Date of Award

2017

Degree Type

Thesis

Degree Name

Doctor of Philosophy

School

School of Engineering

First Advisor

Associate Professor Lai-Chang Zhang

Second Advisor

Professor Yu-Lin Hao

Abstract

Tissue engineering through the application of a low modulus, high strength format as a potential approach for increasing the durability of bone implants has been attracting significant attention. Titanium alloys are widely used for biomedical applications because of their low modulus, high biocompatibility, specific strength and corrosion resistance. These reasons affirm why titanium alloy is selected as the specific material to research. The development of low modulus biomaterials is considered to be an effective method to remove the mismatch between biomaterial implants and surrounding bone tissue, thereby reducing the risk of bone resorption. So far, Ti–24Nb–4Zr–8Sn alloy (abbreviated hereafter as Ti2448) is considered to be a biomedical titanium alloy with low modulus, and was invented for biomaterial application. However, the modulus of Ti2448 (42-50 GPa) is still higher than that of bone (1-30 GPa). A scaffold is an ideal structure for bone implants; such a structure can further reduce the modulus of an implant. This structure also has the desired effect of promoting bone in-growth. Additive manufacturing could prepare porous titanium parts with mechanical properties close to those of bone tissue. However, the properties of scaffolds are affected by manufacturing strategies and parameters such as the scanning speed, the input power, the layer thickness, the scanning strategy, the temperature of the platform and the hatch distance. Each of these parameters can affect a scaffold’s properties and performance in terms of density, hardness, super-elastic property, compressive and fatigue properties. For the Ti2448 alloy, all of these manufacturing parameters are still not clear enough to develop the perfect porous structure. This study will examine the performance of biomaterial Ti2448 scaffolds by tuning the main parameters of additive manufacturing (AM) systems through an analysis of the microstructure and the mechanical properties of the produced components.

Access Note

Access to Chapters 3, 4, 5 and 6 of this thesis is not available. The chapters have been published and are listed as Related Publications.

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