Chin, Christopher Kong Ming (2015) Solid state synthesis of forsterite and its mechanical properties / Christopher Chin Kong Ming. PhD thesis, University of Malaya.
Abstract
Forsterite (Mg2SiO4) has the potential for biomedical application. There were various synthesis methods developed over the years to produce nanocrystalline forsterite by conventional pressureless sintering. However, a systematic study on the factors controlling the properties of forsterite during powder processing and sintering has not been established. Hence, the aim of this research is to develop a well-defined phase pure forsterite ceramic employing conventional presureless sintering and to determine the optimum conditions to produce a sintered body with improved mechanical properties. In this study, 3 hours ball milling without heat treatment was determined as the optimum powder preparation method. There were 3 different holding time which were 2 hours (Group 1), 1 hour (Group 2) and 1 minute (Group 3) employed for the conventional pressureless sintering. The studies revealed that the combination of ultrasonic bath, 3 hours ball milling and abstinence of heat treatment proved to be the optimum and energy efficient method because no secondary phase was detected in Group 1 and Group 2 for all temperature range studied (1200°C, 1300°C, 1400°C, 1500°C). The highest Vickers hardness and fracture toughness were recorded in Group 2 at 1500°C with 5.01 GPa and 3.75 MPam1/2 respectively. Young’s modulus of 90.46 GPa was the highest recorded value for Group 2 at 1400°C. Therefore, Group 2 at 1400°C and 1500°C were the optimal holding time that showed improved mechanical properties even though Group 2 showed more porosity than Group 1 as reflected in the sintered microstructure. The use of higher sintering temperature in Group 1 was the probable cause resulted in lower fracture toughness properties. No sign of liquid phase sintering observed from the quenching experiment.
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