caa a22 4500 47578233X CHVBK 20180406123648.0 cr unu---uuuuu 170329e20000601xx s 000 0 eng 10.1023/A:1008934024440 doi (NATIONALLICENCE)springer-10.1023/A:1008934024440 α-Tricalcium phosphate hydrolysis to hydroxyapatite at and near physiological temperature [Elektronische Daten] [C. Durucan, P. Brown] The kinetics of hydroxyapatite (HAp) formation by direct hydrolysis of α-tricalcium phosphate (α-TCP) [α-Ca3(PO4)2] have been investigated. Transformation kinetics were examined for reactions at 37 °C, 45 °C and 56 °C by isothermal calorimetric analysis. Setting times and morphologies of the resultant HAp were found to be strongly dependent on reaction temperature. XRD analysis accompanied by FTIR confirmed that phase pure calcium-deficient hydroxyapatite (CDHAp) [Ca10-x(HPO4)x(PO4)6-x(OH)2-x] was formed. Complete reaction occurs within 18, 11, 6.5 h at 37, 45 and 56 °C, respectively. The extent of HAp formation differs for particulate slurries and pre-shaped forms of reactant α-TCP. Formation of hydroxyapatite in pre-formed pellets was hindered due to limited water penetration, but enhanced with the presence of NaCl as a pore generator. Regardless of the precursor characteristics and temperature, HAp formation is characterized by an initial period of wetting of the α-TCP precursor, an induction period and a growth period during which the bulk transformation to HAp occurs. The microstructures of the resultant HAp at all temperatures were generally similar and are characterized by the formation porous flake-like morphology. Microstructural coarsening was observed for the CDHAp formed above the physiological temperature. The hardening generated by the hydrolysis reaction was demonstrated using diametrical compression tests. The original tensile strength of 56% dense α-TCP increased from 0.70±0.1 MPa to 9.36±0.4 MPa after hydrolysis to CDHAp at 37 °C, corresponding to a density of 70%. ©2000 Kluwer Academic Publishers Kluwer Academic Publishers, 2000 Durucan C. Materials Research Laboratory, The Pennsylvania State University, 16802, University Park, PA, USA aut Brown P. Materials Research Laboratory, The Pennsylvania State University, 16802, University Park, PA, USA aut Journal of Materials Science: Materials in Medicine Kluwer Academic Publishers 11/6(2000-06-01), 365-371 0957-4530 11:6<365 2000 11 10856 https://doi.org/10.1023/A:1008934024440 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1008934024440 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Durucan C. Materials Research Laboratory, The Pennsylvania State University, 16802, University Park, PA, USA aut NATIONALLICENCE 700 1- Brown P. Materials Research Laboratory, The Pennsylvania State University, 16802, University Park, PA, USA aut NATIONALLICENCE 773 0- Journal of Materials Science: Materials in Medicine Kluwer Academic Publishers 11/6(2000-06-01), 365-371 0957-4530 11:6<365 2000 11 10856 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer