Publication: State reaction to produce hydroxyapatite and study on effect of silicate towards the sintering behavior of hydroxyapatite
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Date
2009-05-01
Authors
Tan, Yew Leong
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Abstract
The solid-state reaction of Ca(OH)2 and (NH4)2HPO4 powders to produce hydroxyapatite were studied. These additives were mixed into the hydroxyapatite (HAP) powder and the prepared powder was pressed into pellets for further calcination and sintering. The sintered samples were characterized by FESEM and EDX. The micrograph of FESEM shows there were uncontrollable grain growth of different sizes. On the other hand, the study on effect of silicate towards sintering behavior of hydroxyapatite was done by using additives of Na2SiO3 and CaCO3. The additives acted as binders and mixed into the HAP powder before they were sintered at various temperatures of 850 oC, 950 oC, 1000 oC and 1100 oC respectively. All samples were characterized with FESEM and EDX. Additional FTIR and XRD testing were also used to analyze the functional groups and also the thermal stability of the samples. The FESEM results show 3D network porous structure with increasing particles coarsening as the sintering temperature increases. This structure inhibits the grain growth of HAP and the possible cause for this is the formation of silicocarnotite, Ca5(PO4)2SiO4 within the HAP phase. XRD result further proves the formation of this phase.