledge of the development behavior, especially the development rate, is of primary importance for the study of deep x-ray lithography in LIGA technique. In the first part of this paper, we have measured the development rates of crosslinked PMMA foils irradiated in NSRL covering a wide dose range (bottom dose in the range:2.5-8.0 kJ/cm3). After the exposure, we use a so-called period-development method (to dip development in GG-developer for 20 minutes and clean in rinse solution for 40 minutes as a development period). For processing the experiment data, we get the KDβ model to describe our PMMA/GG-developer system. The aim of this work is to find out a stable experiment condition for deep X-ray lithography and development. The result shows that in small amount of dose (bottom dose range: 2.5-4 kJ/cm3), this model is very stable. While in large amount of dose (bottom dose range: 5-8kJ/cm3), the model becomes very sensitive and even unavailable. To verify the conclusion validity, the fixed dose range (bottom dose range: 3.5-4 kJ/cm3) is applied on PMMA microstructures. And the result shows an effective development process. In the following procedure, mold inserts can be produced by micro-electroforming and plastic replicas can be mass produced by hot embossing. To emboss high-aspect-ratio microstructures, the deformation of microstructures usually occurs due to the demolding forces between the sidewall of mold inserts and the thermoplastic (PMMA). To minimize the friction force the optimized experiment has been performed using Ni-PTFE compound material mold inserts. Typical defects like pull-up and damaged edges can be greatly reduced.

  19. Comparison of a Directionally Solidified TiAl Alloy by Φ15 mm Cylindrical and 29 × 6 mm Plate Y2O3 Molds

    NASA Astrophysics Data System (ADS)

    Zhang, Hailong; Ding, Hongsheng; Wang, Qiang; Chen, Ruirun; Guo, Jingjie; Fu, Hengzhi

    2017-07-01

    To begin a preliminary exploration on the effect of shape, the effect of a novel shaped 29 × 6 mm plate mold on the microstructure and mechanical properties of directionally solidified (DS) Ti-45Al-2Cr-2Nb was investigated. For comparison, Φ15 mm cylindrical molds with an equivalent cross-sectional area were used. Experimental results show that the typical microstructures of the DS region in all samples consist of regular well aligned α 2/γ lamellar structure, B2 phase and Y2O3 particles. Due to the lower strength of flow generated by the shape factor of the mold, the plate sample has coarser lamellae and more B2 phase, but fewer Y2O3 particles. Additionally, the room temperature (RT) fracture toughness and tensile properties of the plate sample are improved.

  20. Comparison of a Directionally Solidified TiAl Alloy by Φ15 mm Cylindrical and 29 × 6 mm Plate Y2O3 Molds

    NASA Astrophysics Data System (ADS)

    Zhang, Hailong; Ding, Hongsheng; Wang, Qiang; Chen, Ruirun; Guo, Jingjie; Fu, Hengzhi

    2017-10-01

    To begin a preliminary exploration on the effect of shape, the effect of a novel shaped 29 × 6 mm plate mold on the microstructure and mechanical properties of directionally solidified (DS) Ti-45Al-2Cr-2Nb was investigated. For comparison, Φ15 mm cylindrical molds with an equivalent cross-sectional area were used. Experimental results show that the typical microstructures of the DS region in all samples consist of regular well aligned α 2/ γ lamellar structure, B2 phase and Y2O3 particles. Due to the lower strength of flow generated by the shape factor of the mold, the plate sample has coarser lamellae and more B2 phase, but fewer Y2O3 particles. Additionally, the room temperature (RT) fracture toughness and tensile properties of the plate sample are improved.

  1. Online Measurement for Transient Mold Friction Based on the Hydraulic Oscillators of Continuous-Casting Mold

    NASA Astrophysics Data System (ADS)

    Wang, Xudong; Wang, Zhaofeng; Yao, Man

    2013-12-01

    The interaction of the strand shell surface and mold copper plates has significant effects on the slab surface quality and casting productivity. This article focuses on developing a reliable approach to measure the transient friction force between the slab and the mold for the purpose of the investigation of lubrication and friction behavior inside a mold. This method is presented to monitor transient mold frictions for the slab continuous caster equipped with hydraulic oscillators. A mathematical model is also developed to calculate the empty working force of the no casting state, and a new algorithm, based on the particle swarm optimization, is proposed to predict the dynamic characteristic parameters of mold oscillation. The results have shown that the method has a sufficient sensitivity to variation, especially to the periodical variation of the mold friction, and it has been identified that the transient mold friction can be used as an effective index with regard to detecting mold oscillation and optimizing the casting parameters for process control. It may lay the practical foundation for the online detection of powder lubrication and the visualization of the continuous-casting mold process.

  2. Organic materials for ceramic molding processes

    NASA Technical Reports Server (NTRS)

    Saito, K.

    1984-01-01

    Ceramic molding processes are examined. Binders, wetting agents, lubricants, plasticizers, surface active agents, dispersants, etc., for pressing, rubber pressing, sip casting, injection casting, taping, extrusion, etc., are described, together with forming machines.

  3. Antimicrobial Treatments of Indoor Mold and Bacteria

    EPA Science Inventory

    Biological contaminants especially mold in buildings are known to act as sources of indoor air pollution, discomfort, asthma and pulmonary disease to building occupants. Sick buildings are evidence of extremely problematic indoor air quality (IAQ), often resulting from unacceptab...

  4. Secondary metabolites of slime molds (myxomycetes).

    PubMed

    Dembitsky, Valery M; Rezanka, Tomás; Spízek, Jaroslav; Hanus, Lumír O

    2005-04-01

    The compounds reported from the slime molds (myxomycetes) species are described. Almost 100 natural compounds including their chemical structures and biological activities are described in this review article. Only metabolites with a well-defined structure are included.

  5. Binding agent for molding ceramic items

    NASA Technical Reports Server (NTRS)

    Beshentsev, B. D.; Vityuk, N. P.; Volkov, A. V.; Yevdokimov, A. I.; Novikov, M. N.; Piskunov, Y. G.; Pobortsev, E. P.; Sadovnichaya, L. M.

    1983-01-01

    The invention refers to the fabrication of ceramic items by the molding method. It can be used to produce items of complicated configuration, in particular composition of binding agent for electroceramic items.

  6. Sacrificial Plastic Mold With Electroplatable Base

    DOEpatents

    Domeier, Linda A.; Hruby, Jill M.; Morales, Alfredo M.

    2005-08-16

    A sacrificial plastic mold having an electroplatable backing is provided. One embodiment consists of the infusion of a softened or molten thermoplastic through a porous metal substrate (sheet, screen, mesh or foam) and into the features of a micro-scale molding tool contacting the porous metal substrate. Upon demolding, the porous metal substrate will be embedded within the thermoplastic and will project a plastic structure with features determined by the mold tool. This plastic structure, in turn, provides a sacrificial plastic mold mechanically bonded to the porous metal substrate which provides a conducting support suitable for electroplating either contiguous or non-contiguous metal replicates. After electroplating and lapping, the sacrificial plastic can be dissolved to leave the desired metal structure bonded to the porous metal substrate. Optionally, the electroplated structures may be debonded from the porous substrate by selective dissolution of the porous substrate or a coating thereon.

  7. Sacrificial plastic mold with electroplatable base

    DOEpatents

    Domeier, Linda A.; Hruby, Jill M.; Morales, Alfredo M.

    2002-01-01

    A sacrificial plastic mold having an electroplatable backing is provided. One embodiment consists of the infusion of a softened or molten thermoplastic through a porous metal substrate (sheet, screen, mesh or foam) and into the features of a micro-scale molding tool contacting the porous metal substrate. Upon demolding, the porous metal substrate will be embedded within the thermoplastic and will project a plastic structure with features determined by the mold tool. This plastic structure, in turn, provides a sacrificial plastic mold mechanically bonded to the porous metal substrate which provides a conducting support suitable for electroplating either contiguous or non-contiguous metal replicates. After electroplating and lapping, the sacrificial plastic can be dissolved to leave the desired metal structure bonded to the porous metal substrate. Optionally, the electroplated structures may be debonded from the porous substrate by selective dissolution of the porous substrate or a coating thereon.

  8. Injection molded optical backplane for broadcast architecture

    NASA Astrophysics Data System (ADS)

    Rosenberg, Paul; Mathai, Sagi; Sorin, Wayne V.; McLaren, Moray; Straznicky, Joseph; Panotopoulos, Georgios; Warren, David; Morris, Terry; Tan, Michael R. T.

    2012-01-01

    A low cost, blind mate, injection molded optical backplane is presented. The optical backplane is comprised of 12 channel optical broadcast buses, operating at 10Gbps/channel with six blindmate optical output ports spaced 1U apart.

  9. Mold and Indoor Air Quality in Schools

    MedlinePlus

    ... exhaust fans whenever cooking, dishwashing and cleaning in food service areas. Inspect the building for signs of mold, moisture, leaks or spills Check for moldy odors. Look for water stains or discoloration on ...

  10. Antimicrobial Treatments of Indoor Mold and Bacteria

    EPA Science Inventory

    Biological contaminants especially mold in buildings are known to act as sources of indoor air pollution, discomfort, asthma and pulmonary disease to building occupants. Sick buildings are evidence of extremely problematic indoor air quality (IAQ), often resulting from unacceptab...

  11. Frequency and amplitude dependences of molding accuracy in ultrasonic nanoimprint technology

    NASA Astrophysics Data System (ADS)

    Mekaru, Harutaka; Takahashi, Masaharu

    2009-12-01

    We use neither a heater nor ultraviolet lights, and are researching and developing an ultrasonic nanoimprint as a new nano-patterning technology. In our ultrasonic nanoimprint technology, ultrasonic vibration is not used as a heat generator instead of the heater. A mold is connected with an ultrasonic generator, and mold patterns are pushed down and pulled up at a high speed into a thermoplastic. Frictional heat is generated by ultrasonic vibration between mold patterns and thermoplastic patterns formed by an initial contact force. However, because frictional heat occurs locally, the whole mold is not heated. Therefore, a molding material can be comprehensively processed at room temperature. A magnetostriction actuator was built into our ultrasonic nanoimprint system as an ultrasonic generator, and the frequency and amplitude can be changed between dc-10 kHz and 0-4 µm, respectively. First, the ultrasonic nanoimprint was experimented by using this system on polyethylene terephthalate (PET, Tg = 69 °C), whose the glass transition temperature (Tg) is comparatively low in engineering plastics, and it was ascertained that the most suitable elastic material for this technique was an ethyl urethane rubber. In addition, we used a changeable frequency of the magnetostriction actuator, and nano-patterns in an electroformed-Ni mold were transferred to a 0.5 mm thick sheet of PET, polymethylmethacrylate (PMMA) and polycarbonate (PC), which are typical engineering plastics, under variable molding conditions. The frequency and amplitude dependence of ultrasonic vibration to the molding accuracy were investigated by measuring depth and width of imprinted patterns. As a result, regardless of the molding material, the imprinted depth was changed drastically when the frequency exceeded 5 kHz. On the other hand, when the amplitude of ultrasonic vibration grew, the imprinted depth gradually deepened. Influence of the frequency and amplitude of ultrasonic vibration was not observed

  12. Indoor Molds and Respiratory Hypersensitivity: A Comparison of Selected Molds and House Dust Mite Induced Responses in a Mouse Model**

    EPA Science Inventory

    Molds are ubiquitous in the environment and exposures to molds contribute to various human diseases. Damp/moldy environments have been associated with asthma exacerbation, but mold's role in allergic asthma induction is less clear. The molds selected for these studies are commonl...

  13. 21 CFR 133.184 - Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk. 133.184 Section 133.184 Food and Drugs FOOD AND DRUG ADMINISTRATION..., sheep's milk blue-mold, and blue-mold cheese from sheep's milk. (a) Description. (1) Roquefort...

  14. 21 CFR 133.184 - Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk. 133.184 Section 133.184 Food and Drugs FOOD AND DRUG ADMINISTRATION..., sheep's milk blue-mold, and blue-mold cheese from sheep's milk. (a) Description. (1) Roquefort...

  15. 21 CFR 133.184 - Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk. 133.184 Section 133.184 Food and Drugs FOOD AND DRUG ADMINISTRATION..., sheep's milk blue-mold, and blue-mold cheese from sheep's milk. (a) Description. (1) Roquefort...

  16. 21 CFR 133.184 - Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk. 133.184 Section 133.184 Food and Drugs FOOD AND DRUG ADMINISTRATION..., sheep's milk blue-mold, and blue-mold cheese from sheep's milk. (a) Description. (1) Roquefort...

  17. Traditional Mold Analysis Compared to a DNA-based Method of Mold Analysis with Applications in Asthmatics' Homes

    EPA Science Inventory

    Traditional environmental mold analysis is based-on microscopic observations and counting of mold structures collected from the air on a sticky surface or culturing of molds on growth media for identification and quantification. A DNA-based method of mold analysis called mol...

  18. Indoor Molds and Respiratory Hypersensitivity: A Comparison of Selected Molds and House Dust Mite Induced Responses in a Mouse Model**

    EPA Science Inventory

    Molds are ubiquitous in the environment and exposures to molds contribute to various human diseases. Damp/moldy environments have been associated with asthma exacerbation, but mold's role in allergic asthma induction is less clear. The molds selected for these studies are commonl...

  19. Traditional Mold Analysis Compared to a DNA-based Method of Mold Analysis with Applications in Asthmatics' Homes

    EPA Science Inventory

    Traditional environmental mold analysis is based-on microscopic observations and counting of mold structures collected from the air on a sticky surface or culturing of molds on growth media for identification and quantification. A DNA-based method of mold analysis called mol...

  20. Effects of a Destabilization Heat Treatment on the Microstructure and Abrasive Wear Behavior of High-Chromium White Cast Iron Investigated Using Different Characterization Techniques

    NASA Astrophysics Data System (ADS)

    Gasan, Hakan; Erturk, Fatih

    2013-11-01

    The hypoeutectic white cast iron was subjected to various destabilization heat treatment temperatures of 1173 K, 1273 K, and 1373 K (900 °C, 1000 °C, and 1100 °C) for 2 hours. The as-cast and destabilized specimens were characterized by optical metallography, classical direct comparison, and the Rietveld method. The volume fractions of carbides were measured by optical metallography. Moreover, the volume fractions of retained austenite and martensite were measured by the classical direct comparison method. Despite the limitations of optical metallography and the classical direct comparison method, the Rietveld method was successively and accurately applied to determine the volume fractions of all phases. In addition, the Rietveld analysis yielded certain results, such as the crystallographic properties of the phases that can be used to explain the relationship between the microstructural parameters and the wear behavior. Abrasive wear tests with different sliding speeds were carried out on the as-cast and destabilized alloys to identify the effect of microstructural parameters on the wear behavior. The results indicated that the morphologies of secondary carbides, the crystallographic properties of the phases, and the proper combination of the amount of martensite, retained austenite, and carbides were the principle parameters that affect the hardness and wear behavior of the alloy.