College of Engineering

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    INVESTIGATION OF POST-WELD HEAT TREATMENT EFFECTS ON SIMILAR AND DISSIMILAR LOW-CARBON AND STAINLESS-STEEL WELDMENTS
    (Covenant University, Ota, 2025-05) FASUYI, AKINBAYONLE AYOMIDE; Covenant University, Thesis
    This study investigated the effect of post-weld heat treatment (PWHT) on the mechanical properties and corrosion behaviour of dissimilar metal (DM) weldments of carbon steel and AISI 304 austenitic stainless steel, as well as similar metal (SM) stainless steel-to-stainless steel weldments. PWHT of the specimens was performed at three temperatures (900⁰C, 1000⁰C, and 1100⁰C), along with an as-welded control. Tensile testing, weight-loss corrosion measurement, corrosion-rate determination, and Vickers microhardness profiling were conducted, and a two-way analysis of variance (ANOVA) was used to determine the statistical significance of the effects of material type and treatment temperature. The findings showed that the tensile strength of the two types of welds was similar, at about 240 MPa in the as-welded condition. Following PWHT, SM welds exhibited a significantly greater improvement, with a maximum ultimate tensile strength of 466 MPa at 1000⁰C, compared to 321 MPa in DM welds at the same temperature. ANOVA confirmed highly significant effects of material type, temperature, and their interaction on tensile performance. The corrosion analysis showed that DM welds had much higher weight loss and corrosion rates than SM welds in all conditions, with material type identified as the dominant controlling factor. Raising the PWHT temperature progressively reduced corrosion in DM welds, with 1100⁰C yielding the greatest effect. Hardness profiling showed that PWHT reduced peak fusion-zone hardness and enhanced distribution uniformity in both weld types, but DM welds consistently exhibited asymmetric softening attributable to compositional mismatch at the weld interface. The results indicate that 1000⁰C is the optimum PWHT temperature for tensile performance and that SM weldments outperform DM weldments under all tested treatment conditions.
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    Thermodynamic and Adsorption Influence on the Corrosion Inhibitive Performance of Pawpaw Seed on A36 Mild Steel in 1 M H2SO4 Medium
    (2021) Ayoola, Ayodeji Ayodele; Fayomi, O. S. I.; Agboola, Oluranti; Durodola, B. M.; Adegbite, A. O.; Etoroma, A. A.
    This research work investigated the corrosion inhibitive performance of the nano-sized pawpaw seeds on A36 mild steel in 1 M H2SO4 medium. The metal samples were subjected to corrosive environment (with and without varied concentrations of the inhibitor) using both the weight loss and potentiodynamic polarization tests at different temperatures (278.15–318.15) K for weight loss and (30.15–323.15) K for potentiodynamic polarization study). The equipment used include Thermo scientific ARL OP-TIM’X 166 spectrometer (for metal composition analysis) and Autolab PGSTAT 302 N (for potentiodynamic polarization test). The results obtained showed that the nano-sized pawpaw seed is an effective organic inhibitor with optimum inhibitor concentration of 4 g/cm3 having inhibitor efficiency of 92% from the weight loss test. The inhibition performance of pawpaw seed increased with decrease in temperature for both the gravimetric tests (between 278.15 K and 318.15 K) and potentiodynamic polarization study (between 300.15 K and 323.15 K). The Langmuir adsorption isotherm with correlation coefficient (R2) of 0.99 accurately predicted the adsorption mechanism of the inhibitor on the metal surface. The thermodynamic change in Gibbs free energy (ΔGads) of (-12.9544 to -11.5409) kJ/mol and adsorption equilibrium constant ( Kads) of (1.70–2.99) of the adsorbed inhibitor on metal surface revealed both the spontaneous and physisorption nature of the inhibitor-adsorbed process. Also, the tafel plot showed that the inhibitor acted as a mixed-typed inhibitor.
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    Synthetic Heat Transfer Fluids: Alternative to Steam in Chemical Industries – A Review
    (Bioenergy and Biochemical Processing Technologies, Green Energy and Technology (Springer), 2022) Ayoola, Ayodeji Ayodele; Ogunlade, S.; Vershima, D.; Olomukoro, O.; Sonia, N.
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    Synthesis of PET-Magnesium Oxide-Chitosan Nanocomposite Membranes for the Dehydration of Natural Gas
    (Periodica Polytechnica Chemical Engineering, 67(2),, 2023) Agboola, Oluranti; Oginni, Grace Ayomide; Oladokun, Olagoke; Efeovbokhan, Vincent; Ayeni, Augustine Omoniyi; Ayoola, Ayodeji Ayodele; Adedamola, Adedayo Adeyanju; Alagbe, Edith Egbimhanlu; Fayomi, O.S.I.; Moropeng, Lucey; Ogunlade, Stephen Kehinde
    Flat thin-film magnesium oxide-chitosan nanocomposite membranes were synthesized with polyethylene terephthalate (PET) and employed for natural gas dehydration. The water vapor permeation was most pronounced with a nanocomposite membrane doped with 0.9 g MgO nanoparticles (NP) as a result of a significant upsurge in the permeability of water vapor in the membrane (0.87). With the increase in MgO NP, large macro-voids are created, substratum pore size, and thickness together with the water vapor permeation were upsurged. The dehydration of natural gas performance of magnesium oxide-chitosan nanocomposite membranes synthesized with PET was enhanced with the increase in MgO NP embedded in the membrane. Though water vapor permeation was restricted by the polyester non-woven material used as a support for the nano composite membranes, as the three membranes did not reach the permeation coefficient of 1. However, the permeation coefficient increased with an increased MgO NP, with three mambrane samples (M1, M2 and M3) having permeation coefficient of 0.763, 0.77 and 0.87 respectively. The gas reduced with an increase MgO NP, with M1, M2 and M3 having 3.46 × 10−2, 3.17 × 10−2 and 3.88 × 10−3 kg/m3 respectively. From the adsorption study, the discrepancy observed between CH4 and vapor with isotherm models was ascribed to the different adsorption behavior of CH4 and vapor on the membrane-active area. The cost of making the membrane cannot be considered as a terminal criterion because most of the cost-effective option is not always the optimum one. The membranes confirmed their suitability for the dehydration of natural gas.
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    Kinetic and Thermodynamic Properties of Locally Sourced Calcium in the Zinc Phosphating of Mild Steel
    (Journal of Bio- and Tribo-Corrosion (Springer), 2024) Ayoola, Ayodeji Ayodele; Ogbuigbo, Chijioke Henry; Agboola, Oluranti; Fayomi, O.S.I.
    The present study is on the establishment of the kinetic and thermodynamic performance of the locally sourced calcium used in the zinc phosphating of mild steel substrates. Calcium oxide was obtained from the calcination of periwinkle shells (at 800 °C for 4 h) and then applied as an additive in the zinc phosphating bath formulation. Metal samples were coated in the bath at different temperature (50 °C and 70 °C), different coating time durations (35, 50 and 65 min) and different CaO concentrations (0, 0.7, 1.4 and 2.0 g/L). The coated samples were subjected to 3.5wt.% NaCl solution, for corrosion test. The surface morphology of phosphate coatings was examined using SEM coupled with EDX to establish the quality and uniformity of the coating on the mild steel. The addition of calcium in the coating process significantly enhanced the corrosion resistance of mild steel relative to uncoated specimens, as justified by the lowest corrosion rate results when calcium was utilized at 70 °C, 65 min and 2.0 g/L CaO concentration. Higher positive value of the equilibrium adsorption constant, Kads, obtained (2.857) at 70 °C compared to the value (0.139) at 50 °C indicated a higher and stronger affinity of the calcium molecules for the adsorbent surface, with Langmuir isotherm fitness of R2 of 0.9319. The feasibility of the electrochemical process and the spontaneity of the adsorption process were affirmed by the negative values of the change in Gibbs free energy obtained (−592.69 kJ/mol of Δ G at 50 °C and −335.51 kJ/mol of Δ G at 70 °C). −3.271 kJ/mol of Δs (negative change in entropy) implied that the particles actually move from a disordered state (liquid) to an ordered state (solid) and forming a complex compound on the metal surface. 16.431 kJ/mol of the Enthalpy change ( Δ H) revealed the amount of heat gained for the coating (adsorption) to take place. The significance of this study, as justified by the results obtained, is that the mass transfer coefficient, kf, is directly proportional to the calcium concentration and temperature, as observed with a good driving force of 1.9267 × 10− 7 kg/m2.s at CaO concentration of 2.0 g/L and coating temperature of 70 °C.
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    Chemical deposition and corrosion perspectives on the development of pipe union steel in automobile industry
    (The International Journal of Advanced Manufacturing Technology (Springer), 2024) Omoegun, Olumide; Fayomi, O. S. I; Ayoola, Ayodeji Ayodele; Agboola, Oluranti
    Pipe union steel development in the automobile industry necessitates a diversified strategy, notably in terms of surface protection, durability enhancement, and corrosion resistance. This comprehensive research dives into the domain of chemical deposition technologies, primarily electroplating and its derivatives to strengthen steel surfaces against environmental, thermal, and cyclic stressors inherent in car exhaust systems. Electroplating is a flexible technology with numerous applications ranging from corrosion protection and microstructure formation to alloying and the development of high-magnetic force actuators. The research examines electroplating mechanisms, classifies chemical deposition methods, and defines the parameters of an ideal electroplating process. It assesses thin film electrodeposition and autocatalytic or electroless metal deposition, analyzing their benefits, disadvantages, and real-world applications in the automotive industry. It also investigates current research on electroplating applications, environmental problems, and pipe union steel challenges in engineering applications, such as fracture inclinations and material fatigue. Furthermore, this study investigates studies that address environmental contamination caused by electroplating applications, as well as novel methods for reducing hazardous waste. Several experimental and computational researches on steel compositions, alloys, and alternative coatings provide vital insights into enhancing the durability and corrosion resistance of pipe union steel for automotive applications.
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    Corrosion Inhibitive Behaviour of Moringa Oleifera in Acidic Medium
    (Springer Nature, 2022) Ayoola, Ayodeji Ayodele; Okwuonu, S. C.; Durodola,, B. M.; Alagbe, E. E.; Oladokun, O.; Agboola, Oluranti; Babalola, R.
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    Production of Adhesive from Cassava Starch
    (International Conference on Engineering for Sustainable World, 2019) Ayoola, Ayodeji Ayodele; Fayomi, O. S. I.; Akande, I. G.; Adeeyo, O. A.; Obanla, O. R.; Abatan, O. G.; Babatunde, D. E.; Olawepo, V. A.; Fagbiele, O. O.; Olomo, V. D.
    The research work investigated the production of adhesive from cassava starch. Cassava tubers were processed into starch-based adhesives, using two different gelatinization enhancers (that is HCl and NaOH) which were introduced separately. The adhesives were produced by considering two varied process parameters, namely percentage weight of borax in starch solution (8 – 20%) and reaction temperature (65 – 850C). Comparative analysis of the adhesive obtained (using HCl and NaOH as gelatinization enhancers) include the determination of its bond strength, viscosity, drying time, pH and density. As the borax weight percent increases up to 14 % and reaction temperature reduces (using NaOH) the drying time increases, while the drying time reduces as both the borax weight percent and temperature reduce (using HCl). The results of the adhesive physical properties fall within the standard range for each of the properties and this implied that the adhesive produced was of high quality.
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    A Reviewon Polymer Nanocomposites and Their Effective Applications in Membranes and Adsorbents for Water Treatment and Gas Separation
    (Membrane (MDPI), 2021) Agboola, Oluranti; Fayomi, O. S. I.; Ayoola, Ayodeji Ayodele; Ayeni, Augustine Omoniyi; Alagbe, Edith E; Sanni, Samuel E; Okoro, Emmanuel E.; Moropeng, Lucey; Sadiku, Rotimi; Kupolati, Kehinde Williams; Oni, Babalola Aisosa
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    EVALUATION OF THE CORROSION INHIBITIVE BEHAVIOUR OF PAWPAW FLUID ON A315 MILD STEEL AND A304 STAINLESS STEEL IN H2SO4 MEDIUM
    (Rasayan J. Chem., 14(4), 2022) Ayoola, Ayodeji Ayodele; Fayomi, O. S. I.; Akande, Godwin I,; Mgbahurike,Chinemerem F.
    In this research work, the evaluation of the corrosion inhibitive performance of pawpaw fluid on A315 mild and 304 stainless steels in 0.5M H2SO4 (through weight loss approach) was investigated. The investigation involved the effects of variation in the inhibitor concentrations (0 – 10 %vol/vol) on weight loss, corrosion rate, inhibitor efficiency and the morphological structure of the metal samples. The weight-loss method involved the subjection of metal samples to the corrosion process in the acidic medium for 21 days. The results of both weight loss and corrosion rates revealed that pawpaw fluid inhibitor with a concentration of 10 %vol/vol gave the highest inhibitor efficiency of 89.9% and 87.1% for A315 mild and A304 stainless steels respectively. Also, results obtained showed that Langmuir adsorption isotherm accurately described the behavior of the adsorption mechanism and the physical adsorption (spontaneous) nature of the inhibitor was justified by the negative values of ∆Gads. Chemical composition results and the SEM analysis revealed that stainless steel has better corrosion resistance performance in 0.5M H2SO4 medium compared to mild steel (under the same experimental condition).