Study on the fabrication of hydroxyapatite-beta- tricalcium phosphate (HA-β-TCP) composite with 4k general factorial design
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Date
2016-06
Authors
Beh Chin Ye
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Abstract
HA/β-TCP composite is reported to have high bioactivity levels but still low in mechanical strength which is not suitable for load bearing applications. Therefore, a dense HA/β-TCP composite is fabricated to improve its mechanical properties by altering the composition and sintering temperature of the composite. The aim of this study is to fabricate a dense HA/β-TCP composite by varying the HA/β-TCP compositions (50, 60, 80, and 100 %HA) and sintering temperatures (1000, 1100, 1150, and 1200 ⁰C) using design of experiments (DOE) and 4k general factorial design approach to evaluate the characterized results and create a prediction model. The powders are mixed with ethanol by using agate mortar, dried in oven (50 ⁰C, 24 hours) and uniaxially pressed into pellets (diameter: 16 mm) followed by sintering. Samples are characterized by visual observation, volumetric shrinkage, density, and porosity. Vickers hardness, microstructure analysis via Scanning Electron Microscope (SEM), and phase analysis using X-ray Diffraction (XRD) then followed by modelling the data (shrinkage, density, porosity, and hardness) by using 4k general factorial design. Samples with 80 %HA/20 %β-TCP sintered at 1200⁰C show highest hardness (340.60 Hv), density (3.039 g/cm3), and lowest porosity (3.64 %). XRD phase analysis show decrease of HA phase at higher sintering temperature due to phase decomposition of HA into β-TCP. Also, both HA/β-TCP composition and sintering temperature are significant factors to shrinkage and hardness whereas only sintering temperature is more significant for density and porosity results. For 4k general factorial design, interactions also occur between the factors and are significant to all the results. Prediction model is valid for the range used in the HA/β-TCP composition and sintering temperature.