Taylor And Francis

 Journal

 A Comparative Study Of Inconel 625 Laser Cladding By Wire And Powder Feedstock

 TE Abioye, PK Farayibi, AT Clare

 2017

It has been established that laser cladding technique is useful for enhancing surface performances, hence extending the life of many components in severe corrosive-wear environments. However, a comparative study of the surface performances of laser coatings made via powder and wire feeding systems has not been performed. Inconel 625 powder and wire were deposited on the AISI 304 substrate using similar processing parameters. The microstructure, together with the depth of substrate penetration and the degree of dilution of the deposited tracks, was examined using an optical microscope and a scanning electron microscope (equipped with an energy-dispersive spectrometer). The micro-hardness was measured using a Vickers hardness tester. At optimized parameters, laser tracks of Inconel 625 wire and powder had a strong metallurgical bond at the track–substrate interface and no crack and pore were deposited. Due to the higher laser beam infiltration and a larger depth of substrate penetration, higher substrate dilution was observed in the powder-fed tracks. The tracks comprise continuous ϒ-matrix and secondary compounds (rich in Nb and Mb). However, finer dendritic microstructure and higher number density of inter-dendritic precipitates were observed in a typical powder laser track compared with the corresponding wire laser track. The typical powder laser track demonstrated higher hardness (245 HV0.3) compared with the corresponding wire laser track (224 HV0.3).

 

 Routledge

 Journal

 A Study On The Awareness Level Of Additive Manufacturing Technology In South-western Nigeria

 PK Farayibi, TE Abioye

 2017

In this paper, the level of awareness of AM/RP technology in south-western Nigeria was investigated and presented. In asurvey, copies of a questionnaire were administered to sixty (60) engineering personnel in research/tertiary institutions inthe south-western states in Nigeria and forty (40) useful responses were obtained and analyzed. The analysis indicated thatthere was 40% awareness of AM/RP technology in the south-western Nigeria, whereas 60% of the respondents had notpreviously heard of the technologies. It was further deduced that the highest level of awareness of 50% was for inkjet/3D printing, amongst other forms of AM/RP technology in the south-western states in Nigeria. The analysis of theavailability of AM equipment indicated that only 5% of the respondents specified that their institutions in south-westernNigeria possessed inkjet/3D printing AM equipment. This was at one research institute in south-western Nigeria.Though, the amount of AM/RP equipment installed is small at the moment, the level of awareness of this technology isfairly high and it is expected that the awareness level will keep increasing as concerted efforts towards procurement ofAM/RP systems from abroad and by local fabrication/production is made to promote rapid product development. 

 Faculty Of Engineering University Of Nigeria Nsukka

 Journal

 Finite Element Analysis Of Plastic Recycling Machine Designed For Production Of Thin Filament Coil

 PK Farayibi

 2017

This paper presents the conceptual design of plastic recycling machine for production of thin filament coil. The machineis meant to serve as a sustainable means of converting waste Polyethylene Terephthalate (PET) plastic materials intothin filaments to be used as feedstock material in Fused Deposition Modeling (FDM) machine. The machine designconsists of a shredder hopper, two shredder shafts with knife-edge ring cutters, extruder hopper, extrusion barrel withheater jackets and extrusion auger shaft. The design analysis of each of the machine elements was done and structuralintegrity of the machine design was evaluated using finite element analysis (FEA) tool in Solid Works Computer AidedDesign (CAD) application. The FEA result indicated that a maximum stress of 33 MPa was reached in one of the machineframe members when loads mounted on top and below the frame structure are 1204 N and 271 N respectively. Themaximum resultant displacement in the member frame was 0.34 mm and the minimum factor of safety obtained was 8.3.Also, a minimum factor of safety value of 5.3 was obtained for shredder shaft between when subjected to a torque of1000 Nm and it experienced an angle of twist of 0.42o and a maximum stress of 46.8 MPa. The implication of the result isthat the design of the machine is adequate and the machine will fulfill its intended purpose upon fabrication, as the yieldstrengths of selected materials for the fabrication of the machine members are not exceeded. 

 

 Journal

 Laser Metal Deposition Of Multi-Track Walls Of 308LSi Stainless Steel”. Materials And Manufacturing Processes,

 FARAYIBI, P.K., FOLKES, J.A., CLARE, A.T., OYELOLA, O.

 2017

NILL 

 Elsevier

 Journal

 Effect Of Carbide Dissolution On The Corrosion Performance Of Tungsten Carbide Reinforced Inconel 625 Wire Laser Coating

 TE Abioye, PK Farayibi, DG McCartney, AT Clare

 2016

In this work, clad layers of Spherotene (a mixed tungsten carbide)/Inconel 625 wire composite suit-able for hardfacing in corrosive environments were deposited. Varying laser processing conditions wereemployed specifically to investigate carbide dissolution. The relative amount of Spherotene dissolutionin each clad layer was analysed using a combination of methods including mass gain of clad layers, quan-titative microscopic and microchemical analysis of microstructures using scanning electron microscopy(with energy dispersive X-ray analysis) and image processing software. The electrochemical corrosionperformance of two typical composite clad layers formed at low and high Spherotene dissolution lev-els and Inconel 625 wire laser clad were investigated in de-aerated 3.5 wt.% NaCl solution. The resultsindicate that microstructural in-homogeneity, caused by the formation of secondary phases, increasesas the Spherotene dissolution increases. The Spherotene dissolution increases as the energy per unitlength of clad increases. The composite clad layers demonstrate decreasing resistance to corrosion as theSpherotene dissolution increases. Through careful control of process parameters, the corrosion perfor-mance of composite clad layers can be improved by reducing the amount of tungsten carbide dissolution.

 

 Springer London

 Journal

 A Parametric Study On Laser Cladding Of Ti-6Al-4V Wire And WC/W2C Powder

 PK Farayibi, TE Abioye, AT Clare

 2016

In this paper, laser cladding of Ti-6Al-4V wire andWC/W2C powder to produce metal matrix composite cladswith a high ceramic reinforcement and a wider clad widthwas investigated. Taguchi design of experiments and multipleregression models were used to support this. Single clad depositionof Ti-6Al-4V wire and WC/W2C powder was madeon a Ti-6Al-4V substrate using wire and powder co-feedingsystems. Clad samples were made at varying processing parametersusing L9 orthogonal experimental matrix data. Theclad geometries (height and width) and the weight, obtainedusing a Talysurf CLI 1000 surface profiler and a weighingscale with a sensitivity of 0.0001 g, were presented andanalysed. The results showed that a process condition of1800 W laser power, 300 mm/min traverse speed, 700 mm/min wire feed rate and 30 g/min powder feed rate producedthe composite clads with the highest reinforcement fraction of76± 1 wt%, clad height of 1.57± 0.03 mm and clad width of3.91± 0.05 mm. This process condition resulted in a clad withthe highest signal to noise ratio of 37.67 for the WC/W2Creinforcement and the geometrical aspect ratio (H/W) of 0.40which lies within the range of 0.42≥ (H/W) ≥ 0.13 to preventthe formation of inter-run porosity in deposited overlap clads. 

 SCIENCEDOMAIN International

 Journal

 Effect Of Throttling Variation On The Performance Of Vapour Compression Refrigeration System

 PK Farayibi, TS Mogaji, TJ Erinle

 2016

In this paper, the effect of throttling variation on the performance of vapour compressionrefrigeration system using R134a refrigerant as working fluid was investigated and reported. Theinvestigation was carried out using a refrigeration test rig with capillary line as throttling devicewhich was split into three capillary lines of the same length under a room temperature condition of29 – 32°C. The test rig was equipped with four sigma manifold gauges which were installed at theinlet and exit of the condensing and evaporating units to take the pressure and temperaturereadings of the working fluid. Experimental trials were conducted by taking the pressuretemperaturereadings when one-, two- and all the three capillary lines were engaged for thethrottling process. The enthalpy condition of the refrigerant at the inlet and exit of the condenserand evaporator were obtained from a standard COOLPACK saturation table. The performance ofthe refrigeration system was analysed based on the experimental data. Results showed that thetemperature difference between the inlet and exit of the evaporating unit was found to increasefrom 8.66°C to 24.65°C, refrigerating effect increase s from 141.2 kJ/kg to 144.6 kJ/kg while workdone by compressor decreases from 24.8 kJ/kg to 21.6 kJ/kg as the number of capillary lines employed increases from one to three. The coefficient of performance of the system was found toincrease from 5.69±0.04 to 6.71±0.04 which was 17.9% and 7.5% higher than the COP of thesystem if only one- and two capillary lines were respectively employed for the throttling process.The system behaviour has been attributed to earlier development of the two-phase mixture fromthe saturated liquid as the number of capillary line increases, thus improving the systemperformance. 

 SCIENCEDOMAIN International

 Journal

 Effect Of Throttling Variation On The Performance Of Vapour Compression Refrigeration System

 PK Farayibi, TS Mogaji, TJ Erinle

 2016

In this paper, the effect of throttling variation on the performance of vapour compressionrefrigeration system using R134a refrigerant as working fluid was investigated and reported. Theinvestigation was carried out using a refrigeration test rig with capillary line as throttling devicewhich was split into three capillary lines of the same length under a room temperature condition of29 – 32°C. The test rig was equipped with four sigma manifold gauges which were installed at theinlet and exit of the condensing and evaporating units to take the pressure and temperaturereadings of the working fluid. Experimental trials were conducted by taking the pressuretemperaturereadings when one-, two- and all the three capillary lines were engaged for thethrottling process. The enthalpy condition of the refrigerant at the inlet and exit of the condenserand evaporator were obtained from a standard COOLPACK saturation table. The performance ofthe refrigeration system was analysed based on the experimental data. Results showed that thetemperature difference between the inlet and exit of the evaporating unit was found to increasefrom 8.66°C to 24.65°C, refrigerating effect increase s from 141.2 kJ/kg to 144.6 kJ/kg while workdone by compressor decreases from 24.8 kJ/kg to 21.6 kJ/kg as the number of capillary lines employed increases from one to three. The coefficient of performance of the system was found toincrease from 5.69±0.04 to 6.71±0.04 which was 17.9% and 7.5% higher than the COP of thesystem if only one- and two capillary lines were respectively employed for the throttling process.The system behaviour has been attributed to earlier development of the two-phase mixture fromthe saturated liquid as the number of capillary line increases, thus improving the systemperformance. 

 Elsevier

 Journal

 Surface Improvement Of Laser Clad Ti–6Al–4V Using Plain Waterjet Andpulsed Electron Beam Irradiation

 P.K. Farayibi, T.E. Abioye, J.W. Murray, P.K. Kinnell, A.T. Clare

 2015

Laser cladding is a flexible process which can be used to enhance the lifetime of components and repairthem when worn. This is especially relevant where components are highly valued, and therefore costlyto replace. To date, the surface finish achievable by laser cladding is poor and is characterised by ridgeswhich correspond to the individual beads associated with the process. Increasingly laser cladding isbeing applied to conformal surfaces which are difficult to process by conventional grinding procedureswhich may also be ineffective because of discontinuous clad regions. There is therefore a need for afreeform approach which is capable of introducing specific surface finishes to complex components.Hence, in this study, a process chain incorporating plain water jet (PWJ) followed by a pulsed electronbeam irradiation was used for the surface modification of laser clad surfaces of Ti–6Al–4V. Initially thesurface was characterised by large recesses with peak-trough heights of 200 ± 18 m and waviness of49 m. Upon processing employing water head pressure of 345 MPa impinging the clad surface at anangle 90◦, 250 mm/min jet traverse speed, 3 mm stand-off distance and 0.25 mm milling overlap with2 passes, it was possible to eliminate the peak-trough profile by milling to a depth of 480 ± 10 m. Aflat surface characterised by a surface waviness of 14.9 m, 12.6 m Ra and 44 m straightness wasachieved. PWJ milled surfaces were characterised by deep cavities, stepped fractured surfaces, cracksand sub-surface tunnels, however, with application of pulsed electron beam irradiation, most of thesesurface features were eliminated with a relatively smooth surface produced with 6.2 m Ra finish.

 

 Springer

 Journal

 Functionally Graded Ni-Ti Microstructures Synthesised In Process By Direct Laser Metal Deposition

 TE Abioye, PK Farayibi, Peter Kinnell, AT Clare

 2015

The fabrication of biomedical devices usingNi-Ti compositions is limited to conventional techniquesand the use of near equiatomic pre-alloyed Ni and Tipowders. In this study, functionally graded walls andcylinder built by concurrent feeding of Ni powder andcommercially pure (CP) Ti wire using direct laser metaldeposition technique are presented. The built structuresconsist of CP Ti wire-deposited layers and Ni-Ti layersof varying Ni composition. The microstructures of thebuilt Ni-Ti structures including phase identification,phase compositions and area fractions of the phases presentat various processing parameters were determinedusing a combination of scanning electron microscopy/energy dispersive X-ray spectroscopy, X-ray diffractometryand image processing software. Vickers microhardnesstest was conducted on the deposited structures.It was found that the Ni-Ti layers comprise of NiTi andNiTi2 phases. The area fraction of the NiTi phase increases,whereas NiTi2 decreases with increasing the Nipowder feed rate. Ni-Ti layers with higher area fractionsof NiTi2 phase are found to be harder with a maximumof 513 HV0.3 found in this study. The micro-hardness ofNi-Ti layers is, by at least a factor of 1.5, higher than theCP Ti wire laser-deposited layers.