TY - JOUR
T1 - Phase transformation on hydroxyapatite decomposition
AU - Ou, Shih Fu
AU - Chiou, Shi Yung
AU - Ou, Keng Liang
N1 - Funding Information:
The authors would like to thank the Center of Excellence for Clinical Trial and Research in Neurology and Neurosurgery, Taipei Medical University-Wan Fang Hospital , for financially supporting this research under contract No. DOH 101-TD-B-111-003 .
PY - 2013/5
Y1 - 2013/5
N2 - The collapse of sintered hydroxyapatite (HA) has been attributed to HA decomposition; however, the detailed variations in microstructure are still unclear. Two phase transformation routes of HA decomposition during sintering were identified by transmission electron microscopy in this study. In the first route, HA is transformed to tetracalcium phosphate and needle-like β-tricalcium phosphate which is subsequently converted to α-tricalcium phosphate (α-TCP) above 1100 °C. In the second route, HA is transformed directly to α-TCP and calcium oxide at 1400 °C, accompanied by nanopore formation. In the second route, the α-TCP grew with a preferred orientation to form stripe-like grains. Further holding at 1400 °C for 4 h resulted in recrystallization; i.e., equi-axial grains formed within a stripe-like grain. Nanopore defects dispersed in the α-TCP grains are the main factor for the low density and decreased mechanical strength of the sintered bulk.
AB - The collapse of sintered hydroxyapatite (HA) has been attributed to HA decomposition; however, the detailed variations in microstructure are still unclear. Two phase transformation routes of HA decomposition during sintering were identified by transmission electron microscopy in this study. In the first route, HA is transformed to tetracalcium phosphate and needle-like β-tricalcium phosphate which is subsequently converted to α-tricalcium phosphate (α-TCP) above 1100 °C. In the second route, HA is transformed directly to α-TCP and calcium oxide at 1400 °C, accompanied by nanopore formation. In the second route, the α-TCP grew with a preferred orientation to form stripe-like grains. Further holding at 1400 °C for 4 h resulted in recrystallization; i.e., equi-axial grains formed within a stripe-like grain. Nanopore defects dispersed in the α-TCP grains are the main factor for the low density and decreased mechanical strength of the sintered bulk.
KW - B. Electron microscopy
KW - C. Diffusion
KW - D. Apatite
KW - E. Biomedical applications
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U2 - 10.1016/j.ceramint.2012.10.221
DO - 10.1016/j.ceramint.2012.10.221
M3 - Article
AN - SCOPUS:84874654354
SN - 0272-8842
VL - 39
SP - 3809
EP - 3816
JO - Ceramics International
JF - Ceramics International
IS - 4
ER -