Thermal stability of hydroxyapatite whiskers derived from the hydrolysis of α-TCP

Figure 2 SEM micrographs of sample: (a) A, (b) B, (c) C and (d) D. Whisker shaped hydroxyapatite (Ca10(PO4)6(OH)2, HAp) is a promising candidate material for reinforcing ceramic or polymer matrices to be used in the biomedical and dental fields [1]. Various techniques for preparation of whiskerlike or fibrous HAp have been reported [2–6]. Among these, the hydrolysis of α-Ca3(PO4)2 (α-TCP) under controlled processing conditions (aqueous pH, temperature and time) is often adopted to generate a whisher shaped form of HAp [2, 3]. Several authors [7–10] have reported on the thermal stability of synthetic HAp but the results are not generally coincident. It is suggested that the reason for this that the thermal decomposition of HAp is inherently dependent on the crystallinity, stoichiometry and atmosphere conditions prevailing during the reactions