Research Articles in Mechanical Engineering

Permanent URI for this collectionhttps://repository.nileuniversity.edu.ng/handle/123456789/130

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Author: search.filters.author.Makanjuola OkiSubject: search.filters.subject.02 engineering and technology

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    Corrosion rates of green novel hybrid conversion coating on aluminium 6061
    (Elsevier, 2020-08-19) Makanjuola Oki; A.A. Adediran; Peter Pelumi Ikubanni; O.S. Adesina; Adekunle Akanni Adeleke; S.A. Akintola; F. Edoziuno; A. Aleem
    The use of chromate conversion coatings have been limited by several protocols as a result of their carcinogenicity and toxicity towards humans and the environment. Searches are ongoing for chromate replacement in coating baths and processes. This paper describes the comparison among the corrosion rates of a novel hybrid conversion coating derived from water extracts of hibiscus sabdariffa calyx in conjunction with ammonium molybdate, a molybdate conversion coating and the so-called chromate conversion coating. Potentiodynamic polarization measurement in 3.5 ​wt% sodium chloride solution was employed in ranking the coatings as sabdariffa molybdate being more corrosion resistant than chromate, which in turn out performed molybdate.
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    Influence of temperature on the chemical compositions and microstructural changes of ash formed from palm kernel shell
    (Elsevier, 2020-09-30) Peter Pelumi Ikubanni; Makanjuola Oki; Adekunle Akanni Adeleke; Adediran, A.A; O.S. Adesina
    This study investigated the characteristics of raw palm kernel shell (raw PKS) and the influence of temperature variation on palm kernel shell ash (PKSA). The PKSA was obtained under different temperature regimes of 900, 1000, and 1100°C. The characterization of the samples was carried out using X-ray Fluorescence (XRF), Fourier Transform Infrared (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) with attached Energy Dispersive X-ray (EDX) facilities. The results showed that moisture and ash contents and the density of raw PKS were 6.56%, 8.86%, and 745 ​kg/m3, respectively. The colour of the pulverized PKS was dark brown, as observed by visual examination based on standard colour gradation. This colour transformed into various shades of brown when PKS was subjected to different temperature regimes to form PKSA. The XRF analysis showed that silica is the main constituent of the raw PKS and PKSA samples. Silica content in the PKSA increased with the rise in the heating temperature. The FTIR and EDX spectra confirmed the predominance of silicon compounds with functional groups associated with silanol and siloxane. Also, XRD analysis revealed that the silica contents in the samples are quartz, while SEM examinations indicated that temperature increases during processing influenced the microstructure through the reduction of pore concentration in the samples. The silica obtained from the PKSA would find applications in metal matrix composites as partial reinforcing materials.
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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.