Analysis of Titanium Oxide powders and pellets for optimisation of the mechanical properties of sintered Titanium Oxide
Chew, Bo Shen
Date of Issue2015
School of Mechanical and Aerospace Engineering
Corneal opacity is the second leading cause of impaired vision and blindness in developing countries. Apart from transplantation of human cornea from donors, an alternative medical procedure, the Osteo-odonto Keratoprosthesis (OOKP) was developed to help patients regain their vision by creating an artificial corneal implant. Despite being widely practised, the procedure is prone to failure due to degradation of the artificial cornea, specifically the OOKP skirt which is made from the tooth of the patient (primarily composed of biological hydroxyapatite). Biological hydroxyapatite is susceptible to corrosion and synthetic hydroxyapatite has insufficient mechanical strength. Thus there is a need to develop new bio-inert materials and one potential candidate is titanium dioxide (TiO2). TiO2 commonly exists as a white powder and it requires sintering before being used in the proposed application as the OOKP skirt. In this research, the focus will be on optimising the mechanical properties of TiO2 pellets sintered with the Spark Plasma Sintering (SPS) method. The first objective of the research is to determine the ideal TiO2 powder out of five different powders (Nano TiO2, Inframat, Alfar Aesar, Materion and Amperit). The powders were analysed on their grain size and were sintered into pellets subsequently. Five primary properties of the pellets: elastic modulus, hardness, fracture toughness, density and surface grain size were selected and analysed in this research to determine the pellet with the best properties for use in OOKP development. The mechanical properties of the sintered TiO2 pellets are dependent on three variable sintering parameters which can be varied individually; temperature, hold time and pressure. Thus, the second main objective of this research is to obtain the optimum SPS sintering parameters of TiO2 powder. The Inframat was concluded to be the best powder among the five with the Inframat pellet having the smallest surface grain size, highest density and hardness value. The optimised sintering parameters were found to be 1100℃, five minutes and 50MPa.
Final Year Project (FYP)
Nanyang Technological University