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. 

 Hummingbird Publications

 Journal

 Potential Opportunities Of Additive Manufacturing Technology In Nigeria

 PK Farayibi, MS Bakare, TE Abioye, PK Oke

 2015

Additive manufacturing is a rapidly developing technology which allows metallic or plastic component parts to be produced in a layer by layer fashion using the desired material which can be in a form of powder, filament or liquid resin. However, the awareness of this technology in Nigeria is limited when compared to subtractive aspect of manufacturing which involves machining of component parts from metallic blocks. In light of this, this paper discussed various additive manufacturing techniques available in terms of their energy sources and consumables. It further looked into research and market opportunities for additive manufacturing technologies in Nigeria. Despite the numerous opportunities, there are challenges in the area of acceptance of the technique, availability of AM equipment and consumables and cost. Moreover, the awareness of this technology needs to be encouraged in Nigeria and other parts of West Africa due to its potential opportunities for economic growth.

 

 Elsevier

 Journal

 Erosion Resistance Of Laser Clad Ti-6Al-4V/WC Composite For Waterjet Tooling

 PK Farayibi, JW Murray, L Huang, F Boud, PK Kinnell, AT Clare

 2014

In waterjet operations, milled surfaces are left with some undesirable dimensional artefacts, thus the useof abrasion resistant mask has been proposed to improve the surface quality of machined components.In this study, the erosion performance of laser clad Ti-6Al-4V/WC composite coating subjected to plainwater jet (PWJ) and abrasive water jet (AWJ) impacts to evaluate its potentials for use as waterjet impactresistant mask material and coating on components was investigated. Results showed that compositewith 76 wt.% WC composition subjected to PWJ and AWJ impacts offered resistance to erosion up to 13and 8 times that of wrought Ti-6Al-4V respectively. Scanning electron microscopy (SEM) examinationof the eroded composite surfaces showed that the erosion mechanism under PWJ impacts is based onthe formation of erosion pits, tunnels and deep cavities especially in the interface between the WCparticles and the composite matrix owing to lateral outflow jetting and hydraulic penetration. Compositesuffered ploughing of the composite matrix, lateral cracking and chipping of embedded WC particlesand WC pull-out under AWJ impacts. The composite performance is attributed to the embedded WCparticles and the uniformly distributed nano-sized reaction products (TiC and W) reinforcing the ductile-Ti composite matrix, with its mean hardness enhanced to 6.1 GPa. The capability of the Ti-6Al-4V/WCcomposite coating was demonstrated by effective replication of a pattern on a composite mask to analuminium plate subjected to selective milling by PWJ with an overall depth of 344 m. Thus, compositecladding for tooling purpose would make it possible to enhance the lifetime of jigs and fixtures andpromote rapid machining using the water jet technique.

 

 Taylor & Francis Group

 Journal

 Laser Deposition Of Ti-6Al-4V Wire With WC Powder For Functionally Graded Components

 PK Farayibi, JA Folkes, AT Clare

 2013

In this study, metal matrix ceramic (MMC) functionally graded components are fabricated using a method based upon shape metal deposition.Laser deposition provides a suitable means for metallic coating and surface alloying for many applications. New functionally gradedcomponents can be built with surface and bulk properties locally modified. Tailoring to meet location specific demands such as modifiedtribological, corrosion, and thermal properties is achievable. This article investigates the cladding of Ti-6Al-4V wire and WC powder concurrentlyfed into the laser generated melt pool on a Ti-6Al-4V substrate. The addition of WC particles promotes its hardness and improveswear resistance. Results obtained showed the micrograph of the functionally graded area coating of Ti-6Al-4V/WC matrix in which WCparticles are dissolved resulting in TiC/W two phase nodules. Scanning electron microscope (SEM), energy dispersive X-ray (EDX),X-ray diffraction (XRD), and microhardness characterization is presented for the coating. Fiber laser deposition is demonstrated as a meansto produce titanium matrix ceramic composite structures with a demonstrator part is presented. 

 Taylor And Francis

 Journal

 Laser Cladding Of Rail Steel With Co–Cr

 AT Clare, O Oyelola, TE Abioye, PK Farayibi

 2013

Degradation and subsequent failure of rail tracks are commonly caused by rolling contact fatigueamong other mechanisms of wear. Rail crossings are known to exhibit more of these failures due toincreased localised traffic and environmental conditions. A high proportion of the costs associatedwith the repair of rail tracks was due to the rolling contact fatigue phenomenon. In order to mitigatethese costs, laser cladding of worn regions has been proposed for the repair of used tracks in situ tolimit the need for them to be replaced and for the preservice protection of newly rolled rails and castcrossings. A Co–Cr, Stellite 6, alloy is chosen to demonstrate repair and also surface coating/protection of R260 rail steel. Results showed that cladded Stellite 6 possessed improved hardness,good tribological performance and excellent workhardening ability when compared with rail steel.These demonstrate laser cladding as a viable solution for repair worn rail track. 

 Laser Institute Of America

 Journal

 Laser Cladding For Railway Repair And Preventative Maintenance

 Adam Clare, Olusola Oyelola, Janet Folkes, Peter Farayibi

 2012

Rolling contact fatigue, amongst other mechanisms of wear, between railway track and train wheelensures that periodic replacement of worn track and other key components such as switches mustbe undertaken. The cost associated with repairing/replacing track is significant. This places afinancial burden upon the rail network provider, creates a significant carbon footprint associatedwith remanufacture of track, and also interruption to train services. It is proposed that lasercladding, when deployed strategically, can reduce the costs associated with replacing worn trackby enhancing the longevity of new rail components (preservice) and also for the repair of sectionsof track which are prone to excessive wear (in service). This will lead to a cheaper, more reliable,and sustainable rail network. This paper details a series of investigations undertaken to laser cladwith premium wear resistant alloys (nickel alloy, Stellite 6, maraging steel, and hadfield steel) tomuch cheaper rail material substrates. The methodology for process optimization is presented,and the specimens are characterized for suitability. Laser cladding is demonstrated to be aviable solution to repair worn track, and a deposition process for actual track sections is presented. 

 Elsevier

 Journal

 Cladding Of Pre-blended Ti–6Al–4V And WC Powder For Wear Resistant Applications

 PK Farayibi, J Folkes, A Clare, O Oyelola

 2011

In this paper, a cladding investigation to achieve uniform distribution of WC particles which is crack-free, non-porous and without delamination using a 2 kW IPG Ytterbium doped, continuous wave, fibre laser with 1070 nm wavelength was reported. The single track deposition of a pre-blended powder, 27 wt.% Ti–6Al–4V/73 wt.% WC with a particle size range of 40–120 μm was made on Ti–15V–3Cr–3Sn–3Al substrate using a co-axial nozzle and a standard powder feeding system. The laser cladding samples were subjected to various microstructure examinations, microhardness and micro-abrasion tests. The results revealed that the best clad layers were achieved at an energy density of 111.10 J.mm−2, 15–18.3 mm.s−1 traverse speed; (583–667) mg.s−1 powder feed rate with substrate surface irradiated by laser beam raising its temperature to about 200 °C. This resulted in a uniform distribution of WC within the clad and the results obtained from SEM, EDS and XRD revealed that the WC particles experienced surface melting with some diffusion into the matrix, thus promoting excellent bonding with the matrix and the formation of titanium and tungsten carbides, which include TiC and W2C. The emergence of β-Ti, TiC and W in the clad resulted in enhanced hardness values. The mean value of microhardness in clad matrix is 678 HV when measured from the top of a transverse cross section of the clad sample into the interface region with the Ti substrate which has a hardness of 396 HV. Wear tests indicated the wear resistance of the clad was seven times that of the Ti alloy substrate.

 

 

 Conferenceproceeding

 Influence Of Process Parameters And Energy Density On The Microstructure Of Ti-6Al-4V Wire And WC Powder Cladding”. Proceedings Of 30th International Congress On Application Of Lasers And Electro-optics (ICALEO), Florida

 FARAYIBI, P.K., FOLKES, J., CLARE, A.T., McCARTNEY, D.G

 2011

NILL 

 

 Conferenceproceeding

 Microstructural Characterisation And Wear Performance Of Laser Deposited Ti-6Al-4V Wire And WC Powder

 FARAYIBI, P.K., ABIOYE, T.E., CLARE, A.T.,

 2004

nil 

 

 Conferenceproceeding

 Direct Laser Metal Deposition Of Inconel 625 Wire Tracks: Microstructural Variation With Processing Parameters”. Proceedings Of 26th Surface And Modification Technique (SMT), Lyon

 ABIOYE, T. E., CLARE, A. T., FARAYIBI, P. K.

 2004

nil