Influence of temperature and additives on the microstructure and sintering behavior of hydroxyapatites with different Ca/P ratio.

M.A. FANOVICH, J.M. PORTO LÓPEZ

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE

Springer Netherlands

Año: 1998 p. 53 - 60

0957-4530

Abstract  Sintering of two hydroxyapatite (HA) samples with different Ca/P ratios was studied as a function of thermal pretreatments, sintering temperature and additives (0–0.6 ion % Li+ or 0–5 ion % Mg2+). The samples were sintered in air and characterized by density measurements, scanning electron microscopy, differential thermal analysis, X-ray diffraction and dilatometry. Upon sintering, samples with Ca/P ratio of 1.51 (HA C) transformed to -Ca3(PO4)2 and Ca10(PO4)6(OH)2, resulting in materials with low densities and containing agglomerated -Ca3(PO4)2 when sintered above 1200°C. Samples with a Ca/P ratio of 1.77 (HA S), without -Ca3(PO4)2, showed better sinterability and homogeneous microstructures. Li+ additions favoured liquied-phase sintering and reduced the -Ca3(PO4)2 content in sintered materials. Mg2+ additions did not result in higher densities, but inhibited the hydroxyapatite grain growth rate. A significant percentage of the added Mg2+ was incorporated into the -Ca3(PO4)2 structure.