Browsing by Author "Onuoha, C."
Now showing 1 - 8 of 8
Results Per Page
Sort Options
Item Open Access Characterization of Ibere clay for the production of electrical porcelain pin insulators(International Research Journal Publishers, 2014-06) Onuoha, C.; Ovri, J. E. O.; Mark, U.The characterization of Ibere clay for the production of porcelain pin insulators was carried out for both the locally made porcelains and the standard. Test samples were made by varying the compositions of feldspar and quartz needed to form a mouldable plastic body with the clay. The following properties were determined: electrical resistivity, apparent porosity, water absorption, bulk density and linear shrinkage. Results obtained showed that apparent porosity, water absorption and electrical resistivity increased with increase in the composition of the non-plastic materials (feldspar and quartz) while bulk density and linear shrinkage decreased with increase in non-plastic materials. The chemical composition of the clay (43.94%SiO2, 26.54%Al2O3) compares well with previous works (40-60%Si2O, 25-45%l2O3) for the production of ceramic refractories. Linear shrinkage (8.33-9.68%), apparent porosity (10.81-17.30%) and water absorption (5.4110.84%) are in conformity with standards (7-10%, 16.45% and 8.20% respectively). Electrical resistivities recorded (0.79-1.39 x 107Ω-m) are in agreement with results obtained for standard (0.45 x 107Ω-m). These results are obtained in samples containing 50-70% clay, 20-30% feldspar and 10-20% quartz. It is therefore concluded that imported porcelains used by Power Holding Company of Nigeria (PHCN) can be replaced with porcelains made from Ibere clay.Item Open Access Characterization of some Nigerian local clays for electrical porcelain applications(American Institute of Science, 2015) Ovri, J. E. O.; Onuoha, C.Clays from Ibere and Awo-omama were characterized for electrical porcelain application. Test samples were made by varying the compositions of feldspar and quartz required to form mouldable plastic bodies with each clay. The following properties were determined: electrical resistivity, apparent porosity, water absorption and linear shrinkage. This characterization was carried out for both the locally made porcelains and the Power Holding Company of Nigeria (PHCN) (standard) porcelain. Results obtained showed that, for both clays, apparent porosity, water absorption and electrical resistivity increased with increase in the composition of the non-plastic materials (feldspar and quartz) while linear shrinkage decrease with increase in non-plastic materials. Also, for both clays, samples containing 50-70% clays, 20-30% feldspar and 10-20% quartz were found to yield results that compared well with results found in the literature as well as results obtained for PHCN (Standard) porcelain. It is therefore concluded that both clays are suitable for electrical porcelain applicationItem Open Access Determination of the durability of polyurethane coating on mild steel in various soil media(Asian Research Association, 2022-05-24) Anyanwu, K. O.; Anyakwo, C. N.; Ndukwe, A. I.; Onuoha, C.; Agu, P. C.In this paper, effort has been made to determine the durability of polyurethane coating on mild steel in acid, alkaline and neutral soil. A total of 42 mild steel coupons were used. Out of the 42 coupons, 21 were coated with polyurethane and the remaining 21 were left uncoated. Acid soil (pH = 4.5), Alkaline soil (pH =13.5) and neutral soil (pH = 6.8) were used as the test media. Seven each of the coated and uncoated coupons were buried in each soil media. On weekly basis, one coated and one uncoated coupon were withdrawn from each of the soil media and reweighed. The durability of the coating in each soil media was calculated using a proposed model. From the results obtained, the durability of polyurethane coating was found to be 7.0yrs, 4.5yrs and 2.9yrs in neutral, acid and alkaline soil respectivelyItem Open Access Development and evaluation of composite brake pad using pulverized snail shell and mucuna sloanei shell as base materials(College of Engineering and Engineering Technology, MOUAU, 2020-06) Chima, O. M.; Simeon, B. I.; Onuoha, C.The development and evaluation of a new composite material for automobile brake pad application has been carried out in this study. The brake pad sample was produced with the geometric specification of 504 saloon model. The constituent materials include snail shell with mucuna sloanei shell as filler, iron oxide as abrasive, epoxy resin as matrix, glass fiber as reinforcement and graphite as the friction modifier. The weight composition in grams of the first three constituent materials were kept constant while those of the reinforcement and friction modifier materials were varied at various values of (30 and 25), (20 and 30), (15 and 15) and (5 and 20) grams to develop four different formulations represented as A, B, C and D. These formulated composite mixtures were used to produce the brake pad samples using standard factory procedures. The test samples were thereafter tested for both coefficients of dynamic and static friction, wear rate and hardness. The results obtained showed that formulations A, B, C, and D have values of (0.46 and 0.43), (0.47 and 0.44), (0.42 and 0.37) and (0.43 and 0.40) for static and dynamic coefficients of friction respectively. The wear rate values of 3.5, 3.6, 4.7 and 4.9mg/m were obtained for formulations A, B, C and D respectively while the hardness values of 46, 44, 38 and 30 HRB were noted in the similar order. The optimum value for coefficient of friction was obtained in formulation B while the best wear behavior and hardness value were given by formulation A. It was found that increase in the percentage weight composition of the friction modifier improved the coefficient of friction while increase in the percentage weight composition of the reinforcement material decreased or enhanced the wear rate. The performance evaluation of the formulated brake pad material shows that the properties compare well with the foreign asbestos-based products. Hence, it was concluded that snail shell and mucuna sloanei shell should be used based at the specified composition as base materials for brake pad applicationItem Open Access Effect of austempering process parameters on the mechanical properties of ductile cast iron quenched in moringa seed oil(2020) Chima, O. M.; Onuoha, C.; Nwokeocha, T. O.; Uwalaka, A.The use of Austempered Ductile Iron (ADI) is rapidly gaining ground because of its excellent properties such as high strength, high wear and abrasion resistance, excellent fatigue, high toughness and high strength-to-weight ratio, that are suitable for most of engineering applications. However, determination of the right process parameters needed to developADI products with combination of desirable properties that are most appropriate for specific application is a major challenge that faces production and material design engineers. There is need to ensure that ADI materials are either over-or under- processed to guarantee the development of the candidate material required for an engineering application. Hence, the effects of austempering process parameters on the mechanical properties of austempered ductile cast iron were studied. Ductile cast iron was developed by alloying cast with 0.06% magnesium. The cast samples were machined and then austenized at 9500C, held at this temperature for 1 hour before quenching in moringa seed oil. Thereafter, the samples were subjected to isothermal treatment at different austempering temperatures of 2400C, 3500C and 4200C for different time durations of 2.5, 3.5 and 4 hours. The samples of the austempered ductile cast iron were examined for microstructural details and then subjected to tensile testing, hardness and percentage elongation. The results obtained within the time range of 2.5 – 4 hours for the various temperatures of 2400C, 3500C, 4200C indicate that the values of tensile strength, hardness and percentage elongation were within the ranges of 1151 – 849MPa, 306 – 267BHN and 2.86 – 5.97% respectively. It was found that austempering temperature range of 350 - 4200C yielded increase in percentage elongation with decrease in tensile strength and hardness. This is due to the presence of coarser ausferrite matrix with higher amount of carbon diffusion. However, lower temperature austempering process such as 2500C showed improved tensile strength and hardness with low ductility. This shows that optimum tensile strength value of ADI is obtainable at low austempering temperature while maximum elongation requires higher austempering temperature. It was therefore concluded that at specific austempering temperature, the mechanical properties of austempered ductile cast iron could vary with time and temperature. Thus, there is a strong correlation between specific engineering properties of austempered cast iron and the austempering parametersItem Open Access Effect of filler loading and particle size on the mechanical properties of periwinkle shell-filled recycled polypropylene composite(U. P., 2017) Onuoha, C.; Onyemaobi, O. O.; Anyakwo, C. N.; Onuegbu, G. C.Mechanical properties of composites of recycled polypropylene filled with periwinkle shell powder were investigated. Periwinkle shells used in this study were thoroughly cleaned, ground and sieved to three particle sizes of 150, 300 and 425 µm respectively. Filler loadings of 0 to 25 wt% were used in compounding the composites in an injection moulding machine and the resulting composites were extruded as sheets. Some mechanical properties were determined. Results showed that periwinkle shell powder improved the tensile strength, flexural strength, tensile modulus and hardness of polypropylene composites. These properties were found to increase with filler loading up to 15 wt% or 20 wt% loading (optimal filler loading) but decrease with filler particle size. However, elongation at break was found to decrease with increasing filler loading. Highest tensile and flexural strengths were obtained at 15 and 20 wt% respectively at 150 µm particle size. It is therefore concluded that periwinkle shell powder is suitable for the production of polypropylene compositesItem Open Access Evaluation of non-asbestos brake pads using yates analysis(U. P., 2021) Asotah, W. A.; Onuoha, C.Non-asbestos brake pads are a suitable alternative to asbestos-filled brake pads. The carcinogenic nature of asbestos necessitates this. Organic, non-asbestos brake pads were evaluated to attain their effectiveness at elevated temperatures of 250˚C, 260˚C and 270˚C. Using the Yates approach, asbestos-free (corn husk based) brake pads were subjected to a heating regime for 7s, 8s, and 9s. Microstructural examination, hardness and tensile tests were then carried out. The values obtained showed that approximately the overall hardness of the brake pad specimen did not change during use. This suggests that brake pads made using corn husks as filler for the given formulation maintain their microstructural and physical integrity at slightly elevated temperatureItem Open Access Physical and morphological properties of periwinkle shell-filled recycled polypropylene composites(U. P., 2017) Onuoha, C.; Onyemaobi, O. O.; Anyakwo, C. N.; Onuegbu, G. C.Physical and morphological properties of periwinkle shell-filled recycled polypropylene composites were studied. Periwinkle shells used in this study were processed and sieved to three particle sizes of 150, 300 and 425 µm respectively. Filler loadings of 0 to 25 wt% were used in compounding the composites in an injection moulding machine and the resulting composites were extruded as sheets. Some physical and morphological properties were determined. Results showed that the incorporation of periwinkle shell powder into the recycled polypropylene matrix increased the specific gravity of the composites. Increase in filler loading resulted to increase in specific gravity probably due to enhanced dispersion of fillers. However, increase in filler particle size led to decreased specific gravity due to poor filler dispersion and consequent filler agglomeration. Water sorption was found to increase with increase in both filler loading and filler particle size due to the hydrophilic nature of the filler and enhanced porosity created by large particles. Flame propagation was found to decrease with increase in both filler loading and filler particle size due to the evolution of CO2 in the combustion process, which suppresses the burning rate. There was increase in solvent sorption with increase in both filler loading and filler particle size. It was also noticed that solvent sorption was most pronounced in benzene, followed by toluene and lastly xylene. This is in accordance with the order of closeness of their solubility parameters with that of polypropylene. Morphological analysis revealed enhanced spherulization and dispersion with smaller particle sizes but enlarged spherulization and consequent agglomeration at larger particles sizes. Based on these results, periwinkle shell can be considered suitable for the production of recycled polypropylene composites