Selective Laser Melting of Novel Titanium-Tantalum Alloy as Orthopaedic Biomaterial

110 Pages·2019·5.68 MB·English

by  Swee Leong Sing

Springer Theses
Recognizing Outstanding Ph.D. Research
Swee Leong Sing

Selective Laser
Melting of Novel
Titanium-Tantalum
Alloy as Orthopaedic
Biomaterial
Springer Theses
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Swee Leong Sing
Selective Laser Melting
of Novel Titanium-Tantalum
Alloy as Orthopaedic
Biomaterial
Doctoral Thesis accepted by
the Nanyang Technological University,
Singapore
123
Author Supervisors
Dr. Swee Leong Sing Dr. Wai Yee Yeong
Singapore Centrefor 3DPrinting, Singapore Centrefor 3DPrinting,
Schoolof Mechanicaland Schoolof Mechanicaland
Aerospace Engineering Aerospace Engineering
NanyangTechnological University NanyangTechnological University
Singapore Singapore
Dr. FlorenciaEdith Wiria
Singapore Institute of Manufacturing
Technology
Agency for Science, Technology
andResearch(A*STAR)
Singapore
ISSN 2190-5053 ISSN 2190-5061 (electronic)
SpringerTheses
ISBN978-981-13-2723-0 ISBN978-981-13-2724-7 (eBook)
https://doi.org/10.1007/978-981-13-2724-7
LibraryofCongressControlNumber:2018955911
©SpringerNatureSingaporePteLtd.2019
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’
Supervisors Foreword
We are very pleased that Springer is publishing Swee Leong’s dissertation titled
Selective Laser Melting of Novel Titanium-Tantalum Alloy as Orthopaedic
Biomaterial. It is an honour that this research work is recognised as impactful and
outstanding in the global arena. Selective laser melting (SLM) is a powder bed
fusion additive manufacturing (AM) technique that is capable offabricating com-
plexfunctionalthree-dimensional(3D)metalpartsofhighrelativedensitywiththe
complete melting and fusion of powders. There are many research works reported
on SLM. The key unique novelty of this work is that Swee Leong successfully
identifiedanewresearchdimensioninAMandutilisedSLMasanultra-precise3D
toolinmaterialformulationandformation.SLMhasthepotentialinexpandingthe
materials library by in situ formation of alloys that were previously difficult to
achievebyusingmetalpowdermixtures.Thisnewcapabilityaddsanewdimension
to the advantages of enabling customisation according to the application require-
ments.Thisdissertationusedtitanium-tantalumasaproofofconceptforthisinsitu
alloying method.
Titanium-tantalum(TiTa)isapotentialmaterialforbiomedicalapplicationsdue
toitshighstrength-to-modulusratio.However,itisstillnotwidelyusedduetothe
difficulties in obtaining this alloy. Due to its versatility in processing metallic
materials and good results obtained from commercially pure titanium (cpTi) and
Ti6Al4V, Swee Leong has chosen SLM as the process to tackle this problem. His
research developed TiTa as a potential material for biomedical applications and
paved the way for better understanding and control of the SLM process in porous
lattice structure fabrication through statistical modelling.
From the 3D printing process perspective, Swee Leong studied TiTa formation
tounderstandtheformingmechanismandtheeffectofSLMprocessingparameters
on the resulting density and macrostructure of the parts. The processing window
and optimised parameters based on optimum relative density achieved are then
presented.
In addition, Swee Leong examined theresulting microstructure of TiTa parts to
gain extensive knowledge behind the material formation by SLM. The SLM TiTa
parts exhibited a microstructure characterised by homogenous b titanium and
v
vi Supervisors’Foreword
tantalum matrix with randomly distributed tantalum particles.It isfound that SLM
TiTa parts have lower Young’s modulus and comparable strength to Ti6Al4V and
cpTi.
It is tedious and time-consuming to gather data solely from physical experi-
ments,especiallyinthedynamicfieldofAM.Onewaytocircumventthatchallenge
is by utilising data analysis. In this thesis, Swee Leong statistically modelled the
effectofSLMprocessingparametersonlatticestructurepropertiesusingregression
analysisandanalysisofvariance(ANOVA).Itisshownthatlaserpowerandlayer
thicknessaredominantfactorsinaffectingthepropertiesofthelatticestructuresthat
could correlate to better cellular attachment.
These favourable findings ascertained the feasibility of SLM TiTa as a 3D tool
that can build a new biomaterial at the microstructure level, and contributed to the
scientific knowledge of a novel in situ alloying process. The unique experimental
methodsandresults,withthesystematicanalysisinthisthesis,providedavaluable
referenceforresearchersinthefieldofAMand3Dprintingofmetallicbiomedical
devices.
Wehaveembarkedonthisjourney4yearsagowhenSweeLeongisanaspiring
research student learning and eager to contribute to the scientific world. We are
extremelyproudthatSweeLeongisnowreadytobeanimpactfulcontributortothe
scientific community and this thesis is the perfect gift to mark that milestone.
Singapore Dr. Wai Yee Yeong
September 2018 Associate Professor
Dr. Florencia Edith Wiria
Research Scientist
Parts of this thesis have been published in the following journal articles:
1. S. L. Sing, F. E. Wiria & W. Y. Yeong (2018), Selective laser melting of
titanium alloy with 50wt% tantalum: Effect of laser process parameters on
parquality, International Journal of Refractory Metals and Hard Materials 77,
pp 120–127
2. S.L.Sing,F.E.Wiria&W.Y.Yeong(2018),Selectivelasermeltingoflattice
structures: A statistical approach to manufacturability and mechanical behav-
ior, Robotics and Computer Integrated Manufacturing 49, pp 170–180
3. S.L.Sing,Y.Miao,F.E.Wiria&W.Y.Yeong(2016),Manufacturabilityand
mechanical testing considerations of metallic scaffolds fabricated using selec-
tive laser melting: A review, Biomedical Science and Engineering 1(1),
pp 18–24
4. S. L. Sing, W. Y. Yeong & F. E. Wiria (2016), Selective laser melting of
titanium alloy with 50 wt% tantalum: microstructure and mechanical proper-
ties, Journal of Alloys and Compounds 660, pp 461–470
5. S.L.Sing,J.An,W.Y.Yeong&F.E.Wiria(2016),Laserandelectron-beam
powder-bedadditivemanufacturingofmetallicimplants:areviewonprocesses,
materials and designs, Journal of Orthopaedic Research 34(3), pp 369–385
vii
Acknowledgements
First and foremost, I would like to express heartfelt gratitude and appreciation for
mysupervisors,AssistantProfessorWaiYeeYeongandDr.FlorenciaEdithWiria
for their invaluable advice and patience throughout my candidature. Their dedi-
cationtotheresearchhasbeenaconstantsourceofinspirationforme.Appreciation
isalsoextendedtoAssociateProfessorSiawMengChouandDr.BeeYenTayfor
being members of my Thesis Advisory Committee.
I would like to thank Professor Chee Kai Chua, Associate Professor Kah Fai
Leong and Dr. Jun Wei for the opportunity in pursuing my research in Singapore
Centre for 3D Printing (SC3DP) and SIMTech-NTU Joint Lab (3D Additive
Manufacturing). I would also like to acknowledge the research funding received
from these institutions.
I am grateful for the companionship from fellow researchers in SC3DP who
have begun this enriching journey with me, Dr. Alexander Zhonghong Liu, Dr.
Danqing Zhang, Dr. Denise Loong Ee Loh and Dr. Chor Yen Yap. Their cama-
raderie and support during this study have been delightful. I would also like to
express thanks to the other researchers who have helped me along the way.
Thisreportwouldnothavebeenpossiblewithouttheassistanceofthelaboratory
specialists from School of Mechanical and Aerospace Engineering, Nanyang
Technological University and Singapore Institute of Manufacturing Technology.
Lastly,butcertainlynottheleast,Iwouldliketothankmyfamilyandfriendsfor
their constant encouragement and understanding.
ix
Contents
1 Introduction to Additive Manufacturing for Orthopaedic
Implants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Motivations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.4 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.5 Organisation of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Concepts of Selective Laser Melting for Orthopaedic Implants . . . . 9
2.1 Orthopaedic Implants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 Selective Laser Melting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 Materials for Selective Laser Melting of Metallic Implants
and Scaffolds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3.1 316L Stainless Steel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3.2 Cobalt Chromium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.3.3 Titanium-6Aluminium-4Vanadium . . . . . . . . . . . . . . . . . . 17
2.3.4 New Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.4 Design Consideration for Metallic Implants and Scaffolds
Using Selective Laser Melting. . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.4.1 Manufacturability of Metallic Scaffolds Using Selective
Laser Melting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.4.2 BiologicalCompatibilityofMetallicScaffoldsFabricated
Using Selective Laser Melting . . . . . . . . . . . . . . . . . . . . . 22
2.4.3 Mechanical Properties of Metallic Scaffolds Fabricated
Using Selective Laser Melting . . . . . . . . . . . . . . . . . . . . . 26
2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
xi