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At least 181 records · Page 10

All sources NASA NTRS DOE OSTI

NASA NTRS1991

Modeling of life limiting phenomena in the discharge chamber of an electron bombardment ion thruster

An experimental facility to study the low energy sputtering of metal surfaces with ions produced by an ion gun is described. The energy of the ions ranged from 10 to 500 eV. Cesium ions with energies from 100 to 500 eV were used initially to characterize the operation of the ion gun. Next, argon and xenon ions were used to measure the sputtering yields of cobalt (Co), Cadmium (Cd), and Chromium (Cr) at an operating temperature of 2x10(exp -5) Torr. The ion current ranged from 0.0135 micro-A at 500 eV. The targets were electroplated on a copper substrate. The surface density of the electroplated material was approx. 50 micro-g/sq cm. The sputtered atoms were collected on an aluminum foil surrounding the target. Radioactive tracers were used to measure the sputtering yields. The sputtering yields of Cr were found to be much higher than those of Co and Cd. The yields of Co and Cd were comparable, with Co providing the higher yields. Co and Cd targets were observed to sputter at energies as low as 10 eV for both argon and xenon ions. The Cr yields could not be measured below 20 eV for argon ions and 15 eV for xenon ions. On a linear scale the yield energy curves near the threshold energies exhibit a concave nature.

Handoo, Arvind K.↗

NASA NTRS1921

Moisture Resistant Finishes for Airplane Woods

This report describes briefly a series of experiments made at the Forest Products Laboratory, Madison, Wisconsin, to determine the comparative moisture resistance of linseed oil, impregnation treatments, condensation varnishes, oil varnishes, enamels, cellulose varnishes, rubber, electroplated and sprayed metal coatings, and metal-leaf coatings when applied to wood. All coatings except rubber and electroplated metal coatings, which were not developed sufficiently to make them practical, admitted moisture in varying degrees. The most effective and most practical coating was found to be that of aluminum leaf.

Dunlap, M E↗

NASA NTRS1998

Electroformed Nickel Mirrors for the Next Generation Space Telescope

This paper summarizes the work to date on a novel mirror fabrication technique being developed at the Marshall Space Flight Center for potential use on the Next Generation Space Telescope (NGST). This technique involves forming an extremely lightweight mirror by electroplating nickel and nickel based alloys onto a highly polished precision mandrel. The resulting mirror shell can then be backed up with or attached to a lightweight structure to produce a mirror element that is on the order of 15 kg/sq m areal density. Since the mirrors are fabricated from a mandrel (or master), subsequent mirrors can be made with very high economy; this technique is particularly suited to segmented mirrors schemes whereby large apertures are achieved through the deployment of smaller segments. Control of the electroplating process is the key element for producing high quality optics; bath chemistry and real time control of the plating current density yields uniform grained electroforms with zero residual stress. To accomplish this, a special electronic sensor was developed whereby the residual stress can be monitored as the nickel is electrolytically deposited. This information is used in a feedback loop to modulate current density which, in turn, directly governs the residual stress. Details pertaining to this and other aspects of the fabrication of a half meter mirror will be published along with test results and metrology data.

Redmon, John W.↗

NASA NTRS2005

In Situ Electrochemical Deposition of Microscopic Wires

A method of fabrication of wires having micron and submicron dimensions is built around electrochemical deposition of the wires in their final positions between electrodes in integrated circuits or other devices in which the wires are to be used. Heretofore, nanowires have been fabricated by a variety of techniques characterized by low degrees of controllability and low throughput rates, and it has been necessary to align and electrically connect the wires in their final positions by use of sophisticated equipment in expensive and tedious post-growth assembly processes. The present method is more economical, offers higher yields, enables control of wire widths, and eliminates the need for post-growth assembly. The wires fabricated by this method could be used as simple electrical conductors or as transducers in sensors. Depending upon electrodeposition conditions and the compositions of the electroplating solutions in specific applications, the wires could be made of metals, alloys, metal oxides, semiconductors, or electrically conductive polymers. In this method, one uses fabrication processes that are standard in the semiconductor industry. These include cleaning, dry etching, low-pressure chemical vapor deposition, lithography, dielectric deposition, electron-beam lithography, and metallization processes as well as the electrochemical deposition process used to form the wires. In a typical case of fabrication of a circuit that includes electrodes between which microscopic wires are to be formed on a silicon substrate, the fabrication processes follow a standard sequence until just before the fabrication of the microscopic wires. Then, by use of a thermal SiO-deposition technique, the electrodes and the substrate surface areas in the gaps between them are covered with SiO. Next, the SiO is electron-beam patterned, then reactive-ion etched to form channels having specified widths (typically about 1 m or less) that define the widths of the wires to be formed. Drops of an electroplating solution are placed on the substrate in the regions containing the channels thus formed, then the wires are electrodeposited from the solution onto the exposed portions of the electrodes and into the channels. The electrodeposition is a room-temperature, atmospheric-pressure process. The figure shows an example of palladium wires that were electrodeposited into 1-mm-wide channels between gold electrodes.

Yun, Minhee↗

NASA NTRS2018

Method of Fabricating X-Ray Absorbers for Low-Energy X-Ray Spectroscopy

A method of forming low-energy x-ray absorbers. Sensors may be formed on a semiconductor, e.g., silicon, wafer. A seed metal layer, e.g., gold, is deposited on the wafer and patterned into stem pads for electroplating. Stems, e.g., gold, are electroplated from the stem seed pads through a stem mask. An absorber layer, e.g., gold, is deposited on the wafer, preferably e-beam evaporated. After patterning the absorbers, absorber and stem mask material is removed, e.g., in a solvent bath and critical point drying.

Stevenson, Thomas R.↗

DOE OSTI2014

Electrodeposited copper front metallization for silicon heterojunction solar cells: materials and processes

Even though screen-printing of low-temperature silver paste remains the state-of-the-art technique for the front-metallization of SHJ solar cells, recent studies have demonstrated large efficiency improvements when copper-electroplated contacts are used instead of screen-printed ones. However, due to the new materials and the new processes introduced by this technique, it is crucial to individually investigate their compatibility with the SHJ cell structure. In this study, we present a detailed analysis of how the performances of SHJ devices may be modified by these new materials and processes. First, effects on the amorphous silicon (a-Si:H) passivation have been studied for various processes such as DI water rinsing, dips in a copper removal solution and direct evaporation of copper on the a-Si:H. Finally, copper electroplating technique has been adapted in order to be applied to more complex cell structures such as high-efficiency IBC-SHJ.

Geissbühler, J.↗

DOE OSTI2016

Electrodeposition of gallium for photovoltaics

An electroplating solution and method for producing an electroplating solution containing a gallium salt, an ionic compound and a solvent that results in a gallium thin film that can be deposited on a substrate.

14 SOLAR ENERGY↗

DOE OSTI2017

Micro-fabricated integrated coil and magnetic circuit and method of manufacturing thereof

A micro-fabricated electromagnetic device is provided for on-circuit integration. The electromagnetic device includes a core. The core has a plurality of electrically insulating layers positioned alternatingly between a plurality of magnetic layers to collectively form a continuous laminate having alternating magnetic and electrically insulating layers. The electromagnetic device includes a coil embedded in openings of the semiconductor substrate. An insulating material is positioned in the cavity and between the coil and an inner surface of the core. A method of manufacturing the electromagnetic device includes providing a semiconductor substrate having openings formed therein. Windings of a coil are electroplated and embedded in the openings. The insulating material is coated on or around an exposed surface of the coil. Alternating magnetic layers and electrically insulating layers may be micro-fabricated and electroplated as a single and substantially continuous segment on or around the insulating material.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Zinc-based electrolyte compositions, and related electrochemical processes and articles

An aqueous electrolyte composition is described, including a zinc salt based on zinc acetate or zinc glocolate. The saturation concentration of zinc in the electrolyte composition is in the range of about 2.5M to about 3.5M. The composition also contains at least one salt of a monovalent cation. The molar ratio of zinc to the monovalent cation is about 1:2. An aqueous zinc electroplating bath, containing the aqueous electrolyte composition, is also disclosed, along with a method for the electrochemical deposition of zinc onto a substrate surface, using the electroplating bath. Related flow batteries are also described, including a catholyte, as well as an anolyte based on the aqueous electrolyte composition, with a membrane between the catholyte and the anolyte.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2018

Laser Shock Fresh Fuel Bond Strength Studies

Laser-based characterization of base monolithic U-10Mo fuel is being conducted by the USHPRR Fuel Qualification project to support fabrication development and ensure the fuel maintains mechanical integrity and does not delaminate during normal operating conditions. Characterization involves laser shock experiments, combined with laser-based ultrasonic scanning, to evaluate the bonding integrity and relative strength of interfaces within fuel plates. This report documents fresh fuel studies that were carried out on a series of fuel plates manufactured at Los Alamos National Laboratory in which various, controlled levels of interfacial contamination were intentionally introduced into the fuel plates during fabrication in order to vary the bond strength. Additional scoping studies were conducted on several developmental fuel plates supplied by the USHPRR Fuel Fabrication Pillar in which the Zr diffusion barrier was applied to the U-Mo foils by electroplating and plasma spraying. The electroplating and plasma spraying processes are being evaluated as potential alternatives to the baseline co-rolling fabrication process.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2019

Ion beam modification of noble metals for electrical contacts

Ion beam modification of noble metal electrical contact coatings can achieve suitable friction and wear behavior with inherently stable low ECR. For example, this method of producing Au electrical contact coatings can produce wear properties similar to electroplated hard Au, but without the environmental concerns due to stringent OSHA regulations on the use and disposal of toxic chemicals associated with Au electroplating baths. Integration of physical vapor deposition techniques with ion implantation can produce noble metal coatings with surfaces modified to achieve the desired balance between adhesion/friction/wear and electrical contact resistance on a commercial scale.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Cathode system for electrodeposition of metals on microspheres

The present disclosure relates to an apparatus for electroplating an element. The apparatus may comprise a cathode cage assembly. The cathode cage assembly may include a cage member and at least one electrically conductive wire extending along at least a portion of the cage member. The wire may be arranged to form at least one volume within the cage member for retaining an element within the cage member. The cage member and the wire permit a degree of movement of the element during an electroplating process while retaining the element within the volume.

Bunn, Thomas L.↗

DOE OSTI2020

Large Volume Airborne Contamination Monitoring To Support Nuclear Processes' Deactivation and Decommissioning

Current D and D operations at Hanford have demonstrated a flaw in the current state of the art capability of defining airborne contamination boundaries - Airborne particulate emissions of Pu-239 from CM2H operations on the Hanford Pu Finishing Plant were detected well beyond areas controlled for airborne Pu, putting numerous workers at risk for radiological assimilations - Current air samplers and CAM systems were surveying insufficient volumes of air to accurately predict where respiratory protection was required - Hanford is located in a high radon environment, making air monitoring for alpha emitting actinides challenging in high alpha radon induced backgrounds. - Inexpensive HEPA based home and industrial air purifiers filter significantly higher volumes of air than commercially available continuous-air monitoring (CAM) systems. - Inexpensive models capable of filtered air volumes exceeding 1000 times that of a CAM. - Detector system can be built to detect x-rays generated from actinide decay. - Branching ratios of x-rays are 4 orders of magnitude more intense from Plutonium decay than its gamma emissions. - Detector system can be a low resolution systems, as x-ray region of interest is not terribly congested. - Detection systems evaluated will be designed based on slabs of NaI or pixelated NaI or CsI panels. - Simple graphical user interface software will be developed to operate the detection system. - Concept is to deploy some of these air-purifying systems in nonradiological areas around SRNL to confirm radon can be rejected with confidence. - Generate some filters contaminated with plutonium via electroplated Pu or lab generated simulated particles. - then deploy units in known airborne radiological environments to establish systems ability to accurately measure actinide based hot particles Lab analyses will follow up the system analyses to ensure hot particles were correctly identified. Analysis by Scintillation: - Application of scintillation media to the surface of the filters is being explored. - Evaluating slabs of ZnS(Ag), application of powdered ZnS(Cu) and spray on Perkin Elmer Enhance. - Scintillation events would then be digitized with a digital camera and quantified. - Comparing against sensitivity of a PMT or SiPD readout. - Currently evaluating a Thorlabs 8 Megapixel Monochrome Scientific CCD Camera, hermetically sealed cooled package with a wide angle lens. - Wide angle lens allows complete view of HEPA filter from 7 inches away. - Images taken of glow in the dark paint, as well as plutonium-induced fluorescence. - Plutonium was flamed mounted on a 1 inch diameter stainless steel planchet, covered with a layer of mylar and a section of scintillating ZnS obtained from Eljon. - Currently working on reducing signal-to-noise levels to boost sensitivity. - Dark box to hold contaminated or electroplated source covered filters under fabrication. Analysis by x-ray Spectroscopy: - Branching ratios for x-ray emissions from Plutonium isotopes are orders of magnitude more intense than gamma-ray emissions. - The nuclear databases are incomplete on the branching ratios of some of the isotopes. - Evaluating some custom built SrI2 x-ray spectrometers vs a conventional windowed NaI detector. - SrI2 detectors are carbon-composite-windowed 51 mm x 51 mm. - MCNP calculations to establish self absorbance of filter media on 17 keV x-ray. Radon Rejection: - Activated charcoal pre-filter acts as a Radon trap. - Adding a time lapse feature to camera to aid in radon rejection. SRS Plutonium Fuel Form D and D Operations: Currently deploying air sampler to D and D operation of Pu-238 facility at SRS to generate some field samples to analyze.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2017

LCA to Evaluate the Environmental Impact for Chemical Pre-treatment in Plastics Metallization

The life cycle assessment methodology was used to calculate the environmental impacts of the current chemical pre-treatment with chromium(VI) for electroplating acrylonitrile butadiene styrene. The inventory comprised: the procurement of chemicals; the manufacturing process with successive baths and rinses that requires, in addition to chemicals, energy to heat baths, air agitation, filtration, and so forth, wastewater treatment and air emissions; and also the treatment of sludges from wastewater treatment and exhausted baths. Chromic acid was almost the unique responsible of eco-toxicity (97.5 %) and human toxicity-cancer (99.8 %) and it was one of the highest contributor to climate change, cumulative energy demand, fossil fuel depletion, human toxicity non-cancer, and in abiotic depletion.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2015

Magnetic Properties of Electroformed Ni and Ni-Fe for Micromagnetic MEMS Applications

This paper reports a new technique which is based on electroforming process for high permeability Ni and Ni-Fe alloy. The magnetic properties of Ni and Ni-Fe alloy are investigated as a function of plating current density via scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and vibrating sample magnetometer (VSM). Concentration-dependent kinetics is used to formulate the deposition rate and also the same is verified by using finite element analysis tool COMSOL Multiphysics. Several experiments are performed to derive the relation between electroplating parameters and magnetic properties. The process conditions are optimized to develop high permeability (∼16000) Ni-Fe alloy (85.71–14.29 %). The higher current density shows a monotonically increasing behavior of relative permeability (μ{sub r}). In addition, the B-H curves indicate that the saturation magnetization (B{sub sat}) increases and coercivity decreases with increasing plating current density. Our experimental data confirms that the higher current density increase the softness of Ni. The observed properties of Ni and Ni-Fe based on experimental results can be used to study the magnetic behavior of micromagnetic sensors and large force actuators.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2017

Thin film surface modifications of thin/tunable liquid/gas diffusion layers for high-efficiency proton exchange membrane electrolyzer cells

We present that a proton exchange membrane electrolyzer cell (PEMEC) is one of the most promising devices for high-efficiency and low-cost energy storage and ultrahigh purity hydrogen production. As one of the critical components in PEMECs, the titanium thin/tunable LGDL (TT-LGDL) with its advantages of small thickness, planar surface, straight-through pores, and well-controlled pore morphologies, achieved superior multifunctional performance for hydrogen and oxygen production from water splitting even at low temperature. Different thin film surface treatments on the novel TT-LGDLs for enhancing the interfacial contacts and PEMEC performance were investigated both in-situ and ex-situ for the first time. Surface modified TT-LGDLs with about 180 nm thick Au thin film yielded performance improvement (voltage reduction), from 1.6849 V with untreated TT-LGDLs to only 1.6328 V with treated TT-LGDLs at 2.0 A/cm 2 and 80°C. Furthermore, the hydrogen/oxygen production rate was increased by about 28.2% at 1.60 V and 80°C. The durability test demonstrated that the surface treated TT-LGDL has good stability as well. Finally, the gold electroplating surface treatment is a promising method for the PEMEC performance enhancement and titanium material protection even in harsh environment.

08 HYDROGEN↗

DOE OSTI2015

An AlCl 3 based ionic liquid with a neutral substituted pyridine ligand for electrochemical deposition of aluminum

We study a new ionic liquid (IL) based on a neutral ligand, 4-propylpyridine, is obtained via complexation with AlCl 3 . It is found that the asymmetric cleavage of AlCl 3 generates AlCl 2 + and AlCl 4 , and the former is coordinated by 4-Pr-Py to produce the Al-containing cations ([AlCl 2 (4-Pr-Py) 2 ] + ). The AlCl 3 /4-propylpyridine IL with a molar ratio of 1.3/1 is highly fluidic with a viscosity of 42.8 mPa s and an ionic conductivity of 5.0 x 10 -4 S/cm at room temperature. In contrast to conventional ILs for electroplating aluminum in which the electrochemically active species are Al-containing anions (for example Al 2 Cl 7 - ), this new IL has an Al-containing cation as the electroactive species, which is beneficial to electrodeposition of aluminum.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Bipolar plate development with additive manufacturing and protective coating for durable and high-efficiency hydrogen production

Additive manufacturing (AM) of the complex devices for energy application remains an almost unexplored area, and the harsh acidic environment also limits the application of AM parts in water splitting for hydrogen production. Here, bipolar plates (BPs), which are used to transport reactants/products and conduct electrons in proton exchange membrane electrolyzer cells (PEMECs), are printed from stainless steel (SS) with selective laser melting (SLM). Then surface treatments are employed on those BPs by thin film electroplating with Au, and the protective thin layer enables the utilization of AM SS parts to both cathode and anode sides of water electrolyzer cells and exhibits superior corrosion resistances and electronic conductivities. The Au-coated AM SS BPs deliver a low interfacial contact resistance (6.4 mO cm 2 under 1.45 MPa) and an excellent performance in PEMECs (1.71 V at 2 A/cm 2 ), and maintain a remarkable durability in the simulated anode environment compared with the uncoated AM SS BPs and conventional graphite BPs. In conclusion, this approach demonstrates the possibility of 3-dimensional printing fully integrated water electrolyzer cells at both anode and cathode sides.

08 HYDROGEN↗