Browsing by Author "Olanrewaju Seun Adesina"

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Characterization of some commercially available Nigerian coals as carbonaceous material for direct reduced iron production
(Elsevier, 2020-02-16) Peter Pelumi Ikubanni; Adekunle Akanni Adeleke; O.O. Agboola; Olanrewaju Seun Adesina; C.T. Nnodim; Ayokunle O. Balogun; C.J. Okonkwo; A.O. Olawale
Commercially available coals were characterized in this study in order to ascertain their suitability as carbonaceous materials for direct reduced iron (DRI) production. The proximate, elemental and heating value analyses were carried out based on different ASTM standards. Fourier transform infrared spectrometer and scanning electron machine equipped with energy dispersive x-ray spectroscopy (EDX) spectrometer were further used to obtain the structural components and elemental contents. The samples possess moisture content (2.16–2.41%), ash (78.88–86.28%), and fixed carbon (1.22–4.38%). The samples contain carbon in the range of 1.18–5.24%. The heating values of the sample were in the range of 0.45–1.94 MJ/kg. The predominant functional group in the samples were Si-C and Si-O-Si at 722–817 cm−1 and 1200–1050 cm−1, respectively. The micrographs of the samples also displayed agglomeration of silica and carbide with silicon and aluminum dominating the EDX spectra. It was concluded that the samples characterized in this study were not coals but they belong to the clay/sedimentary rock family. Thus, they are not suitable as carbonaceous material for DRI making.
Effect of Heat Treatment on Micro Hardness and Microstructural Properties of Al 6063 Alloy Reinforced with Silver Nanoparticles (AgNps)
(IOP Publishing, 2021-04-27) T.M. Azeez; L. O. Mudashiru; Adekunle Akanni Adeleke; Peter Pelumi Ikubanni; O.O. Agboola; Olanrewaju Seun Adesina
The demand for light weight metals in engineering design has led to the increasing use of aluminum and its alloys. However, conventional high-strength casting aluminum alloys usually exhibit low ductility and toughness, as a result of boundary segregation and coarse dendritic grains which result in its limited application in large-sized and complex shaped work pieces. Also, the possession of a significant low resistance to corrosion of Al 6063 alloys has been a major challenge in applications involving acidic and alkaline media. In this study, silver nano-particle was extracted from a fixer solution. Al 6063 was impregnated with silver Nano-particle at different percentage ratio to form a metal matrix nano composite and the Hardening heat treatment of the reinforced metal matrix nano composite was performed. The elemental composition of Al 6063 prepared from scrap was determined using Light Emission Polyvac Spectrometer. The hardness and microstructural analyses of the composites were evaluated. The micro hardness of the composites was positively influenced by the addition of AgNps and the hardening heat treatment process it was subjected to. The percentage increase in micro hardness of the sample not heat treated but impregnated with 3% and 9% weight nano particles are 20% and 22% respectively. Subjecting these samples to heat treatment further increased the micro hardness to 33% and 37% respectively. The morphology of the composites revealed reasonably homogenous distribution of the reinforcement in the matrix of Al 6063 alloy. It can be concluded that both percentage increase in weight fraction of AgNps and hardening has significantly increased the micro hardness and refined the grain morphology of the Al-AgNps composites.
Effect of nickel-based laser coatings on phase composition and corrosion behaviour of titanium alloy for offshore application
(Elsevier, 2020-05-15) Olanrewaju Seun Adesina; Makanjuola Oki; G. A. Farotade; O. T. Adesina; Olanrewaju Seun Adesina; O. F. Ogunbiyi; Adekunle Akanni Adeleke
Abstract Recent advances in titanium alloy applications in the offshore industry have been realized through the development of laser surface modification technique. The distinctive outcome of this technique has provided increase in the utilization of titanium in offshore drilling risers for special drilling operations and various subsea and tubing applications. In this work, surface mitigation and corrosion degradation of titanium alloy in aggressive sulfuric acid were investigated using electrochemical technique (linear potentiodynamic polarization) while the surface characterization (morphology) and phases of the resultant coatings were analyzed using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Prior to that, laser surface technique was used to fabricate Nickel-based powder on the substrate (Ti-6Al-4V). Results revealed that laser clad sample with high scan speed was more effective in improving the corrosion resistance compared to low scan speed. The enhanced corrosion resistance with high laser scan speed has been attributed to the presence of hard intermetallic compounds in the metallic coating.
Non-isothermal kinetic parametric evaluation of Tectona grandis using model-fitting methods
(Elsevier, 2021-02-07) Adekunle Akanni Adeleke; Peter Pelumi Ikubanni; Jamiu Kolawole Odusote; Thomas A. Orhadahwe; O. A. Lasode; Samuel Oluwafikayo Adegoke; Olanrewaju Seun Adesina
Abstract Non-isothermal kinetic parameters of the pyrolysis process of Tectona grandis were evaluated with different model-fitting methods. The thermal degradation of the Tectona grandis was examined using a thermogravimetric analyser. Pulverized Tectona grandis (6.5 mg) was heated from 30 to 800 °C at varying heating rates (5, 10 and 15 °C / m i n ) in an inert environment. The results depicted that heating rate has no effect on weight loss during the reactive drying zone. However, as the thermal analysis progressed into the active pyrolysis and passive pyrolysis zones, the weight loss decreased with increase in heating rate. The kinetic parameters evaluation revealed that the GB model was best fit to evaluate the kinetic parameters of teak in the active pyrolysis zone, while GB and Mampel models were considered most appropriate for the evaluation of the kinetic parameters in the passive pyrolysis zone. Model-fitting method has the capacity to capture wide range of fractional conversion.