Caracterização química e morfológica dos fosfatos de cálcio - CPP, HAp e TeCP.

Abstract

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.