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Search Results: 1 - 10 of 411206 matches for " S. O. Adeosun "
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Optimum Calcium Carbonate Filler Concentration for Flexible Polyurethane Foam Composite  [PDF]
M. A. Usman, S. O. Adeosun, G. O. Osifeso
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2012, DOI: 10.4236/jmmce.2012.113023
Abstract: The production cost of flexible polyurethane foam is significantly dependent on the cost of polyol, which constitute the largest percentage of materials used in foam production with the characteracterics to induce superior mechanical properties. Suitable fillers that are relatively cheap can be introduced in the foam matrix as replacement for polyol. However, certain compositions of filler have deleterious effect on some relevant mechanical properties of the foam. This paper investigates the effect of CaCO3 filler in flexible polyurethane foam matrix for the dual purposes of achieving sustained mechanical properties and reduction in production cost. The optimum CaCO3 composition was found to be 20 wt % representing a concomitant 18.54% reduction in cost of production.
Effect of Deformation on the Mechanical and Electrical Properties of Aluminum-Magnesium Alloy  [PDF]
S. O. Adeosun, O. I. Sekunowo, S.A. Balogun, L.O. Osoba
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.106042
Abstract: This paper presents the effect of deformation on the tensile strength, toughness, hardness and electrical resistance of aluminum 6063 alloy. Cast samples were cold rolled in the range of 0-24 percent thickness reduction and subjected to mechanical (static, dynamic) and electrical resistance tests. Results show significant improvement in hardness and electrical resistance properties of the alloy. The nature, amount and distribution of the secondary phase, Mg2Si,particles precipitated within the matrix which was influenced by the extent of cold-work, are responsible for the observed behaviour. The resistance of the alloy also depends on the degree of cold work carried out prior to use.
Effects of Heat Treatment on Strength and Ductility of Rolled and Forged Aluminum 6063 Alloy  [PDF]
S. O. Adeosun, S.A. Balogun, O.I. Sekunowo, M.A. Usman
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2010, DOI: 10.4236/jmmce.2010.98054
Abstract: This work examines the effect of heat treatment on tensile strength and ductile responses of rolled and forged AA6063 aluminum alloy. Some cast samples were rolled while some were forged at ambient temperature (32℃). The deformed samples were subjected to heat treatment processes. The tensile strengths of rolled (212 MPa) and forged (127 MPa) samples are enhanced at ambient temperature but with poor elongation responses. A combination of improved strength and elongation (127 MPa, 24%) can be obtained in rolled sample when solution heat treatment (SHT) is applied after deformation and cooling in water. The forged sample when homogenized, solution treated and water quenched has elongation of about 24% with improved strength of 137 MPa. These results were obtained because of the development of very fine AlFeSi texture in the matrix and along the grain boundaries.
A Semi-Analytical Method for Solutions of a Certain Class of Second Order Ordinary Differential Equations  [PDF]
S. O. Edeki, H. I. Okagbue, A. A. Opanuga, S. A. Adeosun
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.513196
Abstract:

This paper presents the theory and applications of a new computational technique referred to as Differential Transform Method (DTM) for solving second order linear ordinary differential equations, for both homogeneous and nonhomogeneous cases. For the robustness and efficiency of the method, four examples are considered. The results indicate that the DTM is reliable and accurate when compared to the exact solutions of the solved problems.

Mechanical Response of Al-1.09Mg2Si Alloy under Varying Mould and Thermal Ageing Conditions
O. I. Sekunowo,G. I. Lawal,S. O. Adeosun
Journal of Metallurgy , 2012, DOI: 10.1155/2012/921235
Abstract:
Mechanical Response of Al-1.09Mg2Si Alloy under Varying Mould and Thermal Ageing Conditions
O. I. Sekunowo,G. I. Lawal,S. O. Adeosun
Journal of Metallurgy , 2012, DOI: 10.1155/2012/921235
Abstract: Samples of the 6063 (Al-1.09Mg2Si) alloy ingot were melted in a crucible furnace and cast in metal and sand moulds, respectively. Standard tensile, hardness, and microstructural test specimens were prepared from cast samples, solution treated at 520°C, soaked for 6?hrs, and immediately quenched at ambient temperature in a trough containing water to assume a supersaturated structure. The quenched specimens were then thermally aged at 175°C for 3–7?hrs. Results show that at different ageing time, varied fractions of precipitates and intermetallics evolved in the specimens’ matrices which affect the resulting mechanical properties. The metal mould specimens aged for four hours (MTA-4) exhibited superior ultimate tensile strength of 247.8?MPa; microhardness, 68.5?HV; elongation, 28.2% . It is concluded that the extent of improvement in mechanical properties depends on the fractions, coherence, and distribution of precipitates along with the type of intermetallics developed in the alloy during ageing process. 1. Introduction Casting is one of the most versatile methods of producing structural aluminium alloy components. However, the rather large preponderance of defects in cast aluminium components often limits their performance and adversely impacts their commercial values. Hence there is the need for a novel processing approach to improve the cast microstructure for enhanced performance. Generally, the poor mechanical properties of cast aluminium alloys can be improved through either alloy addition or various forms of heat treatment [1]. During the heat treatment of cast aluminium alloys, an advantage is made of the characteristic decrease in solubility at low temperature of magnesium (Mg) and silicon (Si) which are the main alloying elements in Al-Mg-Si alloy. Further, Keist [2] confirms that the appreciable decrease in concentration of the alloying elements at room temperature is the fundamental phenomenon that provides the basis for increasing substantially the hardness and strength of aluminium alloys through isothermal treatment. Similarly, Siddiqui et al. [3] have shown that improved ductility can be achieved by process annealing at 415°C, soaked between two and three hours coupled with a cooling rate 30°C per hour. Generally, strength improvement of most 6063 aluminium alloys can be effected in a three-pronged approach comprising solution heat treatment, quenching, and precipitation of solute atoms [4]. However, the greatest challenge usually encountered with this approach is effective control of the second-phase precipitates. Lumley et al. [5]
Wrought Aluminium Alloy Corrosion Propensity in Domestic Food Cooking Environment
S. O. Adeosun,E. I. Akpan,S. A. Balogun
ISRN Corrosion , 2012, DOI: 10.5402/2012/432342
Abstract:
Wrought Aluminium Alloy Corrosion Propensity in Domestic Food Cooking Environment
S. O. Adeosun,E. I. Akpan,S. A. Balogun
ISRN Corrosion , 2012, DOI: 10.5402/2012/432342
Abstract: The study on corrosion behaviour of wrought aluminium alloy in domestic food cooking conditions has been examined using the gravimetric approach. Flat cold rolled and annealed sheets were subjected to solutions of Capsicum annuum, L. esculentum, Allium cepa, and their blend under three conditions, namely, heating and cooling in still air, heating and cooling in refrigerator, and leaving some in open still atmosphere. Results show that corrosion occurred within the test period (288 hours) in the test environments. There was severe degradation within the first 70 hours of test when coupons were heated and cooled while unheated coupon showed low corrosion propensity. Microstructural analysis show the presence of corrosion pits on coupon surface with second phase particles sandwiched in α-aluminium matrix. Immersed coupon in the blend media show higher number of pits on the surface. Rapid corrosion of wrought aluminium alloy in Capsicum annuum, L. esculentum and Allium cepa media is attributed to the presence of corrosion aggressive elements such as allicin, diallyl-disulphide, and allyl-propyl disulphide present in the corrosion media. 1. Introduction Aluminium alloy cookware, containers, cooking utensil, and aluminium beverage cans contribute substantially to the consumption load of aluminium [1, 2]. Deep drawn aluminium utensils are widely used as domestic cooking vessel in the third world countries. Such utensils are subjected to several heating cycles during their service lives. In aggressive cooking environment the aluminium is very prone to localized attack and progressive failure that occurs due to pitting which shortens the service life span of these cooking utensils [3, 4]. A study conducted at the University of Cincinnati Medical Centre [5] reveal that acid forming foods dissolve aluminium more rapidly and that tomatoes cooked in an aluminium pot had 2 to 4 milligram aluminium content in serving. The corrosion products particle is leached from the utensil into the foods being cooked. It has been shown that healthy human body can handle up to twenty milligrams of aluminium ingestion per day [1], this absorbed aluminium is eliminated through the kidney in form of urine and unabsorbed aluminium is excreted in the faeces [1, 6]. Unfortunately, the activity of the kidney decreases with age [3, 6]. At 65 years and above, the ability of the kidney to eliminate aluminium diminishes [3], resulting in the accumulation of these particles in the body. These particles are distributed mainly in bone, liver, testes, kidneys, and brain [1, 6]. Numerous studies
Deformation and fracture of dika nut (Irvingia gabonensis) under uni-axial compressive loading
B.S. Ogunsina,O.A. Koya,O.O. Adeosun
International Agrophysics , 2008,
Abstract: Fracture behaviour of dika nut under quasi-static loading along the longitudinal axis and the transverse axis was investigated. The fracture resistance of the nut was measured in terms of average force, deformation and toughness at nutshell fracture, and nut stiffness. Physical dimensions and shape of the nut, to provide for complementary input in design of handling equipment, were also determined. The force required to crack the nut increased with nut diameter but was not significantly different in both loading orientations. The mean cracking force was in the range of 2.06 to 3.67 kN. The compression of the nut exhibited a pronounced linearity between load and deflection. Dika nuts loaded along the transverse axis required less energy for nutshell fracture than those loaded along the longitudinal axis. Minimum toughness occurred with the small size nuts loaded along the transverse axis, thus providing base-line data in future design of an appropriate nutcracker.
Corrosion Behaviour of Heat-Treated Aluminum-Magnesium Alloy in Chloride and EXCO Environments
S. O. Adeosun,O. I. Sekunowo,S. A. Balogun,V. D. Obiekea
International Journal of Corrosion , 2012, DOI: 10.1155/2012/927380
Abstract: Machines designed to operate in marine environment are generally vulnerable to failure by corrosion. It is therefore imperative that the corrosion susceptibility of such facilities is evaluated with a view to establishing mechanism for its mitigation. In this study, the corrosion behaviour of as-cast and retrogression-reagion (RRA) specimens of aluminum alloy containing 0.4–2.0 percent magnesium additions in NaCl, FeCl3, and EXCO solutions was investigated. The corrosion simulation processes involved gravimetric and electrochemical techniques. Results show substantial inducement of Mg2Si precipitates at a relatively higher magnesium addition, 1.2–2.0 percent, giving rise to increased attack. This phenomenon is predicated on the nature of the Mg2Si crystals being anodic relative to the alloy matrix which easily dissolved under attack by chemical constituents. Formation of Mg2Si intermetallic without corresponding appropriate oxides like SiO2 and MgO, which protect the precipitates from galvanic coupling with the matrix, accentuates susceptibility to corrosion. 1. Introduction Aluminum and its alloys are widely used in industry because of their light weight, high strength, and good corrosion resistance which is due to the formation of a protective oxide layer. However, under saline conditions such as those encountered in marine environments, aluminum alloys are vulnerable to localised degradation in forms of pitting and crevice corrosion. This type of corrosion involves the adsorption of an anion in particular chloride ion, Cl-, at the oxide-solution interface. In conventional metallic materials, the strong oxidizing power of the environment is required to establish spontaneous passivity; hence, to be of practical use, metallic materials must exhibit significant level of passivity in a given environment. The passive stable surface film acts as a barrier for the transfer of cations from the metal to the environment and for the counter diffusion of oxygen and other anions. The air-formed film must be stable without damage to the underlying alloy surface in a given environment. Chemically homogenous, single-phase amorphous alloys free from crystalline defects such as precipitates, segregates, grain boundaries, and dislocations often create conducive environment for the formation of uniform passive film without any weak points [1]. Aluminum forms a protective oxide film in the pH range 4.0–8.5, but this depends on temperature, form of oxide present, and the presence of substances that form soluble complexes or insoluble salts with aluminum. This implies that
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