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EFFECT OF FILTER TEMPERATURE ON TRAPPING ZINC VAPOR

Description: To address the {sup 65}Zn contamination issue in the TEF, a multi-task experimental program was initiated. The first experimental task was completed and is reported in Ref. 1. The results of the second experimental task are reported here. This task examined the effect of filter temperature on trapping efficiency and deposit morphology. Based on the first experimental tasks that examined filter pore size and trapping efficiency, stainless steel filter media with a 20 {micro}m pore size was selected. A series of experiments using these filters was conducted during this second task to determine the effect of filter temperature on zinc vapor trapping efficiency, adhesion and morphology. The tests were conducted with the filters heated to 60, 120, and 200 C; the zinc source material was heated to 400 C for all the experiments to provide a consistent zinc source. The samples were evaluated for mass change, deposit adhesion and morphology. As expected from the physical vapor deposition literature, a difference in deposit morphology and appearance was observed between the three filter temperatures. The filter held at 60 C had the largest average mass gain while the 120 and 200 C filters exhibited similar but lower weight gains. The standard deviations were large and suggest that all three temperatures exhibited comparable gains. No zinc was detected on the backside surface of the filters indicating high efficiency for front and internal trapping. A zinc rich deposit was formed on the surface of the 60 C filter. Based on a simple tape adhesion test, the surface zinc was readily removed from the 60 C filter while less zinc deposit was removed from the 120 and 200 C filter samples. It is surmised that the higher temperatures enable the zinc to deposit within the filter media rather than on the surface. Based on the ...
Date: March 25, 2011
Creator: Korinko, P.
Partner: UNT Libraries Government Documents Department

Rapid tooling by electron-beam vapor deposition

Description: Electron-beam physical vapor deposition (EBPVD) of tooling metal, onto a shaped substrate to produce a replica of the substrate surface, offers the potential for significant cost savings over present methods of injection mold manufacturing. These savings are realized by the high deposition rate and the corresponding short manufacturing times provided by the EBPVD process. However, on route to realizing these gains, there are process technical issues which need to be resolved. Mold surfaces typically contain relatively high aspect ratio details that must be replicated to dimensional tolerances within +/- 2 mils. The deposited mold material must also provide high surface hardness and high fracture toughness. Good quality grain structure can be obtained in deposited Al 10-wt% Cu mold material when the substrate and corresponding deposit are at high process temperature. However, the resulting mold is subject to distortion during cooldown due to differential temperatures and shrinkage rates. Thermally controlled cooldown and the use of crushable substrate materials reduce these distortions, but not to the required levels of tolerance. Deposition of the Al-Cu at lower temperature produces columnar, poorly joined grains which result in a brittle and weakened mold material. When Al 10-wt% Cu metal vapor is deposited across high aspect ratio step features on the substrate surface, a grain growth defect can form in the step-shadowed regions of the deposited material, alongside the step feature. The step coverage defect consists of entrained voids which persist at intermediate deposition temperatures and produce a weakened mold. This final 1997 LDRD report investigates causes of this step coverage defect and offers methods for their control and elimination.
Date: February 25, 1998
Creator: Meier, T. C., LLNL
Partner: UNT Libraries Government Documents Department

Application of CIS of high-efficiency PV module fabrication. Annual technical progress report, April 1, 1996--March 31, 1997

Description: This is the Phase II Annual Technical Report of the subcontract titled {open_quotes}Application of CIS to High Efficiency PV Module fabrication.{close_quotes} The general objectives of the program are the development of a novel, non-vacuum process for CIS film deposition, optimization of the various layers forming the CIS device structure, and fabrication of high efficiency submodules. The specific goals of the project are the development of 13% efficient small area cells and 10% efficient submodules using a novel, low-cost CIS deposition approach. During this research period, the authors concentrated their efforts on three different areas of research. Within the National CIS Partnership Program, they participated in the {open_quotes}substrate/Mo interactions{close_quotes} working group and investigated issues such as Na diffusion from the soda-lime glass substrate into the Mo layers and CIS films. It was determined that the Na content within the Mo layers was not a strong function of the nature of the Mo film. However, diffusion through the Mo layers was found to be a function of the Mo film characteristics as well as a very strong function of the CIS growth process. Na was found to be on the grain boundaries in Mo and CIS layers.
Date: August 1, 1997
Creator: Basol, B.; Kapur, V. & Leidholm, C.
Partner: UNT Libraries Government Documents Department

Process for strengthening aluminum based ceramics and material

Description: A process for strengthening aluminum based ceramics is provided. A gaseous atmosphere consisting essentially of silicon monoxide gas is formed by exposing a source of silicon to an atmosphere consisting essentially of hydrogen and a sufficient amount of water vapor. The aluminum based ceramic is exposed to the gaseous silicon monoxide atmosphere for a period of time and at a temperature sufficient to produce a continuous, stable silicon-containing film on the surface of the aluminum based ceramic that increases the strength of the ceramic.
Date: December 1, 1998
Creator: Moorhead, Arthur J. & Kim, Hyoun-Ee
Partner: UNT Libraries Government Documents Department

15.4% CuIn1-XGaXSe2-Based Photovoltaic Cells from Solution-Based Precursor Films

Description: We have fabricated 15.4%- and 12.4%-efficient CuIn1-XGaXSe2 (CIGS)-based photovoltaic devices from solution-based electrodeposition (ED) and electroless-deposition (EL) precursors. As-deposited precursors are Cu-rich CIGS. Additional In, Ga, and Se are added to the ED and EL precursor films by physical vapor deposition (PVD) to adjust the final film composition to CuIn1-XGaXSe2. The ED and EL device parameters are compared with those of a recent world record, an 18.8%-efficient PVD device. The tools used for comparison are current voltage, capacitance voltage, and spectral response characteristics.
Date: May 25, 1999
Creator: Bhattacharya, R. N.; Batchelor, W.; Contreras, M. A.; Noufi, R. N. (National Renewable Energy Laboratory); Hiltner, J. F. & Sites, J. R. (Department of Physics, Colorado State University)
Partner: UNT Libraries Government Documents Department

Energetic Deposition in Vacuum

Description: In hoping to improve Niobium deposition on Copper cavity, a vacuum deposition system has been built to test the idea of Nb energetic condensation on copper substrate. The system directly uses microwave power to create the pure Nb plasma, which can be used to extract energetic Nb ion flux to do direct deposition on copper substrate. In this paper, we briefly describe the system, discuss the potential benefit of this technique and report the initial result of Nb plasma creation and Niobium thin film deposition.
Date: September 1, 2001
Creator: Wu, G.; Phillips, L.; Sundelin, R. & Goodman, T.
Partner: UNT Libraries Government Documents Department

Understanding Thermal Behavior in Lens Processing of Structural Materials

Description: In direct laser metal deposition technologies, such as the Laser (LENS) process, it is important to understand and control the Engineered Net Shaping thermal behavior during fabrication. With this control, components can be reliably fabricated with desired structural material properties. This talk will describe the use of contact and imaging techniques to monitor the thermal signature during LENS processing. Recent results show a direct correlation between thermal history and material properties, where the residual stress magnitude decreases as the laser power, and therefore thermal signature, increases. Development of an understanding of solidification behavior, residual stress, and microstructural evolution with respect to thermal behavior will be discussed.
Date: November 5, 1998
Creator: Ensz, M.T.; Greene, D.L.; Griffith, M.L.; Harwell, L.D.; Hofmeister, W.H.; Nelson, D.V. et al.
Partner: UNT Libraries Government Documents Department

Influence of EB-PVD TBC Microstructure on Thermal Barrier Coating System Performance Under Cyclic Conditions

Description: The lifetimes of electron beam physical vapor deposited (EB-PVD) thermal barrier coating systems (TBCs) with three different microstructures of the Y<sub>2</sub>O<sub>3</sub>-stabilized ZrO, YSZ) ceramic top layer were investigated in lh thermal cycles at 1100 and 1150°C in flowing oxygen. Single crystal alloys CMSX-4 and Rene N5 that had been coated with an EB-PVD NiCoCrAlY bond coat were chosen as substrate materials. At 1150°C all samples failed after 80-100, lh cycles, predominantly at the bond coat/alumina interface after cooling down from test temperature. The alumina scale remained adherent to the YSZ after spallation. Despite the different YSZ microstructures no clear tendency regarding differences in spallation behavior were observed at 1150°C. At 1100°C the minimum lifetime was 750 , lh cycles for CMSX-4, whereas the first Rene N5 specimen failed after 1750, lh cycles. The longest TBC lifetime on CMSX-4 substrates was 1250, lh cycles, whereas the respective Rene N5 specimens have not yet failed after 2300, lh cycles. The failure mode at 1100°C was identical to that at 115O�C, i.e. the TBC spalled off the surface exposing bare metal after cooling. Even though not all specimens have failed to date, the available results at 1100°C suggested that both, the substrate alloy chemistry and the YSZ microstructure significantly affect the spallation resistance of the TBC.
Date: April 12, 1999
Creator: Leyens, C.; Pint, B.A.; Schulz, U. & Wright, I.G.
Partner: UNT Libraries Government Documents Department

Optical Coatings for Thermophotovoltaic Spectral Control

Description: The efficiency of thermophotovoltaic (TPV) energy conversion is dependent on efficient spectral control. An edge pass filter (short pass) in series with a highly doped, epitaxially grown layer has achieved the highest performance of TPV spectral control. Front surface, tandem filters have achieved the highest spectral efficiency and represent the best prospect for even higher spectral efficiency for TPV energy conversion systems. Specifically, improvements in the physical vapor deposition process, identification of other materials with a high index of refraction and a low absorption coefficient, and more efficient edge filter designs could provide higher TPV spectral performance.
Date: April 29, 2004
Creator: Fourspring, PM; DePoy, DM; TD Rahmlow, Jr; Lazo-Wasem, JE & Gratrix, EJ
Partner: UNT Libraries Government Documents Department

High energy density capacitors fabricated by thin film technology

Description: Low energy density in conventional capacitors severely limits efforts to miniaturize power electronics and imposes design limitations on electronics in general. We have successfully applied physical vapor deposition technology to greatly increase capacitor energy density. The high dielectric breakdown strength we have achieved in alumina thin films allows high energy density to be achieved with this moderately low dielectric constant material. The small temperature dependence of the dielectric constant, and the high reliability, high resistivity, and low dielectric loss of Al 2 O 3 , make it even more appealing. We have constructed single dielectric layer thin film capacitors and shown that they can be stacked to form multilayered structures with no loss in yield for a given capacitance. Control of film growth morphology is critical for achieving the smooth, high quality interfaces between metal and dielectric necessary for device operation at high electric fields. Most importantly, high rate deposition with extremely low particle generation is essential for achieving high energy storage at a reasonable cost. This has been achieved by reactive magnetron sputtering in which the reaction to form the dielectric oxide has been confined to the deposition surface. By this technique we have achieved a yield of over 50% for 1 cm 2 devices with an energy density of 14 J per cubic centimeter of Al 2 O 3 dielectric material in 1.2 kV, 4 nF devices. By further reducing defect density and increasing the dielectric constant of the material, we will be able to increase capacitance and construct high energy density devices to meet the requirements of applications in power electronics.
Date: March 30, 1999
Creator: Barbee, T W; Johnson, G W & Wagner, A V
Partner: UNT Libraries Government Documents Department

Development of a sensor and control system for the production of titanium matrix composites

Description: Titanium matrix composites promise to dramatically increase the thrust-to-weight ratio of gas turbine engines. Electron Beam Physical Vapor Deposition (EB-PVD) is ideal for coating fibers if issues with composition control can be worked out. LLNL is developing a control system based on Diode Laser Absorption Spectroscopy (DLAS) for the deposition of titanium orthorhombic alloys. In this paper, the important features and components of a DLAS control system are reviewed and a methodology for selecting the appropriate atomic transitions is described. Data characterizing the diagnostic performance as well as information on potential control strategies is presented. Finally, applications of this diagnostic to other alloy systems are discussed.
Date: March 1, 1995
Creator: Berzins, L.V.; McClelland, M.A. & Anklam, T.M.
Partner: UNT Libraries Government Documents Department

Multilayer coatings on flexible substrates

Description: Thin-film optical and non-optical multilayer coatings are deposited onto flexible substrates using a vacuum web coater developed at Pacific Northwest Laboratory. The coater`s primary application is rapid prototyping of multilayer (1) polymer coatings, (2) polymer/metal coatings, (3) ceramic/metal coatings, and (4) hybrid polymer, ceramic, and metal coatings. The coater is fully automated and incorporates polymer evaporation and extrusion heads, high-rate magnetron sputtering cathodes, and e-beam evaporation sources. Polymer electrolytes are deposited by extrusion techniques. Flexible plastic, metal, and ceramic substrates can be coated using roll-to-roll or closed-loop configurations. Examples of multilayer optical coatings demonstrated to date are solar reflectors, heat mirrors, Fabry-Perot filters, and alpha particle sensors. Nonoptical coatings include multilayer magnetic metal/ceramic and lamellar composites.
Date: April 1, 1995
Creator: Martin, P.M.; Affinito, J.D.; Gross, M.E.; Coronado, C.A.; Bennett, W.D. & Stewart, D.C.
Partner: UNT Libraries Government Documents Department

Impurities in chromium deposits produced by electroplating and physical vapor deposition

Description: Impurity contents in electrodeposited (hexavalent and trivalent) chromium deposits and physically vapor deposited (thermal evaporation, electron beam evaporation and rf-sputtering) were compared. Oxygen is the key impurity obtained in electrodeposited films but it can be minimized in hexavalent plating solutions by operating at high temperature, e. g., 85 C. Electrodeposits produced in trivalent chromium plating solutions and physically vapor deposited films have much higher oxygen contents than electrodeposits produced in hexavalent chromium solutions operated at temperatures around 85 C. Depending on the target material used for physically vapor deposited films, these films can also have high amounts of other impurities.
Date: May 1, 1994
Creator: Dini, J. W.
Partner: UNT Libraries Government Documents Department

RECRYSTALLIZATION OF CERAMIC MATERIAL FABRICATED FROM Cd1-xZnxTe.

Description: Binary and ternary A(illegible)B(illegible) compounds are conventionally grown from melt. This technique is very complicated and requires complex equipment to provide high pressures and high temperatures to grow stoichiometric compositions. New opportunities for designing materials used in the infrared technique and ionizing radiation detectors are opened by advantages in nanotechnology. In particular difficulties in Cd{sub 1-x}Zn{sub x}Te with various Zn content are traditionally used in infrared optics and as a material for ionizing radiation detectors. Zn concentration in the nanopowders produced by the new vapor deposition technique varies from x=0.02 to x=0.1, including the composition Cd{sub illegible}Zn{sub illegible}Te, which is the most promising as a material for ionizing radiation detectors working at room temperature without cooling.
Date: August 29, 2007
Creator: KOLESNIKOV,N.N.; BORISENKO, E.B.; BORISENKO, D.N.; KVEDER, V.V. & JAMES, R.B.
Partner: UNT Libraries Government Documents Department

Novel Low Cost Organic Vapor Jet Printing of Striped High Efficiency Phosphorescent OLEDs for White Lighting

Description: In this program, Universal Display Corporation and University of Michigan proposed to integrate three innovative concepts to meet the DOE's Solid State Lighting (SSL) goals: (1) high-efficiency phosphorescent organic light emitting device (PHOLED{trademark}) technology, (2) a white lighting design that is based on a series of red, green and blue OLED stripes, and (3) the use of a novel cost-effective, high rate, mask-less deposition process called organic vapor jet printing (OVJP). Our PHOLED technology offers up to four-times higher power efficiency than other OLED approaches for general lighting. We believe that one of the most promising approaches to maximizing the efficiency of OLED lighting sources is to produce stripes of the three primary colors at such a pitch (200-500 {mu}m) that they appear as a uniform white light to an observer greater than 1 meter (m) away from the illumination source. Earlier work from a SBIR Phase 1 entitled 'White Illumination Sources Using Striped Phosphorescent OLEDs' suggests that stripe widths of less than 500 {mu}m appear uniform from a distance of 1m without the need for an external diffuser. In this program, we intend to combine continued advances in this PHOLED technology with the striped RGB lighting design to demonstrate a high-efficiency, white lighting source. Using this background technology, the team has focused on developing and demonstrating the novel cost-effective OVJP process to fabricate these high-efficiency white PHOLED light sources. Because this groundbreaking OVJP process is a direct printing approach that enables the OLED stripes to be printed without a shadow mask, OVJP offers very high material utilization and high throughput without the costs and wastage associated with a shadow mask (i.e. the waste of material that deposits on the shadow mask itself). As a direct printing technique, OVJP also has the potential to offer ultra-high deposition rates (&gt; 1,000 ...
Date: December 31, 2008
Creator: Hack, Mike
Partner: UNT Libraries Government Documents Department

Rapid mold replication

Description: 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.
Date: June 1, 1995
Creator: Heestand, G.M.; Beeler, R.G. Jr. & Brown, D.L.
Partner: UNT Libraries Government Documents Department

Reactive sputter deposition of boron nitride

Description: The preparation of fully dense, boron targets for use in planar magnetron sources has lead to the synthesis of Boron Nitride (BN) films by reactive rf sputtering. The deposition parameters of gas pressure, flow and composition are varied along with substrate temperature and applied bias. The films are characterized for composition using Auger electron spectroscopy, for chemical bonding using Raman spectroscopy and for crystalline structure using transmission electron microscopy. The deposition conditions are established which lead to the growth of crystalline BN phases. In particular, the growth of an adherent cubic BN coating requires 400--500 C substrate heating and an applied {minus}300 V dc bias.
Date: October 1, 1995
Creator: Jankowski, A.F.; Hayes, J.P.; McKernan, M.A. & Makowiecki, D.M.
Partner: UNT Libraries Government Documents Department

Modeling of dynamical processes in laser ablation

Description: Various physics and computational approaches have been developed to globally characterize phenomena important for film growth by pulsed-laser deposition of materials. These include thermal models of laser-solid target interactions that initiate the vapor plume, plume ionization and heating through laser absorption beyond local thermodynamic equilibrium mechanisms, hydrodynamic and collisional descriptions of plume transport, and molecular dynamics models of the interaction of plume particles with the deposition substrate.
Date: December 31, 1995
Creator: Leboeuf, J.N.; Chen, K.R.; Donato, J.M.; Geohegan, D.B.; Liu, C.L.; Puretzky, A.A. et al.
Partner: UNT Libraries Government Documents Department