The effect of magnesium oxide to the properties of hydroxyapatite
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Date
2016-06
Authors
Nur Adriana Nazifa Abu Bakar
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Abstract
Dense hydroxyapatite (HA) biomaterials are suitable for load bearing applications. The densification of HA can be obtained by combination of magnesium oxide (MgO) as sintering additive with sintering process. The aim of this study is to fabricate a dense HA/MgO by varying the MgO composition (0.00wt%MgO , 0.25wt%MgO, 0.50wt%MgO and 1.00wt%MgO) and sintering temperature (1050⁰C, 1100⁰C, 1150⁰C, and 1200⁰C) using design of experiments (DOE) and 4k general factorial design approach to evaluate the characterized results and create a prediction model. HA and MgO powders are mixed with ethanol by using agate mortar, dried in oven (80⁰C, 24 hours) and uniaxially pressed into pellets (diameter: 16mm) followed by sintering. Samples are characterized by visual observation, shrinkage, bulk density, apparent porosity, Vickers hardness, microstructure images via Scanning Electron Microscope (SEM), and phase analysis using X-ray Diffraction (XRD) then followed by modelling the data (shrinkage, bulk density, apparent porosity and Vickers hardness) by using 4k general factorial design. From the experiment, the optimum properties of HA/MgO obtained at 1200ºC with 0.25wt%MgO, then, it will contribute to high bulk density (3.14 g/cm3) that influences the high hardness (442.6HV) and lowest apparent porosity (2.56%). The modelling shows that sintering temperature has given a significant effect on the response. While, the composition of MgO has insignificant effect due to the new phase form (α-TCP, β-TCP and whitlockite magnesian) after sintering process.