http://196.220.128.81:8080/xmlui/handle/123456789/200 2026-04-27T01:48:46Z 2026-04-27T01:48:46Z OLORUNYOLEMI, OLADIPUPO http://196.220.128.81:8080/xmlui/handle/123456789/5578 2023-02-07T11:03:40Z 2022-02-01T00:00:00Z

DEFORMATION BEHAVIOUR OF ALUMINIUM BASED COMPOSITES REINFORCED WITH SHALE AND COAL FLY ASH OLORUNYOLEMI, OLADIPUPO Aluminium Matrix Composites (AMCs) have limited ductility and toughness, which limits their processing windows during hot forming for complicated component designs such as those used in automobiles. To solve the above problems, this research incorporated shale and coal fly ash into aluminium matrix and investigated their deformation behaviour at ambient and elevated temperatures. Double stir casting process was used for the production of the composites, tensile test was carried out at room temperature, and hardness was carried out at room temperature, 180oC and 380oC, while isothermal compression testing was done at temperatures 180oC and 380°C at strain rates of 0.5 s-1 and 5 s-1. Gleeble 3500 thermomechanical simulator was used for the generation of data for evaluating the hot deformation behaviour, characterization of the hot deformation samples was carried out using X-Ray diffractometer (XRD), scanning electron microscope (SEM) and optical micrograph. The results obtained show that Al/CFA has the highest UTS value 182.73 MPa and the highest hardness value at room temperature, however the result show Al6063 at 180oC 0.5 s-1 and Al/CFA at 180oC 5 s-1 has the highest hardness value. The Al/CFA at 180oC, 5 s-1 requires the highest flow stress before yielding for the stress strain behaviour and it was observed that the flow stress reduced for the AMCs at high temperature of 380oC, the sample characterization show the (SEM) Al/CFA at 180oC, 5 s-1 has the smallest grain size 41.34 using numerical analysis. In general, the coal fly ash reinforced Aluminium matrix composites yielded the best combination of hot deformation parameters (Temp 180oC, 5 s-1 and 0.5 s-1) suitable for processing components for the target area of application.

2022-02-01T00:00:00Z SAKA, SHERIFF OLALEKAN http://196.220.128.81:8080/xmlui/handle/123456789/5474 2022-12-02T14:17:22Z 2018-09-01T00:00:00Z

PRODUCTION AND PROPERTIES EVALUATION OF ANTIMONY MODIFIED COMPACTED GRAPHITE IRONS SAKA, SHERIFF OLALEKAN In this research, the production of compacted graphite iron (CGI) alloys and the evaluation of their microstructural and mechanical properties were carried out. The CGI samples were produced in a rotary furnace and ladle–treated with alloying addition of predetermined amounts of magnesiumferrosilicon (MgFeSi), cerium-based ferrosilicon (Ce-based FeSi), aluminium (Al), copper (Cu), and antimony (Sb) to produce different alloying compositions. Cylindrical specimens of Ø 25 mm × 200 mm were produced by sandwich method and designated as C1, C2, C3, C4, A1, A2, A3, A4 and A5. Samples C2, C3 and C4 were the unmodified CGI ladle-treated with MgFeSi, Ce-based FeSi + MgFeSi, and Ce-based FeSi + MgFeSi + Al + Cu alloys respectively. Samples A1, A2, A3, A4 and A5 were the antimony (Sb) modified CGI alloys ladle-treated with constant addition of Ce-based FeSi, MgFeSi, Al, Cu and varying Sb addition at 0.003, 0.006, 0.05, 0.1 and 0.13 wt% respectively. Sample C1 had no treatment and served as control sample. The melts were tapped between 1520oC – 1570oC into the treatment ladle and poured at about 1370oC–1420oC into sand moulds. The result of the chemical analysis of the CGI alloys indicated that the alloys solidified as hypoeutectic (for C1 – C4 and A4 samples) and hypereutectic (for samples A1, A2, A3 and A5). The microstructural examinations revealed that increased antimony addition modified the compacted graphite particles from thick, short, and worm–like with round-ended edges to less thick, short, worm and crab–like graphite with needle-like (Kish) edges interspersed in ferrito – pearlitic matrix. The tensile, % elongation and elastic modulus results showed that sample A1 had the highest value of 327 MPa, 4.11% and 34.2 MPa respectively while alloy A5 had the least 32 MPa, and 0 MPa. Sample C1 had the highest average hardness of 90.7 HRA while sample C4 possessed the least value (83.2 HRA). The impact toughness result showed that sample C2 had the highest toughness value of 34.7 J while the lowest toughness value of 5.4J was recorded for sample A5. Therefore, sample A1 had the best overall properties which fall between Grade 300 – 350 according to ASTM A842 – 85.

2018-09-01T00:00:00Z OSASONA, BABATOLA http://196.220.128.81:8080/xmlui/handle/123456789/5473 2022-12-02T14:09:16Z 2022-01-01T00:00:00Z

ASSESSING THE EXTERNAL TRADE DIMENSIONS OF BENEFICIATING NINGI GRAPHITE ORE DEPOSIT OF NORTH-EASTERN NIGERIA OSASONA, BABATOLA The drastic downfall in crude oil prices since the middle of 2014 puts the Nigerian economy under the burden of financial instability as crude oil accounts for 95% of export and foreign exchange receipt. Such macroeconomic condition that shrinks the economy, led to de-industrialisation, higher unemployment rate, loss of foreign exchange earnings, and stifled national development necessitates this research. To this end, the External Trade dimension of Beneficiating Ningi Graphite deposit of North-Eastern Nigeria becomes exigent due to the economic relevance of graphite as a critical engineering material of the 4th industrial revolution. Randomly sampled run-off-mine was prepared and characterized. Sub-sieve analysis was carried out to determine sized fraction and the economic liberation size of the ore. The Modified Bond work index was used to determine the ore grindability. Crude mineral samples were prepared to the economic liberation size, and concentrated by varying the combination of selected frothers and collectors keeping all other flotation conditions constant. The Grubbel-Llyod index was applied to analyse secondary trade data. The results of three crude samples show that Ningi graphite is a low-grade, complex graphite mineral made up of Quartz, Feldspar, Mica, and silicate, as a dominant inclusion with an average of 81.5% SiO2 and 0.4% C graphitic carbon. Its resistance to grinding is approximately 39.77 kWh/ton, while the graphite flake size is approximately between 10-350 μm, and are best liberated at 63 μm. The combination of Pine oil and Kerosene as Frothers and collectors respectively gives the best yield at 96.08% graphite recovery of 42.65% graphitic carbon grade. Finally, a five-year trade study of Nigeria reveals that the dimension of graphite commodity trade is Inter-Industry and non-homogeneous in nature. All the above concludes that, Ningi graphite deposit can be upgraded but not for export as the economic returns of beneficiating the deposit is at the moment not competitive.

2022-01-01T00:00:00Z OGUNBIYI, KOLAWOLE OLAWUNMI http://196.220.128.81:8080/xmlui/handle/123456789/5472 2022-12-02T14:02:56Z 2022-02-01T00:00:00Z

DEVELOPMENT OF NANOSTRUCTURED DUAL - PHASE STEEL VIA THERMALCYCLING WITH NANOQUENCHING FROM INTERCRITICAL TEMPERATURE RANGE OGUNBIYI, KOLAWOLE OLAWUNMI In this research, investigations were performed on development of nanostructured dual phase steel via thermal-cycling with nanoquenching from inter critical temperature range. A total of 150 standard samples of low carbon steel were prepared for mechanical tests and wear test specimens by a conventional lathe machine. All the samples were made to undergo a full Normalizing, Lamellarizing, Quenching and Tempering (NLQT) process. The steel samples prepared were first normalized in a muffle furnace by heat treating them at 830°C for 30minutes followed by cooling in air in order to eliminate the previous thermal and mechanical history of the steel. 15 samples each represent, tensile, fracture toughness, hardness, impact and wear for 10 experimental runs which were normalized, heat treated within the dual-phase region of 730oC, 750oC and 770oC for a holding time of 20, 40 and 60 minutes respectively. Respective samples were then quenched in a prepared nanofluid (ZnO) followed by tempering at 480oC for a soaking time of 30 minutes, then allowed to air cool. Microstructure, mechanical properties and wear resistance were examined to determine the performance of the developed dual phase steel. The microstructure examination showed ferrites dispersed in pearlite matrix for normalized specimen while homogenously dispersed duplex ferrite – tempered martensite and a fraction of bainite with very little retained austenite was obtained for the developed heat treated dual phase steel samples. The tensile properties showed good improvement due to good synergy between ferrites and martensite grains. However, NLQT770 at 60 minutes displayed better strength with 530.13 MPa and E-modulus while good combination of strength and ductility is obtained for NLQT730 series. Carbon redistribution and grain refinement upon tempering increases hardness in some samples. However, this is more pronounced at NLQT770/40 with 72.15. The improvement observed in the properties tested as compared with literature justify the efficacy of the heat treatment procedure viz a viz the use of the nanoquenchant.

2022-02-01T00:00:00Z