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Forming Of Ferritic Stainless Steel Bipolar Plates, Lakshmi Ravi Narayan
Forming Of Ferritic Stainless Steel Bipolar Plates, Lakshmi Ravi Narayan
Electronic Theses and Dissertations
The effect of temperature and lubrication on the stamping of ferritic stainless steel bipolar plates has been studied. Stamping of micro-scale bipolar plate channels in ferritic stainless steel foils of 75 ╡m thickness was carried out at 25, 100 and 200 ░C with stamping loads varying between 36 and 56 kN, without and with lubrication. In unlubricated stamping, high contact friction between the sheet and the die caused strain localisation that increased with stamping load and temperature, and heavy surface damage was observed. Boron nitride, tungsten disulphide and molybdenum disulphide were used as solid lubricants in the process. No necking …
Sliding Wear Of A Squeeze Cast Magnesium Composite Am60-(Al2o3)F At Low Loads, Anindya Banerji
Sliding Wear Of A Squeeze Cast Magnesium Composite Am60-(Al2o3)F At Low Loads, Anindya Banerji
Electronic Theses and Dissertations
Mg matrix composites AM60-x% (Al2O3)f (x=9,11,26) were fabricated by Al2O3 fibre preform preparation and squeeze casting technique. Sliding wear behaviour of these composites were studied by conducting boundary lubricated pin-on-disk tests under ultra-mild wear conditions at 25 ║C and 100 ║C against AISI 52100 steel balls. The damage in AM60-9% (Al2O3)f at 25 ║C occurred as follows: Al2O3 fibre fracture and fragmentation, sinking in of the fragmented fibres leading to decrease in fibre elevation, and damage to Mg matrix. The fibre fracture and fragmentation process, leading towards damage to the Mg matrix, was attributed to: i) high applied contact pressure, …
Elevated Temperature Lubricated Wear Of Al-Si Alloys, Sanjib Dey
Elevated Temperature Lubricated Wear Of Al-Si Alloys, Sanjib Dey
Electronic Theses and Dissertations
Cast hypereutectic Al-Si alloys made monolithic engine blocks is an outcome of the global drive towards lightweight vehicles. Eutectic alloys provide cost effective alternative to those expensive hypereutectic alloys. However, the tribological performances of the eutectic alloys needed rigorous evaluation and the objectives of this dissertation were to investigate the ultra-mild wear (UMW) mechanisms of eutectic Al-12.6%Si alloys, chemical and mechanical properties of tribolayers and their long term stability at elevated temperatures under boundary lubricated conditions. Sliding experiments were conducted using 5W30 engine oil on three etched Al-Si alloys containing 12-25% silicon at temperatures between 25 C and 160 C …
Determination Of The Deformation State Of A Ti-6al-4v Alloy Subjected To Orthogonal Cutting Using Experimental And Numerical Methods, Md Aquidul Islam
Determination Of The Deformation State Of A Ti-6al-4v Alloy Subjected To Orthogonal Cutting Using Experimental And Numerical Methods, Md Aquidul Islam
Electronic Theses and Dissertations
Orthogonal cutting of Ti-6Al-4V alloy was studied. Surface roughness, chip thickness and shear band frequency increased with the feed rate and cutting speed. Serrated chips were formed due to shear band. Strain and flow stress distributions in the material ahead of the tool tip were estimated from shear angle measurements and microhardness measurements respectively. The stress-strain data obtained in this way was used in numerical models. Two numerical models were developed by using two-dimensional Lagrangian element formulation and Smoothed-particle hydrodynamics formulations employing the Johnson-Cook constitutive relationship that utilised the experimental data generated from the machined material with the damage criteria. …
Minimum Quantity Lubrication Machining Of Aluminum And Magnesium Alloys, Sukanta Bhowmick
Minimum Quantity Lubrication Machining Of Aluminum And Magnesium Alloys, Sukanta Bhowmick
Electronic Theses and Dissertations
The use of minimum quantity lubrication (MQL) machining, i.e. drilling and tapping of aluminum and magnesium alloys using very low quantities of cutting fluids was studied and the MQL machining performance was compared to dry and conventional flooded conditions. An experimental drilling station with an MQL system was built to measure torque and thrust force responses. Uncoated and diamond- like carbon (DLC) coated HSS drills were tested against 319 Al and AZ91 alloys using 10-50 ml/h of distilled water (H2O-MQL) and a fatty acid based MQL agent (FA-MQL). The results indicated that H2O-MQL used in conjunction with non-hydrogenated DLC (NH-DLC) …
Thin Film Metallization And Protective Top-Coat Development, Jack Bekou
Thin Film Metallization And Protective Top-Coat Development, Jack Bekou
Electronic Theses and Dissertations
This research involved an investigation to find an alternative technology to chrome plating. The proposed system used a plastics substrate, a metalized layer, and a protective top-coat. The interfaces between the layers are the challenges and thus various experiments are conducted to examine the different possibilities for each layer and find the most suitable combination for the system meeting the appearance and functional requirements. Various studies, using different techniques such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and profilometery have been presented to examine different failure modes and identify the root cause of the failures. This …
The Effect Of Sliding Contact Friction On Surface Quality Of Aluminum Sheet Products, Olufisayo Gali
The Effect Of Sliding Contact Friction On Surface Quality Of Aluminum Sheet Products, Olufisayo Gali
Electronic Theses and Dissertations
The surface defects of aluminum alloys that have undergone high temperature processing are studied. The effects of rolling passes and forward speed on the generation of a disturbed layer on aluminum alloy sheet surfaces were investigated with a hot rolling simulator. The results showed that by increasing the forward speed and number of rolling passes, the localized shear deformation became more pronounced on the surface. However, when the two rolling passes were in opposite directions, the defects induced by the localized shear deformation were embedded into the aluminum surface. The use of WS2 as a solid lubricant in hot forming …
Plastic Deformation And Surface Damage Mechanisms During Hot-Forming Of Al And Mg Alloy Sheets, Sarmistha Das
Plastic Deformation And Surface Damage Mechanisms During Hot-Forming Of Al And Mg Alloy Sheets, Sarmistha Das
Electronic Theses and Dissertations
Material transfer and adhesion to die surface are major tribological issues encountered during hot-forming of aluminum and magnesium alloys, reducing process efficiency. This study aimed at understanding the tribological contact interface generated between material and die surface under dynamic conditions created by simultaneous effect of temperature and strain rate. Micromechanisms of plastic deformation occurring under simulated hot-forming conditions were identified and related to the coefficient of friction (COF). Sliding contact experiments were done using specially designed tribometer (operating temperature: 25 to 545░C, strain rate: 10-3 to 10-1s-1). COF of AA5083(Al-4.5%Mg-0.7%Mn) and AZ31(Mg-3%Al-0.7%Zn) alloys were measured during their plastic deformation by …
Sliding Wear Behaviour Of Eutectic Al-Si Alloy Under Lubricated Conditions: An Investigation On The Effect Of Ethanol (E85) Addition, Victor Francis
Sliding Wear Behaviour Of Eutectic Al-Si Alloy Under Lubricated Conditions: An Investigation On The Effect Of Ethanol (E85) Addition, Victor Francis
Electronic Theses and Dissertations
Bio-fuels such as E85 (85% ethanol and 15% gasoline) are clean and cost effective alternative fuel sources. Their effects on the tribological performance of the IC Al-Si engine alloy needs to be investigated. This study explores the ultra mild wear (UMW) mechanisms of an Al-12.6%Si alloy operating under a mixture of E85 fuel and motor oil (5W30) blended at a 1:1 ratio and only engine oil using boundary lubricated condition. Wear tests were conducted at room temperature using a pin-on-disk configuration and 52100 steel balls counterface. They show that samples lubricated with only engine oil and an engine oil E85 …
Measuring The Sensitivity Of Interfacial Gaps In Laser Transmission Welding Using Manufactured Voids, Stephanie Masse
Measuring The Sensitivity Of Interfacial Gaps In Laser Transmission Welding Using Manufactured Voids, Stephanie Masse
Electronic Theses and Dissertations
The efforts of this research were to determine the sensitivity to interfacial gaps in laser transmission welding using various laser welding parameters. Note that the melting of the transparent side of the interface relies mainly on heat conduction from the absorbing side since the laser beam energy is mainly absorbed in the non-transparent material. If a gap exists between the parts at the faying surface, the weld may not form at that location. For this study, interfacial gaps created via manufactured voids were moulded into the components to be welded. After welding, the samples were then assessed using microstructural analysis, …
Plasma Electrolytic Oxidation (Peo)Coatings On A Zirconium Alloy For Improved Wear And Corrosion Resistance, Ying Chen
Electronic Theses and Dissertations
A Plasma Electrolytic Oxidation (PEO) process was used to produce thin oxide coatings on a Zr-2.5wt%Nb alloy. Effects of current density on surface morphologies and wear properties of PEO coatings were investigated and compared to the substrate and the black oxide coating. Corrosion properties at ambient and high temperature/pressure conditions were studied using potentiodynamic polarization tests and autoclave tests, respectively. Autoclave tests were carried out at 300░C and 10MPa in 0.05M LiOH solutions. After the autoclave tests, PEO coatings had larger weight gains in the first 10-day-exposure than the black oxide coating. However, the black oxide coating exhibited a similar …
Development Of Hybrid Mg-Based Composites, Zhang Qiang
Development Of Hybrid Mg-Based Composites, Zhang Qiang
Electronic Theses and Dissertations
In this study, a novel approach of making hybrid preforms with two or more types of reinforcements, i.e., low-cost and different sized particles and fibres, for magnesium-based composites was developed. An advanced and affordable technique of fabricating hybrid magnesium based composites named the preform-squeeze casting was employed successfully. The microstructural analyses show that both the particles and fibres distribute homogeneously in the preform and its matrix materials of the composites. The grain refinement mechanisms of the hybrid composites during solidification were investigated. The engineering performance of the composites was evaluated by tensile testing in comparison with the matrix alloy. The …
Tensile Behaviour And Microstructure Of Permanent Mould Cast Magnesium Alloy Aj62 Subject To Corrosion, Jonathan Burns
Tensile Behaviour And Microstructure Of Permanent Mould Cast Magnesium Alloy Aj62 Subject To Corrosion, Jonathan Burns
Electronic Theses and Dissertations
AJ62, containing notable amounts of strontium, exhibits a microstructure unique among aluminum-manganese based magnesium alloys. The benefit is improved high temperature mechanical performance among magnesium alloys, which are not known for this trait. Capacity for high temperature application makes AJ62 the focus of much research. The high temperature properties, coupled with the high strength to weight ratios of magnesium alloys, promise lightweight powertrain components for the automotive industry to lower fuel consumption, reduce emissions, and improve performance. Castability of the alloy is demonstrated by its adaptation to the gravity-fed permanent mould casting process. Influential characteristics of its solidified microstructures are …
Deformation State Of Aluminum-6% Silicon Alloy (319 Al) Subjected To Orthogonal Cutting At Different Speeds And Feed Rates, Shilpi Pratibha
Deformation State Of Aluminum-6% Silicon Alloy (319 Al) Subjected To Orthogonal Cutting At Different Speeds And Feed Rates, Shilpi Pratibha
Electronic Theses and Dissertations
Dry machining of cast aluminum 6%-Si alloy 319 Al was studied. Investigations were carried out to understand deformation mechanisms leading to discontinuous chip formation during the process. A force transducer was constructed for measuring cutting and thrust forces which increased with an increase in feed and with a decrease in cutting speed. Surface roughness increased with an increase in feed. Plastic strain and flow stress estimations in region ahead of tool-tip indicated high strains (1.8) and stresses (369MPa) in shear zone. Optical investigations showed that zone of silicon particle damage below machined surface increased with feed. Theoretically estimated specific energy …
Investigation Of Pvd And Cvd Coatings For Manufacturing, Fuel Cell And Biomedical Applications, Linlin Wang
Investigation Of Pvd And Cvd Coatings For Manufacturing, Fuel Cell And Biomedical Applications, Linlin Wang
Electronic Theses and Dissertations
In this dissertation, wear and corrosion properties of hard coatings were characterized under simulated dry machining, fuel cell and biomedical application conditions. The test results were analyzed, and potentials of the coatings for the targeted applications were discussed. To evaluate the effect of high temperature during the dry machining on the wear performance of various tool coatings, including TiN, TiAlN, CrN, CrAlN and DLC, the phase structurures as well as mechanical and tribological properties of un-annealed and annealed coatings were characterized. An industrial trial of CrAlN- and TiN-coated punches in an auto stamping plant was also conducted. The test results …
Correlation Between The Microstructure Of Dual Phase Steel And Industrial Tube Bending Performance, Chongzhi Chang
Correlation Between The Microstructure Of Dual Phase Steel And Industrial Tube Bending Performance, Chongzhi Chang
Electronic Theses and Dissertations
Dual phase (DP) steels, are currently one of the choice automotive materials in terms of potential for weight reduction and cost. More specifically, DP steel tubes are increasingly being used to produce automotive structural components. In this study, tensile tests, rotary draw bending tests and microstructural analyses were conducted in order to identify which mechanical properties and microstructural features have an influence on the onset of failure in bent DP steel tubes. Several important microstructural features, such as martensite banding and non-metallic inclusions, were investigated with a view to understanding their effect on the deformation behaviour of DP steels. The …
Dual Phase Steel Characterization For Tube Bending And Hydroforming Applications, Chad Oliver
Dual Phase Steel Characterization For Tube Bending And Hydroforming Applications, Chad Oliver
Electronic Theses and Dissertations
This study examined the behaviour of dual phase steel tubes from three different strength grades undergoing rotary draw bending and pressure sequence hydroforming. It was found that the level of strain experienced by the tubes was independent of the steel grade. It was also shown that the same microstructural features that affect strength and elongation in uniaxial tensile testing affected dual phase steel tubes undergoing tube bending. Seven commercial dual phase steels from three different suppliers were compared. It was found that the strength of the steels was mainly dependent on martensite volume fraction, while elongation was influenced by the …
Effect Of Thermal Treatment On Tensile Properties Of A Vacuum Die Cast Hypoeutectic Al-Si Alloy, Kazi Ahmmed
Effect Of Thermal Treatment On Tensile Properties Of A Vacuum Die Cast Hypoeutectic Al-Si Alloy, Kazi Ahmmed
Electronic Theses and Dissertations
Vacuum assisted high pressure die casting processes appear to gain popularity in automotive industry. A number of thermal treatment schemes have been experimented in an effort to understand the effect of thermal treatment on tensile properties of vacuum die cast modified AA365 alloy. The results of tensile testing indicate that, high temperature treatments have an observable effect on tensile properties. The average ultimate tensile strength of about 286 MPa is achieved at 200˚C thermal treatment for 90 minutes. However, the ductility has reduced to 7.8% from 10.7% in as-cast condition. The morphology of eutectic silicon and magnesium-based phase has sound …
Linerless Eutectic Al-Si Engine Wear: Microstructural Evolution, Benjamin Slattery
Linerless Eutectic Al-Si Engine Wear: Microstructural Evolution, Benjamin Slattery
Electronic Theses and Dissertations
The wear mechanisms of novel linerless eutectic Al-Si engines subjected to extensive dynamometer testing have been thoroughly investigated using an array of surface and subsurface techniques to elucidate the effects of alloying, surface preparation, and temperature on the overall wear progression of linerless Al-Si engines. The efforts of this research have revealed that the long term wear resistance of linerless eutectic Al-Si engine bores is derived from the combined effects of oil deposits, silicon exposure, and the formation of reduced grain structures in the aluminum-matrix. Under this criterion, silicon particles maintained exposure at an equilibrium height of ~0.4 to 0.6 …
Characterization Of Fracture And Debonding Of Silicon Particles In Aluminium Silicon Alloys, Jun Feng Su
Characterization Of Fracture And Debonding Of Silicon Particles In Aluminium Silicon Alloys, Jun Feng Su
Electronic Theses and Dissertations
AlSi alloy engines have been used to reduce fuel consumption and CO2 emission. The wear resistance of AlSi surface is thought to originate from the high hardness of the silicon surface formed by the primary Si particles (inclusions). The mechanical strength of the Al/Si interface and fracture toughness of Si particles in Al matrix are the primary factors determining the strength on the load bearing formation. In this work, a hybrid method to characterize the fracture and interface debonding of Si particles in an AlSi alloy has been developed, which combining a nanoindentation experiment and a finite element analysis. The …
Biotextured Nanocrystalline Materials With Superhydrophobic Surfaces And Controlled Friction And Wear, Mehdi Shafiei
Biotextured Nanocrystalline Materials With Superhydrophobic Surfaces And Controlled Friction And Wear, Mehdi Shafiei
Electronic Theses and Dissertations
This study aimed to develop new wear-resistant materials with superhydrophobic surfaces and low friction by combining the high strength of nanocrystalline (NC) materials with the biological surface textures. This goal was accomplished in three stages. First, the tribological properties of electrodeposited NC Ni and NC Co were studied, and the role of the oxide-rich tribolayers in reducing the friction and wear rates was delineated. For the NC Ni, micromechanisms of wear in different testing environments were characterized, and the sliding-speed sensitivity of friction and wear rate was investigated. A modified Archard equation was proposed to predict the wear rates of …
Numerical Optimization Of Gating Systems For Light Metals Sand Castings, Zhizhong Sun
Numerical Optimization Of Gating Systems For Light Metals Sand Castings, Zhizhong Sun
Electronic Theses and Dissertations
This thesis proposed an optimization technique for design of gating system parameters of a light metal casting based on the Taguchi method with multiple performance characteristics. Firstly, the casting model with a gating system was designed and exported as International Graphics Exchange Standard (IGES) models by Unigraphic NX4.0. Based on the IGES models of the casting, Finite Element (FE) Models were generated using Hypermesh software. Then, mold filling and solidification processes of the castings were simulated with the MAGMASOFT. Finally, the simulation result can be converted to numerical data according to the 3D coordinates of the FE model by MAGMALink …
Finite Element Modeling Of Dynamic Impact And Cornering Fatigue Of Cast Aluminum And Forged Magnesium Road Wheels., Shixian (Robert) Shang
Finite Element Modeling Of Dynamic Impact And Cornering Fatigue Of Cast Aluminum And Forged Magnesium Road Wheels., Shixian (Robert) Shang
Electronic Theses and Dissertations
Numerical investigation of wheel dynamic impact and cornering fatigue performance is essential to shorten design time, enhance mechanical performance, and lower development cost. This dissertation focused on two objectives. First, finite element models of the dynamic impact test on a wheel and tire assembly were developed, which considered the material inhomogeneity of the wheel. The model complexity and resultant additional analysis time led to the development of a simplified approach for wheel impact testing without the tired. Comparison of the numerical predictions with the experimental measurements of wheel impact indicated that an approximate 20% reduction of the initial striker kinetic …
Anode Electrocatalysts For Direct Borohydride Fuel Cells., Mohammed Hassan Atwan
Anode Electrocatalysts For Direct Borohydride Fuel Cells., Mohammed Hassan Atwan
Electronic Theses and Dissertations
Colloidal Os and Os-alloys, Pt and Pt-alloys, Au and Au alloys, Ir and Ir-alloys, and Pd and Pd alloys (1:1 atomic ratio for all alloys) supported on Vulcan XC-72 (20 wt% metal) were prepared according to the Bonneman method and investigated for their electrocatalytic activity with respect to methanol and borohydride oxidation for Os and with respect to borohydride oxidation only for Pt, Au, Ir, and Pd for fuel cell applications. Voltammetry on static and rotating electrodes, chronoamperometry and chronocoulometry were performed on the colloidal catalysts immobilized on glassy carbon with the help of a NafionRTM 117 solution acting as …
Plasma Electrolytic Oxidation Process For Corrosion Protection Of Two Aluminium Alloys Used In Automotive Applications., Xia Li
Electronic Theses and Dissertations
Plasma electrolytic oxidation (PEO) is an emerging environmentally friendly process, which can be used to form thick, hard coatings on aluminum alloys. In this study, PEO coatings were produced on two Al alloys, Al6061 and Al319, using a DC power mode. The effects of the process parameters, including the electrolyte concentration, treatment time and current density, on the formation and properties of the PEO coatings were systematically investigated and analyzed. Cyclic potentiodynamic polarization measurements were conducted to evaluate the corrosion properties of the samples. The polarization resistance of the PEO coatings in a 3.5wt.% NaCl solution were determined and compared …
Tribological Failure Analyses Of Automotive Engine Blocks Subjected To Sliding Wear Damage, Hongmei Yu
Tribological Failure Analyses Of Automotive Engine Blocks Subjected To Sliding Wear Damage, Hongmei Yu
Electronic Theses and Dissertations
This thesis presents the tribological failure analyses of sliding wear damage on a linerless engine block made of a new near-eutectic aluminum silicon alloy Al-11%Si. The stereological, optical metallographic, SEM/EDS and surface profile examinations and microhardness testing were used to investigate the wear performance and the types of sliding damages, as well as the microstructure variation, phase fragmentation underneath the damage surface. The effect of the different honing processes of cylinder bore surface preparation on bore surface morphology and quality was studied to understand the original surface features before engine testing. Excepting virgin areas on the bore surface, five types …
Development Of An Advanced Aluminum Thermal Analysis System For The Characterization Of The 319 Aluminum Alloy Solidification Process., Todd J. Stockwell
Development Of An Advanced Aluminum Thermal Analysis System For The Characterization Of The 319 Aluminum Alloy Solidification Process., Todd J. Stockwell
Electronic Theses and Dissertations
Thermal analysis is the study of heat evolution as a molten alloy transforms to a solid. Studying the evolution of heat results in a temperature, time relationship in the form of a cooling curve. Specific characteristics of the 319-aluminum cooling curve are described and related to specific metallurgical properties. Variations in the cooling curves represent changes within the solidification of the alloy and are correlated to changes in the metallurgical properties. In the present work, an aluminum thermal analysis system (AITAS) is constructed to withstand the rigors of day to day foundry conditions. Complete automation has been introduced to reduce …
Microstructural Studies Of Wear Mechanisms In Cast Aluminum Alloys., Mustafa Elmadagli
Microstructural Studies Of Wear Mechanisms In Cast Aluminum Alloys., Mustafa Elmadagli
Electronic Theses and Dissertations
The microstructural basis of wear and surface degradation mechanisms in Al-Si alloys has been investigated in order to improve the current understanding of the requirements for wear resistant aluminum alloy design. The wear behaviour of three commercial alloys namely: a sand cast A390 (Al-18.4%Si), a spray formed Al-25%Si, and a die cast 383 (Al-9.5%Si) have been investigated. Dry sliding wear tests were performed using a block on ring type tribometer under controlled environments. The experiments were performed in a load range between 0.2 N and 300 N at a constant speed of 1 m/s. The testing environments were a dry …
Adhesion And Material Transfer Between Aluminum And Surfaces Coated With Diamond-Like Carbon And Other Coatings., Erkan Konca
Adhesion And Material Transfer Between Aluminum And Surfaces Coated With Diamond-Like Carbon And Other Coatings., Erkan Konca
Electronic Theses and Dissertations
Adhesion and transfer of aluminum to the surfaces of tool coatings that are potential candidates for dry machining of Al-Si alloys were investigated. First, 319 Al alloy pins were tested against various industrial coatings (CrN, TiB2, TiAlN, TiN, and TiCN) using a pin-on-disc tribometer. The analyzed Scanning Electron Microscope (SEM) images of the wear tracks were used to rank the coatings according to the amount of Al transferred on their surfaces. In general, the TiB2 and TiCN coatings exhibited the least amount of Al transfer on their surfaces compared to the other coatings. Second, the tribological behaviour of the diamond-like …
An Investigation Of The Electrolytic Plasma Oxidation Process For Corrosion Protection Of Pure Magnesium And Magnesium Alloy Am50., Yueyu Ma
Electronic Theses and Dissertations
In this study, silicate and phosphate EPO coatings were produced on pure magnesium using an AC power source. It was found that the silicate coatings possess good wear resistance, while the phosphate coatings provide better corrosion protection. A Design of Experiment (DOE) technique, the Taguchi method, was used to systematically investigate the effect of the EPO process parameters on the corrosion protection properties of a coated magnesium alloy AM50 using a DC power. The experimental design consisted of four factors (treatment time, current density, and KOH and NaAlO2 concentrations), with three levels of each factor. Potentiodynamic polarization measurements were conducted …