FACULTY OF TECHNOLOGY
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Item Effect of iso-thermal treatment on the corrosion behaviour of low carbon steel (Nigerian C2R grade) in a buffered solution containing chloride and carbonate ions(2012) Atanda, P. O.; Olorunniwo, O. E.; Alabi, O. D.; Oluwole, O. O.This work has investigated the corrosion behavior of low carbon steel subjected to four different modes of iso-thermal heat treatment and then immersed in a neutral buffer corrosive medium containing carbonate and chloride ions. The low carbon steel material was cut into twenty small pieces of length 18±2mm, put in groups of five and subjected to: Annealing, Hardening, Normalizing and tempering, each corresponding to an iso-thermal mode of treatment. The samples were ground and polished, and micrographs taken for each mode of treatment. The samples were then immersed into the corrosion medium; a neutral buffer and samples were withdrawn for measurement every 72 hours. The experiment lasted 360 hours (15 days). The weight loss due to corrosion of the samples, the corrosion rate of the samples and the pH variation of the samples were monitored against time of exposure. It was observed that samples which had undergone tempering mode of heat treatment turned out to be the ones with the best corrosion resistance.Item Investigation of the effect of the addition of petroleum waste to interlocking brick constituent(2011) Atanda, P. O.; Oluwole, O. O.; Olumor, I. D."Incinerator ash was investigated for its potential use as a replacement for sand and cement in concrete interlocking bricks. The physical characteristics of the raw materials were examined. Two sets of mixes were prepared. For the first set, sand and water quantities were fixed while incinerator ash was used at 0% to 100% replacement by weight for cement in steps of 10%. In the second set, incinerator ash was used at 0% to 100% replacement by weight for sand while cement and water quantities was fixed. The mixing proportions for cement, sand and water were 1:3:0.7, respectively. Compressive strength and leachability tests were performed on the specimens. Results showed that the replacement of sand by incinerator ash up to 40% exhibited higher compressive strength than the control mix (0% incinerator ash) after 28 days curing. Maximum compressive strength of 33.33N/mm2 was obtained after 28 days curing using using 20% incinerator ash substitution for sand. Replacement of cement by incinerator ash up to 20% exhibited higher compressive strength than the control mix. Compressive strength of 28.2 N/mm2 was achieved after 28 days curing period using a 20% ash substitution for cement. Leaching of heavy metals (Pb and Cd ) present in the ash was observed in concentrated nitric acid. "Item Sensitisation study of normalized 316L stainless steel(2010) Atanda, P. O.; Fatudimu, A.; Oluwole, O."Austenitic stainless steels with excellent corrosion resistance and good weldability have wide applications in industry. These iron-based alloys contain a high level of chromium which form protective oxide film on the surface hence resisting corrosion. The oxide film regenerates when damaged, making the steel 'stainless'. However, carbide precipitation due to a welding process or heat treatment can cause the occurrence of chromium-depleted zones at the boundaries, leading to a phenomenon known as sensitisation, in which the depleted zones become the focus of the intense corrosion. The present work was concerned with the study of the sensitization and desensitisation of 316L steel at the normalizing temperatures of 750- 9500 C and soaking times of 0.5, 1, 2 and 8 hrs. 316L stainless steel was observed to be sensitized when heated to 750- 8500 C and held for short soaking times of 0.5 – 2hrs before normalizing. Increasing soaking times at these temperatures to 8 hrs triggered the desensitization process which was fully accomplished at 7500 C but ongoing at 800 and 8500 C. At 9000 C, sensitization did not occur at 30 mins soaking time but observed at soaking times of 1 and 2hrs. At a longer soaking time of 8 hrs, there was full desensitization. At 9500 C, sensitization was already observed at 30 mins. Soaking time and desensitization was observed to be in progress at 1 and 2 hrs soaking time. By 8 hrs there was full desensitization. Thus it was observed that at 9500 C, diffusion of Cr was thermally aided making desensitization fast. The hardness of normalized 316L stainless steel was also observed to decrease with soaking time and normalization temperature "Item Corrosion behavior of 18/8 stainless steel and nickel-plated low carbon steel in cassava fluid(2009) Oluwole, O. O.; Atanda, P. O.; Odekunbi, O. A.; Odegbaju, E."This research work investigated the corrosion resistance of nickel- plated medium carbon steel and 18/8 stainless steel in cassava fluid (i.e. containing hydrogen cyanide). It simulated the effect of continuous use of the materials in a cyanide environment where corrosion products are left in place. Low carbon steel sample was nickel electroplated at 4V for 35 minutes. The plated sample, the unplated and the 18/8 stainless steel were then subjected to a cassava fluid environment for thirty days. The electrode potentials, in mV (SCE), were measured every day. Weight loss was determined at intervals of 5 days for duration of the exposure period. The result showed little corrosion attack on the nickel-plated steel on the fifth and tenth days which quickly dropped to zero by the 15th day and remained at the passive state till the 20th day when corrosion picked up again increasing steadily, linearly until the end of the test day. Corrosion of the 18/8 stainless steel was very low as well decreasing till the last day of the test. The pH of the cassava solution which initially was acidic because of the cyanide content in the cassava was observed to progress to neutrality within five days and to alkalinity at the end of the thirty days test (because of corrosion product contamination of the cyanide). Un-plated steel was found to be unsuitable for the fabrication of cassava processing machinery because of the very high corrosion rate.18/8 stainless steel was found suitable for use in this environment. The renewed corrosion activity on nickel plated steel after the 20th day (pH=12) of continuous use in cyanide environment makes it unsuitable for use. "Item Finite element modeling of heat transfer in salt bath furnaces(2009) Oluwole, O. O.; Atanda, P. O.; Imasogie, B. I."Heat flow patterns in two salt bath furnaces were studied in this work using finite element(FE) analysis. The implications of the heat flows on long term stability of furnace performance were evaluated. One design had a purely silica brick back-up after the embedded heating element with asbestos and glass-wool fiber insulation just before the outer steel shell. The other had an additional air-gap insulation formed by cylindrical steel belts with spacers placed after the silica back-up. It was observed that the design with additional air-gap insulation had tremendous insulation effect, necessitating a drastic thinning down of the silica brick thickness and glass wool fiber. "Item Adaptation of Ushafa clay, Abuja, as a suitable replacement for bentonite in the foundry industry(2008) Atanda, P. O.; Oluwole, O. O.; Ogale, O. T.This work investigated the possible use of Ushafa clay in Abuja, Nigeria as a suitable replacement for bentonite clay in foundry use. Moulding sand mixes with compositions of 8,10 and 13%. Ushafa clay, silica sand and 5,7,8,9,10 and 11% coal dust additives were mulled. From each mix, cylindrical specimens were prepared and subjected to permeability, shatter index, compression and shear strength tests . The results from the Ushafa mix were compared with results from bentonite mixes. The results showed that moulding sand compositions having 13%. Ushafa clay, and coal dust additions of 8% produced specimens with good permeability, dry strength, green strength and collapsibility for foundry use. This work has confirmed the possible use of Ushafa clay as suitable replacement for bentonite binder in foundryItem Simulation of riser size from musty zone of unrisered Alsi7mg alloy(INSInet Publication, 2007) Oluwole, O. O.; Olorunniwo, O. E.; Atanda, P. O.Solidification simulation packages incorporate risers in their Finite Element meshing programs. The placement of the risers is normally juggled in different positions until the best positions are obtained. Also riser sizes are also determined based on riser size calculations. This work has narrowed down position options by first simulating unrisered castings of an AlSi7Mg alloy. Using the location of the mushy zone and the size of the zone, appropriate size and locations were determined for the riser thus limiting the number of trial and error simulation runs. Using the size and locations of mushy zone it has been discovered that risers of equivalent lineal size should be placed in the locations of these mushy-zones. Simulations were done using a rectangular block and a gas burner.Item Earing characteristics of cold-rolled and temper annealed aluminium 1200(Asian Network for Scientific Information, 2006) Aderibigbe, D. A.; Oluwole, O. O.; Olorunniwo, O. E.; Atanda, P. O.; Ogundare, O.Earing characteristics of deep-drawn cold-rooled and temper-annealed 1200 was studied at high deformation levels of 75,85,and 90% cold rolling. The relationshp of earing with varying degrees of cold roll was studied and the effect of different annealing temperatures on earing. Hardness, ductility and strength variations with earing were also studied. Earing was at an aneeal-temperature. The relationship of earing to hardness, ductibility and strength properties were observed to follow the same pattern. Hardness, ductility and strength properties of cold-rolled and temper-annealed Aluminium 1200 at lowest eaaring did not necessarily correspond to the materials lowest hardness, highest ductility or lowest strength respectively and were found to vary for varying degrees of cold-roll.Item A Study of Processing Parameters on the Carburization of C2R Steels(Scientific Research Publishing, 2009) Atanda, P. O.; Olorunnuwo, O. E; Umoru, L. E.; Adeyeye, A. D.; Adeyeye, A. D.This study reports an investigation of the effect of carburizing variables - temperature, time and percentage of energizer on the case properties of C2R steel obtained from HMT Ltd. India. A carburizer consisting of hardwood charcoal and coke respectively in the ratio of 2:1 was used for the research with sodium carbonate as the energizer. The carburizing box was filled with 20mm thick carburizer compound prior to fixing the steel samples in place. The specimens were carburized using different percentages of energizers (10, 20 and 30%) at different temperatures (820, 860, 900 and 940°C) for different times (from one to five hours). All the specimens were quenched from carburizing temperature, ground to polished surfaces and then etched for ten minutes in 25% Nital. The case depth was measured using the calibrated ocular of an inverted metallurgical microscope fixed at 100 x magnification. The hardness values of the C2R steel cases were measured with a micro hardness tester that uses diamond pyramid indenter. The results of the study showed that the average hardness of the C2R steel cases increased with temperature for any given carburizing time and temperature. For a given percentage energizer and temperature, the case depths and hardness increased with time. Increase in the percentage energizer however decreased the activation energy required for diffusion to occur exponentially.