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A long essay or dissertation or thesis involving personal research, written by postgraduates of University of Ghana for a university degree.
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Item Hydroxyapatite ceramics prepared from two natural sources by direct thermal conversion: From material processing to mechanical measurements(Materials Today: Proceedings, 2020) Akpan, E.S.; Dodoo-Arhin, D.; Dauda, M.; et al.In this study, hydroxyapatite (HAp) was extracted from catfish bones (CB) and non-separated animal bones (NB). The bioceramic samples were prepared by a facile synthesis route and the representative scaffolds were prepared by cold compaction and sintered at 900 C, 1000 C, and 1100 C. To evaluate the properties of the produced HAp, X-ray diffraction (XRD) and Fourier Transform Spectroscopy (FT IR) analyses were carried out. The evaluation of the hardness of the representative bio-derived scaffolds was experimentally conducted while the fracture toughness and brittleness index were obtained by calculation using the hardness test parameters. The experimental data showed that as temperature increased up to 1000 C for CB, there was a consequential increase in hardness, while for NB, hardness values reduced throughout the sintering regimes. These gradients in mechanical measurements are ascribed to phase changes during heat treatment. 2020 The Authors. Published by Elsevier Ltd. This is an open-access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by nc-nd/4.0). Selection and Review under the responsibility of the scientific committee of the International Conference & Exposition on Mechanical, Material and Manufacturing TechnologyItem Effect of mechanical activation on mullite formation in an alumina-silica ceramics system at lower temperature(World Journal of Engineering, 2016) Obada, D.O.; Dodoo-Arhin, D.; Dauda, M.; et al.Purpose – This work aims to analyze the effect of mechanical activation on structural disordering (amorphization) in an alumina-silica ceramics system and the formation of mullite most notably at a lower temperature using X-ray diffraction (XRD). Also, an objective of this work is to focus on a low-temperature fabrication route for the production of mullite powders. Design/methodology/approach – A batch composition of kaolin, alumina, and silica was manually pre-milled and then mechanically activated in a ball mill for 30 and 60 min. The activated samples were sintered at 1,150°C for a soaking period of 2 h. Mullite formation was characterized by XRD and scanning electron microscopy (SEM). Findings – It was determined that the mechanical activation increased the quantity of the mullite phase. SEM results revealed that short-milling times only helped in mixing the precursor powders and caused partial agglomeration, while longer milling times, however, resulted in greater agglomeration. Originality/value – It is noted that a manual pre-milling of approximately 20 min and a ball milling approach of 60 min milling time can be suggested as the optimum milling time for the temperature decrease succeeded in the production of mullite from the specific stoichiometric batch formed.Item Potentials of fabricating porous ceramic bodies from kaolin for catalytic substrate applications(Applied Clay Science, 2016) Obada, D.O.; Dodoo-Arhin, D.; Dauda, M.; et al.In this work, the suitability of using kaolin–styrofoam, sawdust, and high-density polyethylene to produce porous ceramic bodies was experimentally investigated. The kaolin samples (raw and beneficiated) were characterized by the XRD, SEM, TGA/DSC, and FTIR methods. Batch formulations of the samples including the kaolin and pore formers were formed into green bodies and fired to 1150 °C. The porosities of sintered bodies were calculated and given the following: apparent porosity: 28.63%–67.13% for all the samples investigated. Samples with high-density polyethylene (HDPE) pore formers showed minor surface cracks after firing but exhibited the highest porosity levels while samples with styrofoam and saw dust exhibited uniform surface characteristics with pores, thermal stability, and no visible surface cracks. It can be concluded that formulations containing 80% kaolin can be used for the production of ceramics with porosities as high as 67% if the right pore formers are used.Item Physical and Mechanical Properties of Porous Kaolin Based Ceramics at Different Sintering Temperatures(The West Indian Journal of Engineering, 2016) Obada, D.O.; Dodoo-Arhin, D.; Dauda, M.; et al.In this work, kaolin-based ceramics using styrofoam, sawdust, and powdery high-density polyethylene as pore formers were experimentally investigated. Before batch formulations, the kaolinite used was wet-beneficiated. This was followed by mixing starting materials with pore formers, producing green bodies which were then uni-axially compacted into standard sample dimensions and fired at various sintering temperatures of 850°C, 1000°C, and 1150°C for 2 hours in a furnace. The physical and mechanical properties of the sintered samples were investigated and the generated data was analyzed. It was observed that the apparent porosity and water absorption of the samples decreased with increased sintering temperature, while the bulk density, apparent density, and cold crushing strength of the samples increased with increased sintering temperature. It was concluded that the samples that were sintered at 850°C with 5% wt pore former of powdery high-density polyethylene gave the optimum properties in terms of the porosity and mechanical strength of the samples.Item Characterization of zeolites as environmental washcoat materials on cordierite ceramics(Conference Paper, 2016) Obada, D.O.; Dodoo-Arhin, D.; Dauda, M.; et al.Small engines, such as conventional two-stroke engines used in marine outboards and personal watercraft (PWC), are high polluters relative to their engine size and usage. Porous structures based on zeolites show promising characteristics as wash coat materials on cordierite ceramics for tailpipe exhaust emission control. This study reports the characterization of commercial grades of zeolites (Ammonium form of ZSM-5, Zeolite Y, and Mordenite) and several transition phases of these zeolites aiming at their use as environmental washcoat materials. Thermogravimetry, X-ray diffraction, specific surface area, and electron microscopy were used to characterize the zeolites. ZSM-5 shows high thermal and structural stability compared to the other zeolites investigated. As porogenic and increased active site agents, the transition phases showed a large quantity of meso-macro pores and a variation in the specific surface areas of the zeolites still large enough, which highlights their potential to be used in environmental catalysis.Item Flame Temperature Characteristics and Flue Gas Analysis of an Improvised Biogas Burner(The West Indian Journal of Engineering, 2016) Obada, D.O.; Dodoo-Arhin, D.; Dauda, M.This study presents the results of an experimental investigation of an initial burner prototype and an improved prototype to report on the quality of biogas, which was produced from a mixture of cattle dung and poultry droppings, operated as feedstock in the ratio of 1 part of dung and droppings to 2 parts of water at a retention time of 30 days. A liquefied natural gas burner was also used for a comparative analysis. The flame temperature testing was carried out with the aid of a Kane–May (KM340) thermocouple. The ambient temperature of the flame produced was taken at three positions—the cone flame, the burning flame, and the flue gas. The results showed that the improved burner had the lowest temperature at the three positions of measurement and needs improvement for household use. Also, a flue gas analysis was carried out to establish the emissions of the stove. The combustion efficiency of the improved stove recorded by the flue gas analyzer was 86.9%.