Characterization of functionally graded commercially pure titanium (CPTI) and titanium carbide (TiC) powders
- Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2015-07-01
- Subjects: Functional graded materials , Laser metal deposition , Titanium , Titanium carbide
- Type: Article
- Identifier: uj:5136 , ISBN 9789881404701 , http://hdl.handle.net/10210/14102
- Description: Functionally Graded Materials (FGM) are advanced materials fabricated using additive manufacturing techniques. It belongs to a class of advanced material characterization in which the properties of the material composition is varied. The resulting property of the composite is always different from the properties of the individual material employed in the formation of the composite. They are known to also exhibit good mechanical and chemical properties and as such, are used for different industrial applications. One of the techniques employed in the fabrication of FGMs is called Laser Metal Deposition (LMD) technique. It uses laser beam to melt powder material on a substrate forming a melt pool that solidifies upon cooling. This paper reports on the material characterization of functionally graded Titanium and Titanium Carbide (TiC) powders deposited on Titanium substrate by laser metal deposition approach. The formed deposits were fabricated by varying the processing parameters such as laser power, scanning speed and the powder flow rate. From the result obtained, the microstructures showed that the laser power has much influence on the grain growth of the material. In addition, with the SEM analysis of the microstructure since the percentages of the titanium and titanium carbide were varied, it was observed that the sharp boundaries of the Titanium Carbide were reduced greatly and this resulting effect can be attributed to the thermal effect of the laser. The microstructures further revealed that as the percentage of TiC decreases, it becomes more difficult to see the TiC as a different material in the composite, emphasizing this as one of the best characteristics of functionally graded materials, which is the elimination of sharp interfaces and layers. Furthermore, it was observed that the laser power has great influence on the evolving hardness of the material compared to the TiC content.
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Laser forming of titanium and its alloys – an overview
- Authors: Akinlabi, Esther Titilayo , Shukla, Mukul , Akinlabi, Stephen A.
- Date: 2012
- Subjects: Titanium , Titanium alloy , Laser beam forming
- Type: Article
- Identifier: uj:5334 , ISSN 2070-3740 , http://hdl.handle.net/10210/8877
- Description: Laser beam forming is a novel technique developed for the joining of metallic components. In this study, an overview of the laser beam forming process, areas of application, the basic mechanisms of the laser beam forming process, some recent research studies and the need to focus more research effort on improving the laser-material interaction of laser beam forming of titanium and its alloys are presented.
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Effect of built orientation on direct metal laser sintering of Ti-6Al-4V
- Authors: Chandramohan, P. , Bhero, Shepherd , Obadele, Babatunde Abiodun , Olubambi, Peter Apata , Ravisankar, B.
- Date: 2018
- Subjects: Titanium , Laser , Sintering
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/273288 , uj:29111 , Citation: Chandramohan, P. et al. 2018. Effect of built orientation on direct metal laser sintering of Ti-6Al-4V. Indian Journal of Engineering & Material Sciences. Vol. 25, February 2018, pp. 69-77.
- Description: Abstract: Please refer to full text to view abstract.
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Synthesis and characterization of commercial pure titanium-nickel alloy behavior reinforced with titanium diboride
- Authors: Falodun, Oluwasegun Eso , Oke, Samuel Ranti , Olubambi, Peter Apata
- Date: 2020
- Subjects: Titanium , Nickel , TiB2
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/458331 , uj:40705 , Falodun, O.E., Oke, S.R., Olubambi, P.A.: Synthesis and characterization of commercial pure titanium-nickel alloy behavior reinforced with titanium diboride.
- Description: Abstract: Commercial pure titanium alloy with Ni-TiB2 ceramic additions (5, 10, 15 and 20 vol.%) were synthesized through the spark plasma sintering approach with sintering temperature of 1000 oC, the heating rate of 100 oC/min, holding time of 5 min at a constant pressure of 50 MPa. The study investigated the effect of Ni-TiB2 on the densification, phase change, microhardness, microstructure, and wear properties of the sintered titanium-based composites. Results showed that Ti-Ni-TiB2 composites relative density ranges from 97 to 99 %, while microhardness values increase with addition of nickel and titanium diboride from 228 to 587 HV0.1. The microstructural evolution shows that pure titanium transformed from lamellar phase to equiaxed alpha phase upon addition of nickel alloy and further get refined with a distinct grain boundary comprises of titanium diboride around the boundaries. The average coefficient of friction for the titanium-based composite was higher for commercially pure titanium (0.73) while the addition of TiB2 exhibit (0.66, 0.63, 0.58, 0.55 and 0.46 respectively) improvement in the wear behavior.
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Residual stress distribution and the concept of total fatigue stress in laser and mechanically formed commercially pure grade 2 titanium alloy plates
- Authors: Mjali, Kadephi V. , Els-Botes, Annelize , Mashinini, Peter M.
- Date: 2018
- Subjects: Mechanical properties , Titanium , Residual stress
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/273165 , uj:29096 , Citation: Mjali, K.V., Els-Botes, A. & Mashinini, P.M. 2018. Residual stress distribution and the concept of total fatigue stress in laser and mechanically formed commercially pure grade 2 titanium alloy plates.
- Description: Abstract: This paper discusses the investigation of residual stresses developed as a result of mechanical and laser forming processes in commercially pure grade 2 Titanium alloy plates as well as the concept of total fatigue stress. The intention of the study was to bend the plates using the respective processes to a final radius of 120mm using both processes. The hole drilling method was used to measure residual strains in all the plates. High stress gradients were witnessed in the current research and possible cases analyzed and investigated. The effects of processing speeds and powers used also played a significant role in the residual stress distribution in all the formed plates. A change in laser power resulted in changes to residual stress distribution in the plates evaluated. This study also dwells into how the loads that are not normally incorporated in fatigue testing influence fatigue life of commercially pure grade 2 Titanium alloy plates...
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Synthesis and photocatalytic performance of Ag-TiVOX nanocomposite
- Authors: Ntobeng, Mahubedu Khutso , Imoisili, Patrick Ehi , Jen, Ten-Chien
- Date: 2020
- Subjects: Titanium , Nanocomposite , Methylene blue
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/458235 , uj:40693 , Ntobeng, M.K., Imoisili, P.E., Jen, T.: Synthesis and photocatalytic performance of Ag-TiVOX nanocomposite. DOI: https://doi.org/10.1016/j.jksus.2020.08.021
- Description: Abstract: A silver, vanadium and silver/vanadium doped titanium dioxide (TiO2, Ag-TiO2, V-TiO2 and Ag-TiVOX) nanocomposite photocatalyst was achieved via a modify sol–gel and hydrothermal method. Structural analysis by X-Ray Diffraction (XRD) depicted the lattice fringes for both anatase and rutile in its crystalline phase in the synthesized nanocomposites. Surface areas (SBET) analysis shows that surface area of synthesized Ag-TiVOX is 46.01 m2/g, compare to TiO2 64.75 m2/g, Ag-TiO2 61.33 m2/g and V-TiO2 62.73 m2/g. Optical absorption results demonstrated by UV–Visible Spectroscopy (UV–Vis) shows that the effects of Ag and V doping was a shift in spectrum to the visible light region, enhancing the visible light absorption capacity of the synthesized photocatalyst. The optical absorption of Ag-TiVOX achieved a reduced bandgap energy of 2.2 eV, as compared to Ag-TiO2 (2.8 eV), V-TiO2 (2.3 eV) and TiO2 (2.9 eV). Morphological characterization by Transition Electron Microscope (TEM) and Scanning Electron Microscope (SEM), depicting a cluster composed of spherical aggregates particles of non-uniform diameter nanoparticles with particle size ranging between 10 and 50 nm. Synthesized Ag-TiVOx demonstrated remarkable photocatalytic capabilities under visible light irradiation, as 99.83 percent of methylene blue (MB) degradation was accomplished during the first 15 min. Impact of Ag and V doping of TiO2 showed enhancement in the photocatalytic activity, reporting excellent removal rates and achieving well desirable decline in the band gap energy.
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Fabrication and characterization of titanium-nickel-zirconia matrix composites prepared by spark plasma sintering
- Authors: Obadele, Babatunde Abiodun , Ige, Oladeji Oluremi , Olubambi, Peter Apata
- Date: 2017
- Subjects: Spark plasma sintering , Zirconia , Titanium
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/225471 , uj:22773 , Citation: Obadele, B.A., Ige, O.O. & Olubambi, P.A. 2017. Fabrication and characterization of titanium-nickel-zirconia matrix composites prepared by spark plasma sintering.
- Description: Abstract: Ti–Ni–ZrO2 composites were prepared by spark plasma sintering (SPS). The effect of ZrO2 content on the densification, microstructure and microhardness properties of the composites were investigated. Samples were characterized by SEM, EDS and XRD analyses. Noticeably, SPS process under the sintering conditions was achieved at a sintering temperature of 950 ºC, for 10 min holding time, at 100 °C/min of heating rate and at an applied pressure of 50 MPa. This resulted in maximum densification of the powder compact and the formation of a distinguishable spherical globules rich in Ni surrounding the retained Ti. Gradient composition distribution of ZrO2 at the grain boundaries resulted into pinning effect of the grain growth. As the ZrO2 content increased from 5 to 10 vol.%, it was accompanied by a significant increase in hardness values of the sintered composites from 480 to 713 HV.
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Microstructure and wear properties of laser cladded cBN/Ti3Al on pure titanium
- Authors: Sobiyi, K. K. , Akinlabi, Esther Titilayo
- Date: 2017
- Subjects: Titanium , Intermetallics , Laser cladding
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/233614 , uj:23856 , Citation: Sobiyi, K.K. & Akinlabi, E.T. 2017. Microstructure and wear properties of laser cladded cBN/Ti3Al on pure titanium.
- Description: Abstract: In order to improve the tribological properties of titanium alloys at high temperature, the possibility of producing Ti3Al intermetallic with the addition of ceramics (cBN) coatings on titanium substrate using laser technique cladding was investigated. cBN is generally known for its high hot hardness, wear resistance and chemical stability. Laser cladding is an emerging material processing technique which is an efficient and cost effective technique for improving the surface properties of general metallic materials. This paper presents the effects of laser cladding on the phase combination, microstructure, hardness and wear resistance of titanium aluminide/cBN IMC composites at different variations in quantity of cBN in the composite. Optical microscopy, X-ray diffraction, and scanning electron microscopy (SEM) with EDX was used for characterizing the microstructure of the coating. In addition the composite coating was subjected to wear testing using the ball-on-disc, friction and wear apparatus. The XRD results revealed phases with small cBN, Ti2N and TiB2 peaks in addition to the rich γ-Ti, α2- Ti3Al and TiAl intermetallics phases in the coatings after cladding process. Whereas, the microstructure of the cBN cladded layer contained partially melted cBN grains evenly dispersed within the laths of alpha Widmanstätten phase in form of dendrites, precipitate of α2- Ti3Al and spherical shaped pure titanium. The effect of the addition of cBN into Ti3Al alloy at increasing weight percentages, showed an improvement in the hardness and wear resistance of the coatings. The increase is attributed to reacted boron nitrides particles with titanium, being distributed uniformly in the intermetallic matrix.
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The influence of scanning speed on laser metal deposition of Ti/TiC powders
- Authors: Sobiyi, K. K. , Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2017
- Subjects: Titanium , Lasers , Metal deposition
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/241302 , uj:24840 , Citation: Sobiyi, K.K. 2017. The influence of scanning speed on laser metal deposition of Ti/TiC powders.
- Description: Abstract: This paper describes the experimental work performed on laser metal deposition (LMD) of titanium carbide powders on pure titanium substrate. The understanding the effect of LMD processing parameters is vital in controlling the properties of the final product fabricated from the LMD process. The objective of the study is to characterize the influence of laser scanning speed of metal deposition of titanium and titanium carbide powders on pure titanium substrate. Microstructural characterization results showed that the substrate is characterized by two-phase morphology; alpha and beta phase. Deposit zone microstructures showed that the grains are of continuous columnar in nature. Heat affected zone region grain areas appear to decrease with increasing in scanning speed for different samples at different scanning speeds. The height of samples at different scanning was observed to decrease with increase in scanning speed. Microhardness results showed that the hardness of the deposits is greater than the hardness of the substrate. Wear resistance performance results showed that the coefficient of friction of substrate is greater than the coefficient of friction of the deposit samples. Wear volume loss of material of the substrate is higher than the deposits. The deposit contains titanium carbide and, as such, this powder has improved the wear resistance performance of the substrate.
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Microstructural and mechanical evaluation of laser-assisted cold sprayed bio-ceramic coatings : potential use for biomedical applications
- Authors: Tlotleng, Monnamme , Akinlabi, Esther Titilayo , Shukla, Mukul , Pityana, Sisa
- Date: 2014
- Subjects: Titanium , Laser power , Cold spray , Laser-assisted cold spray , Hydroxyapatite
- Type: Article
- Identifier: uj:5135 , ISSN 1544-1016 , http://hdl.handle.net/10210/14101
- Description: Bio-composite coatings of 20 wt.%, HAP and 80 wt.%, HAP were synthesized on Ti-6Al-4V substrates using LACS technique. The coatings were produced with a laser power of 2.5 kW, powder-laser spot trailing by 5 s. The coatings were analyzed for the microstructures, microhardness, composition, and bio-corrosion using SEM-EDS, XRD, hardness tester, and Metrohm PGSTAT101 machine. SEM images indicated least pores and crack-free coating with dark-spots of Ti-HAP for the 20 wt.%, HAP as opposed to the 80 wt.%, HAP coating which was solid, porous and finely cracked and had semi-melted Ti-HAP particles. The EDS mappings showed high content of HAP for the 80 wt.%, HAP coating. The diffraction patterns were similar, even though the Ti-HAP peak was broader in the 80 wt.%, HAP coating and the HAP intensities were lower for this coating except for the (004) peak. The hardness values taken at the interface inferred that the 80 wt.%, HAP coating was least bonded. It was possible to conclude that when this phase material increased the hardness dropped considerably. The bio-corrosion tests indicated that the presence of HAP in coating leads to a kinetically active coating as opposed to pure titanium coating.
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