Tratamiento térmico a velocidad controlada como nuevo método pare la preparación de hidroxiapatita sintética .

Abstract

The control of the pore morphology in the hydroxyapatite synthetic ce­ ramics has limited_their application inside the field ofthe bone implant materials, but even when it is used as a filler in cements and other formulations used in the orthope­dic surgery. In this paper, the authors show results that demonstrate the effectiveness of a variant from the novel technique of controlled rate thermal analysis, developed for the preparation of ceramic materials with controlled textural characteristic, in the for­mation of ceramic powders of synthetic hydroxyapatite at lowtemperatures. The ther­mal treatments of the hydroxyapatite were carried out in a device that is connected to a computer with software able to control the system temperature and pressure, main­taining the speed of constant decomposition. The results when preparing ceramic powders of hydroxyapatite to 300 and 365 "C at low controlled pressure, starting from calcium deficient synthetic hydroxyapatite with a molar relationship Ca/P equal to 1.64 are reported; it was ·checked by IR spectroscopy and X-Ray Diffraction, being observed in fuese analyses that the formed phase corresponds to the pure hydroxyapa­tite, even at 300 ºC ofmaximum temperature ofthe experiment. When analyzing the adsorption isotherms of nitrogen for BET, values of specific surface were obtained between 25 and 35 m2/g, with pares size at the range of 5-30 nm in both cases. It was demonstrated that with the use of the control rate thermal treatment technique, the temperature is not the decisive parameter for the formation of the apatitic pure phase.