Synthesis of -tcp powder via nwet precipitation and hydrothermal methods

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Date
2007
Authors
Trung Kien, Pham
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Abstract
The purpose of this study is to synthesize β-TCP [β-Ca3(PO4)2] using Ca(OH)2 and H3PO4 as the starting material. Two approaches were used in this work to produce β-TCP, namely a precipitation method and a hydrothermal method. This research work reveals that the effect of stirring speed plays significant role than that of stirring duration. The optimum conditions to produced a single-phase β-TCP are: (1) stirring speed of 200 rpm; (2) stirring duration of 2 hours; (3) calcination temperature of 900oC for 1 hour soaking time. Since β-TCP cannot be directly precipitated from aqueous solution, it was found that the most optimum precursor phase(s) in the as-prepared powder to produce β-TCP after calcination is a mixture phase of monetite [CaHPO4] and hydroxyapatite [Ca10(PO4)6(OH)2]. Based on the precipitation study, a hydrothermal method was used to synthesize β-TCP using Ca(OH)2 and H3PO4 as the starting materials in a highpressure reactor. XRD study shows that the as-prepared powder is a mixture phase of brushite [CaHPO4.2H2O] and HA instead of monetite and HA as found in the precipitation method. The powder was then calcined at 900oC for 1 hour and it was found that a single-phase β-TCP was also successfully produced. The density of β-TCP obtained by the precipitation method is around 3.1g/cm3 (almost similar to a commercial β-TCP (ρ=3.17g/cm3)) whilst the hydrothermal method produced powders of higher density (density around 3.7 g/cm3). This is attributed to the packing and sintering of the powder into uniformly-sized grains during synthesis. In addition, the β-TCP powders synthesized using both methods satisfy the requirements of the Standard for surgical implant, via ASTM F1088-04a with a very low level of toxic elements.
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Master
Keywords
Materials and Mineral Resources Engineering , TCP powder
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