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Bioceramic hydroxyapatite coating fabricated on TI-6AL-4V using Nd:YAG laser

  • Authors: Tlotleng, M. , Akinlabi, Esther Titilayo , Shukla, M. , Pityana, S. , Mathebula, T. , Chauke, L.
  • Date: 2014
  • Subjects: Bioceramic hydroxyapatite coating , Nd:YAG laser
  • Type: Article
  • Identifier: uj:5015 , ISSN 978-0-7972-1532-0 , http://hdl.handle.net/10210/13155
  • Description: A method of synthesising a biocompatible HAP coating is presented. In the current study, Nd:YAG laser was used to directly melt pre-place HAP powder beds on Ti-6Al-4V. The processing parameters used were 750 W laser power, 5 mm/s scanning speed and 27° inclined beam plane. The coating was studied under white light and scanning electron microscope where it was possible to characterise the microstructures. The produced coating was characterised of mixed morphologies of HAP, short and elongated titanium needles at the surface while in the middle of the coating dendrite trunks without arms were observed. This observation is related to the heat inputs, dilution and melting of the substrate and powder during processing. The absence of the arms growing from the trunks indicated low heat inputs. In addition, the microstructure of the HAP after soaking in Hanks’ solution indicated octagonal and hexagonal crystals of HAP. The hardness values indicated good metallurgical bonding at the interface. In conclusion, this study was successful in fabricating a desirable coating of HAP on Ti-6Al-4V for biomedical applications. This work highlights that even though laser power and scanning speed are predominantly influential parameter settings, it is also necessary to consider the angle at which the laser beam is scanned across the material.
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Characterising the effect of laser metal deposited Ti6Al4V/Cu composites in simulated body fluid for biomedical application

  • Authors: Erinosho, M. F. , Akinlabi, Esther Titilayo , Pityana, S.
  • Date: 2015-01-15
  • Subjects: Hank’s solution , Laser metal deposition , Surface morphologies , Titanium alloys
  • Type: Article
  • Identifier: uj:5120 , ISBN 9789384935108 , http://hdl.handle.net/10210/14078
  • Description: Ti6Al4V alloy has been known to have very excellent corrosion resistance due to the oxide layer formed on its surface. Due to this property, the alloy is found applicable for biomedical implants. Copper shows an excellent antimicrobial property and has been found to stabilize the immune system. In this study, laser metal deposition of Ti6Al4V powder and Cu powder on Ti6Al4V substrates were conducted by varying the laser power between 600 W and 1800 W while the scanning speed, the powder flow rate and the gas flow rate were kept constant. The surface behaviour and the morphologies of the composites were evaluated under the microscope and the SEM after soaking for 4 hours, 5 days and 2 weeks respectively. The simulated body fluid (hank’s solution) was maintained at normal body temperature of about 37±1oC. The surfaces showed fracture topography with porous bone-like structures and some trivial pitting were observed.
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Characterization of laser deposited Ti6Al4V/TiC composite powders on a Ti6Al4V substrate

  • Authors: Mahamood, R. M. , Akinlabi, Esther Titilayo , Shukla, M. , Pityana, S.
  • Date: 2014
  • Subjects: Laser metal deposition , Material characterization
  • Type: Article
  • Identifier: uj:4986 , http://hdl.handle.net/10210/13118
  • Description: This paper reports the material characterization of Ti6Al4V/TiC composite produced by laser metal deposition. The Ti6Al4V/TiC composites were deposited with a composition ratio of 50 wt.% Ti64l4V and 50 wt.% TiC. The depositions were achieved by delivering the two powders from a powder feeder consisting of two different hoppers and each hopper contains each of the powders. A total of eight experiments were performed, the scanning speed was kept constant at 0.005 m/s and the laser power varied between 0.4 and 3.2 kW. The gas flow rate and the powder flow rates were also kept at constant settings of 1.44 g/min and 1 l/min respectively for each hopper. The deposits were laterally sectioned, metallographically prepared and characterized through microstructural evaluation, microhardness and wear resistance performance. The effects of varying the laser power on the resulting properties of the composites were studied extensively. The microstructure consists of un-melted carbide (UMC) in the matrix of alpha and prior beta grain structure of Ti6Al4V, and in varying degrees in all the samples. The results showed that the microhardness and the wear resistance performance were dependent on the laser power.
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Characterization of laser metal deposited 316L stainless steel

  • Authors: Bayode, A. , Akinlabi, Esther Titilayo , Pityana, S.
  • Date: 2016
  • Subjects: Laser metal deposition , Microhardnes , Stainless steel
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/92382 , uj:20223 , Citation: Bayode, A., Akinlabi, E.T. & Pityana, S. 2016. Characterization of laser metal deposited 316L stainless steel.
  • Description: Abstract: Laser metal deposition (LMD) is an innovative manufacturing technique that uses laser to melt powders to fabricate fully dense components layer by layer. It is capable of processing different metallic powders and can also be used for consolidating different powder to produce custom alloys or functionally graded materials (FGM). The properties of laser processed materials is dependent on the final microstructure of the parts which in turn is dependent on the LMD processing parameters. This study investigates the effects of laser power on the structural integrity, microstructure and microhardness of laser deposited 316L stainless steel. The result showed that the laser power has much influence on the evolving microstructure and microhardness of the components. The average microhardness of the samples were observed to decrease as the laser power increased due to grain coarsening.
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Influence of laser power on microstructure of laser metal deposited 17-4 ph stainless steel

Microstructure and microhardness of 17-4 ph stainless steel made by laser metal deposition

Revolutionary additive manufacturing : an overview

  • Authors: Mahamood, R. M. , Akinlabi, Esther Titilayo , Shukla, M. , Pityana, S.
  • Date: 2014
  • Subjects: Adaptive control , Additive manufacturing
  • Type: Article
  • Identifier: uj:4993 , http://hdl.handle.net/10210/13128
  • Description: Consumer demands are moving away from standardized to customized products, as such, the evolution of alternative manufacturing techniques has become imperative. Additive manufacturing (AM) is a process of building components layer by layer as against the traditional methods which are subtractive in nature. Though AM offers lots of advantages over traditional manufacturing techniques, its wide application is still however in the infancy phase. Despite all the benefits derived from AM technology, there are still a lot of unresolved issues with the technology that has hindered its performance thereby limiting its application to high tolerant jobs. This paper takes a look at some important AM technologies, some problems currently facing AM technology at large and proposes some solutions to these problems. A major known drawback in AM is poor dimensional accuracy and poor surface finish, only the layer height and melt pool temperature are controlled to solve this problem in the literature. The stair-stepping effect in adaptive manufacturing is rooted in a natural phenomenon of surface tension which is the cause of the poor surface finish and in combination with other factors is responsible for the poor dimensional accuracy. An adaptive controller is proposed for removing stair-stepping effect to improve the dimension accuracy, the surface finish and the mechanical properties of the components. Successful implementation of these proposed controllers will greatly improve the performance of AM technologies and also aid its wide application for end use products. Further research work is also suggested to improve the overall AM performance.
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