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Olakanmi E.O.,University of Johannesburg | Olakanmi E.O.,University of Leeds | Olakanmi E.O.,Minna Federal University Of Technology
Journal of Materials Processing Technology | Year: 2013

Selective laser sintering/melting (SLS/SLM) processing difficulties of aluminium powders had been attributed to issues associated with laser-materials interaction only while neglecting the role of powder properties. This study provides a wholistic understanding of factors that influence the development of SLS/SLM processing window, densification, and microstructure of pure Al, Al-Mg, and Al-Si powders, fabricated in single and multiple layer parts by exploring the roles of processing and material parameters. It was demonstrated that similarities existing in the SLS/SLM processing maps of the powders could be attributed to similarities in their packing densities with the alloying addition of magnesium and silicon having no predominant effect on their processing maps' boundaries. Rather, alloying addition has significant effect on the nature of the evolved surface morphology of SLS/SLM processed aluminium powders in their processing windows. In addition, the flow and solidification behaviour of the melt pool of the powders during single layer scan was strongly influenced by the particle morphology and oxygen content of the powders as well as applied energy density. The energy density in the range of 12-16 J/mm2 was found to be the threshold below which SLS was predominant and above which SLM occurred for the investigated powders. Moreover, successful oxide disruption phenomena which is necessary for inter-particulate coalescence in multi-layered SLS/SLM processed aluminium powders are found to be mainly controlled by the amount of oxide in the as-received powder, the degree of the uniformity of the distribution of the surface oxide film covering the aluminium particles, the nature of thermal mismatch existing between the oxide film and the parent aluminium particle which was dependent on the phase present in the oxide film. Al-12 wt% Si powder is hereby affirmed as a suitable candidate material for SLS/SLM process due to its low thermal expansion and uniform distribution of its surface oxide films as well as the mullite phase in its oxide film. © 2013 Elsevier B.V. All rights reserved. Source


Lawal S.A.,University of Malaya | Lawal S.A.,Minna Federal University Of Technology | Choudhury I.A.,University of Malaya | Nukman Y.,University of Malaya
International Journal of Machine Tools and Manufacture | Year: 2012

The increasing attention to the environmental and health impacts of industrial activities by governmental regulations and by the growing awareness level in the society is forcing industrialists to reduce the use of mineral oil-based metalworking fluids as cutting fluid. Cutting fluids have been used extensively in metal cutting operations for the last 200 years. In the beginning, cutting fluids consisted of simple oils applied with brushes to lubricate and cool the machine tool. As cutting operations became more severe, cutting fluid formulations became more complex. There are now several types of cutting fluids in the market and the most common types can be broadly categorized as cutting oils or water-miscible fluids. In this review, the applicability of vegetable oil-based metalworking fluids in machining of ferrous metals has been undertaken. The advantages of metalworking fluids and its performances with respect to the cutting force, surface finish of work piece, tool wear and temperature at the cutting zone have been investigated. It has been reported in various literature that metalworking fluids, which are vegetable oil-based, could be an environmentally friendly mode of machining with similar performance obtained using mineral oil-based metalworking fluids. © 2011 Elsevier Ltd. Allrightsreserved. Source


Amadi A.A.,Minna Federal University Of Technology
Geotechnical and Geological Engineering | Year: 2010

Long term competent performance of liner systems is a critical issue in the design and construction of waste repositories due to adverse interactions associated with leachate generated by wastes. This study was conducted to verify the efficacy of fly ash stabilization in enhancing compatibility between lateritic soil and municipal waste leachate. Applications investigated include soil mixtures containing 0, 5, 10, 15, and 20% fly ash compacted at approximately 2% wet of optimum moisture content with modified proctor energy. Baseline hydraulic conductivity was first established at every level of fly ash content by permeating soil mixtures with tap water before permeation with leachate in a compaction mould permeameter using the falling head test method. Results show that the trend in hydraulic conductivity of specimen containing 0% fly ash was characterized by a gradual but erratic decrease which may suggests partial entry of the leachate cations into the double layer. Conversely, specimens containing fly ash showed a general trend consisting of an initial drop in k (up to an order of magnitude) that was followed by slight decrease sustained until k stabilized and later terminated. Above 10% fly ash content, the relatively high values of k observed was not connected with the reactivity of the soil mixtures with leachate, rather it may be attributed to excessive fly ash content that altered their textural and hydraulic properties. The result of this study is potentially significant in the assessment of fly ash as a compatibility enhancing agent which can be admixed in barrier materials that are susceptible to adverse reactions with the liquid to be contained. © 2010 Springer Science+Business Media B.V. Source


Lawal S.A.,University of Malaya | Lawal S.A.,Minna Federal University Of Technology | Choudhury I.A.,University of Malaya | Nukman Y.,University of Malaya
Journal of Cleaner Production | Year: 2013

In this study, a review of the available literature on lubrication techniques during machining processes was conducted. Factors such as workpiece material, tool material and machining conditions were observed to be vital to the performance of any of the techniques. The performance and drawback of each technique were highlighted based on the machining conditions. It concludes by making a case forminimum quantity lubrication (MQL) method using vegetable oil-based lubricant in different machining processes, as a way of addressing the environmental health issues and cost associated with the application of lubricant in machining processes. © 2012 Elsevier Ltd. All rights reserved. Source


Olatomiwa L.,Minna Federal University Of Technology
Energy Reports | Year: 2016

This paper assessed optimal configurations of hybrid renewable system for rural health clinic (RHC) application in three grid-unconnected rural villages in Nigeria. The RHC consist of an emergency room, consulting room, nurse/injection room, male ward, female ward, a delivery room and a laboratory with average total daily energy consumption of 15.5 kWh and 2.75 kW peak demand. The assessment of configurations that optimally meet the daily load demand with zero loss of power supply probability (LPSP) was carried out using HOMER software, by considering three energy resources; photovoltaic (PV), wind and diesel with battery energy storage. The result obtained revealed hybrid PV/wind/diesel/battery system as the most cost-effective configuration for powering rural health clinic in both Maiduguri and Enugu sites, while that of Iseyin site was found to be hybrid PV/diesel/battery system. In all the sites, the selected optimal configuration is far better than the conventional diesel stand-alone system in terms of cost and emission reduction. © 2016 Published by Elsevier Ltd. Source

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