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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Experimental and numerical analysis of geometrical properties of laser metal deposited titanium
- Authors: Akinlabi, Esther Titilayo , Tayob, Mohammed A. , Pietra, Francesco
- Date: 2016
- Subjects: Ansys , Heat-Affected zone , Laser metal deposition , Microhardness , Microstructure , Porosity , Powder flow rate , Titanium
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/93300 , uj:20330 , Citation: Akinlabi, E.T., Tayob, M.A. & Pietra, F. 2016. Experimental and numerical analysis of geometrical properties of laser metal deposited titanium.
- Description: Abstract: Laser metal deposition (LMD) is a manufacturing process, which can be used to manufacture a complete, fully functional part by building it up layer-by-layer using the data from a Computer-Aided-Design (CAD) file. The layer-by-layer addition can also be used to rebuild worn-out sections of existing parts, as well as to deposit protective coatings to protect parts in surface engineering. The process involves laser heating a substrate, on which a metal powder is deposited. The powder solidifies, when mixed with the substrate, thereby creating a metallurgical bond. In order to produce parts with high geometrical tolerances and desirable material properties, the process parameters have to be carefully controlled. Since the LMD process requires the interaction of parameters, it is not always easy to predict the output geometry. In this paper, the laser metal deposition process was modelled in ANSYS Parametric- Design-Language (APDL), using a transient thermal analysis, in order to determine the geometrical properties of the clad, that is, the width and the height of the resulting clad. The simulated results were then compared experimentally by depositing Commercially Pure (CP) titanium powder onto a Ti-6Al-4V substrate, in order to verify the simulation. The varying parameter in the experimental process was the powder flow rate, which was varied between 0.5-2.5g/min. In addition to the geometrical properties, the microstructure, microhardness; and the porosity levels of the deposited clads were also analyzed, in order to better determine the clad quality and integrity. The model showed good agreement in predicting both the height and the width of the clads. Porosity was noticed in all the samples with the exception of the clad deposited at the lowest powder flow rate setting of 0.5 g/min. An increase in the powder flow rate also led to a smaller fusion zone, due to a lower laser-material interaction period, which was the result of the increase in the quantity of powder causing attenuation of the beam, and less laser power being absorbed by the substrate. The smaller fusion zone meant that the clads could not bond to the substrate properly, which led to the clad in the sample produced with the highest powder flow rate falling off the substrate. There was a significant increase in the microhardness of the clad zone, which was due to a combination of alloying with Ti- 6Al-4V and a change in the microstructure to an acicular alpha martensite microstructure; while the Heat-Affected-Zone (HAZ) in the substrate only showed a slight increase in microhardness.
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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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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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