Protective coatings is used to enhance the corrosion resistance of buried pipelines. However, the effectiveness of epoxy-coatings may be compromised due to inadvertent presence of surface damage and coating disbondment. Additionally, the disbonded coated panels is expected to be less effective than that of scratched or un-defected panels. This research was designed to evaluate the coating performance of FBE and hybrid epoxy in simulated Arabian Gulf water and synthetic Sabkha. The influence of coating damage and disbondment on corrosion resistance was also investigated. Results of this research indicated a reduction in the adhesion bond between the coatings and substrate. The electrochemical impedance measurements demonstrated the need for an appropriate interpretation of results when this technique is used. The corrosion current density measurements indicated that both media are corrosive. Protective coatings under investigation did not show any blistering effect, loss of adhesion or color change under test conditions, thus reflecting their excellent corrosion resistance property.

<p>Thin films prepared by electrochemical and physical vapor deposition (PVD) methods were investigated for corrosion protection of metals and alloys. Various electrochemical methods were developed, such as electrophoretic deposition (EPD), electrolytic deposition (ELD) and combined methods. EPD method has been developed for the deposition of polymer films, including poly(2-vinylpyridine) (PVP) and co-polymer poly(4-vinylpyridine-<em>co</em>-butyl methacrylate) (PVPBM). The method involved the electrophoresis of protonated polymer macromolecules, base generation at the cathode surface, charge neutralization and deposition of water insoluble polymer films. Nanostructured CeO₂ films were prepared by cathodic ELD and EPD. Cathodic ELD involved electrosynthesis of CeO₂ nanoparticles in the cathodic reaction and film formation. New dispersion agents were developed for CeO₂ particles for application in EPD processes. The kinetics of ELD and EPD and deposition mechanisms were investigated.</p> <p>Composite polymer-CeO₂ films were deposited using various strategies, based on ELD or EPD of CeO₂ and EPD of polymers. The composite films were deposited as monolayers, multilayers or materials of graded composition. The deposition yield and film composition can be varied.</p> <p>The composite films were studied by electron microscopy, X-ray diffraction, thermogravimetric and differential thermal analysis. Electrochemical testing showed that polymer and composite films provided corrosion protection of stainless steel substrates.</p> <p>Corrosion protection properties of coatings deposited on commercial AMPCO and TZM alloys was investigated. CrN, CrN-D, and TiC were deposited by PVD method. Ni coatings were deposited by electroplating. The analysis of Tafel plots and impedance spectroscopy data showed that CrN and CrN-D coatings deposited by PVD showed better corrosion protection of AMPCO and TZM alloys, compared to TiC and Ni coatings. The results of this investigation pave the way for the fabrication of novel coatings with advanced corrosion protection, wear and mechanical properties, using combined PVD and electrochemical methods.</p> / Master of Applied Science (MASc)

<p>Proton exchange membrane fuel cells (PEMFC) are a technology of high interest for the automotive and power generation industry. The catalyst layer plays a critical role in fuel cells as it is responsible for catalyzing hydrogen oxidation and oxygen reduction to generate electricity. The current challenge in catalyst development is to produce highly active and economical catalysts. This challenge cannot be overcome without an accurate understanding of catalyst surfaces and morphology since the catalytic reactions occur on the surface active sites. Transmission electron microscopy (TEM) is an excellent tool to understand the structures of the nanoparticles down to the atomic level in determining the relationship with the catalyst’s performance in fuel cell applications. Platinum (Pt) is one of the best commercially available catalysts for PEMFC due to its highly active, inert, and relatively stable properties. However, Pt is a rare precious metal due to its low abundance and high demand. Further research is aimed at developing highly active and more economical catalysts in order to mass produce PEMFC. A strategic approach is to use platinum bimetallic alloys, which greatly reduce the platinum loading as they enhance the oxygen reduction reaction. A detailed understanding of the nanoparticle surface is critical as the catalyst surface strongly determines its catalytic activity. Furthermore, another challenge in utilizing fuel cells is the life-time of the catalysts. It is known that electrochemical cycling affects Pt alloys. As a result, the understanding of the effect of electrochemical treatments on the catalyst’s v morphology and composition is key to improving the fuel cell’s performance and durability. This thesis demonstrates that through the use of TEM, useful insights regarding the morphology, surfaces, and compositions of the catalysts can be gained and contribute to the improvement in catalyst development for next generation fuel cells.</p> / Master of Applied Science (MASc)

<p>No comments. Thanks.</p> / <p>Advanced electrodes based on MnO₂ for the electrochemical supercapacitor (ES) application have been fabricated using electrochemical and chemical methods.</p> <p>Electrosynthesis method has been utilized for the in-situ impregnation of manganese dioxide in commercial Ni plaque current collectors. Dipping-reduction, cathodic galvanostatic and reverse pulse electrosynthesis methods were investigated. The material loading was varied by the variation of the number of the dipping-reduction procedures in the chemical precipitation method or by the variation of charge passed in the electrochemical methods. The results obtained by different methods were compared. The dipping-reduction method offered the advantage of higher specific capacitances (SCs) at high scan rates, whereas other methods allowed higher material synthesis rate.</p> <p>Cathodic electrolytic deposition (ELD) has been utilized for the fabrication of Ag-doped MnO₂ films. The Ag-doped MnO₂ films showed improved capacitive behavior and lower electrical resistance of 0.6 Ohm compared to pure MnO₂ films. The highest SC of 770 F g^-1 was obtained at a scan rate of 2 mV s^-1 in the 0.5 M Na₂SO₄ electrolyte.</p> <p>Electrodes for ES application were fabricated by cathodic electrodeposition of MnO₂ on CNTs, which were grown by chemical vapor deposition on stainless steel meshes. The MnO₂-CNT nanocomposites showed excellent capacitive behavior and low electrical resistance of 0.5 Ohm.</p> <p>Electrophoretic deposition (EPD) has been utilized for the deposition of composite MnO₂-multiwalled carbon nanotube (MWCNT) films for the ES application. Dopamine (DA), caffeic acid (CA), tyramine (TA), gallic acid (GA), polyacrylic acid (PAA) and pyrocatechol violet (PV) were shown to be effective and universal charging additives, which provide stabilization of MnO₂ nanoparticles and MWCNTs in the suspensions. The influence of the structure of the organic molecules on their adsorption on the oxide nanoparticles has been investigated. We discovered that the number and site of OH group for dispersants were essential for the adsorption on oxide materials, and the number of aromatic ring was important for the adsorption on carbon materials. Pure CNT films were deposited using PV as a dispersant, which was the first time in literature to prepare pure CNT film using a dispersant. SCs decrease with increasing film thickness. SCs of composite MnO₂-MWCNT obtained using EPD were in the range of 350-650 F g^-1 depending on material loadings.</p> / Doctor of Science (PhD)

<p>Ni-Fe alloys have been used in industrial applications over the past century due to their unique mechanical and magnetic properties. Currently, researchers are interested in enhancing the performance of Ni-Fe alloys by modifying their microstructure. An example of this would be the use of ultra-fine nanocrystalline Ni-Fe alloys for magnetic shielding products that are uniquely shaped and cost effective. These nanocrystalline materials usually exhibit good soft magnetic properties, such as high saturation magnetization, low coercivity and good magnetic permeability. The following study has been devoted to the magnetic properties of electrodeposited nanocrystalline Ni-Fe alloys.</p> <p>The structure and texture of electrodeposited Ni-Fe alloys was studied by two-dimensional XRD. The Ni-Fe alloys with Fe content from 24.9at. % to 54.2at. % were comprised exclusively of the FCC phase. For 60.2at. % Fe sample, a mixed phase of BCC and FCC structure was found. The lattice parameter increased with increasing Fe content until 54.2at. %, and then decreased due to the presence of BCC structure. The increase in lattice parameter was attributed to the iron replacement of nickel in the Ni crystalline lattice. Texture analysis shows that all Ni-Fe alloys with different Fe content exhibit the fiber texture with a major component of theaxis aligned perpendicular to the sample plane. A second component iswith a significantly lower volume fraction. It also shows that the Ni-Fe alloy with 44.2at. % Fe exhibits the highest volume fraction of random orientation.</p> <p>Magnetic measurements showed that all Ni-Fe nanocrystalline alloys exhibit soft magnetic properties with narrow hysteresis loops. The saturation magnetization increased linearly with increasing Fe content. The magnetization at T = 2K were slightly higher than that at T = 298K. The lowest coercivity~6Oe was obtained at 44.2 at. % Fe content.</p> <p>Good agreement between Random Anisotropy Model (RAM) theory and experimental data for all the Ni-Fe alloys has been obtained. By fitting the high field magnetization curve with the Law of Approach to Saturation (LATS), the magnetocrystalline anisotropy constant (K_eff) were obtained. K_eff decreased with increasing temperature. Also, the ferromagnetic exchange lengths for each Ni-Fe alloy were calculated. They are 26nm, 21nm, 19nm, 18nm, 17nm for Ni-24.9at.%Fe, Ni-33.1at.%Fe, Ni-44.2at.%Fe, Ni-54.2at.%Fe, Ni-60.2at.%Fe at room temperature, respectively. The exchange lengths are larger than the average grain size (D) for all of the samples. The results confirmed the feasibility of Random Anisotropy Model for the prediction of the magnetic properties of the nanocrystalline Ni-Fe alloys fabricated by electrodeposition.</p> / Master of Applied Science (MASc)

<p>Solid oxide fuel cells are an efficient method of converting hydrocarbon fuels to electrical power. However, due to some problems with poisoning, these have made no headway in the energy market. The evaporation of chromium oxides from metallic current collectors causes rapid degradation of the cells on the cathode side. It has been shown that spinel coatings reduce the effects of chromium oxide evaporation. In this thesis, two spinel systems are explored for potential application. Cobalt-manganese spinel is a stable spinel which have a wide range of composition, while remaining sufficiently conductive. Copper-manganese spinel, which is much more conductive than cobalt-manganese, is slightly less stable, but nonetheless a candidate. All components of the spinels explored can be electrodeposited from aqueous solutions, at room temperature. By controlling the concentrations of metallic ions, and other additives, coatings can be deposited on interconnecting plates with reproducible results. The newly coated interconnects can be oxidized in-situ. For characterization, the samples for this thesis were oxidized at 800°C. Two substrate materials were used, ferritic stainless steel and a chromium-iron alloy. Stainless steel substrates showed good coating adhesion, but high concentrations of iron were found in the spinel structure. Chromium alloy substrates were better protected by spinel coatings. However, nitride formation at the substrate interface caused localized delamination of the coating. It was shown that plating operations can be scaled up to 10 cm by 10 cm plates, with little modification of the processes used.</p> / Master of Applied Science (MASc)

<p>This thesis presents an investigation into the structure and composition of the surface film formed on Mg in aqueous solutions and describes the influence of film stability on corrosion resistance. The composition and structure of the surface film formed on pure Mg in pure H₂O exposed at E_corr for 48 h was investigated using plan-view SEM-EDS imaging and STEM–EDS analysis of a FIB cross-section. The film formed was duplex in nature, consisting of a thinner, more-porous, nano-crystalline MgO-rich inner layer (50-100 nm), and a thicker, less-porous, Mg(OH)₂-rich outer platelet layer (700 nm). The results were consistent with the theory that a chemical breakdown (hydration) of the bulk inner MgO layer (native oxide) is a necessary precursor step to the corrosion process resulting in a significant thickening of the partially protective outer Mg(OH)₂ layer.</p> <p>The surface film formed on pure Mg exposed in 0.01 M NaCl for 24 h at E_corr was found to be a diffuse bilayer structure similar to pure H₂O, including a thin and porous nano-crystalline MgO-rich inner layer (50-100 nm), and a thicker, more porous Mg(OH)₂-rich outer layer (300-600 nm). The un-pitted film region formed in 0.01 M NaCl solution at +0.1 V above E_b for 0.5 h after 24 h aging at E_corr exhibited a similar duplex structure. However, the thickness of both Mg(OH)₂-rich (~450 nm) and MgO-rich layers (~30-60 nm) appeared to be decreased. Furthermore, the pitted region film formed on an anodically polarized Mg sample exhibited thinner MgO-rich layer (~20-30 nm), decorated with macro-pores (~50 nm), and Mg(OH)₂ rich middle layer (~200-300 nm) buried under a thick, more porous needle-like Mg(OH)₂-rich top layer (~0.2-1 µm). EDS analysis confirmed the presence of Cl within the films formed in 0.01 M NaCl, and Fe containing particles within the pitted region anodic film. These results were consistent with an accelerated hydration of MgO to Mg(OH)₂ at lower pH and in presence of Cl^-, formation of more soluble Mg-hydroxy-chlorides, enhanced Mg dissolution due to Cl^- ingress via increased film porosity, and influence of more noble impurities on the pit initiation and growth.</p> <p>The ~50-150 nm film formed spontaneously on Mg exposed to 1 M NaOH was found to consist mainly of a crystalline MgO layer that has been hydrated to Mg(OH)₂ to a variable degree. Although the film exhibited excellent corrosion resistance, it was not stable. The film tended to experience an irregular breakdown/repair process, which was characterized by large irregular potential drops (about 1 V) under E_corr conditions. The breakdown/repair process is believed to involve the hydration-induced stress-rupture of the MgO film at discrete sites and the subsequent formation of a Mg(OH)₂ self-healing corrosion product nodule (~ 500 nm).</p> <p>To understand the corrosion mechanisms and propose surface film evolution models, EIS behavior of Mg in all environments was investigated. The EIS spectra were compared with the proposed Nyquist behavior based on the film structure results. It was confirmed that the diffuse bilayer films formed in pure H₂O and 0.01 M NaCl possessed porosity, in which the electrolyte ingressed, forming the double layer and facilitating Mg faradic dissolution reaction across the Mg/film interface. Decreased porosity and R_ct along with the absence of a C_film/R_por loop, were respectively consistent with lower corrosion resistance of Mg in 0.01 M NaCl and a severely damaged pitted region film. Furthermore, the film compactness and increased R_ct in 1 M NaOH were consistent with a more stable film with excellent corrosion resistance in alkaline environments. In this film, liberated Mg²⁺ ions at the Mg/film interface have to diffuse through the film to facilitate the Mg(OH)₂ precipitation, thus a thicker Mg(OH)₂ film forms.</p> / Doctor of Philosophy (PhD)

<p>Case hardening distortions are a major problem for gear manufacturers. The aim of the current work is to create a simulation model, able to predict how and when case hardening distortions arise. The results presented in this thesis form a basis for such a model.</p><p>Two case hardening steels, with base carbon contents of 0.20 and 0.21 % C were studied using dilatometer experiments. One of them was carburized to 0.36, 0.52 and 0.65 % C in order to investigate the influence of carbon content. Experiments were performed during both isothermal and continuous heating and cooling conditions. The results were used to evaluate phase transformations, heat expansion behaviors and phase transformation strains. The expansion behavior of the material was modeled as a function of temperature, carbon content and phase fractions. The phase transformations to martensite and bainite were modeled, using the Koistinen-Marburger equation and a transformation rate equation based on Austin-Rickett kinetics, respectively. Experiments were simulated using the COMSOL Multiphysics software, to verify the model with respect to martensite and bainite transformations, heat expansion behavior and phase transformation strains.</p>

<p>Summary</p><p>I have a great interest in bouzoukis and since I, during my education in guitar making, mainly have focused on building bouzoukis and other traditional folk instruments, I have chosen the bouzouki as the object of my degree project.</p><p>In connection to the making of these instruments, I started to consider the construction of the bouzouki and why the bouzouki has such a characteristic sound.</p><p>One of my theories is based on the fact that most bouzoukis are made with floating bridges instead of glued pinbridges. Do these types of bridges differ from each other tonally and if so, how much and in what way?</p><p>To receive answers to my questions, I have built two identical bouzoukis with different types of bridges, one with a glued pinbridge and one with a floating bridge. I have been very precise in the making of these instruments, giving them the exact same dimensions and using material from the same piece of wood. This to make sure that the instruments should be as exactly alike as possible.</p><p>After finishing the making of the bouzoukis, I arranged for a sound test where I let musicians play and listen to the instruments. After doing this I let the same musicians fill in a form with questions regarding each instruments tonal characteristics and it’s fields of application.</p><p>By compiling the answers from the sound test, I have come to a conclusion regarding what tonally separates a bouzouki with a glued pinbridge from a bouzouki with a floating bridge.</p><p>In addition to this I have found out what other instrument makers considers to be the difference between these two types of bridges.</p><p>Beside the project described above I also present a brief history of the bouzouki.</p> / <p>Sammanfattning</p><p>Jag har valt att göra ett examensarbete som grundar sig på mitt stora intresse för bouzoukis. Jag har under min utbildning i gitarrbyggeri främst riktat in mig på att bygga bouzoukis samt liknande folkinstrument. I samband med dessa byggen så har jag fundera mycket över instrumentets konstruktion och vad det är som gör att bouzoukin har ett så karakteristiskt ljud.</p><p>En av mina funderingar består i varför de flesta bouzoukis är utrustade med ett tryckande stall istället för ett limmat stall. Skiljer sig dessa stalltyper från varandra tonalt och i sådant fall hur mycket och på vilket sätt?</p><p>För att få svar på mina frågor har jag byggt två stycken bouzoukis som är identiskt lika bortsett från stalltypen. Den ena har ett limmat stall och den andra ett tryckande stall.</p><p>Jag har varit mycket noggrann med att tillverka bouzoukierna med exakt samma dimensioner och med material som kommer från samma trästock. Detta för att försäkra mig om att instrumenten ska bli så lika som det bara går.</p><p>Därefter har jag anordnat ett ”lyssningstest” där jag har låtit musiker spela och lyssna på instrumenten. Musikerna har sedan fått fylla i ett formulär innehållande frågor om instrumentens tonala egenskaper samt om deras användningsområden.</p><p>Genom att sammanställa svaren från lyssningstestet har jag kommit fram till en slutsats om vad det är som tonalt skiljer ett limmat från ett tryckande stall hos en bouzouki.</p><p>Jag har även att tagit reda på vad andra instrumentbyggare anser att det är för skillnader mellan de olika stalltyperna, samt hur bouzoukins historia i stora drag ser ut.</p>

Summary I have a great interest in bouzoukis and since I, during my education in guitar making, mainly have focused on building bouzoukis and other traditional folk instruments, I have chosen the bouzouki as the object of my degree project. In connection to the making of these instruments, I started to consider the construction of the bouzouki and why the bouzouki has such a characteristic sound. One of my theories is based on the fact that most bouzoukis are made with floating bridges instead of glued pinbridges. Do these types of bridges differ from each other tonally and if so, how much and in what way? To receive answers to my questions, I have built two identical bouzoukis with different types of bridges, one with a glued pinbridge and one with a floating bridge. I have been very precise in the making of these instruments, giving them the exact same dimensions and using material from the same piece of wood. This to make sure that the instruments should be as exactly alike as possible. After finishing the making of the bouzoukis, I arranged for a sound test where I let musicians play and listen to the instruments. After doing this I let the same musicians fill in a form with questions regarding each instruments tonal characteristics and it’s fields of application. By compiling the answers from the sound test, I have come to a conclusion regarding what tonally separates a bouzouki with a glued pinbridge from a bouzouki with a floating bridge. In addition to this I have found out what other instrument makers considers to be the difference between these two types of bridges. Beside the project described above I also present a brief history of the bouzouki. / Sammanfattning Jag har valt att göra ett examensarbete som grundar sig på mitt stora intresse för bouzoukis. Jag har under min utbildning i gitarrbyggeri främst riktat in mig på att bygga bouzoukis samt liknande folkinstrument. I samband med dessa byggen så har jag fundera mycket över instrumentets konstruktion och vad det är som gör att bouzoukin har ett så karakteristiskt ljud. En av mina funderingar består i varför de flesta bouzoukis är utrustade med ett tryckande stall istället för ett limmat stall. Skiljer sig dessa stalltyper från varandra tonalt och i sådant fall hur mycket och på vilket sätt? För att få svar på mina frågor har jag byggt två stycken bouzoukis som är identiskt lika bortsett från stalltypen. Den ena har ett limmat stall och den andra ett tryckande stall. Jag har varit mycket noggrann med att tillverka bouzoukierna med exakt samma dimensioner och med material som kommer från samma trästock. Detta för att försäkra mig om att instrumenten ska bli så lika som det bara går. Därefter har jag anordnat ett ”lyssningstest” där jag har låtit musiker spela och lyssna på instrumenten. Musikerna har sedan fått fylla i ett formulär innehållande frågor om instrumentens tonala egenskaper samt om deras användningsområden. Genom att sammanställa svaren från lyssningstestet har jag kommit fram till en slutsats om vad det är som tonalt skiljer ett limmat från ett tryckande stall hos en bouzouki. Jag har även att tagit reda på vad andra instrumentbyggare anser att det är för skillnader mellan de olika stalltyperna, samt hur bouzoukins historia i stora drag ser ut.