Research Articles in Mechanical Engineering

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    A comprehensive review of hydrogen production and storage: A focus on the role of nanomaterials
    (The University of Edinburgh, 2022-05-20) Emmanuel I. Epelle; Kwaghtaver S. Desongu; Winifred Obande; Adekunle Akanni Adeleke; Peter Pelumi Ikubanni; Jude A. Okolie; Burcu Gunes
    Nanomaterials are beginning to play an essential role in addressing the challenges associated with hydrogen production and storage. The outstanding physicochemical properties of nanomaterials suggest their applications in almost all technological breakthroughs ranging from catalysis, metal-organic framework, complex hydrides, etc. This study outlines the applications of nanomaterials in hydrogen production (considering both thermochemical, biological, and water splitting methods) and storage. Recent advances in renewable hydrogen production methods are elucidated along with a comparison of different nanomaterials used to enhance renewable hydrogen production. Additionally, nanomaterials for solid-state hydrogen storage are reviewed. The characteristics of various nanomaterials for hydrogen storage are compared. Some nanomaterials discussed include carbon nanotubes, activated carbon, metal-doped carbon-based nanomaterials, metal-organic frameworks. Other materials such as complex hydrides and clathrates are outlined. Finally, future research perspectives related to the application of nanomaterials for hydrogen production and storage are discussed.
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    Comparative Analyses of the Inhibitive Influence of Cascabela thevetia and Jatropha curcas Leaves Extracts on Mild Steel
    (Nature Environment and P ollution Technology, 2020-09-04) A. S. Adekunle; Adekunle Akanni Adeleke ; Peter Pelumi Ikubanni; O. A. Adewuyi
    The inhibitive properties of the extracts of Cascabela thevetia and Jatropha curcas were comparatively studied on corrosion of mild steel in H2SO4 acid. The extracts of both plants contained active phytochemical constituents such as tannins, saponins, alkaloids, flavonoids, terpenes and phenols which made them useful as good corrosion inhibitors. The extract concentrations were varied from 0.3 to 1.5 g/L during both the gravimetric and gasometric analyses for an exposure time of 7-28 days. The weight loss of the coupon, corrosion rate, surface coverage and inhibitive efficiency was evaluated for both the extracts. The results of the gravimetric and gasometric analyses indicated that inhibitive efficiency increased with an increase in the concentration of inhibitors and the highest was 55.77% for Jatrophas curcas at the concentration of 1.5 g/L. The weight loss was a little lower for Cascabela thevetia (4.36 g) compared to Jatrophas curcas (4.66 g) at the highest exposure time used (28 days). Cascabela thevetia has a better surface coverage (0.68) than Jatropha curcas (0.61), hence, Cascabela thevetia inhibits better for a 7-day exposure time. However, when the mild steel was further exposed for more than 7 days, Jatropha curcas exhibited a better inhibitive property. The highest and least hydrogen gas evolution was obtained at 0.3 g/L concentration (7 minutes) and 1.5 g/L concentration (1 minute) for both Cascabela thevetia and Jatropha curcas leaves extracts, respectively. Based on the results, the utilization of extracts of Cascabela thevetia and Jatropha curcas leaves as replacements for toxic organic inhibitors in industries are recommended.
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    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.