Engineering Commons^™

Research Progresses Of Cobalt Interconnect And Superfilling By Electroplating In Chips, Li-Jun Wei, Zi-Han Zhou, Yun-Wen Wu, Ming Li, Su Wang

Journal of Electrochemistry

Copper interconnect using dual damascene technology has always been the main means for metallization in the back end of line process. However, with the size effect becoming more and more obvious due to feature size reduction, copper interconnect can no longer meet the demand for high circuit speed in Post-Moore era. Following copper interconnection, cobalt interconnection in chips attracts much attention as an interconnect technology by the next generation, which has been introduced in 7 nm node of integrated circuit manufacturing and below. The electron mean free path of cobalt (~10 nm) is much shorter than copper’s (39 nm), thus …

Corrosion Protection Mechanisms Of Trivalent Chromium Based Passivations On Γ-Znni Coated Al6061-T6 Alloy, Kevin Foster

Doctoral Dissertations

“The role of cobalt in trivalent chromium passivations (TCPs) to improve corrosion resistance of γ-ZnNi coated steel and aluminum is based on its effect on hexavalent chromium content in the passive layer. Investigations of both a cobalt-containing and cobalt-free TCP on SAE 1008 steel indicated that both passivations protect well for up to 1000 hours in neutral salt spray exposure (SSE). A repetition on Al 6061-T6 alloy indicated that TCP performed much better than cobalt-free TCP implicating the underlying substrate. Optical and electron micrographs indicated physical changes such as crack thickness, crack density, passivation porosity, and passivation thickness existed between …

Various Operational Aspects Of The Extraction Of Critical Minerals From Acid Mine Drainage And Its Treatment By-Product, Zhongqing Xiao

Graduate Theses, Dissertations, and Problem Reports

Acid mine drainage (AMD) is environmentally hazardous acidic water, which is continuously generated in large volumes at coal mining sites, typically when pyrite is exposed to oxygen and water. As its continuous migration under the geologic conditions, AMD tends to leach metal elements out from the surrounding minerals, leading to high concentrations of metal elements, like iron, aluminum, magnesium, manganese, lead, arsenic, as well as critical cobalt and rare earth elements (REEs). AMD must be treated and monitored to meet the effluent limits, under U.S.C §1251, the Clean Water act, before being discharged to receiving streams.

Recently, the research is …

Effect Of Cobalt In Thin Wall Ductile Iron And Solid Solution Strengthened Ferritic Ductile Iron, Alejandra I. Almanza

Dissertations, Master's Theses and Master's Reports

Ductile Iron is a material that is constantly evolving. Consequently, the ferrous industry is not only focusing on lightweighting but also on improving the impact strength and fracture toughness of typical ferritic-pearlitic ductile iron grades and solid solution strengthened ferritic ductile irons. Recently, the demand for thin-wall ductile iron and solid solution strengthened ferritic ductile iron grades has increased. The challenges behind the fabrication of these two ductile iron materials are the presence of carbides and the embrittlement of ferrite. In response, research has been focused on looking at alternative methods that can mitigate carbide formation in thin sections and …

Cobalt Partitioning And Solubility In Low-Temperature Carbonate-Hydrothermal Systems, Seth Kurtis Coursey

Graduate Research Theses & Dissertations

Cobalt mineralization has been documented in low temperature Mississippi Valley-type (MVT) deposits in southeast Missouri. Lead and zinc are the most economically important metals in these deposits and are contained within galena (PbS) and sphalerite (ZnS), respectively. Cobalt is also mined in some of the deposits with cobalt-bearing ores, e.g., siegenite ((Ni,Co)3S4) and fletcherite (Cu,(Ni,Co)2S4), occurring stratigraphically below main-stage galena and sphalerite. The hydrothermal fluids responsible for cobalt mineralization are thought to be chemically distinct from the predominant MVT ore-bearing fluids and represent a distinct mineralizing event. Cobalt is likely transported as CoCl2 in hydrothermal fluids and sourced from structures …

Experimental Investigation Of The Thermochemical Reduction Of Arsenite And Sulfate: Low Temperature Hydrothermal Copper, Nickel, And Cobalt Arsenide And Sulfide Ore Formation, Nicholas Allin

Graduate Theses & Non-Theses

Experiments were conducted to determine the relative rates of reduction of aqueous sulfate and aqueous arsenite (As(OH)₃,aq) using foils of copper, nickel, or cobalt as the reductant, at temperatures of 150ºC to 300ºC. At the highest temperature of 300°C, very limited sulfate reduction was observed with cobalt foil, but sulfate was reduced to sulfide by copper foil (precipitation of Cu₂S (chalcocite)) and partly reduced by nickel foil (precipitation of NiS₂ (vaesite) + NiSO₄·xH₂O). In the 300ºC arsenite reduction experiments, Cu₃As (domeykite), Ni₅As₂, or CoAs (langisite) …

High-Performing Pgm-Free Aemfc Cathodes From Carbon-Supported Cobalt Ferrite Nanoparticles, Xiong Peng, Varchaswal Kashyap, Benjamin Ng, Sreekumar Kurungot, Lianqin Wang, John R. Varcoe, Mustain E William

Faculty Publications

Efficient and durable non-precious metal electrocatalysts for the oxygen reduction reaction (ORR) are highly desirable for several electrochemical devices, including anion exchange membrane fuel cells (AEMFCs). Here, cobalt ferrite (CF) nanoparticles supported on Vulcan XC-72 carbon (CF-VC) were created through a facile, scalable solvothermal method. The nano-sized CF particles were spherical with a narrow particle size distribution. The CF-VC catalyst showed good ORR activity, possessing a half-wave potential of 0.71 V. Although the intrinsic activity of the CF-VC catalyst was not as high as some other platinum group metal (PGM)-free catalysts in the literature, where this catalyst really shined was …

Fischer–Tropsch: Product Selectivity–The Fingerprint Of Synthetic Fuels, Wilson D. Shafer, Muthu Kumaran Gnanamani, Uschi M. Graham, Jia Yang, Cornelius M. Masuku, Gary Jacobs, Burtron H. Davis

Center for Applied Energy Research Faculty and Staff Publications

The bulk of the products that were synthesized from Fischer–Tropsch synthesis (FTS) is a wide range (C₁–C₇₀₊) of hydrocarbons, primarily straight-chained paraffins. Additional hydrocarbon products, which can also be a majority, are linear olefins, specifically: 1-olefin, trans-2-olefin, and cis-2-olefin. Minor hydrocarbon products can include isomerized hydrocarbons, predominantly methyl-branched paraffin, cyclic hydrocarbons mainly derived from high-temperature FTS and internal olefins. Combined, these products provide 80–95% of the total products (excluding CO₂) generated from syngas. A vast number of different oxygenated species, such as aldehydes, ketones, acids, and alcohols, are also embedded in this product range. …

Effect Of Support, Preparations Methods, Ag Promotion And Nc Size On The Activity, Selectivity And Sintering Deactivation Of Supported Co Fischer-Tropsch Catalyst, Mahmood Rahmati

Theses and Dissertations

A series of silver-promoted, 20 wt% cobalt Fischer-Tropsch synthesis (FTS) catalysts supported on an alumina modified with 5 wt% silica were prepared using two methods: traditional incipient wetness impregnation (IWI) and a new solvent-deficient precipitation (SDP) technique. Catalysts containing silver promoter concentrations of 0.3, 0.6, 1.2, and 2.5 wt% were prepared using each of the two methods. Silver improved the reducibility of the cobalt significantly, lowering reduction temperatures by up to 100°C, and increasing the extent of reduction by up to 35%. Further, in both preparation methods, changing the silver loading altered the cobalt dispersion. The smallest Co crystallite size …

Synthesis And Applications Of Ceramic (Silicon Carbide And Silicon Nitride), Metallic (Cobalt(0)) And Polymeric (Polyurethane) Aerogels, Parwani M. Rewatkar

Doctoral Dissertations

"A new method has been demonstrated for the synthesis of monolithic ceramic and purely metallic aerogels from xerogel powder compacts, and the use of polyurethane aerogels based on cyclodextrins as efficient desiccants.

I. Highly porous ( > 80%) monolithic SiC and Si₃N₄, aerogels were prepared from compressed compacts of polyurea-crosslinked silica xerogel powders. The process is time efficient as solvent-exchange through powders is fast, and energy efficient as it bypasses drying with supercritical fluids. The final ceramic objects were chemically pure, sturdy, with compressive moduli at 37 ±7 MPa and 59 ± 7 MPa, and thermal conductivities …

Electrodeposition Of Cobalt From Eutectic-Based Ionic Liquid, Rostom Ali M., Sankar Saha S, Ziaur Rahman Md

Journal of Electrochemistry

The electrodeposition of cobalt from a solution containing cobalt chloride in either a urea-choline chloride based or an ethylene glycol (EG)-choline chloride based ionic liquid has been carried out onto copper and steel cathodes by constant current and constant potential methods at different temperatures. The influences of various experimental conditions on electrodeposition and morphology of the deposited layers have been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD)technique. It has been shown that the smooth, shiny with good adherence and bright metallic coloured cobalt coatings were obtained from both urea and EG based ionic liquids at the applied …

Electrodeposited Epitaxial Cobalt Oxides And Copper Metal, Caleb M. Hull

Doctoral Dissertations

"Electrochemical deposition methods are presented for the deposition of Co(OH)₂ and Cu metal. Paper I shows the deposition of β-Co(OH)₂ on Ti through electrochemical reduction of [Co(en)₃]³⁺ to [Co(en)₃]²⁺ in 2M NaOH. The catalytic properties of the deposited Co(OH)₂ towards water oxidation is found comparable to Co₃O₄, with the surface of the Co(OH)₂ converting to CoOOH during the reaction. Paper II gives the conditions suitable for epitaxial growth of Co(OH)₂ on Au(100), Au(110), and Au(111) following the same reduction mechanism as described in Paper I. …

Effect Of Different Alumina Supports On Performance Of Cobalt Fischer-Tropsch Catalysts, Thomas H. Fletcher

Faculty Publications

Four identically-prepared 20 wt% cobalt/0.15 wt% ruthenium Fischer-Tropsch catalysts, supported on different aluminas, were synthesized by incipient wetness impregnation, characterized, and compared based on their performance under standard Fischer-Tropsch synthesis conditions. Three alumina supports were obtained from commercial sources (Sasol, St. Gobain, and Alfa Aesar), while the fourth was made using a published technique that included 5 wt% silica. The silica-stabilized alumina catalyst produced superior Fischer-Tropsch rates of 49 mmol CO/gcat h, compared to the other catalysts on the commercial supports with rates of 26–39 mmol CO/gcat h. The improved performance of the silica-stabilized alumina support compared to the commercially …

Selective Deposition Of Platinum By Strong Electrostatic Adsorption Onto Cobalt- And Iron-Based Catalysts For Fischer-Tropsch Synthesis, Fahad A. Almalki

Theses and Dissertations

Cobalt and iron based catalysts are commercially predominant for Fischer-Tropsch synthesis, Co-based catalysts for their stability, activity, and inactivity for the water gas shift reaction and Fe-based catalysts for their cheap cost, high light-olefins and alcohols selectivity, and tolerance to H2/CO ratio. These catalysts are structure sensitive with lower activity at nanoparticle sizes smaller than 6-8 nm. Co-based catalysts exhibit high activity, low CH4 selectivity, and high C5+ selectivity, while Fe-based catalysts are more selective to low-molecular-weight hydrocarbons such as olefins and alcohols. The reducibility of cobalt and iron is another important factor which may be key for improving their …

Homo- And Heterometallic Bis(Pentafluorobenzoyl)Methanide Complexes Of Copper(Ii) And Cobalt(Ii), Janell Crowder

Legacy Theses & Dissertations (2009 - 2024)

β-Diketones are well known to form metal complexes with practically every known metal and metalloid. Metal complexes of fluorinated β-diketones generally exhibit increased volatility and thermal stability compared to the non-fluorinated analogues, and thus are used extensively in various chemical vapor deposition (CVD) processes for the deposition of metal, simple or mixed metal oxides, and fluorine-doped metal oxide thin films. Furthermore, the electron-withdrawing nature of the fluorinated ligand enhances the Lewis acidity of a coordinatively unsaturated metal center which facilitates additional coordination reactions. The physical and structural properties of fluorinated β-diketonate complexes are discussed in Chapter 1 …

Symbiotic Plasmonic Nanomaterials: Synthesis And Properties, Abhinav Malasi

Doctoral Dissertations

Metal particles of the dimensions of the order of 1 to 100's of nanometers show unique properties that are not clearly evident in their bulk state. These nanoparticles are highly reactive and sensitive to the changes in the vicinity of the particle surface and hence find applications in the field of sensing of chemical and biological agents, catalysis, energy harvesting, data storage and many more. By synthesizing bimetallic nanoparticles, a single nanoparticle can show multifunctional characteristics. The focus of this thesis is to detail the synthesis and understand the properties of bimetallic nanomaterial systems that show interesting optical, chemical, and …

Fundamental Interdiffusion Analysis Of Ruthenium And Cobalt Films, Bartlet Deprospo

Nanoscale Science & Engineering (discontinued with class year 2014)

No abstract provided.

Fretting Corrosion Of Cocrmo Alloy Biomaterials: Instrumentation Development, Heredity Integral Modeling And The Effect Of Frequency, Zhe Li

Dissertations - ALL

Mechanically assisted crevice corrosion, a process of corrosion that generally occurs in joint replacements of the hip and knee, is a major problem for metallic biomaterials. Though extensive research has already been undertaken, the basic concepts of fretting corrosion including prediction of the instantaneous current response during fretting corrosion, still needs to be understood in a systematic form. The aim of this study is to present the mechanical and electrochemical elements of a model pertaining to the process of fretting crevice corrosion and the prediction of fretting corrosion current transients. The influence of sliding speed on fretting corrosion severity of …

Effect Of Ce And Co Addition To Fe/Al2o3 For Catalytic Methane Decomposition, Ahmed S. Al-Fatesh, Ashraf Amin, Ahmed A. Ibrahim, Wasim Ullah Khan, Moustafa A. Soliman, Raja L. Al-Otaibi, Anis H. Fakeeha

Chemical Engineering

Catalytic methane decomposition is studied in a fixed bed reactor. Two sets of bimetallic catalysts are employed, namely: 30%Fe-X%Ce/Al2O3 and 30%Fe-X%Co/Al2O3, and compared with monometallic 30%Fe/Al2O3 catalyst. The effect of promoting Fe with Ce and Co and reduction temperature are investigated. The results reveal that Ce addition has shown a negative impact on H2 yield while a positive effect on H2 yield and catalyst stability are observed with Co addition. In terms of number of moles of produced hydrogen per active sites, Fe/Al2O3 has shown a higher number of moles of hydrogen compared to bimetallic catalysts. The catalyst reduced at …

Characterisation Of A Cobalt-60 Small-Beam Animal Irradiator Using A Realtime Silicon Pixelated Detector, C Porumb, Jocelyn Davies, Vladimir Perevertaylo, Anatoly B. Rosenfeld, Marco Petasecca

Faculty of Engineering and Information Sciences - Papers: Part A

The paper presents a study performed by the Centre for Medical Radiation Physics (CMRP) using a high spatial and temporal resolution silicon pixelated detector named MagicPlate- 512. The study focuses on the characterisation of three pencil beams from a low-dose rate, 6 TBq, cobalt-60 source, in terms of percentage depth dose, beam profiles, output factor and shutter timing. Where applicable, the findings were verified against radiochromic EBT3 film and ionization chambers. It was found that the results of the MagicPlate-512 and film agreed within 0.9 mm for penumbra and full-width at half-maximum measurements of the beam profiles, and within 0.75% …

Novel Carbon-Supported Transition Metal Phosphide Catalysts For Hydrodeoxygenation Of Fast Pyrolysis Oil, Cheng Guo

Electronic Thesis and Dissertation Repository

Catalytic hydrodeoxygenation (HDO) is considered to be the most promising route to upgrade pyrolysis oil to liquid transportation fuels. The objective of this research was to explore inexpensive supported metal oxides/metal phosphide catalysts for the upgrading of pyrolysis oil into advanced drop-in hydrocarbon liquid fuels by HDO.

The first stage of this thesis project investigates a series of molybdenum oxides/phosphide catalysts on different supports that were prepared in-house, such as Al₂O₃, activated carbon (AC), MgAl₂O₄ and Mg₆Al₂(CO₃)(OH)₁₆. The HDO activity of these catalysts were investigated …

Self-Healing Catalysts: Co3O4 Nanorods For Fischer-Tropsch Synthesis, Cun Wen, Darrius Dunbar, Xin Zhang, Jochen Lauterbach, Jason Hattrick-Simpers

Jason R. Hattrick-Simpers

We combine kinetic and spectroscopic data to demonstrate the concept of a self-healing catalyst, which effectively eliminates the need for catalyst regeneration. The observed self-healing is triggered by controlling the crystallographic orientation at the catalyst surface.

One-Dimensional Manganese-Cobalt Oxide Nanofibres As Bi-Functional Cathode Catalysts For Rechargeable Metal-Air Batteries, Kyu-Nam Jung, Soomin Hwang, Min-Sik Park, Ki Jae Kim, Jae-Geun Kim, S X. Dou, Jung Ho Kim, Jongwon Lee

Australian Institute for Innovative Materials - Papers

Rechargeable metal-air batteries are considered a promising energy storage solution owing to their high theoretical energy density. The major obstacles to realising this technology include the slow kinetics of oxygen reduction and evolution on the cathode (air electrode) upon battery discharging and charging, respectively. Here, we report non-precious metal oxide catalysts based on spinel-type manganese-cobalt oxide nanofibres fabricated by an electrospinning technique. The spinel oxide nanofibres exhibit high catalytic activity towards both oxygen reduction and evolution in an alkaline electrolyte. When incorporated as cathode catalysts in Zn-air batteries, the fibrous spinel oxides considerably reduce the discharge-charge voltage gaps (improve the …

Influence Of Reduction Promoters On Stability Of Cobalt/Γ-Alumina Fischer-Tropsch Synthesis Catalysts, Gary Jacobs, Wenping Ma, Burtron H. Davis

Center for Applied Energy Research Faculty and Staff Publications

This focused review article underscores how metal reduction promoters can impact deactivation phenomena associated with cobalt Fischer-Tropsch synthesis catalysts. Promoters can exacerbate sintering if the additional cobalt metal clusters, formed as a result of the promoting effect, are in close proximity at the nanoscale to other cobalt particles on the surface. Recent efforts have shown that when promoters are used to facilitate the reduction of small crystallites with the aim of increasing surface Co⁰ site densities (e.g., in research catalysts), ultra-small crystallites (e.g., < 2–4.4 nm) formed are more susceptible to oxidation at high conversion relative to larger ones. The choice of promoter is important, as certain metals (e.g., Au) that promote cobalt oxide reduction can separate from cobalt during oxidation-reduction (regeneration) cycles. Finally, some elements have been identified to promote reduction but either poison the surface of Co⁰ (e.g., Cu), or produce excessive light gas selectivity (e.g., Cu and Pd, or Au at …

Enhanced Electrochemical Properties Of Cobalt Doped Manganese Dioxide Nanowires, Byoung Chul Kim, C Justin Raj, W J. Cho, W G. Lee, Hyeon Taek Jeong, K H. Yu

Australian Institute for Innovative Materials - Papers

The various molar concentrations of cobalt doped manganese dioxide (Co-MnO2) nanostructures were synthesized by an hydrothermal technique for electrochemical supercapacitor application. The X-ray diffraction analysis showed that the samples were composed of multiphase of MnO2 with dominant reflections of γ-MnO2 structure of crystallization. The morphological studies displayed the existence of MnO 2 nanowires with the width of 10-20 nm and showing a good degree of crystallization. The electrochemical characterization was performed using cyclic voltammetry, galvanostatic charge/discharge test and impedance spectroscopy in 1 M Na2SO4 aqueous electrolyte. All the samples exhibit a typical ideal capacitive behavior with an increasing order of …

Self-Healing Catalysts: Co3O4 Nanorods For Fischer-Tropsch Synthesis, Cun Wen, Darrius D. Dunbar, Xin Zhang, Jochen A. Lauterbach, Jason R. Hattrick-Simpers

Faculty Publications

We combine kinetic and spectroscopic data to demonstrate the concept of a self-healing catalyst, which effectively eliminates the need for catalyst regeneration. The observed self-healing is triggered by controlling the crystallographic orientation at the catalyst surface.

Hydrothermal Synthesis And Optical, Magnetic And Supercapacitance Properties Of Nanoporous Cobalt Oxide Nanorodes, Guoxiu Wang, Xiaoping Shen, Josip Horvat, Bei Wang, Hao Liu, David Wexler, Jane Yao

Josip Horvat

Nanoporous cobalt oxide nanorods were synthesized by a hydrothermal method. Transmission electron microscopy analysis showed that the individual Co3O4 nanorods have a nanoporous structure, consisting of the textured aggregations of nanocrystals. Optical properties of Co3O4 nanorods were characterized by Raman and UV−vis spectroscopy. Magnetic property measurement shows that Co3O4 nanorods have a low Néel transition temperature of 35 K. We observed quite significant exchange bias for nanoporous Co3O4 nanorods, indicating the existence of magnetic coupling between the nanocrystals in Co3O4 nanorods. When applied as electrode materials in supercapacitors, Co3O4 demonstrated a high capacitance of 280 F/g.

Single-Crystal Growth And Anisotropic Magnetic Properties Of Nonstoichiometric Three-Layer Sodium Cobalt Oxides, Dapeng Chen, Xiaolin Wang, C T Lin, S X. Dou

Shi Xue Dou

Large single crystals of α-NaxCoO2 (x=0.91, 0.92, and 0.93) have been successfully fabricated by using the traveling solvent floating zone method. Details on the crystal growth are discussed. The crystal structures were characterized using powder x-ray diffraction and Rietveld refinement. The magnetic susceptibility measurements show that the magnetic properties depend strongly on x. The compound was found to be antiferromagnetic at TN ≈ 20 K for x=0.91 and x=0.92, and paramagnetic for x=0.93. The in-plane and out-of-plane anisotropies were observed for the x=0.91 crystals. In addition, the derived anisotropic g-factor ratios (gab /gc) from the anisotropic susceptibility along H||ab and …

A Sign Of Field-Induced First Order Magnetic State Transition And Giant Reversible Magnetocaloric Effect In Cobalt Hydroxide Nanosheets, Precious Shamba, Rong Zeng, J Q Wang, S X. Dou

Shi Xue Dou

We report the synthesis of β−Co(OH)2 nanosheets using microwave assisted hydrothermal and conventional chemical reaction methods. A magnetic transition at an onset temperature, T1 ~ 96 K, and a sign of antiferromagnetic state transition at the Néel temperature, TN=9~10 K, can be determined from M-T curves and M-H curves magnetic properties investigation. It is found that a sign of field-induced first order transition below 9 K, act as a role of reversing the magnetocaloric effect from negative to positive value. The large reversible magnetic-entropy change (∆SM) of 17 J/kg K around 11 K for a field change of 5 T …

Travelling In Cuba, Fathi Habashi

Fathi Habashi

Contact with Cuban scientists was established in 1986 when two researchers from Centro de Investigaciones para Industria Minero Metalurgica in Havana visited Laval University to get acquainted with research activities in the area of extractive metallurgy. This was followed in early 1987 by two more researchers from the same centre. Invitations were then received in late 1987, 1989, and 2008 to visit the nickel refineries in Cuba and to hold seminars at the University of Havana. The present report outlines these activities.