Engineering Commons^™

The Microstructure And The Electrochemical Behavior Of Cobalt Chromium Molybdenum Alloys From Retrieved Hip Implants, Christopher P. Emerson

FIU Electronic Theses and Dissertations

Because of their excellent mechanical, tribological, and electrochemical properties, Cobalt Chromium Molybdenum alloys have been used as the material for both the stem and head of modular hip implants. Corrosion is one mechanism by which metal debris, from these implants, is generated, which can lead to adverse events that requires revision surgery. Manufacturing process such as wrought, as-cast, and powder metallurgy influences the microstructure, material properties, and performance of these implants

The current research focuses on analyzing the microstructure of CoCrMo alloys from retrieved hip implants with optical and scanning electron microscopy. Additionally, energy disperse spectroscopy was utilized to determine …

The Tribological And Electrochemical Behavior Of Hvof-Sprayed Cr3c2-Nicr Ceramic Coating On Carbon Steel

Faculty of Engineering University of Malaya

High Velocity Oxygen Fuel (HVOF) is an excellent approach to prepare a good, wear-resistant lamella of Chromium Carbide-Nickel Chrome (Cr3C2-NiCr) on carbon steel for high temperature application. This research investigates the effect of a thin, deposited layer of Cr3C2-NiCr on carbon steel in terms of wear and corrosion properties. The microstructure of the HVOF-sprayed Cr3C2-NiCr coating was characterized at each step by scanning electron microscopy. Wear testing was performed with a pin-on-disk tester. Wear weight loss was examined by applying different loads over a 9048.96 m sliding distance. Experimental results show that the wear resistance of the coated sample reduced …

A Novel Combined Severe Plastic Deformation Method For Producing Thin-Walled Ultrafine Grained Cylindrical Tubes

Faculty of Engineering University of Malaya

A novel severe plastic deformation (SPD) process entitled combined parallel tubular channel angular pressing (PTCAP) and tube backward extrusion (TBE) is proposed for producing thin-walled ultrafine-grained (UFG) tubes. In this new combined SPD approach, the PTCAP and TBE processes are consequently applied to the tube material in which a severe plastic strain is applied to produce a UFG thin-walled tube. This technique was performed on an AZ31 magnesium tube, and a remarkable grain refinement was achieved. The results showed that this method could easily produce a high strength thin walled tube. The microhardness increased significantly to 70 HV after the …

Redox Stable Anodes For Solid Oxide Fuel Cells, Guoliang Xiao, Fanglin Chen

Fanglin Chen

Solid oxide fuel cells (SOFCs) can convert chemical energy from the fuel directly to electrical energy with high efficiency and fuel flexibility. Ni-based cermets have been the most widely adopted anode for SOFCs. However, the conventional Ni-based anode has low tolerance to sulfur-contamination, is vulnerable to deactivation by carbon build-up (coking) from direct oxidation of hydrocarbon fuels, and suffers volume instability upon redox cycling. Among these limitations, the redox instability of the anode is particularly important and has been intensively studied since the SOFC anode may experience redox cycling during fuel cell operations even with the ideal pure hydrogen as …

Dissimilar Friction Stir Welding Between Polycarbonate And Aa 7075 Aluminum Alloy

Faculty of Engineering University of Malaya

In this paper, the effects of process parameters, such as the tool rotational and traverse speeds, on temperature evolution and the microstructural and mechanical properties of dissimilar friction stir welding between 3 mm thick AA 7075 aluminum alloy and polycarbonate (PC) plates were investigated. The tool rotational and traverse speeds were varied from 3 000 to 3 500 rpm and 50 to 150 mm min(-1), respectively. The joint fabricated at 3 250 rpm and 100 mm min(-1) yielded a highest tensile load of 586 N. Microstructural analysis of the stir zone revealed an interlock phenomenon, the transportation of AA 7075 …

Microstructure And Mechanical Properties Of Multipass Friction Stir Processed Aluminum Silicon Carbide Metal Matrix, Innovative Research Publications Irp India, V V Murali Krishna G, K.S Atyanarayana

Innovative Research Publications IRP India

In this study, SiC particles were incorporated by using Friction Stir Processing (FSP) into the 6351 aluminium alloy to form particulate composite materials. Sampels were subjected to constant rotational and traverse speeds of the FSP tool with and without SiC reinforcements. Microstructural observations were carried out by employing optical microscopy of the modifiedsurfaces. Mechanical properties were evaluated by tensile test on UTM. For the 100% overlapping, No.of passes caused grain modification in the processed zone. The tensile test results indicate an improvement of strength and Microhardness for Single Pass FSP samples and a reduction in the strength of FSP samples …

Fuzzy Logic Based Model For Predicting Surface Roughness Of Machined Al-Si-Cu-Fe Die Casting Alloy Using Different Additives-Turning

Faculty of Engineering University of Malaya

This paper presents a fuzzy logic artificial intelligence technique for predicting the machining performance of Al-Si-Cu-Fe die casting alloy treated with different additives including strontium, bismuth and antimony to improve surface roughness. The Pareto-ANOVA optimization method was used to obtain the optimum parameter conditions for the machining process. Experiments were carried out using oblique dry CNC turning. The machining parameters of cutting speed, feed rate and depth of cut were optimized according to surface roughness values. The results indicated that a cutting speed of 250 m/min, a feed rate of 0.05 mm/rev, and a depth of cut of 0.15 mm …

Investigating The Machinability Of Al-Si-Cu Cast Alloy Containing Bismuth And Antimony Using Coated Carbide Insert

Faculty of Engineering University of Malaya

Surface roughness and cutting force are two key measures that describe machined surface integrity and power requirement evaluation, respectively. This investigation presents the effect of melt treatment with addition of bismuth and antimony on machinability when turning Al-11% Si-2% Cu alloy. The experiments are carried out under oblique dry cutting conditions using a PVD TIN-coated insert at three cutting speeds of 70, 130 and 250 m/min, feed rates of 0.05, 0.1, 0.15 mm/rev, and 0.05 mm constant depth of cut. It was found that the Bi-containing workpiece possess the best surface roughness value and lowest cutting force due to formation …

Investigating The Electrical Discharge Machining (Edm) Parameter Effects On Al-Mg2si Metal Matrix Composite (Mmc) For High Material Removal Rate (Mrr) And Less Ewr-Rsm Approach

Faculty of Engineering University of Malaya

Al-Mg2Si composite is a new group of metalmatrix composites (MMCs). Electrical discharge machining (EDM) is a nonconventional machining process for machining electrically conductive materials regardless of hardness, strength and temperature resistance, complex shapes, fine surface finish/textures and accurate dimensions. A copper electrode and oil-based dielectric fluid mixed with aluminum powder were used. The polarity of electrode was positive. Response surface methodology (RSM) was used to analyze EDM of this composite material. This research illustrates the effect of input variables (voltage, current, pulse ON time, and duty factor) on material removal rate (MRR), electrode wear ratio (EWR), and microstructure changes. The …

Edge Fracture Prediction Of Dual Phase Steels With Consideration Of Microstructures, Ming Wen

Wayne State University Dissertations

In recent years, Advanced High Strength Steels (AHSS) have been used for the lightweight structural design and manufacturing in automotive industry. This class of sheet metals are prone to edge fracture during stamping production, and the fracture often occurs at much lower strain than that predicted based on the forming limit curves. The uncertainty in predicting edge fracture represents a great challenge in the application of AHSS. This dissertation is focused on the better understanding of edge fracture phenomenon through experimental observation and computer modeling with the consideration of microstructure effect.

In this dissertation, Hole Expansion (HE) test was used …