OLIVEIRA, S. V.; http://lattes.cnpq.br/2988178262762974; OLIVEIRA, Sara Verusca de.
Résumé:
The calcium phosphates bioceramics are made of different compositions
and widely investigated for bone replacement due to the similarity with the
mineral phase of bone tissue. Amid the biological calcium phosphate are found
in bones and teeth of vertebrates beings and hawe respectivelly Ca/P ratio
sanging from 0.5 to 2.0. The proportions of these elements determine the
properties of calcium phosphates and is an Important aspect in determining the
ratio between the ions C a 2 * and PO43" in the process of obtaining calcium
phosphates by chemical reactions, in this research, we observed the influence
of different molar concentration of calcium hydroxide and phosphoric acid
solutions obtaining and training phases of calcium phosphate in relation Ca/P
1.0, 1.67 and 2.0. To obtain these calcium phosphate solutions were prepared
acidic and basic solutions of H3PO4 and CafOHJa, in three different
concentrations, 1 molar, 3 molar and 5 molar. The reactions were performed
using the same concentration of solutions, adding up volumes that respected
the relationship for the calcium and phosphorus, appropriated to the calcium
phosphate that you want to obtain calcium pyrophosphate, relation Ca/P 1.0
(Ca2P207), hydroxyapatite, relation Ca/P 1.67 (CehotPO^OHfe) and
tetracaicium phosphate, relation Ca/P 2.0 {Ca40{PO4)2), respectively. The from
material was obtained in powder form, and heat treatefat of 900 °C for two
hours. The samples were characterized by X-ray diffraction, infrared
spectroscopy of, scanning electron microscopy. The material obtained in
powder form, a part was separated to be characterized without heat treatment,
and the other was subject to heat treatment at 900 0 C for two hours. The
samples were characterized by X-ray diffraction, infrared spectroscopy,
scanning electron microscopy and X-ray microanalysis. The results obtained by
FTIR revealed the incorporation of ions HP04
2 , P04
3-and CO32-, during the
synthesis of calcium phosphates or no conditioning heat treatment except for
samples prepared with Ca/P 1.0 which was not subjected to heat treatment.
The X-ray diffraction showed some combination of phases for samples that
were subjected to heat treatment and others were presented in a single phase
known as hydroxyapatite, which was due to temperature conditioning the
ceramic material. The samples were not subjected to heat treatment also
showed .combinations of phases except the sample prepared with Ca/P from
1.67 to 1 molar. It was found that increasing the molarity of the solutions do not
influence starting to obtain the ceramic powders, that were prepared with Ca/P
1.0 and 2.0, but for those prepared with Ca/P 1.67 increased concentration
induces a new phase resoling in a combination of steps, both for the ceramic
powder that was not the conditioning heat treatment, and for those subjected to
heat treatment. The micrographs were obtained characteristics of ceramic
materials, known as calcium phosphate. The x-ray microanalysis confirmed the
presence of the elements Ca, P and O in all samples studied in this research.