Browsing by Author "Onuoha, C."
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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 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 On weekly basis, one coated and one uncoated coupon were withdrawn from each of the soil media and reweighed.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 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 temperature